Human Biology Lecture Exam 2

Heart and blood vessels function

Transport of gases, nutrients, waste, hormones, vitamins. Protection from disease by white blood cells and bleeding by way of blood clotting. Regulates blood pressure, pH, and body temperature

Blood Vessels

Artery carries oxygenated blood away from the heart to the body tissues. Arterioles are the smaller branches of the artery. Capillaries are the smallest of all the blood vessels with thinnest walls and exchange nutrients and waste. Capillaries come together to form a venule, a small vein which leads into a bigger vein which heads back to the heart. This vein going back to the heart carries deoxygenated blood, but that is not true for all veins. Veins carry back to the heart and arteries carry away from the heart.

The Heart function and tissues

Double pump - pumping out blood to body systems and to the lungs (must keep the circulatory systems separate). Different layers of tissue on the heart: pericardium to protect it, myocardium which is the muscle (has intercalated discs with gap junctions for communication btwn cells).

Inner structure of heart

Four chambers in the heart: right and left atrium, right and left ventricle. Left side of the heart is bigger and works harder. There are four valves that control the backflow of blood: right atrioventricular valve (tricuspid) and the left one (bicuspid or mitral). The other two valves are the pulmonary semilunar valve and the aortic semilunar valve. The atrioventricular valves have cords attached to them that are being pulled on by papillary muscles. The function is to prevent the valve from being inverted. If it is inverted, the blood will flow backwards.

Veins

Superior vena cava is a large vein that drains the top half of the body and sends the blood to the right atrium. Inferior vena cava drains the bottom half of the body and sends that blood to the right atrium. There are four pulmonary veins going into the heart which bring oxygen-rich blood from the lungs to the heart through the left atrium.

Arteries

Pulmonary trunk sends blood from the heart to the lungs, and the aorta delivers oxygenated blood to the other body systems.

Pathway of Blood Flow

Blood comes from the top half and the bottom half of body through the superior and inferior vena cava. Those vessels will empty into the right atrium, which contracts and pushes blood into the right ventricle. Blood goes into the pulmonary trunk and then to the lungs. Lungs will remove CO2 and add oxygen, then send the oxygen rich blood back to the heart through the pulmonary veins. They empty into the left atrium, which pushes the blood to the left ventricle through the left atrioventricular valve. After that the blood is transported to the aorta, which sends the blood to the body systems. Body systems pull oxygen out of the blood to use for energy, push in CO2 and sends it back to the heart through the vena cava.

Cardiovascular Pathways

Pulmonary circuit will receive deoxygenated blood from the body and send it to the lungs. The lungs will release CO2 and pull in oxygen, then send oxygenated blood to the heart. Systemic circuit is the oxygenated blood being pumped out by the left ventricle to the aorta, then to the body systems. Systems pull in oxygen and dump out CO2, using the oxygen for energy.

Cardiac Cycle

Systole is contraction and diastole is relaxation. This cycle includes atrial systole, ventricular systole, then atrial and ventricular diastole. Atrial systole is where the atria contract and push blood to the ventricles. The ventricles will fill and contract upwards to the arteries. This goes to the pulmonary trunk and the right aorta. The ventricles and atria relax and the heart refills. Venous blood comes from the vena cava to the right and pulmonary veins to the left. This passively flows through the relaxed atria. The ventricles receive blood from the atria.

Heart Sounds: Lub

"Lub" sound is created when the atrioventricular valves close during ventricular systole when the ventricles squeeze from the bottom up. The cusps of the atrioventricular valves slam shut, and the blood hits them and makes the lub sound.

Sounds of the heart: Dub

"Dub" is caused by the closing of the semi lunar valves. During ventricular diastole, the blood has been injected into the pulmonary trunk in the aorta. It trickles backwards from the arteries back to the ventricles. The cusps of the semi lunar valves close and the blood hits them to make the dub sound.

Internal Control of Heartbeat (Conduction System)

Muscle cells in this system do not contract and act like nerves, stimulating other cells to contract. It starts in the SA node, which is in the right atrium and is called the pacemaker. The information is sent to the next system, the AV node. It goes to the septum, which leads to the bundle branches which head to the apex of the heart and the fibers run up the lateral walls of the heart (purkinje fibers).

External Control of Heartbeat (Nervous regulation)

This is by way of the cardiac control center, which controls how quickly or slowly the heart beats. We can increase our heart rate by neurons called sympathetic neurons, which are involved in the flight-of-fight response. The parasympathetic nervous system helps us to rest and digest to decrease heart rate instead of fighting or fleeing.

