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CH.6 NOTES
Beginning of PP #1
Functions and Structures of the LYMPHATIC SYSTEM
LYMPHATIC SYSTEM FUNCTIONS
The lymphatic system consists of a series of vessels and nodes throughout the body, as well as some organs. The lymphatic system is closely related to the immune system.
Lymphat/o refers to the lymphatic system, and –ic means “pertaining to.”
The Lymphatic system has some broad functions
To produce, maintain, and distribute lymphocytes to resist or overcome infections
To absorb fats, fats-substance (A, D,E, K) and distribute them through the body
To distribute hormones and nutriets from the tissues to the blood and remove waste from the tissues
To return filtered lymph fluid to the venous system (veins at the base of the neck)
Lymphocytes and Absorption
Lymphocytes are white blood cells
Lymphocytes are produced and stored in the spleen, thymus, and bone marrow.
Lymph/o means “lymphatic,” and –cytes means “cells.”
Lymphocytes respond to pathogens, abnormal cells (such as virus-infected cells or cancerous cells), foreign proteins (antigens), and use physical and chemical attacks to neutralize them.
Lymphocytes mount a specific response, which is called immunity.
The lymphatic system also plays a role in the absorption of materials. Villi located along the small intestine absorb fats and the fat-soluble vitamins.
Villi are small projections which contain lacteals and blood vessels.
The lacteals absorb the fats that the blood cannot transport, and convert those fats to a usable form.
The blood vessels then absorb all the other nutrients from the small intestine and send them throughout the body.
Interstitial Fluid and Lymph Fluid
Interstitial fluid is also called intercellular or tissue fluid, and is composed of plasma from the blood that migrates to the space between the cells in tissues.
Inter- means “between.”
Interstitial fluid provides tissues with nutrients, oxygen, and hormones, and removes wastes from those tissues.
90% of the interstitial fluid goes to the bloodstream, and the other 10% makes the lymph fluid.
Lymph fluid is a clear fluid that flows through the lymphatic vessels. It is similar to plasma, but contains less protein.
Lymph collects the protein, dead cells, pathogens, and debris from the interstitial spaces, and moves them to ducts in the neck.
The lymph system coordinates with the immune system to fight off infection.
Structure of the Lymphatic System
Lymphatic circulation is the overarching structure of the lymphatic system.
It is sometimes called the secondary circulatory system, because it works in conjunction with the blood vessel system. There are significant differences, however.
Blood circulates the body through the action of the heart, but lymph fluid only moves in one direction and relies on the pumping motion of individual muscles for movement.
Blood is filtered by the kidneys, but lymph is filtered by the lymph nodes.
Blood’s color makes the blood vessels easy to see through the skin, but since lymph is clear, the lymph vessels cannot be seen externally.
Just like the blood vessels, the lymph system has vessels of different sizes.
Lymphatic Circulation
Lymphatic capillaries are the smallest of the lymph vessels, and are lined with endothelium, which allows fluids to move freely in and out of the capillary.
When fluid enters the capillary, it eventually moves to the lymphatic vessels, which get progressively larger.
Similar to the venous system, valves keep the fluid moving in one direction. The lymphatic system has a low pressure that keep it moving upward
Eventually, the fluid moves into one of two ducts.
The thoracic duct drains the lower abdomen, pelvis, legs, and the left half of the head, neck, and chest.
Thorac/o means “thorax,” and –ic means “pertaining to.”
The right lymph duct drains lymph from the right side of the body superior to the diaphragm.
The thoracic duct empties into the left subclavian vein, and the right lymphatic duct empties into the right subclavian vein.
A blockage of a lymphatic vessel or duct can cause fluid buildup and swelling of a limb, which is called lymphedema.
Lymph/o means “lymphatic,” and –edema means “swelling.”
The image to the right shows an example of the integration of different body systems in the absorption of nutrients.
Lymph Nodes
Lymph nodes, which are also called lymphoid nodules, are masses of lymphoid tissue. Their size can increase or decrease rapidly.
Usually, lymph nodes are small, bean-shaped structures
Unfiltered lymph flows to the nodes, and lymphocytes destroy the pathogens, viruses, abnormal cells, and other structures located in the fluid to remove impurities. The lymph fluid then leaves the nodes and returns to circulation.
The body has 400-700 lymph nodes, about 50% of which are in the digestive tract. This is because much of the food and drink we consume has a lot of impurities
There are four major groups of lymph nodes:
Cervical lymph nodes are located along the sides of the neck
Axillary lymph nodes are located under the arms, around the armpit
Mediastinal lymph nodes are located in the chest, between the sternum and spine
Inguinal lymph nodes are located in the groin area.
Lymphocytes: T-cells
Lymphocytes are white blood cells that are formed by the bone marrow.
There are three types of lymphocytes: T-cells, B-cells, and NK cells.
T-lymphocytes, or T-cells, usually compose about 80% of lymphocytes. The “T” means “thymus-dependent.”
There are three subtypes of T-cells: cytotoxic T-cells, helper T-cells, and suppressor T-cells.
Cytotoxic T-cells attack foreign body cells and viruses directly.
Cyt/o means “cell,” tox/o means “harmful,” and –ic means “pertaining to.”
Helper T-cells stimulate the activity of the T- and B-cells.
Suppressor T-cells inhibit the T- and B-cells.
Together, the helper and suppressor T-cells are known as the regulatory T-cells.
T-LYMPHOCYTES
T-lymphocytes also release cytokines, which are intercellular signals involved in activating the immune response.
Interferons are cytokines produced in the presence of antigens of viruses and tumor cells.
Interferons stimulate the immune system, as well as signal other cells to activate.
Interleukins direct the T- and B-lymphocytes to proliferate, as well as serving other functions.
Lymphocytes: B-cells
B-lymphocytes usually account for 10-15% of lymphocytes. Their most important function is to produce antibodies.
Antibodies are soluble proteins that bind to specific targets called antigens.
Antigens are usually proteins on pathogens or other foreign compounds. Antigens will elicit an immune response.
B-cells are most effective in the blood and body fluids, so they are sometimes referred to as humoral (liquid) immunity.
B-cells can transform into plasma cells when confronted with an antigen that it is coded to destroy.
A plasma cell secretes a large amount of antibodies to destroy a specific antigen.
NK Cells and Lymphocyte Maturation
NK Cells, or Natural Killer cells, account for 5-10% of lymphocytes, and they attack foreign cells, cells infected by viruses, and cancer cells.
NK cells are important to a process called immunological surveillance. They circulate in the blood and body constantly, looking for abnormal cells to destroy. Lymphocytes undergo changes in the body, which usually occur to allow them to attack a specific target.
Maturation means that the lymphocytes are maturing into their active form.
Differentiation is the modification of a structure to perform a specific function.
Other Lymph Structures
There are other structures in the body that are made of lymphoid tissue that also work in conjunction with the immune system.
The tonsils are actually 3 sets of tissue located in the nose and upper portion of the throat.
They prevent pathogens from entering the respiratory system through breathing.
The nasopharyngeal tonsils are also called the adenoids.
Nas/o means “nose,” pharyng/o means “pharynx,” and –eal means “pertaining to.”
The palatine tonsils are located to the left and right sides of the throat at the back of the mouth.
The lingual tonsils are located at the base of the tongue, and are not readily visible.
The vermiform appendix is located hanging from the lower portion of the first section of the large intestine.
The vermiform appenix role in immunity is unknown, but research indicates that it could play a larger role than previously considered.
Lymph Structure (continue)
The thymus is an organ located in the mediastinal area, superior to the heart.
It is at its largest size during puberty, then gets smaller with age.
The thymus secretes a hormone that stimulates the maturation of lymphocytes to T-cells.
The T-cells leave the thymus, and take up their functions in the blood and lymphatic systems.
The spleen is the largest collection of lymphatic tissue in the body.
The spleen is located in the left upper quadrant of the abdomen, inferior to the diaphragm, and posterior to the stomach.
The spleen has multiple functions:
It filters pathogens and foreign material from the blood
It forms lymphocytes and monocytes
It destroys abnormal or aged red blood cells, meaning that it is hemolytic
It stores extra red blood cells to help regulate the red blood cell/plasma ratio in the blood.
Beggining of PP#2
Functions and Structure of the IMMUNE SYSTEM
Functions of the Immune system
There are 4 major functions of the immune system:
The immune system maintains health and protects the body from harmful substances, such as:
1.1 Pathogens, which are disease-causing organisms such as bacteria, fungi, and viruses
1.2 Allergens, which are foreign substances that stimulate an allergic reaction
1.3 Toxins, which are poisonous and harmful substances 1.4 Malignancies, which are cancer cells, and potentially life-threatening.
The immune system prevents the entry of foreign bodies, and then destroys and/or neutralizes them if they do enter.
The immune system has some nonspecific defenses, which are physical barriers, phagocytic cells, immunological surveillance, the complement system, interferons, and fever.
The immune system also employs specific defenses, which are designed to protect against particular threats. Specific defenses are immunity. An example of this is the antigen/antibody reaction.
First-line Defenses
The immune system has some first-line defenses, meaning that they attempt to prevent an infection from ever occurring.
Intact skin is one of the most important first-line defenses. It acts as a physical barrier for pathogens and allergens.
If there are no cuts or abnormal breaks in the skin, it is said to be intact.
