BIOD 152 Module 5 Lymphatic System

Lymphatic System

helps with immunity to defend the body against disease. The Lymphatic System is closely associated with the cardiovascular system. Lymphatic system consists of lymphatic vessels and the lymphoid organs:

Lymphatic vessels

take up excess tissue fluid and return it to the bloodstream.

Lymphatic capillaries

absorb fats and transport them to the bloodstream.

Interstitial Fluid

Fluid begins in the interstitial fluid between the cells. Most, but not all, of the fluid is returned to the heart via the veins of the cardiovascular system. Fluid that is not returned through the veins of the cardiovascular system enters lymphatic capillaries and flows into a lymphatic vessel.

Lymphatic capillaries

are closely connected to the capillaries of the cardiovascular system. They take up plasma fluid, which, under great pressure (osmotic pressure), has been forced out of the capillaries of the circulatory system and has not been reabsorbed.

Plasma Fluid

This fluid bathes the cells assisting the capillaries in delivering glucose, oxygen, salts, amino acids, and other nutrients.

Lymph

Excess tissue fluid entering the lymphatic capillaries is now called lymph. Lymph flows one way from the lymphatic capillaries into larger lymphatic vessels until it eventually empties into venous blood of the cardiovascular system (subclavian veins)

Lymph vessels

have one-way flow valves similar in structure to the large veins of the cardiovascular system. Valves prevent the backward flow of lymph. The return of the lymph fluid into circulation is solely dependent on the squeezing action of skeletal muscles, squeezing the fluid one way through the lymphatic vessels.

Thoracic Duct

Left lymphatic duct. Larger , located at shoulder of body. flows from the thoracic duct into the left subclavian vein (of the cardiovascular system). drains fluid from both lower extremities, the abdomen, the left arm, and the left side of both the head and the neck.

Right Lymphatic Duct

located at shoulder of body, smaller than thoracic duct Drains into the right subclavian vein (of the cardiovascular system). Drains fluid from the right arm, the right side of both the head and the neck, and the right thoracic area.

Lymphoid organs

lymph nodes, spleen, thymus gland, tonsils.

Lymph nodes

The body has hundreds of lymph nodes which are found at junctions of lymphatic vessels. Encapsulated in fibrous connective tissue Act as a filtering center, which rid the flowing lymph of infectious organisms and other debris as it passes through a series of sinuses (cortical, subcapsular, and medullary). Tend to be grouped together in regions of the body, particularly the groin and axilla (armpit) regions.

Incoming vessels (afferent vessels)

flow through a network of sinuses that contain cells. The lymph then flows out of the lymph node through the efferent vessel.

Nodules

The interior of the lymph node is divided into open spaces called nodules, containing lymphocytes and macrophages.

Spleen

is in the upper-left abdomen and functions to extract old or defective blood cells and platelets. It is encapsulated in a thin, fragile fibrous connective tissue with an incoming Splenic artery and an outgoing Splenic vein.

Secondary Spleen Functions

removes debris, foreign matter, bacteria, viruses, and toxins from the blood that flows through it.

Lobules

Interior of the spleen is divided into open spaces called Lobules, containing lymphocytes and macrophages that carry out the functions of the spleen.

Explain the flow of blood through the Lyphatic organs

Blood enters the spleen via the splenic artery. Blood leaves the spleen via the splenic vein, which flows to the Hepatic portal vein (also called the hepatic portal system).

Hepatic portal system aka Hepatic Portal Vein

carries blood drained from the veins of the spleen, intestines, stomach, and pancreas to the liver. Hepatic portal vein transports blood into the liver where it is detoxified before returning to general circulation.

Thymus gland

is located on the anterior surface of the heart. It secretes Thymosin and Thymopoietin hormones, which enable T lymphocytes (T cells) to mature and function as part of the immune system.

Mature T cells

attack body cells, which are cancerous or infected with pathogens.

Explain developed vs undevelopled thymus

Thymus is prominent in newborns and becomes larger during childhood when it is most active. Growth of the thymus stops during adolescence, and the gland withers away to a mass of fibrous-fatty tissue by old age.

Tonsils (palatine tonsils)

are a group of small lymphoid organs in the lateral, posterior portions of the throat. The tonsils gather and destroy bacteria inhaled in air or food.

Crypts

Lymphoid tissue of the tonsils is invaginated by channels called crypts, which trap bacteria and foreign matter. The bacteria then work their way into the lymphoid tissue where most are destroyed.

Immune response

involves identifying foreign, invading particles and eliminating them. Some immune responses are specific, while others are nonspecific.

Nonspecific immune system (innate immune system)

serves as a first line of defense through physical and chemical barriers to prevent pathogens from entering the body. The response is the same to all threats that attempt to enter the body. This generalized defense system rapidly destroys large numbers of pathogens.

Specific immune system

is targeted and extremely effective against pathogens. Main lymphocytes involved in specific immune responses are the T-cells and the B-cells.

Skin (integumentary system)

is part of the nonspecific immune response system. Very few pathogens can penetrate the intact human skin.