External Control of Heartbeat (Hormonal Regulation)

This is by the adrenal gland, which increases heart rate by secreting epinephrine and norepinephrine. They are similar to the neurotransmitters in the sympathetic nervous system.

Electrocardiography (ECG)

See distinctive wave forms to measure electrical activity. The first P wave is the atrial excitation, then the large wave is the QRS complex which represents ventricular excitation. the last T wave is the ventricular relaxation. Atrial relaxation and atrial recovery happens at the same time as QRS so it is not able to seen on the ECG.

Blood Pressure

Measure pressure of blood against blood vessel walls. First tighten and increase pressure of the arm cuff so there's no blood flow going through, then slowly release the pressure as the vessel begins to open. While this occurs, you will hear a thumping sound which is systolic pressure, the pressure of the blood against the vessel walls while the heart is contracting. A healthy systolic pressure is 120. The blood is squirting through the vessel and is doing turbulent flow. When there is no more pressure in the cuff, the vessel is completely open and the blood freely moves in laminar (smooth) flow. That point is diastolic pressure is the blood against the vessel walls when the heart is relaxed. A healthy diastolic pressure is 80.

Blood Pressure Values

If systolic pressure (top number) is less than 95 and bottom number (diastolic) is less than 50, that is classified as hypotension. Low blood pressure can be bad if it is very low and you have trouble getting oxygen to tissues. About 120/80 is a normal healthy value for adults, but 120-139 for systolic and 80-89 for diastolic is prehypertension. Stage 1 hypertension is 140-159/90-99, and stage 2 hypertension is 160+/100+. Hypertensive crisis is 180+/110+, the point where you need to go to a hospital and take antihypertensive medication (emergency).

Blood Flow

Accomplished by pressure gradient: pressure in arteries is very high and it goes downhill to the veins which is very low pressure (high to low pattern). Flow in the capillaries slows down so there is enough time for exchange of nutrients and wastes. The capillaries have a high cross sectional area for this slow travel.

Flow through capillaries

Controlled by precapillary sphincters which are smooth muscle cells which wrap around the tubes close to the capillary. To shunt blood away from the capillary, the sphincters would contract and squeeze the tube so the blood can go to other organs when needed.

Flow through veins

Blood pressure drops here and the velocity increases. This flow is assisted by respiratory and skeletal muscle and valves to prevent backflow of blood.

Capillary Exchange

Nutrient and waste exchange occurs in the capillaries. In filtration, substances leave the blood, and in absorption substances enter the blood. This is driven by pressure gradients: blood pressure which promotes filtration, and osmotic pressure which opposes filtration. This is so blood can absorb substances. Systemic capillary has arterial on top carrying oxygenated blood and venule has deoxygenated blood going to the heart. Filtration is water, oxygen, amino acids, and glucose. On the venus end, blood pressure is lower than osmotic to promote absorption. CO2, metabolic waste, acid, and uric acid is absorbed.

Role of lymphatic system in capillary exchange

Removes excess ISF. Green structures around capillary bed are lymphatic capillaries. Amount of fluid leaving the arterial and through filtration is greater than the amount of fluid coming back into the venus by absorption. As a result, excess fluid builds in the interstitium. The lymphatic system gets rid of the interstitial fluid excess to prevent the swelling of the tissues.

Hypertension

Treatment: Diuretics (urination to release water to lower blood volume), beta-blockers (blocks hormones like norepinephine and epinephrine from increasing blood pressure), and ACE inhibitors (act on system of hormones in kidney to lower BP). Lifestyle changes like exercise can strengthen your heart to deliver oxygen to tissues easier and lose weight to lose adipose tissue (lose more blood vessels, reduce BP), and reduce cholesterol and saturated fat intake (reduces atherosclerosis).

Atherosclerosis

It is a plaque formation in blood vessels which closes off a blood vessel, slowing down or preventing blood flow. Smoking can put you at risk for this, along with a high fat diet. This can lead to aneurysm (rupture) because so much blood pressure is put on the blocked wall and it will burst. An aneurysm in your brain is quite deadly, and so is an aorta aneurysm (causes instant death)

Thrombus/Embolus

The first is a clot in an unbroken vessel, due to atherosclerotic plaque. It closes off the vessel and causes damage to the organs it is serving/ The second is a moving clot which can move to a cardiac vessel (heart attack) and if it goes to the brain it is a stroke, and if it goes to the lungs it is a pulmonary embolism. All three are very deadly. Treatments include anticoagulants (tissue plasminogen activator) which does a series of reactions to break down the clot. An angioplasty is where you insert a needle which balloons up and pushes the clot against the vessel walls to restore flow. Bypass surgery is where you use other vessels in the body to bypass and supply the heart with oxygenated blood.