The skin is also slightly acidic, which prevents bacteria from easily growing on it.
The respiratory system is another first-line defense. It traps foreign matter via the tiny nose hairs and mucous membranes.
The tonsils provide the throat with extra protection.
Coughing and sneezing are defense mechanisms to expel foreign material from the lungs.
The digestive system is another first-line defense. It is acidic, so enzymes work with the acids to destroy any pathogens that may have been ingested.
The lymphatic system structures work to attack and destroy pathogens. It is both specific and non-specific in nature
Secondary Non-Specific Defenses
Once an infection begins to occur, a secondary line of non-specific defenses works to destroy the causative agents.
Phagocytes are cells that destroy foreign materials through the act of phagocytosis. Phagocytosis is the process of surrounding pathogens and engulfing them, destroying them.
Phag/o means “to eat,” and –cyte means “cell.”
Monocytes are leukocytes that circulate in the blood to provide defense against many infectious agents.
Macrophages are monocytes that have left the bloodstream and moved into the tissues.
Macrophages, in addition to removing pathogens, can remove debris and dead cells, as well as stimulate other immune cells to activate.
Different body systems have specific types of macrophages. For example, Küpffer cells are macrophages in the liver, and microglia are macrophages in the nervous system.
Dendritic cells patrol the body to provide immune surveillance.
Once a pathogen is found, the dendritic cell phagocytizes the pathogen and alerts the Tand B-cells to its presence.
Secondary Defenses: Complement
Complement is a system of cascading proteins that exist in the plasma to supplement the action of the antibody system.
The proteins of the complement system combine with pathogens they encounter to dissolve them. Once the complement cascade is activated, proteins stimulate the activation of other proteins.
The complement system has 4 major actions:
Attract cells that perform phagocytosis
Stimulate phagocytosis
Destroy cell membranes
Promote inflammation throughout the body
The membrane attack complex (MAC) is a group of cascade proteins that work to destroy the cell membranes of invading pathogens.
Specific Immune Mechanisms
The major specific mechanism for immunity is the antibody/antigen reaction.
This is also called the immune reaction.
Antigens (abbreviated Ag) are any substance that the body sees as foreign. This could include pathogens, viruses, toxins, and transplanted organs.
Antigens stimulate an immune response.
Antigens are located, in most cases, on cell surfaces.
Tolerance is a lack of immune response to an antigen over time; the immune system has encountered it so frequently, it becomes accustomed to it.
Specific Immune Mechanism (CONTINUED)
Antibodies (abbreviated Ab) are proteins that are created in response to a specific antigen. Antibodies are also called immunoglobulins.
Immunoglobulins (abbreviated Ig) bind with specific antigens.
Immun/o means “immune,” and –globulin means “protein.”
Immunoglobulins are made by activated B-cells called plasma cells.
There are 5 major categories of immunoglobulins:
IgG is the most abundant of the immunoglobulins, and is fights active infections.
IgM circulates primarily in body fluids, and is the first immunoglobulin to appear in an infection.
IgA is produced in response to ingested antigens, and is generally found in body secretions. IgA prevents the attachment of viruses and bacteria.
IgE is found in the lungs, skin, and mucous membranes, and causes allergic reactions.
IgD is the least common immunoglobulin. It is found only on the B-cell surface, and serves to activate the B-cells.
Types of Immunity
Immunity is the state of resistance to a specific disease. There are different types of immunity.
Natural immunity is also called passive immunity, and is present at birth or passed to a child through breastmilk.
Natural immunity provides resistance to a disease without exposure to that disease or antigen.
An example of this is blood types. A person with A blood will always react to the B antigen, regardless of previous exposure.
Acquired immunity is obtained by having exposure to a disease.
Vaccination provides acquired immunity without the risk of actually becoming ill with a disease.
A vaccine is a preparation containing an antigen, which is from whole or partial viruses or bacteria that have been killed or weakened. Sometimes, a booster is needed to maintain immunity.
A vaccine stimulates antibody production, which provides immunity if the disease is ever encountered.
Herd immunity is an important concept to understand. Vaccines only work if enough of a population is vaccinated. There are always people for whom vaccines do not work, or people that cannot be vaccinated. If a certain percentage of the population is vaccinated, those people will also have protection.
Immune System Effectiveness
The effectiveness of the immune system as a whole depends on 3 major factors:
Overall health:
If a person is in poor health, their immune system will not be as effective as a person who is in better health.
Age:
Older people have more acquired immunity, but their immune system is slower to respond. Babies have little acquired immunity, but their immune system responds rapidly.
Heredity:
Genetic disorders can affect the function of the immune system.
Beginning of PP #3
PATHOLOGY AND TREATMENT OF THE LYMPHATIC AND IMMUNE SYSTEMS
Medical Proffesionals of the Lymphatic and Immune system
There are a few medical professionals that specialize in the lymphatic and immune systems:
An allergist diagnoses and treats altered immunologic activity, such as allergies and asthma.
An immunologist diagnoses and treats immune system disorders.
Immun/o means “immunity,” and –ologist means “specialist.”
A lymphologist diagnoses and treats lymphatic system disorders.
Lymph/o means “lymphatic,” and –logist means “specialist.”
An oncologist diagnoses and treats tumors and cancer. Onc/o means “cancer,” and –ologist means “specialist.
Pathology of the Lymphatic System
The following are some general terms related to pathology of the lymphatic system.
Lymphadenopathy is a general term meaning any disease that affects the lymph nodes.
Lymphaden/o means “lymph node,” and –pathy means “disease.”
Lymphadenitis is a condition of swollen or inflamed lymph nodes.
Lymphaden/o means “lymph node,” and –itis means “inflammation.”
A lymphangioma is a benign tumor that is composed of a collection of lymph vessels. It is similar in structure to a hemangioma.
Lymph/o means “lymph,” angi/o means “vessel,” and –oma means “tumor.”
Splenomegaly is the enlargement of the spleen. This may be due to injury, an immune response, or an abnormal immune system.
Splen/o means “spleen,” and –megaly means “enlargement.”
A splenectomy is the removal of the spleen.
Splen/o means “spleen,” and –ectomy means “the surgical removal.”
Splenorrhea is bleeding from the spleen, often as a result of injury.
Splen/o means “spleen,” and –rrhea means “bleeding.”
Tonsillitis is the condition of large, inflamed tonsils.
Tonsill/o means “tonsil,” and –itis means “inflammation.”
A tonsillectomy is the surgical removal of the tonsils.
Tonsill/o means “tonsil,” and –ectomy means “the surgical removal.
Lymphedema
Lymphedema is swelling due to a damaged lymph system, which causes incomplete draining of lymph fluid and accumulation of that fluid in the tissues.
Lymph/o means “lymph,” and –edema means “swelling.”
Primary lymphedema is hereditary, and is most common in females. Swelling begins in the feet and progresses up the body from there.
Secondary lymphedema is due to damaged lymph vessels, which can occur due to cancer treatment, surgery, trauma, or burns.
Lymphedema is treated with the use of compression and exercise, but there is no cure.
Bioimpedence spectroscopy measures the electrical current passed through a swollen limb, which shows the extent of the lymph buildup. This diagnostic procedure can help prevent progression.
Lymphoscintigraphy is a diagnostic procedure to detect damaged or malformed lymph vessels. A radioactive dye is injected, and a scanner is used to follow the movement of the dye to map the vessels.
Lymph/o means “lymph, and scintigraphy is a diagnostic method using radioactive dye.
Pathology of the Immune System: Allergic Reactions
Allergic reactions occur when the immune system responds to a harmless antigen, which could be pollen, food, animal dander, etc.
An allergy is a hypersensitivity reaction, or an overreaction, to an antigen.
An allergen is the substance that produces an allergic reaction.
There are two types of allergic reactions:
Localized allergic responses are also called cellular responses, and cause redness, itching, and burning skin.
Systemic, or anaphylactic, reactions are a severe response, and requires immediate medical attention. The patient can quickly die due to airway constriction.
The diagnosis of allergic reactions is achieved through scratch tests, which can identify commonly triggering allergens. A small amount of an allergen is scratched onto the patient’s skin, and swelling and itching indicate an allergic reaction.
Treatments for allergic reactions involve the use of antihistamines, which counter the affects of histamine, the substance primarily responsible for allergy symptoms.
Autoimmune Disorders
Autoimmune disorders occur when the immune system produces antibodies against its own tissues.
Auto- means “self,” an immun/o means “immune system.”
Up to 3% of all Americans experience an autoimmune disorder.
There is also a genetic component, and they are more common in women.
The following are some examples of autoimmune disorders:
Systemic lupus erythematosus affects numerous body systems.
Rheumatoid arthritis affects the joints and connective tissues of the body.
Myasthenia gravis affects the nerves and muscle synapses of the muscular system.
Pernicious anemia affects the red blood cells.
Crohn’s disease affects the intestines, small intestine, or colon.
Multiple sclerosis affects the brain and spinal cord.
Scleroderma affects the skin and connective tissues.
Grave’s disease affects the thyroid gland.
Immunodeficiency Disorders
Immunodeficiency disorders are characterized by a compromised or weakened immune response.
One of the most prevalent causes of immunodeficiency is the Human Immunodeficiency Virus, or HIV.
HIV is a bloodborne virus that kills helper T-cells, causing the immune system to weaken and eventually fail.