Normal Flora

Tears and sweat produce an environment on which only good bacteria can grow. These beneficial bacteria produce lactic acid, which inhibits pathogenic (disease-causing) bacteria.

Stomachs Role in Immunity

Microorganisms entering the stomach are destroyed by stomach acids and digestive secretions.

Respiratory System

Pathogens entering the respiratory system are trapped by mucus membranes and then brought up to the throat to be spit out or swallowed and killed in the stomach acid.

Inflammatory response

is a localized response in the tissue. Inflammation increases blood flow to the infected region causing swelling. Tissue swelling dilates blood vessels in the affected area to help increase the number of immune cells responding to the infection. Increase of blood also causes redness and pain, helping to bring a conscious awareness of the infection

Cytokines

Within the blood circulate many cytokines, not cells> SECRETED PROTIENS. Help to regulate and signal both the specific and nonspecific immune systems.

The two main groups of cytokines

include Interferons and Interleukins.

What produces cytokines

Both types of cytokines are produced by a variety of immune cells, including macrophages, T-cells, B-cells, and fibroblasts.

Interferons

A type of cytokine. inhibit viral replication and assist in activating natural killer cells, functioning as chemical activators, sending signals throughout the body to increase the immune response.

Interleukins

a type of cytokine. function to activate different types of immune cells and there are many various types

Pyrogens

During an infection, this subtype of interleukins reset the body's thermostat in the hypothalamus. The temperature set-point during homeostasis (normal body temperature) is raised to create a fever.

Fevers

help the body fight infection by interfering with the growth and replication of pathogens. Also cause lysosomes to break down. The lysosomes release digestive enzymes that lyse (destroys) a cell infected by a virus Can promote the activity of white blood cells.

What the 2 main types of Leukocytes

Granulocytes and Agranulocytes.

Granulocytes

have granules in the cytoplasm Include neutrophils, eosinophils, and basophils. All the granulocytes are capable of Phagocytosis

Agranulocytes

do not contain granules. .

Neutrophils

are responsible for fighting infections, especially those that involve bacteria and most abundant white blood cell. Uses phagocytosis or the ingestion of foreign materials Neutrophils recognizes a pathogen by its cell surface receptors. The neutrophil then binds to the pathogen and brings it inside the cell forming a vacuole. The vacuole fuses with cell lysosomes, which release digestive enzymes to destroy the pathogen. .Once the pathogen is destroyed, the contents are released from the cell. .Neutrophils have a short life span and die quickly after the pathogen is ingested. After cell death, neutrophils exit the body as pus (white fluid). Phagocytosis protects the body by engulfing and destroying pathogens.

Eosinophils

respond to allergic reactions and parasitic infections. As a granulocyte, eosinophils are also capable of phagocytosis. They are similar in appearance to neutrophils, except that their granules stain a darker pink to red and are less commonly seen.

Basophils

are the rarest of the granulocytes and are also capable of phagocytosis. They are involved in the release of histamines and heparin. Basophils have similar morphology (shape) to neutrophils and eosinophils, but the granules stain dark blue/purple.

Histamines

are a vasodilator,which increase blood flow through the dilation of vessels and capillaries.

Heparin

is a blood anticoagulant, which helps to prevent the formation of blood clots.

What are the 2 Agranulocytes

Monocytes & Lymphocytes

Monocytes

are large white blood cells with a "U" or kidney bean shaped nucleus.

Macrophages

Monocytes can move into the tissue where they are then called Macrophages.

Which cells are the greatest phagoctytes

Monocytes and macrophages are the greatest phagocytes of all the blood cells. These cells are more effective than neutrophils because they live longer and have greater phagocytic ability.

3 Major Types of Lymphocytes

T-cells, B-cells, and natural killer cells are three of the major types of lymphocytes. The specific immune response depends on the activity of lymphocytes.

Lymphocyte

functions include making antibodies, attacking foreign cells, and destroying body cells that have lost normal function. Have a large dark nucleus with little cytoplasm. The main lymphocytes involved in specific immune responses are the T-cells and the B-cells

Antibody-mediated immunity (Humoral Response)

defends the body against pathogens through the secretion of antibodies. The antibodies bind to the pathogen, making it unable to cause further damage in the body and marking it for phagocytosis. B cells use this method

B- Cells

Millions of B-cells (bone-marrow derived) are produced in the bone marrow daily. Genetically programmed to produce a Glycoprotein receptor as part of its cell coat. Each receptor binds with a specific type of antigen. B-cells become activated when an antigen binds with its receptor. (Plasma Cell). Plasma cells produce Antibodies (Immunogobulins). Immunogobulins mark the pathogen for destruction or cause it to be inactive. Phagocytes can identify the marked cell and engulf it through phagocytosis.

Antigen

is any molecule that can be specifically recognized as foreign by the immune system.