Cardiac Arrhythmias

Ventricular fibrillation is where you have an uncoordinated, irregular heartbeat. A fibrillating heart looks like a bag of worms with all the cells contracting at different times. If you cannot effectively move blood to your tissues, your systems start to shut down. This usually causes sudden death if not treated. To treat it, use a defibrillator to give an electric shock to the heart to reset it.

Heart Failure

This process can take many years depending on which part of the heart is affected. There is left side failure (left ventricle too weak to contract), and the blood cannot be forced into aorta and there is fluid buildup in the lungs. Right side failure is where the right ventricle cannot push blood to the pulmonary trunk because it's weak, and the fingers and toes begin to swell (fluid buildup).

Causes and treatment for Heart Failure

First is hypertension and your heart is trying very hard to pump blood, and the second cause is myocardial infraction (heart attack). The ventricular cells affected by a heart attack will weaken and cause heart failure because it fails to pump blood. Treatment is diuretics, which forces excess fluid out of lungs or limbs. The second kind is an implantable cardioverter-defibrillator (ICD) which is transplanted right onto your heart tissue to help with electrical signals in the heart. Otherwise, you can do a heart transplant.

Heart Transplants

Replacing a human heart with another human heart or a different substitute. This procedure is quite risky because there is only one heart in your body and you need to replace it immediately. Human donor hearts are very rare in comparison to kidneys. Pig hearts can be used to do a transplant because it is very similar to human hearts. Some alternatives can prolong the need for a heart transplant or completely replace it, which is a Left ventricular assist device (LVAD) which helps the ventricle get blood to the aorta. The Jarvik 2000 is a pump in the left ventricle which can replace the action of it. There is a total artificial heart (TAH) which is a pump which forces blood out of the heart and into the pulmonary trunk and aorta. It has gotten advanced to the point that people can live for a couple months with this. It is not a permanent solution though.

Prevention of Cardiovascular Disease

Risk factors are smoking, doing drugs, obesity, and a high fat diet. Tips for prevention are reducing fat in diet (reducing saturated fat and getting cal from unsaturated fat), exercise to strengthen heart, reducing stress and anxiety (high BP), consuming resveratrol (antioxidant to reduce free radicals which can break down DNA or cause health issues), and consuming a moderate amount of alcohol (wine which contains resveratrol). Alcohol can also reduce BP and stress and anxiety if you have red wine.

Function of blood

Transport of gases, nutrients/wastes, and hormones. It defends against disease (cells and proteins do this) and against bleeding (proteins like clotting factors clot blood to prevent too much bleeding). It can regulate the body temperature by shunting blood to skin and release heat from it when you're hot, and blood will go to the organs when you are cold so you can still function properly. It keeps a good balance of water and salt, and regulated blood pH which is slightly basic.

Composition of Blood

Overall, it is composed of 45% formed elements and 55% plasma. In a centrifuge, cells and platelets sink to the bottom and plasma rises to the top so you can calculate how much of each there is. It has formed elements: red blood cells to carry oxygen, and transparent white blood cells to keep us healthy, and platelets to blood clot. It is also composed of plasma, the fluid matrix which becomes solid when it is clotted.

Plasma

It is 91% water so one needs to have enough water each day to maintain blood volume. The other 9% is solutes like gases (O2 and CO2), nutrients (glucose, fatty acids, amino acids), wastes (lactic and uric acid, urea), salt, hormones, plasma proteins: albumin to create an osmotic gradient to pull water into blood, globulins (transport proteins, antibodies), clotting proteins. Of the 9%, 7% is proteins and 2% is other solutes like ions, nutrients, wastes, gases, hormones, vitamins.

Red blood cells

Erythrocytes (red cells), transport gases like oxygen and CO2, the structure is biconcave disks and the red color is due to hemoglobin. 4-6 million cells/microliter of blood.