This failure leads to opportunistic infections, which are infections caused by pathogens that do not normally cause infections in healthy people.
An example of this is Kaposi sarcoma, which is a cancer that causes abnormal growth of tissue under the skin, in the mouth and throat, and in other organs. It is often fatal to individuals with AIDS.
Acquired Immunodeficiency Syndrome, or AIDS, is the most advanced and fatal stage of HIV.
HIV Diagnosis and Treatment
HIV diagnosis is achieved with a type of test known as ELISA, which stands for enzyme-linked immunoabsorbent assay.
It is a screening test for the HIV antibodies. Due to the risk of false positives, if the ELISA test is positive, a more sensitive test called a Western blot is done, which is considered confirmatory.
Because there is a lag between infection and the production of HIV antibodies, the ELISA test will not be positive immediately after infection. Regular testing is recommended for individuals at risk.
The treatment for HIV has improved tremendously since the advent of the HIV epidemic in the 1980s.
Medications to inhibit reverse transcriptase, protease, and fusion can prevent the progression of HIV, especially if administered early in the course of the disease.
Often, with proper treatment and adherence to guidelines, people with HIV can live for many years without transforming to AIDS.
Immune System Treatments
There are three main categories of treating immune system disorders: immunotherapy, immunosuppression, and antibody therapy.
Immunotherapy is treatment meant to stimulate or repress the immune response.
Immune stimulation is used to help treat cancer or malignancy. Immune repression is helpful for treating allergies and autoimmune diseases.
Immunosuppression therapy interferes with the ability of the immune system to respond to antigens.
Immunosuppressants are used to prevent rejection of donor tissues and to treat autoimmune disorders.
Corticosteroids are anti-inflammatory drugs with immunosuppressant capabilities.
Cytotoxic drugs are used to kill or damage cells, and are used as antineoplastics to treat cancer, or as immunosuppressants.
Antibody therapy is the use of synthetic materials to support the immune system.
Synthetic immunoglobulins can be administered to provide temporary immunity, by providing post-exposure prevention against some viruses.
Synthetic interferons are used to treat multiple sclerosis, hepatitis C, and some cancers.
Monoclonal antibodies are made in the laboratory using a cloned cell line.
They enhance the patient’s immune system response to some malignancies.
Pathogenic Organisms
A pathogen is an organism that causes disease in humans, and is said to be pathogenic.
Microorganisms are organisms that are so small, they can only be seen with the aid of a microscope.
Pathogenic Bacteria
Not all bacteria are harmful to humans some are beneficial
Bacilli are rod-shaped bacteria that are capable of forming spores, which can survive inhospitable environments. The singular of bacilli is bacillus.
Staphylococci (singular = staphylococcus) are a group of bacteria that form in clusters. These clusters look like clusters of grapes under a microscope. There are over 30 species of staphylococci.
Some staphylococci species are pathogenic, but many are normal flora, meaning that they live harmlessly on the skin and mucous membranes
Streptococci (singular = streptococcus) are a group of bacteria that form chains, as seen under a microscope.
As with staphylococci, many streptococci are considered normal flora, but many are pathogenic.
Certain species of streptococci are responsible for bacterial meningitis, strep throat, endocarditis, and necrotizing fasciitis.
Spirochetes are spiral-shaped bacteria that are motile, or capable of movement.
Syphilis is a disease caused by a spirochete bacteria.
Rickettsia are small bacteria that live in some insects, such as fleas, ticks, lice, and mites.
Rickettsia are significant because they can cause Rocky Mountain Spotted Fever, which is a yearly problem in the Midwest.
Bacteria under a microscope may look purple or pink depending on the the structure of the cell wall, due to the stain used, which is called Gram stain.
Bacteria Disorders
Here are some significant illnesses caused by specific bacteria:
Staphylococcus aureus is a species of staph that causes infection primarily in wounds, and can also cause Toxic Shock Syndrome and food poisoning.
MRSA stands for Methicillin-resistant Staphylococcus aureus, and is a strain of Staphylococcus aureus that is resistant the antibiotic Methicillin.
Anthrax is a disease caused by the bacteria Bacillus anthracis that can be naturally transmitted through livestock, but lab-grown strains can be used as biological warfare.
Lyme disease is caused by the bacteria Borellia burgforderi, which is a spirochete. This disease causes problems with the joints, heart, and central nervous system. It is spread by the bite of a deer tick.
Complications of Bacterial Infections
Septic shock occurs when toxins released by the pathogenic bacteria cause tissue damage directly, which causes damage to vital organs.
Septic shock is very serious, and can be debilitating or fatal.
Antibiotic resistance occurs when the antibiotics do not kill all of the pathogenic bacteria responsible for an infection, and those that survive reproduce.
Resistance can be caused by a variety of factors, including using antibiotics too frequently (as in the case of a virus), and patients not completing the complete course of their antibiotics.
Infections with organisms with antibiotic resistance tend to last longer and cause more complications.
MRSA is a prime example of antibiotic resistance. It is difficult to treat, may be fatal, and is becoming more common in the general population.
Parasites
Parasites are plants or animals that live inside another living organism, causing harm to the host organism.
Parasitic infections are often spread by the bites of infected animals.
There are two major types of parasites that invade red blood cells:
Malaria is a mosquito-borne parasite that is pervasive in tropical areas of the world. The onset of symptoms occur 7 – 28 days after exposure. Signs and symptoms include fever that spikes cyclically, chills, headache, muscle aches, and fatigue.
Babesia is a parasite that is also transmitted by ticks. It causes a flu-like illness, and is present in the United States, in the northeast and the upper Midwest.
Toxoplasmosis is transmitted by contaminated animal feces, especially cats.
Pregnant women must be particularly careful, as infection during pregnancy can cause microcephaly or hydrocephaly in the fetus
Fungal Infections
Fungal infections can be considered a type of parasitic infection. A fungus is a simple organism that can be pathogenic, but many are harmless to humans.
There are many different species of fungus. Some are yeasts, some are molds.
A yeast is a fungus that can cause infections originating in the mucous membranes, for example, the mouth or vagina.
Candida albicans is the most common pathogenic yeast, but other species can cause infection as well.
A yeast infection is called candidiasis.
Candid/o means “yeast,” and –iasas means “infection.”
The Virus
A virus is smaller than a bacterial cell, so it is extremely small – too small to be seen with a conventional microscope in a typical laboratory.
Viruses cannot reproduce independently, but after entering a cell, it hijacks that cell’s ability to make cellular components, or proteins. Using the host cell’s reproductive mechanisms, the virus can reproduce its components, assemble itself, and then burst through the cell membrane of the host cell with more viruses than originally entered.
There is some debate as to whether cells are truly living organisms, since they do not independently reproduce.
Viruses cannot be treated by antibiotics.
Viral Infections
Influenza, or the flu, is a seasonal, highly contagious viral infection, the complications of which can be fatal.
A yearly vaccine is available, but the influenza virus mutates, so the vaccine must be repeated each year to be effective.
Measles is caused by the rubeola virus, which is spread by respiratory droplets and therefore highly contagious.
Measles causes a rash over the entire body, a high fever, runny nose, and coughing. It can also cause photophobia, which is an extreme sensitivity to light.
Mumps is a viral infection that causes swelling of the salivary glands.
Rubella is also called the German measles, and is similar to the measles, but is not usually as severe.
The exception to this is pregnant women; Rubella can cause severe congenital defects.
Rabies is a viral infection that is transmitted by an animal bite. Treatment for rabies must be immediate. Without treatment, the infection is almost always fatal once symptoms begin.
West Nile virus is a viral infection spread by a mosquito, which causes symptoms that present similarly to the flu, but can progress to involve the brain and/or spinal cord.
The Zika virus is an emerging health threat, especially in tropical areas. It causes a mild illness in adults, but if a pregnant woman is infected, it can cause severe microcephaly and disability in the baby.
Viral Infections: Herpesvirus
Herpesviruses are a class of viruses that do not necessarily cause herpes as we usually think of them, but can cause a wide variety of illnesses.
Cytomegalovirus, or CMV, is relatively harmless to healthy adults and children, but can cause severe birth defects in a fetus.
Epstein-Barr virus, or EBV, is one of the causes of infectious mononucleosis, which can cause significant weakness and extended illness.
Varicella zoster is the virus that causes chicken pox, which cause blisters all over the body. They are extremely itchy and unpleasant.
Herpes zoster is the virus responsible for the shingles, which causes painful skin eruptions. The pattern of the skin eruptions follow the route of an affected nerve. Herpes zoster infections are actually due to a dormant varicella zoster virus.
Virus: Ebola
Ebola is a virus that causes a hemorrhagic disease, and is often fatal to those that come in contact with it.
Ebola causes vomiting, bleeding, and diarrhea, amongst other symptoms. It is easily spread this way.
There have been massive outbreaks of Ebola in Africa over the last 5 years. A vaccine has been developed and is currently being tested and administered.
Prevention: Vaccines
Vaccines are available to prevent both bacterial and viral diseases. They have changed the course of human history. Instead of hundreds of thousands of children dying each year across the world from communicable disease, many deaths and disabilities are prevented through vaccination.