Plasma Cell

Once activated, the B cell is called a plasma cell and begins to rapidly divide. Each plasma cell produces Antibodies (immunoglobulins),

Antibodies (Immunogobulins)

are a soluble form of the glycoprotein receptor from the B-cell's surface. There are five major categories of immunoglobulins (Igs) released by B-cells, each with a different purpose in the body: IgG, IgE, IgD, IgM and IgA.

Memory B-Cells

Some activated B-cells become memory B-cells, which continue to produce a small amount of antibody even after the infection is over. If the same pathogen enters the body again, the antibody immediately binds with the antigen. Memory B-cells can produce a specific antibody much faster and targets it for destruction at a much faster rate the second time a pathogen invades the body.

T-cells

(thymus-dependent cells) originate in bone marrow but mature in the thymus gland T-cells work through what is called cell-mediated immunity.

Cell-Mediated Immunity

Instead of using antibodies, cell mediated immunity locally releases contents, such as cytokines or enzymes, to kill a pathogen or infected cell. Cell mediated immunity also includes the direct cellular action, such as phagocytosis by other white blood cells.

Expkain Cell Mediatred Immunitry

T-cells contain antigen receptors that bind to specific glycoproteins in cell membranes. Killer T Cells recognize and destroy invading cells containing foreign antigens.

Killer T cells

(cytotoxic T cells) Killer T-cells attack virus-infected cells or cells infected with cancer cells by releasing cytokines and enzymes locally to lyse the cell.

Helper T-cells

secrete substances that activate or enhance immune responses. B-cells require an interaction with helper T-cells before they can begin rapid division.

Natural killer cells (NK)

also originate in the bone marrow. Natural killer cells seek out abnormal body cells and destroy them. This makes NK cells highly effective against tumor cells.

MHC MajorHistoComapatibility Complex

The glycoprotein surface receptors on all the cells of the body are called the major histocompatibility complex (MHC). MHC enables the immune system to determine what cells are the body's cells and what cells are foreign. Cells of the body also have a way of displaying through the MHC complex if there is something abnormal within the cell (such as cancer). Killer T-cells (cytotoxic T cells) recognize and destroy invading cells through this self or not-self recognition of the MHC complexes on each cell.a

Graft rejection

is the rejection of a transplanted organ by an organ donor. Tissue grafts and organ transplants most often originate from another person's body. MHC on the surface of the graft are recognized by the host body as a foreign pathogen. An identical twin can make donations to his/her sibling without complications.

Immunosuppressant Drugs

Suppressing the immune system is necessary so that the body does not reject the organ transplant or tissue graft. While taking these immunosuppressant drugs, the patient is more susceptible to disease.

AutoImmune Disease

When lymphocytes launch an attack against a person's own body. Occurs when antibodies and T-cells attack the body's own tissues.

Rheumatoid arthritis (RA)

T-cells attack the synovial lining inside joints. T-cells produce interleukins, which cause inflammation inside the joints systemically (body-wide).

Multiple sclerosis

(discussed in the nervous system module). Antibodies attack and/or prevent the formation of the myelin sheath around nerve cells, resulting in muscular weakness.

Allergic reactions

antibodies are produced against mild antigens called allergens.

Allergens

are typically common environmental factors, such as pollen or dust mites. Many people that display allergies have some type of genetic predisposition to this type of body reaction.

Allergic reactions

vary from person to person, but generally include red/watery eyes, sneezing, runny nose, and headaches.

Anaphylaxis

Some people have excessive immune responses to an allergen. It is severe, life-threatening allergic reaction against a pathogen, insect bite, or drug. Antibodies are overproduced by B-cells. These circulating antibodies increase capillary permeability throughout the body, causing symptoms within minutes. Increasing the permeability of the capillaries causes symptoms throughout the body.

What are Symptoms of Anaphylaxis

include swelling in the form of hives (raised red bumps) and narrowed respiratory pathways, causing difficulty breathing

Anaphylactic shock

a severe cases of anaphylaxis, a person's capillaries become so dilated it causes their blood pressure to drop too low, leading to collapse. A person can die from anaphylactic shock because the heart stops beating or the airway passages completely close, so the person can no longer breathe.

EpiPen

People who have severe allergic reactions should always carry an epinephrine auto injector When anaphylaxis begins to occur, the EpiPen is injected into the thigh to release the hormone epinephrine into the bloodstream.

Epinephrine

helps to offset the symptoms of anaphylaxis, constricting blood vessels and raising blood pressure.

Edema

An accumulation of too much fluid in tissues can cause localized swelling called

Lymphedema

is a specific form of edema where the lymphatic system is not functioning properly to return fluid back into circulation. A lymph vessel can become blocked, or the lymph nodes can be removed in an area for testing, causing difficulty with lymph drainage. The interstitial fluid slowly accumulates in the limb (arm or leg), and it becomes extremely swollen and distended. Can become a serious condition if not treated because the swollen tissues are vulnerable to infection. If left untreated the connective tissues and vessels become permanently stretched and distended.

Tonsillitis

is inflammation of the tonsils. The tonsils become infected and appear white and swollen from a viral or bacterial infection