Hemoglobin

When red blood cells transport oxygen, it is being carried by the pigment protein hemoglobin. Hemoglobin has four globin polypeptide subunits, colored in purple and green. You also have heme and iron in hemoglobin. Oxygen is going to bind to the iron, and you have 280 million molecules of hemoglobin per red blood cell. Hemoglobin can each carry four oxygen molecules. Therefore if our blood is completely saturated with oxygen, you have 1 billion molecules of oxygen in each RBC. Deoxyhemoglobin is hemoglobin not yet bound to oxygen, but when it does it becomes oxyhemoglobin which is fully saturated with oxygen. It is a reversible reaction.

Red blood cells gas transport

7% of carbon dioxide is dissolved in blood, 23% is carried on globin, hemoglobin + CO2 reaction makes carbaminohemoglobin. 70% of CO2 is a bicarbonate formed within red blood cells. Carbon dioxide will then diffuse into the red blood cells and combine with water, which makes carbonic acid. The byproduct CO2 will diffuse into the red blood cells which are depleted of oxygen bind with the water and form bicarbonate. All of these reactions are reversible. The bicarbonate can leave red blood cells and buffer the blood, then it will reverse back into carbon dioxide to be exchanged at the lungs and exhale the waste product.

Red blood cells production

Made in red bone marrow, the process is called Erythropoiesis. This is stimulated by a hormone called erythropoietin (EPO). EPO can be taken by athletes to cheat and help boost oxygen carrying capacity to improve performance. If you have low oxygen in blood, your kidneys will sense it and secrete the hormone EPO. Once it is generated, it will go back down to the bone marrow where the stem cells are, and those will start generating red blood cells which will then mature and go into the bloodstream. This is a negative feedback mechanism.

RBC development and lifespan

When developing, RBC gain hemoglobin, lose mitochondria, lose nucleus, and develop biconcave shape. It does not need mitochondria because its only purpose is to transport gases, so it is an unneeded organelle. Mitochondria works in the presence of oxygen, but if a RBC had it, the mitochondria would devour all the oxygen. It does not need nucleus because it needs to conserve space. Overall, RBC are very simple and have short lifespans because it cannot repair itself. They are only useful for 90 days and last for 120 days. At the end of that time, it shrivels because it lacks a nucleus. The shriveled cell is recycled by the liver and spleen, the globin amino acids, the iron are recycled, and heme is converted to bilirubin for excretion or conversion to bile. This is the liver's job. If the bilirubin is not excreted, it will build up and you will get jaundice with yellowish tissues.

White blood cells composition and function

Made of leukocytes and fight infection. The structure is larger than RBC, they have a nucleus, and are transparent unless stained. They undergo diapedesis, which is where WBC squeeze between the linings of our capillaries and exit our blood to enter infected tissues. This is in order to get rid of the pathogen attacking your body. Diabetes is very important in white blood cells. There are 5,000-11,000 WBC per microliter of blood and the count would go up if there is an active infection.

White blood cells types overview

Five kinds: granular leukocytes with neutrophils, eosinophils, and basophils with bubbly vesicles that make them look granular. The other types are agranular leukocytes, which are the lympho and monocytes. Their cytoplasm is smooth and the vesicles do not stain so it does not look granular.

Granular leukocytes - neutrophils

50-70% of WBCs are neutrophils, and they are polymorphonuclear leukocytes which makes them look like they have multiple nuclei but the lobes of the nucleus is just connected by a very thin strand. They have neutral-staining granules. In order to see the white blood cells, one needs to use stain with two portions: acid loving portion called eocene which is red, and a blue portion which is called methylene blue. Altogether, these stains create a purple color and one can see the vesicles of the neutrophils. The function is phagocytes which wander around blood and tissues to get rid of pathogens, old cells, and cellular debris.

Granular leukocytes - eosinophils

These are very rare and have bilobed nucleus. The granules are red-staining and the leukocytes fight parasitic infections like worms and flukes. Eosinophil levels are very low because there aren't many parasites in American food. They are anti-inflammatory (swelling and redness) and get rid of inflammatory chemicals.

Granular leukocytes - basophils

These are rare and have a u-shaped nucleus and blue-staining granules. They are responsible for inflammation and secrete the histamine chemical which causes the effects of inflammation. When you have allergies, you take antihistamine to reduce inflammation.

Agranular leukocytes - lymphocytes

Make up 25-35% of WBCs are there are two types: B and T. They look exactly the same but have different functions. They are the smallest of the WBCs and have no granules. The nucleus is shown in purple and takes up most of the cytoplasm. They are responsible for immunity and you get immune to the same cold after the first time.