Some of the diseases that are prevented by vaccination are: MMR (measles, mumps, and rubella)
Influenza
Varicella zoster
Herpes zoster
Meningitis
Pneumococcus
Haemophilus influenzae B (HiB)
Polio
Hepatitis B and C.
Treatment of Infections
Antibiotics are the first line of defense against bacterial infections.
Antibiotics inhibit the growth of, or kill bacteria. They are not effective against viruses. Prescribing antibiotics for viral infections (including the cold and flu) do nothing but lead to antibiotic resistant bacterial strains.
A bactericide is a type of antibiotic that kills bacteria. Examples are penicillins and cephalosporin antibiotics.
Bacteri/o means “bacteria.” and –cide means “an agent that kills.”
A bacteriostatic slows or stops the growth of bacteria. Examples of this are erythromycin, tetracycline, and sulfonamides.
Bacteri/o means “bacteria,” and – stasis means “stopping.”
Antifungals (also called antimycotics) inhibits the growth of or kills fungi.
Antivirals prevent viral reproduction. Some are used to treat certain viral infections, or they are used to provide temporary immunity to a specific virus.
Beginning of PP #4
Oncology
Oncology is the study of cancer.
Onc/o means “tumor,” and –ology means “the study of.”
This field of medicine is devoted to the prevention, causes, and treatment of all types of cancer, including tumors.
Most cancers are named for their body part of origin.
Cancer is the second leading cause of death among Americans after heart disease.
As we learned previously, an oncologist is a physician who specializes in the diagnosis and treatment of cancer.
Cancer is defined as the uncontrolled division of cells, and the ability of those cells to invade other tissues, either by growing into them or metastasizing.
Metastasize means that a cancer moves from the origin (primary) site and spreads to a secondary site or sites.
Metastasis is the new cancer site. It can be in the same body system as the primary cancer, or in a distant body system.
Types of Cancer: Tumors
Tumors, also called neoplasms, are an abnormal growth of tissue. This growth is rapid, uncontrolled, and progressive. There are two types of tumors:
Benign tumors are not cancerous and not life-threatening, but can cause damage as it displaces normal tissues. For example, a lipoma is a tumor made of fat.
Malignant tumors are cancerous, will spread to distant body sites if left untreated, and are life-threatening. An example is a myosarcoma, or a malignant tumor of muscle tissue.
Angiogenesis occurs when a tumor grows its own blood supply system to nourish itself.
Angi/o means “vessel,” and –genesis means “to create.”
Antiangiogenesis is a treatment strategy that disrupts the tumor’s blood supply to slow or halt its growth.
Anti- means “against,” angi/o means “vessel,” and –genesis means “to create.”
Staging tumors is the act of classifying tumors based on how far the disease has progressed, the prognosis of the patient, and how well the tumor will respond to treatment.
Different staging systems are used for different types of tumors.
Types of Cancer: Carcionoma
A carcinoma is a malignant tumor of epithelial tissue that often can infiltrate other parts of the body and metastasize.
Carcinoma in situ is a tumor that is still in its original tissue and has not invaded any surrounding tissues.
Adenocarcinoma is a carcinoma of glandular tissue.
Aden/o means “gland,” carcin/o means “cancer,” and –oma means “tumor.”
Sarcoma is a malignant tumor of connective tissues.
Sarc/o means “flesh,” and –oma means “tumor.”
Hard-tissue sarcomas arise from bone or cartilage. For example, osteosarcoma is usually in the shaft of long bones, the pelvis, or knee.
Soft-tissue sarcomas are cancers of muscle, fat, fibrous tissue, and synovial tissue. A synovial sarcoma is a cancer of the tissues of the synovial joint, such as in an elbow or knee.
Liquid-tissue sarcomas are cancers of the blood and lymph fluid. Leukemia is an example, and is cancer of the white blood cells in the bone marrow.
Types of Cancer: Lymphoma
Lymphomas are malignancies of lymphoid tissue, including the lymph nodes, spleen, liver, and bone marrow.
Lymph/o means “lymph tissue,” and –oma means “tumor.”
Lymphomas can also be considered leukemias, if they are found in the peripheral blood and bone marrow. Some lymphomas are only found in the lymphoid tissues originally, such as lymph nodes.
Hodgkin’s lymphoma is characterized by large, cancerous lymphoid cells that are include a cell that is diagnostic for Hodgkin lymphoma, called the Reed-Sternberg cell.
Non-Hodgkin lymphoma is any lymphoma that is not considered a Hodgkin lymphoma. This is a very broad category, and an include cancers which are slow-growing, or those which are aggressive.
Breast Cancer
Breast cancer is a type of carcinoma that arises from the breast, and can spread to the lymph nodes and other body sites. There are 5 major types of breast cancer.
Ductal carcinoma in situ is breast cancer that is still located in the milk duct, and has not moved to other structures.
Infiltrating ductal carcinoma is invasive ductal carcinoma, and is cancer that has moved beyond the milk duct and gone into the breast’s fatty tissue.
Infiltrating lobular carcinoma is cancer arising from the milk glands that moves through the glands and into the fatty tissue of the breast. This type of cancer can move to the lymph nodes and quickly spread from there.
Inflammatory breast cancer is a rare, but very aggressive type of breast cancer that can only be detected by MRI initially.
Male breast cancer is similar to the breast cancer that affects women, but is seen in men.
Breast Cancer Staging
The staging of breast cancer is based on the size of the tumors, the degree of lymph node involvement, and the degree to which the cancer is spreading.
Stage 0 is carcinoma in situ, meaning that it has not spread.
Stage 1 is given when the cancer has moved beyond the duct, but not to the lymph nodes.
Stage 2 is given when the cancer has reached the axillary (armpit) lymph node.
Stage 3 is given when the cancer has spread to a cervical (neck) lymph node, and moved to tissues around the breast, such as the skin or chest wall.
Stage 4 is given when the cancer is invasive, meaning it has spread to the brain, lungs, liver, or bones.
Breast Cancer Detection
There are quite a few diagnostic methods for the detection of breast cancer:
The monthly breast self-exam is probably one of the most important things a person can do to discover early-stage breast cancer. The person checks the breast tissue for new lumps or changes of an existing lump, as well as the shape of the nipple, or the skin of the breast.
A professional breast exam is the palpation of the breast by a medical professional to feel the size, texture, and consistency of the breast tissue.
Mammography is the radiologic examination of the breasts to find precancerous cells or tumors. Mamm/o means
“mammary glands,” and –graphy means “the process of creating an image or record.”
Ultrasound is often done as a follow-up to mammography, especially to further examine an abnormality.
Breast Cancer Detection: Invasive Procedures
Some methods of breast cancer detection are more invasive, meaning that the body must be entered and tissue removed for examination.
A needle breast biopsy is the passage of a needle, guided by X-ray, into the breast to remove small tissue samples. The samples are then examined by a pathologist.
A surgical biopsy is the removal of tissue to confirm a diagnosis and to establish a plan of care.
A sentinel node biopsy is a biopsy of the first lymph node to contact the cancer cells. This guides the physician to know which nodes are involved with the cancer and need to be removed.
Lymph node dissection is a surgical procedure to remove all lymph nodes in an area to slow the spread of cancer or to see how far it has spread.
Surgical Treatment of Breast Cancer
There are 5 types of surgery that are done for breast cancer:
A lumpectomy is a surgical procedure in which the cancerous tissue is removed, as well as the surrounding margin of normal tissue. –ectomy means “the surgical removal.”
A mastectomy is the surgical removal of the entire breast, nipple, and usually some lymph nodes of the adjacent axillary area. Mast/o means “breast.”
A radical mastectomy is the surgical removal of the entire breast and the surrounding tissues.
A modified radical mastectomy is the surgical removal of the entire breast and all axillary lymph nodes.
Breast reconstruction can be done after a mastectomy. An immediate breast reconstruction is performed during the same surgery as the mastectomy, and a delayed breast reconstruction is usually done if radiation is needed.
Cancer Treatment
All types of cancers have different methods for treatment, and some types of cancer may need more than one type of treatment.
Surgery is the removal of cancerous tissue and a margin of normal tissue.
Cryosurgery is freezing lymph nodes and cancer cells to destroy the tissue.
Cry/o means “freezing.”
Laser surgery is the use of a targeted light beam to destroy the cancer cells.
Chemotherapy is the use of chemical agents to destroy malignant cells and tissues.
Chem/o means “chemical.”
Chemoprevention is the use of drugs and vitamins to prevent cancer, or to reduce/slow the progression of an existing tumor.
Antineoplastics are drugs that block the development, growth, and reproduction of malignant cells.
Anti- means “against,” neo means “new,” plast/o means “growth,” and –ic means “pertaining to.”
Radiation can also be used to destroy cancerous cells and tissues.
Brachytherapy is the use of radioactive materials in direct contact with the tissues or implanted into the cancerous tissues.
Brachy/o means “short.”
Teletherapy is radiation that is given at a distance from the body.
Tele- means “distance.”
Other cancer treatments:
Targeted treatments are drugs or other substances that are used to specify and attack only cancer cells.
Adjuvant therapy is treatment after the primary therapy to decrease the likelihood that a cancer will return. This could be in the form of chemotherapy, hormone treatments, immunotherapy, and targeted treatments.
Clinical trials are the testing of new drugs and/or techniques that have not been approved by the Federal Drug Administration. These are often done as a last-ditch effort to rid the body of cancer.