Agranular leukocytes - monocytes

Makes up 3-9% of WBCs and is large with a u-shaped nucleus. It is responsible for phagocytosis of pathogens, old cells, and cellular debris. Becomes a macrophage

Platelets

These are cell fragments and are called thrombocytes (clot). They are fragments of megakaryocytes because those blow up like balloons and rupture, then release fragments. There are 130,000-400,000 fragments/microliter. It does clotting/coagulation through hemostasis to stop bleeding out all oxygenated blood.

Blood clotting

Blood vessel gets damaged, and wall is no longer intact. Platelets congregate to form a plug in the gap and stick to the jagged edges of the rupture. It is a positive feedback loop of platelets attaching and stimulating more of a congregation of platelets. However, they are very fragile and cannot plug super well. Platelets and damaged tissue cells release prothrombin activator, which initiates several enzymatic reactions. Fibrin threads form and trap red blood cells, which are much more strong and firm and it will last a couple weeks to a couple months until the blood vessel reforms.

Blood Typing

Cells have antigens on their surface with cell markers, and glycoproteins and glycolipids (coded by genetics). The immune system will be able to tell which cells belong to your body, so they will ignore them because they are specific to you. To donate blood, the donor and recipient must have the same cell markers so the body will not fight against the blood. RBC antigens are very simple and there are not many varieties of antigens: more people within a population will have the same antigen. Must identify antigens in blood transfusions for no immune attacks.

ABO antigens

ABO blood group has two antigens: A and B. If you inherit neither, you have no antigens and have type O. A is a dominant gene, B is co-dominant, and O is recessive. A and B are both dominant and you would express both antigens. Possible blood types are: type A which has A antigens and makes anti-B antibodies and would attack a type B blood. Type B blood has B antigens with anti-A antibodies to attack A type blood. Type AB has both A and B antigens, and does not make any antibodies or it would attack itself. The last blood type is O, which is no A or B without antigens and has anti-A and anti-B antibodies.

Rh Blood Group

Has one possible antigen, Rh. Genetic inheritance is Rh+ dominant allele, and Rh- which is recessive.

Blood Types

A+, A-, B+, B-, AB+, AB-, O+, O-. Positive is when the type has Rh antigen. AB+ is a universal recipient and can receive blood from anyone. O- is a universal donor because it has no antigens to be attacked. However, they can only receive the same blood type.

Blood Compatibility

Important for blood transfusions, and the blood types must be compatible with each other. They test this by putting a few drops of each blood together, and if they clump, then the recipient is creating antibodies against the other and it's incompatible. This is called agglutination. In a human, there is blood clotting which is very bad, so you must make sure the types are compatible.

Hemolytic Disease of the Fetus

If an Rh- mother has a baby with a male who is Rh+ and the dad passes that gene to the fetus, the fetus will also be Rh+. The mom's immune system will be oblivious to the foreign body growing inside, so it won't be producing anti Rh+ antibodies to attack it. When the placenta severs during any process, the fetus cells and the mom's cells will start to mix and go into the mother's bloodstream. The mom's immune system will start making anti Rh+ antibodies, and the next time she gets pregnant the antibodies will cross over the placenta and start to attack the fetus. This will cause hemolytic disease, where the antibodies adhere to red blood cells to destroy them. The cells burst and the fetus becomes anemic. The baby will come out with anemia, but the mom will take a blood type test before childbirth and get injected with rhogam shot so that her immune system will not react to the fetus.

Anemia (iron deficiency and pernicious)

Most common kind of blood disorder. You have reduced oxygen carrying capacity. Symptoms are pallor (pale skin), weakness, and fatigue. There are different types where one has iron deficiency (preventable by ingesting lots of iron-full foods) and pernicious (very devastating). Pernicious causes someone to have incredible weakness and fatigue and results from vitamin B12 deficiency. You need intrinsic factor chemical in your stomach in order to absorb B12, so without that you may get pernicious anemia.

Anemia (Folic acid deficiency, hemolytic)

In pregnant women, folic acid deficiency is common where you do not have enough of a B vitamin. Pregnant women are advised to take folic acid to get red cell count up and keep the developing fetus from getting a neural tube defect. Hemolytic is pretty rare and results when something causes your RBCs to go into hemolysis. Physical symptoms include jaundice, and you start to break down hemoglobin in large quantities, so your liver starts to produce bilirubin. You end up creating too much to excrete, which builds up in your blood and yellows your skin and eyes.