CH.6 NOTES
Beginning of PP #1
Functions and Structures of the LYMPHATIC SYSTEM
LYMPHATIC SYSTEM FUNCTIONS
The lymphatic system consists of a series of vessels and nodes throughout the body, as well as some organs. The lymphatic system is closely related to the immune system.
Lymphat/o refers to the lymphatic system, and –ic means “pertaining to.”
The Lymphatic system has some broad functions
To produce, maintain, and distribute lymphocytes to resist or overcome infections
To absorb fats, fats-substance (A, D,E, K) and distribute them through the body
To distribute hormones and nutriets from the tissues to the blood and remove waste from the tissues
To return filtered lymph fluid to the venous system (veins at the base of the neck)
Lymphocytes and Absorption
Lymphocytes are white blood cells
Lymphocytes are produced and stored in the spleen, thymus, and bone marrow.
Lymph/o means “lymphatic,” and –cytes means “cells.”
Lymphocytes respond to pathogens, abnormal cells (such as virus-infected cells or cancerous cells), foreign proteins (antigens), and use physical and chemical attacks to neutralize them.
Lymphocytes mount a specific response, which is called immunity.
The lymphatic system also plays a role in the absorption of materials. Villi located along the small intestine absorb fats and the fat-soluble vitamins.
Villi are small projections which contain lacteals and blood vessels.
The lacteals absorb the fats that the blood cannot transport, and convert those fats to a usable form.
The blood vessels then absorb all the other nutrients from the small intestine and send them throughout the body.
Interstitial Fluid and Lymph Fluid
Interstitial fluid is also called intercellular or tissue fluid, and is composed of plasma from the blood that migrates to the space between the cells in tissues.
Inter- means “between.”
Interstitial fluid provides tissues with nutrients, oxygen, and hormones, and removes wastes from those tissues.
90% of the interstitial fluid goes to the bloodstream, and the other 10% makes the lymph fluid.
Lymph fluid is a clear fluid that flows through the lymphatic vessels. It is similar to plasma, but contains less protein.
Lymph collects the protein, dead cells, pathogens, and debris from the interstitial spaces, and moves them to ducts in the neck.
The lymph system coordinates with the immune system to fight off infection.
Structure of the Lymphatic System
Lymphatic circulation is the overarching structure of the lymphatic system.
It is sometimes called the secondary circulatory system, because it works in conjunction with the blood vessel system. There are significant differences, however.
Blood circulates the body through the action of the heart, but lymph fluid only moves in one direction and relies on the pumping motion of individual muscles for movement.
Blood is filtered by the kidneys, but lymph is filtered by the lymph nodes.
Blood’s color makes the blood vessels easy to see through the skin, but since lymph is clear, the lymph vessels cannot be seen externally.
Just like the blood vessels, the lymph system has vessels of different sizes.
Lymphatic Circulation
Lymphatic capillaries are the smallest of the lymph vessels, and are lined with endothelium, which allows fluids to move freely in and out of the capillary.
When fluid enters the capillary, it eventually moves to the lymphatic vessels, which get progressively larger.
Similar to the venous system, valves keep the fluid moving in one direction. The lymphatic system has a low pressure that keep it moving upward
Eventually, the fluid moves into one of two ducts.
The thoracic duct drains the lower abdomen, pelvis, legs, and the left half of the head, neck, and chest.
Thorac/o means “thorax,” and –ic means “pertaining to.”
The right lymph duct drains lymph from the right side of the body superior to the diaphragm.
The thoracic duct empties into the left subclavian vein, and the right lymphatic duct empties into the right subclavian vein.
A blockage of a lymphatic vessel or duct can cause fluid buildup and swelling of a limb, which is called lymphedema.
Lymph/o means “lymphatic,” and –edema means “swelling.”
The image to the right shows an example of the integration of different body systems in the absorption of nutrients.
Lymph Nodes
Lymph nodes, which are also called lymphoid nodules, are masses of lymphoid tissue. Their size can increase or decrease rapidly.
Usually, lymph nodes are small, bean-shaped structures
Unfiltered lymph flows to the nodes, and lymphocytes destroy the pathogens, viruses, abnormal cells, and other structures located in the fluid to remove impurities. The lymph fluid then leaves the nodes and returns to circulation.
The body has 400-700 lymph nodes, about 50% of which are in the digestive tract. This is because much of the food and drink we consume has a lot of impurities
There are four major groups of lymph nodes:
Cervical lymph nodes are located along the sides of the neck
Axillary lymph nodes are located under the arms, around the armpit
Mediastinal lymph nodes are located in the chest, between the sternum and spine
Inguinal lymph nodes are located in the groin area.
Lymphocytes: T-cells
Lymphocytes are white blood cells that are formed by the bone marrow.
There are three types of lymphocytes: T-cells, B-cells, and NK cells.
T-lymphocytes, or T-cells, usually compose about 80% of lymphocytes. The “T” means “thymus-dependent.”
There are three subtypes of T-cells: cytotoxic T-cells, helper T-cells, and suppressor T-cells.
Cytotoxic T-cells attack foreign body cells and viruses directly.
Cyt/o means “cell,” tox/o means “harmful,” and –ic means “pertaining to.”
Helper T-cells stimulate the activity of the T- and B-cells.
Suppressor T-cells inhibit the T- and B-cells.
Together, the helper and suppressor T-cells are known as the regulatory T-cells.
T-LYMPHOCYTES
T-lymphocytes also release cytokines, which are intercellular signals involved in activating the immune response.
Interferons are cytokines produced in the presence of antigens of viruses and tumor cells.
Interferons stimulate the immune system, as well as signal other cells to activate.
Interleukins direct the T- and B-lymphocytes to proliferate, as well as serving other functions.
Lymphocytes: B-cells
B-lymphocytes usually account for 10-15% of lymphocytes. Their most important function is to produce antibodies.
Antibodies are soluble proteins that bind to specific targets called antigens.
Antigens are usually proteins on pathogens or other foreign compounds. Antigens will elicit an immune response.
B-cells are most effective in the blood and body fluids, so they are sometimes referred to as humoral (liquid) immunity.
B-cells can transform into plasma cells when confronted with an antigen that it is coded to destroy.
A plasma cell secretes a large amount of antibodies to destroy a specific antigen.
NK Cells and Lymphocyte Maturation
NK Cells, or Natural Killer cells, account for 5-10% of lymphocytes, and they attack foreign cells, cells infected by viruses, and cancer cells.
NK cells are important to a process called immunological surveillance. They circulate in the blood and body constantly, looking for abnormal cells to destroy. Lymphocytes undergo changes in the body, which usually occur to allow them to attack a specific target.
Maturation means that the lymphocytes are maturing into their active form.
Differentiation is the modification of a structure to perform a specific function.
Other Lymph Structures
There are other structures in the body that are made of lymphoid tissue that also work in conjunction with the immune system.
The tonsils are actually 3 sets of tissue located in the nose and upper portion of the throat.
They prevent pathogens from entering the respiratory system through breathing.
The nasopharyngeal tonsils are also called the adenoids.
Nas/o means “nose,” pharyng/o means “pharynx,” and –eal means “pertaining to.”
The palatine tonsils are located to the left and right sides of the throat at the back of the mouth.
The lingual tonsils are located at the base of the tongue, and are not readily visible.
The vermiform appendix is located hanging from the lower portion of the first section of the large intestine.
The vermiform appenix role in immunity is unknown, but research indicates that it could play a larger role than previously considered.
Lymph Structure (continue)
The thymus is an organ located in the mediastinal area, superior to the heart.
It is at its largest size during puberty, then gets smaller with age.
The thymus secretes a hormone that stimulates the maturation of lymphocytes to T-cells.
The T-cells leave the thymus, and take up their functions in the blood and lymphatic systems.
The spleen is the largest collection of lymphatic tissue in the body.
The spleen is located in the left upper quadrant of the abdomen, inferior to the diaphragm, and posterior to the stomach.
The spleen has multiple functions:
It filters pathogens and foreign material from the blood
It forms lymphocytes and monocytes
It destroys abnormal or aged red blood cells, meaning that it is hemolytic
It stores extra red blood cells to help regulate the red blood cell/plasma ratio in the blood.
Beggining of PP#2
Functions and Structure of the IMMUNE SYSTEM
Functions of the Immune system
There are 4 major functions of the immune system:
The immune system maintains health and protects the body from harmful substances, such as:
1.1 Pathogens, which are disease-causing organisms such as bacteria, fungi, and viruses
1.2 Allergens, which are foreign substances that stimulate an allergic reaction
1.3 Toxins, which are poisonous and harmful substances 1.4 Malignancies, which are cancer cells, and potentially life-threatening.
The immune system prevents the entry of foreign bodies, and then destroys and/or neutralizes them if they do enter.
The immune system has some nonspecific defenses, which are physical barriers, phagocytic cells, immunological surveillance, the complement system, interferons, and fever.
The immune system also employs specific defenses, which are designed to protect against particular threats. Specific defenses are immunity. An example of this is the antigen/antibody reaction.
First-line Defenses
The immune system has some first-line defenses, meaning that they attempt to prevent an infection from ever occurring.
Intact skin is one of the most important first-line defenses. It acts as a physical barrier for pathogens and allergens.
If there are no cuts or abnormal breaks in the skin, it is said to be intact.
The skin is also slightly acidic, which prevents bacteria from easily growing on it.
The respiratory system is another first-line defense. It traps foreign matter via the tiny nose hairs and mucous membranes.
The tonsils provide the throat with extra protection.
Coughing and sneezing are defense mechanisms to expel foreign material from the lungs.
The digestive system is another first-line defense. It is acidic, so enzymes work with the acids to destroy any pathogens that may have been ingested.
The lymphatic system structures work to attack and destroy pathogens. It is both specific and non-specific in nature
Secondary Non-Specific Defenses
Once an infection begins to occur, a secondary line of non-specific defenses works to destroy the causative agents.
Phagocytes are cells that destroy foreign materials through the act of phagocytosis. Phagocytosis is the process of surrounding pathogens and engulfing them, destroying them.
Phag/o means “to eat,” and –cyte means “cell.”
Monocytes are leukocytes that circulate in the blood to provide defense against many infectious agents.
Macrophages are monocytes that have left the bloodstream and moved into the tissues.
Macrophages, in addition to removing pathogens, can remove debris and dead cells, as well as stimulate other immune cells to activate.
Different body systems have specific types of macrophages. For example, Küpffer cells are macrophages in the liver, and microglia are macrophages in the nervous system.
Dendritic cells patrol the body to provide immune surveillance.
Once a pathogen is found, the dendritic cell phagocytizes the pathogen and alerts the Tand B-cells to its presence.
Secondary Defenses: Complement
Complement is a system of cascading proteins that exist in the plasma to supplement the action of the antibody system.
The proteins of the complement system combine with pathogens they encounter to dissolve them. Once the complement cascade is activated, proteins stimulate the activation of other proteins.
The complement system has 4 major actions:
Attract cells that perform phagocytosis
Stimulate phagocytosis
Destroy cell membranes
Promote inflammation throughout the body
The membrane attack complex (MAC) is a group of cascade proteins that work to destroy the cell membranes of invading pathogens.
Specific Immune Mechanisms
The major specific mechanism for immunity is the antibody/antigen reaction.
This is also called the immune reaction.
Antigens (abbreviated Ag) are any substance that the body sees as foreign. This could include pathogens, viruses, toxins, and transplanted organs.
Antigens stimulate an immune response.
Antigens are located, in most cases, on cell surfaces.
Tolerance is a lack of immune response to an antigen over time; the immune system has encountered it so frequently, it becomes accustomed to it.
Specific Immune Mechanism (CONTINUED)
Antibodies (abbreviated Ab) are proteins that are created in response to a specific antigen. Antibodies are also called immunoglobulins.
Immunoglobulins (abbreviated Ig) bind with specific antigens.
Immun/o means “immune,” and –globulin means “protein.”
Immunoglobulins are made by activated B-cells called plasma cells.
There are 5 major categories of immunoglobulins:
IgG is the most abundant of the immunoglobulins, and is fights active infections.
IgM circulates primarily in body fluids, and is the first immunoglobulin to appear in an infection.
IgA is produced in response to ingested antigens, and is generally found in body secretions. IgA prevents the attachment of viruses and bacteria.
IgE is found in the lungs, skin, and mucous membranes, and causes allergic reactions.
IgD is the least common immunoglobulin. It is found only on the B-cell surface, and serves to activate the B-cells.
Types of Immunity
Immunity is the state of resistance to a specific disease. There are different types of immunity.
Natural immunity is also called passive immunity, and is present at birth or passed to a child through breastmilk.
Natural immunity provides resistance to a disease without exposure to that disease or antigen.
An example of this is blood types. A person with A blood will always react to the B antigen, regardless of previous exposure.
Acquired immunity is obtained by having exposure to a disease.
Vaccination provides acquired immunity without the risk of actually becoming ill with a disease.
A vaccine is a preparation containing an antigen, which is from whole or partial viruses or bacteria that have been killed or weakened. Sometimes, a booster is needed to maintain immunity.
A vaccine stimulates antibody production, which provides immunity if the disease is ever encountered.
Herd immunity is an important concept to understand. Vaccines only work if enough of a population is vaccinated. There are always people for whom vaccines do not work, or people that cannot be vaccinated. If a certain percentage of the population is vaccinated, those people will also have protection.
Immune System Effectiveness
The effectiveness of the immune system as a whole depends on 3 major factors:
Overall health:
If a person is in poor health, their immune system will not be as effective as a person who is in better health.
Age:
Older people have more acquired immunity, but their immune system is slower to respond. Babies have little acquired immunity, but their immune system responds rapidly.
Heredity:
Genetic disorders can affect the function of the immune system.
Beginning of PP #3
PATHOLOGY AND TREATMENT OF THE LYMPHATIC AND IMMUNE SYSTEMS
Medical Proffesionals of the Lymphatic and Immune system
There are a few medical professionals that specialize in the lymphatic and immune systems:
An allergist diagnoses and treats altered immunologic activity, such as allergies and asthma.
An immunologist diagnoses and treats immune system disorders.
Immun/o means “immunity,” and –ologist means “specialist.”
A lymphologist diagnoses and treats lymphatic system disorders.
Lymph/o means “lymphatic,” and –logist means “specialist.”
An oncologist diagnoses and treats tumors and cancer. Onc/o means “cancer,” and –ologist means “specialist.
Pathology of the Lymphatic System
The following are some general terms related to pathology of the lymphatic system.
Lymphadenopathy is a general term meaning any disease that affects the lymph nodes.
Lymphaden/o means “lymph node,” and –pathy means “disease.”
Lymphadenitis is a condition of swollen or inflamed lymph nodes.
Lymphaden/o means “lymph node,” and –itis means “inflammation.”
A lymphangioma is a benign tumor that is composed of a collection of lymph vessels. It is similar in structure to a hemangioma.
Lymph/o means “lymph,” angi/o means “vessel,” and –oma means “tumor.”
Splenomegaly is the enlargement of the spleen. This may be due to injury, an immune response, or an abnormal immune system.
Splen/o means “spleen,” and –megaly means “enlargement.”
A splenectomy is the removal of the spleen.
Splen/o means “spleen,” and –ectomy means “the surgical removal.”
Splenorrhea is bleeding from the spleen, often as a result of injury.
Splen/o means “spleen,” and –rrhea means “bleeding.”
Tonsillitis is the condition of large, inflamed tonsils.
Tonsill/o means “tonsil,” and –itis means “inflammation.”
A tonsillectomy is the surgical removal of the tonsils.
Tonsill/o means “tonsil,” and –ectomy means “the surgical removal.
Lymphedema
Lymphedema is swelling due to a damaged lymph system, which causes incomplete draining of lymph fluid and accumulation of that fluid in the tissues.
Lymph/o means “lymph,” and –edema means “swelling.”
Primary lymphedema is hereditary, and is most common in females. Swelling begins in the feet and progresses up the body from there.
Secondary lymphedema is due to damaged lymph vessels, which can occur due to cancer treatment, surgery, trauma, or burns.
Lymphedema is treated with the use of compression and exercise, but there is no cure.
Bioimpedence spectroscopy measures the electrical current passed through a swollen limb, which shows the extent of the lymph buildup. This diagnostic procedure can help prevent progression.
Lymphoscintigraphy is a diagnostic procedure to detect damaged or malformed lymph vessels. A radioactive dye is injected, and a scanner is used to follow the movement of the dye to map the vessels.
Lymph/o means “lymph, and scintigraphy is a diagnostic method using radioactive dye.
Pathology of the Immune System: Allergic Reactions
Allergic reactions occur when the immune system responds to a harmless antigen, which could be pollen, food, animal dander, etc.
An allergy is a hypersensitivity reaction, or an overreaction, to an antigen.
An allergen is the substance that produces an allergic reaction.
There are two types of allergic reactions:
Localized allergic responses are also called cellular responses, and cause redness, itching, and burning skin.
Systemic, or anaphylactic, reactions are a severe response, and requires immediate medical attention. The patient can quickly die due to airway constriction.
The diagnosis of allergic reactions is achieved through scratch tests, which can identify commonly triggering allergens. A small amount of an allergen is scratched onto the patient’s skin, and swelling and itching indicate an allergic reaction.
Treatments for allergic reactions involve the use of antihistamines, which counter the affects of histamine, the substance primarily responsible for allergy symptoms.
Autoimmune Disorders
Autoimmune disorders occur when the immune system produces antibodies against its own tissues.
Auto- means “self,” an immun/o means “immune system.”
Up to 3% of all Americans experience an autoimmune disorder.
There is also a genetic component, and they are more common in women.
The following are some examples of autoimmune disorders:
Systemic lupus erythematosus affects numerous body systems.
Rheumatoid arthritis affects the joints and connective tissues of the body.
Myasthenia gravis affects the nerves and muscle synapses of the muscular system.
Pernicious anemia affects the red blood cells.
Crohn’s disease affects the intestines, small intestine, or colon.
Multiple sclerosis affects the brain and spinal cord.
Scleroderma affects the skin and connective tissues.
Grave’s disease affects the thyroid gland.
Immunodeficiency Disorders
Immunodeficiency disorders are characterized by a compromised or weakened immune response.
One of the most prevalent causes of immunodeficiency is the Human Immunodeficiency Virus, or HIV.
HIV is a bloodborne virus that kills helper T-cells, causing the immune system to weaken and eventually fail.
This failure leads to opportunistic infections, which are infections caused by pathogens that do not normally cause infections in healthy people.
An example of this is Kaposi sarcoma, which is a cancer that causes abnormal growth of tissue under the skin, in the mouth and throat, and in other organs. It is often fatal to individuals with AIDS.
Acquired Immunodeficiency Syndrome, or AIDS, is the most advanced and fatal stage of HIV.
HIV Diagnosis and Treatment
HIV diagnosis is achieved with a type of test known as ELISA, which stands for enzyme-linked immunoabsorbent assay.
It is a screening test for the HIV antibodies. Due to the risk of false positives, if the ELISA test is positive, a more sensitive test called a Western blot is done, which is considered confirmatory.
Because there is a lag between infection and the production of HIV antibodies, the ELISA test will not be positive immediately after infection. Regular testing is recommended for individuals at risk.
The treatment for HIV has improved tremendously since the advent of the HIV epidemic in the 1980s.
Medications to inhibit reverse transcriptase, protease, and fusion can prevent the progression of HIV, especially if administered early in the course of the disease.
Often, with proper treatment and adherence to guidelines, people with HIV can live for many years without transforming to AIDS.
Immune System Treatments
There are three main categories of treating immune system disorders: immunotherapy, immunosuppression, and antibody therapy.
Immunotherapy is treatment meant to stimulate or repress the immune response.
Immune stimulation is used to help treat cancer or malignancy. Immune repression is helpful for treating allergies and autoimmune diseases.
Immunosuppression therapy interferes with the ability of the immune system to respond to antigens.
Immunosuppressants are used to prevent rejection of donor tissues and to treat autoimmune disorders.
Corticosteroids are anti-inflammatory drugs with immunosuppressant capabilities.
Cytotoxic drugs are used to kill or damage cells, and are used as antineoplastics to treat cancer, or as immunosuppressants.
Antibody therapy is the use of synthetic materials to support the immune system.
Synthetic immunoglobulins can be administered to provide temporary immunity, by providing post-exposure prevention against some viruses.
Synthetic interferons are used to treat multiple sclerosis, hepatitis C, and some cancers.
Monoclonal antibodies are made in the laboratory using a cloned cell line.
They enhance the patient’s immune system response to some malignancies.
Pathogenic Organisms
A pathogen is an organism that causes disease in humans, and is said to be pathogenic.
Microorganisms are organisms that are so small, they can only be seen with the aid of a microscope.
Pathogenic Bacteria
Not all bacteria are harmful to humans some are beneficial
Bacilli are rod-shaped bacteria that are capable of forming spores, which can survive inhospitable environments. The singular of bacilli is bacillus.
Staphylococci (singular = staphylococcus) are a group of bacteria that form in clusters. These clusters look like clusters of grapes under a microscope. There are over 30 species of staphylococci.
Some staphylococci species are pathogenic, but many are normal flora, meaning that they live harmlessly on the skin and mucous membranes
Streptococci (singular = streptococcus) are a group of bacteria that form chains, as seen under a microscope.
As with staphylococci, many streptococci are considered normal flora, but many are pathogenic.
Certain species of streptococci are responsible for bacterial meningitis, strep throat, endocarditis, and necrotizing fasciitis.
Spirochetes are spiral-shaped bacteria that are motile, or capable of movement.
Syphilis is a disease caused by a spirochete bacteria.
Rickettsia are small bacteria that live in some insects, such as fleas, ticks, lice, and mites.
Rickettsia are significant because they can cause Rocky Mountain Spotted Fever, which is a yearly problem in the Midwest.
Bacteria under a microscope may look purple or pink depending on the the structure of the cell wall, due to the stain used, which is called Gram stain.
Bacteria Disorders
Here are some significant illnesses caused by specific bacteria:
Staphylococcus aureus is a species of staph that causes infection primarily in wounds, and can also cause Toxic Shock Syndrome and food poisoning.
MRSA stands for Methicillin-resistant Staphylococcus aureus, and is a strain of Staphylococcus aureus that is resistant the antibiotic Methicillin.
Anthrax is a disease caused by the bacteria Bacillus anthracis that can be naturally transmitted through livestock, but lab-grown strains can be used as biological warfare.
Lyme disease is caused by the bacteria Borellia burgforderi, which is a spirochete. This disease causes problems with the joints, heart, and central nervous system. It is spread by the bite of a deer tick.
Complications of Bacterial Infections
Septic shock occurs when toxins released by the pathogenic bacteria cause tissue damage directly, which causes damage to vital organs.
Septic shock is very serious, and can be debilitating or fatal.
Antibiotic resistance occurs when the antibiotics do not kill all of the pathogenic bacteria responsible for an infection, and those that survive reproduce.
Resistance can be caused by a variety of factors, including using antibiotics too frequently (as in the case of a virus), and patients not completing the complete course of their antibiotics.
Infections with organisms with antibiotic resistance tend to last longer and cause more complications.
MRSA is a prime example of antibiotic resistance. It is difficult to treat, may be fatal, and is becoming more common in the general population.
Parasites
Parasites are plants or animals that live inside another living organism, causing harm to the host organism.
Parasitic infections are often spread by the bites of infected animals.
There are two major types of parasites that invade red blood cells:
Malaria is a mosquito-borne parasite that is pervasive in tropical areas of the world. The onset of symptoms occur 7 – 28 days after exposure. Signs and symptoms include fever that spikes cyclically, chills, headache, muscle aches, and fatigue.
Babesia is a parasite that is also transmitted by ticks. It causes a flu-like illness, and is present in the United States, in the northeast and the upper Midwest.
Toxoplasmosis is transmitted by contaminated animal feces, especially cats.
Pregnant women must be particularly careful, as infection during pregnancy can cause microcephaly or hydrocephaly in the fetus
Fungal Infections
Fungal infections can be considered a type of parasitic infection. A fungus is a simple organism that can be pathogenic, but many are harmless to humans.
There are many different species of fungus. Some are yeasts, some are molds.
A yeast is a fungus that can cause infections originating in the mucous membranes, for example, the mouth or vagina.
Candida albicans is the most common pathogenic yeast, but other species can cause infection as well.
A yeast infection is called candidiasis.
Candid/o means “yeast,” and –iasas means “infection.”
The Virus
A virus is smaller than a bacterial cell, so it is extremely small – too small to be seen with a conventional microscope in a typical laboratory.
Viruses cannot reproduce independently, but after entering a cell, it hijacks that cell’s ability to make cellular components, or proteins. Using the host cell’s reproductive mechanisms, the virus can reproduce its components, assemble itself, and then burst through the cell membrane of the host cell with more viruses than originally entered.
There is some debate as to whether cells are truly living organisms, since they do not independently reproduce.
Viruses cannot be treated by antibiotics.
Viral Infections
Influenza, or the flu, is a seasonal, highly contagious viral infection, the complications of which can be fatal.
A yearly vaccine is available, but the influenza virus mutates, so the vaccine must be repeated each year to be effective.
Measles is caused by the rubeola virus, which is spread by respiratory droplets and therefore highly contagious.
Measles causes a rash over the entire body, a high fever, runny nose, and coughing. It can also cause photophobia, which is an extreme sensitivity to light.
Mumps is a viral infection that causes swelling of the salivary glands.
Rubella is also called the German measles, and is similar to the measles, but is not usually as severe.
The exception to this is pregnant women; Rubella can cause severe congenital defects.
Rabies is a viral infection that is transmitted by an animal bite. Treatment for rabies must be immediate. Without treatment, the infection is almost always fatal once symptoms begin.
West Nile virus is a viral infection spread by a mosquito, which causes symptoms that present similarly to the flu, but can progress to involve the brain and/or spinal cord.
The Zika virus is an emerging health threat, especially in tropical areas. It causes a mild illness in adults, but if a pregnant woman is infected, it can cause severe microcephaly and disability in the baby.
Viral Infections: Herpesvirus
Herpesviruses are a class of viruses that do not necessarily cause herpes as we usually think of them, but can cause a wide variety of illnesses.
Cytomegalovirus, or CMV, is relatively harmless to healthy adults and children, but can cause severe birth defects in a fetus.
Epstein-Barr virus, or EBV, is one of the causes of infectious mononucleosis, which can cause significant weakness and extended illness.
Varicella zoster is the virus that causes chicken pox, which cause blisters all over the body. They are extremely itchy and unpleasant.
Herpes zoster is the virus responsible for the shingles, which causes painful skin eruptions. The pattern of the skin eruptions follow the route of an affected nerve. Herpes zoster infections are actually due to a dormant varicella zoster virus.
Virus: Ebola
Ebola is a virus that causes a hemorrhagic disease, and is often fatal to those that come in contact with it.
Ebola causes vomiting, bleeding, and diarrhea, amongst other symptoms. It is easily spread this way.
There have been massive outbreaks of Ebola in Africa over the last 5 years. A vaccine has been developed and is currently being tested and administered.
Prevention: Vaccines
Vaccines are available to prevent both bacterial and viral diseases. They have changed the course of human history. Instead of hundreds of thousands of children dying each year across the world from communicable disease, many deaths and disabilities are prevented through vaccination.
Some of the diseases that are prevented by vaccination are: MMR (measles, mumps, and rubella)
Influenza
Varicella zoster
Herpes zoster
Meningitis
Pneumococcus
Haemophilus influenzae B (HiB)
Polio
Hepatitis B and C.
Treatment of Infections
Antibiotics are the first line of defense against bacterial infections.
Antibiotics inhibit the growth of, or kill bacteria. They are not effective against viruses. Prescribing antibiotics for viral infections (including the cold and flu) do nothing but lead to antibiotic resistant bacterial strains.
A bactericide is a type of antibiotic that kills bacteria. Examples are penicillins and cephalosporin antibiotics.
Bacteri/o means “bacteria.” and –cide means “an agent that kills.”
A bacteriostatic slows or stops the growth of bacteria. Examples of this are erythromycin, tetracycline, and sulfonamides.
Bacteri/o means “bacteria,” and – stasis means “stopping.”
Antifungals (also called antimycotics) inhibits the growth of or kills fungi.
Antivirals prevent viral reproduction. Some are used to treat certain viral infections, or they are used to provide temporary immunity to a specific virus.
Beginning of PP #4
Oncology
Oncology is the study of cancer.
Onc/o means “tumor,” and –ology means “the study of.”
This field of medicine is devoted to the prevention, causes, and treatment of all types of cancer, including tumors.
Most cancers are named for their body part of origin.
Cancer is the second leading cause of death among Americans after heart disease.
As we learned previously, an oncologist is a physician who specializes in the diagnosis and treatment of cancer.
Cancer is defined as the uncontrolled division of cells, and the ability of those cells to invade other tissues, either by growing into them or metastasizing.
Metastasize means that a cancer moves from the origin (primary) site and spreads to a secondary site or sites.
Metastasis is the new cancer site. It can be in the same body system as the primary cancer, or in a distant body system.
Types of Cancer: Tumors
Tumors, also called neoplasms, are an abnormal growth of tissue. This growth is rapid, uncontrolled, and progressive. There are two types of tumors:
Benign tumors are not cancerous and not life-threatening, but can cause damage as it displaces normal tissues. For example, a lipoma is a tumor made of fat.
Malignant tumors are cancerous, will spread to distant body sites if left untreated, and are life-threatening. An example is a myosarcoma, or a malignant tumor of muscle tissue.
Angiogenesis occurs when a tumor grows its own blood supply system to nourish itself.
Angi/o means “vessel,” and –genesis means “to create.”
Antiangiogenesis is a treatment strategy that disrupts the tumor’s blood supply to slow or halt its growth.
Anti- means “against,” angi/o means “vessel,” and –genesis means “to create.”
Staging tumors is the act of classifying tumors based on how far the disease has progressed, the prognosis of the patient, and how well the tumor will respond to treatment.
Different staging systems are used for different types of tumors.
Types of Cancer: Carcionoma
A carcinoma is a malignant tumor of epithelial tissue that often can infiltrate other parts of the body and metastasize.
Carcinoma in situ is a tumor that is still in its original tissue and has not invaded any surrounding tissues.
Adenocarcinoma is a carcinoma of glandular tissue.
Aden/o means “gland,” carcin/o means “cancer,” and –oma means “tumor.”
Sarcoma is a malignant tumor of connective tissues.
Sarc/o means “flesh,” and –oma means “tumor.”
Hard-tissue sarcomas arise from bone or cartilage. For example, osteosarcoma is usually in the shaft of long bones, the pelvis, or knee.
Soft-tissue sarcomas are cancers of muscle, fat, fibrous tissue, and synovial tissue. A synovial sarcoma is a cancer of the tissues of the synovial joint, such as in an elbow or knee.
Liquid-tissue sarcomas are cancers of the blood and lymph fluid. Leukemia is an example, and is cancer of the white blood cells in the bone marrow.
Types of Cancer: Lymphoma
Lymphomas are malignancies of lymphoid tissue, including the lymph nodes, spleen, liver, and bone marrow.
Lymph/o means “lymph tissue,” and –oma means “tumor.”
Lymphomas can also be considered leukemias, if they are found in the peripheral blood and bone marrow. Some lymphomas are only found in the lymphoid tissues originally, such as lymph nodes.
Hodgkin’s lymphoma is characterized by large, cancerous lymphoid cells that are include a cell that is diagnostic for Hodgkin lymphoma, called the Reed-Sternberg cell.
Non-Hodgkin lymphoma is any lymphoma that is not considered a Hodgkin lymphoma. This is a very broad category, and an include cancers which are slow-growing, or those which are aggressive.
Breast Cancer
Breast cancer is a type of carcinoma that arises from the breast, and can spread to the lymph nodes and other body sites. There are 5 major types of breast cancer.
Ductal carcinoma in situ is breast cancer that is still located in the milk duct, and has not moved to other structures.
Infiltrating ductal carcinoma is invasive ductal carcinoma, and is cancer that has moved beyond the milk duct and gone into the breast’s fatty tissue.
Infiltrating lobular carcinoma is cancer arising from the milk glands that moves through the glands and into the fatty tissue of the breast. This type of cancer can move to the lymph nodes and quickly spread from there.
Inflammatory breast cancer is a rare, but very aggressive type of breast cancer that can only be detected by MRI initially.
Male breast cancer is similar to the breast cancer that affects women, but is seen in men.
Breast Cancer Staging
The staging of breast cancer is based on the size of the tumors, the degree of lymph node involvement, and the degree to which the cancer is spreading.
Stage 0 is carcinoma in situ, meaning that it has not spread.
Stage 1 is given when the cancer has moved beyond the duct, but not to the lymph nodes.
Stage 2 is given when the cancer has reached the axillary (armpit) lymph node.
Stage 3 is given when the cancer has spread to a cervical (neck) lymph node, and moved to tissues around the breast, such as the skin or chest wall.
Stage 4 is given when the cancer is invasive, meaning it has spread to the brain, lungs, liver, or bones.
Breast Cancer Detection
There are quite a few diagnostic methods for the detection of breast cancer:
The monthly breast self-exam is probably one of the most important things a person can do to discover early-stage breast cancer. The person checks the breast tissue for new lumps or changes of an existing lump, as well as the shape of the nipple, or the skin of the breast.
A professional breast exam is the palpation of the breast by a medical professional to feel the size, texture, and consistency of the breast tissue.
Mammography is the radiologic examination of the breasts to find precancerous cells or tumors. Mamm/o means
“mammary glands,” and –graphy means “the process of creating an image or record.”
Ultrasound is often done as a follow-up to mammography, especially to further examine an abnormality.
Breast Cancer Detection: Invasive Procedures
Some methods of breast cancer detection are more invasive, meaning that the body must be entered and tissue removed for examination.
A needle breast biopsy is the passage of a needle, guided by X-ray, into the breast to remove small tissue samples. The samples are then examined by a pathologist.
A surgical biopsy is the removal of tissue to confirm a diagnosis and to establish a plan of care.
A sentinel node biopsy is a biopsy of the first lymph node to contact the cancer cells. This guides the physician to know which nodes are involved with the cancer and need to be removed.
Lymph node dissection is a surgical procedure to remove all lymph nodes in an area to slow the spread of cancer or to see how far it has spread.
Surgical Treatment of Breast Cancer
There are 5 types of surgery that are done for breast cancer:
A lumpectomy is a surgical procedure in which the cancerous tissue is removed, as well as the surrounding margin of normal tissue. –ectomy means “the surgical removal.”
A mastectomy is the surgical removal of the entire breast, nipple, and usually some lymph nodes of the adjacent axillary area. Mast/o means “breast.”
A radical mastectomy is the surgical removal of the entire breast and the surrounding tissues.
A modified radical mastectomy is the surgical removal of the entire breast and all axillary lymph nodes.
Breast reconstruction can be done after a mastectomy. An immediate breast reconstruction is performed during the same surgery as the mastectomy, and a delayed breast reconstruction is usually done if radiation is needed.
Cancer Treatment
All types of cancers have different methods for treatment, and some types of cancer may need more than one type of treatment.
Surgery is the removal of cancerous tissue and a margin of normal tissue.
Cryosurgery is freezing lymph nodes and cancer cells to destroy the tissue.
Cry/o means “freezing.”
Laser surgery is the use of a targeted light beam to destroy the cancer cells.
Chemotherapy is the use of chemical agents to destroy malignant cells and tissues.
Chem/o means “chemical.”
Chemoprevention is the use of drugs and vitamins to prevent cancer, or to reduce/slow the progression of an existing tumor.
Antineoplastics are drugs that block the development, growth, and reproduction of malignant cells.
Anti- means “against,” neo means “new,” plast/o means “growth,” and –ic means “pertaining to.”
Radiation can also be used to destroy cancerous cells and tissues.
Brachytherapy is the use of radioactive materials in direct contact with the tissues or implanted into the cancerous tissues.
Brachy/o means “short.”
Teletherapy is radiation that is given at a distance from the body.
Tele- means “distance.”
Other cancer treatments:
Targeted treatments are drugs or other substances that are used to specify and attack only cancer cells.
Adjuvant therapy is treatment after the primary therapy to decrease the likelihood that a cancer will return. This could be in the form of chemotherapy, hormone treatments, immunotherapy, and targeted treatments.
Clinical trials are the testing of new drugs and/or techniques that have not been approved by the Federal Drug Administration. These are often done as a last-ditch effort to rid the body of cancer.
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