Anemia (Sickle cell)

Part of sickle cell disease category. It is inherited and is recessive (need copies to inherit it). The hemoglobin created is misshaped and when the blood does not have enough oxygen, the hemoglobin is going to form rod type structures in a cell. Those harmful structures will be destroyed by the liver and spleen, resulting in a lower RBC count and anemia. Sometimes when people are very stressed, they get less oxygen and may develop this.

SCID

Severe Combined ImmunoDeficiency. B and T lymphocytes do not develop, and you simply have no immune system. You are susceptible to disease and the virus can be deadly because they cannot rid themselves of the illness. Patients are often secluded so they do not get in contact with microbes. Treatments are getting a bone marrow transplant with functioning lymphocytes, or one can do gene therapy to fix the defective gene.

Leukemia

Cancer of the WBC cell line. Can cause cells (leukocytes) to not fully mature but you cannot use them which is acute leukemia. Chronic leukemia is where cells fully mature but mutate and cannot function normally. Essentially, you lose your immune system. Treatments are chemotherapy to kill off cancerous cells, or you can do stem cell transplant to grow stem cells from the patient and then give them high levels of chemotherapy. After that, you put the cells back in their body. Another option is a bone marrow transplant from another person, where you destroy lots of the person's bone marrow and transplant. However, one can develop graft versus host disease where the transplant starts attacking the patient's body.

Mononucleosis

Infection of lymphocytes by EBV (epstein-Barr virus). The symptoms are fever, sore throat, and swollen lymph glands. It takes 1-2 months to recover, but the virus remains dormant and can return if you are under a lot of stress.

Thrombocytopenia

Reduced platelet count. Causes are reduced production and increased destruction of the platelets. You will be at risk for abnormal bleeding, starting from bruising to nosebleeds to internal bleeding which can go to the brain and be dangerous. Treatment is a transplant of platelets to replace ones you are not making.

Hemophilia

Is an inherited clotting disorder where there is a deficiency in clotting factor and your platelet count is normal. Most common type is hemophilia A, with a deficiency in CF VIII and is an X-linked trait (occurs more in men bc they only need one recessive X gene to get it) and requires regular injections of the CF VIII to treat it.

Thromboembolism

Thrombus is a clot formation in an unbroken vessel, and once it breaks off and moves as an embolus, it will clog a vessel. That becomes this disorder and may lead to myocardial infarction, stroke, pulmonary embolism, which are all potentially fatal. Take anticoagulants to reduce clotting and plaque formations as treatment.

Lymphatic System functions

To absorb excess interstitial fluid through lymphatic capillaries. This system also absorbs fats in the GI system. It produces and does maintenance and distribution of lymphocytes and defends against pathogens. This way, we can stay mostly healthy in everyday life when exposed to pathogens.

Lymphatic system components

Lymphatic vessels carry lymph which is cleaned out and returned to the blood. Lymphatic organs like tonsils, bone marrow, spleen, and lymph nodes.

Lymphatic vessels

Types: microscopic capillaries closely associated with CV capillaries which pull interstitial fluid out and put it into the system. Capillaries come together to form vessels, which carry fluid to the heart. Large lymphatic vessels are called ducts, and you have two of them. Thoracic duct drains lower half of body, right lymphatic drains upper half. Both ducts empty into the superior vena cava by the subclavian vein. It will return the lymph back into the blood. Vessels have a one way flow and have valves for this to close when fluid tries to move backwards. Lymph started as interstitial fluid and is 92% water with the other percents being solutes.

Lymphatic Organs (Primary)

The primary ones are red bone marrow (ends of long bones) which contains hematopoietic stem cells which can become any blood cells, and the Thymus gland over the heart. Thymus shrinks over time as your immune system develops. There are two types of lymphocytes called B and T, but only B become active in the red bone marrow. T type goes to the thymus to become active with a hormone that the thymus makes.

Lymphatic Organs (Secondary)

It is the spleen which is a reservoir for blood and WBCs which need to fight infection. Lymph nodes are another organ which provide a good place for the system to fight disease. Lymph nodes are in places which are susceptible to disease to protect them. Lymphatic nodules are not an organ because they are only epithelial tissue (needs to be two types in order to be organ). An example of nodules is tonsils and Peyer's patches.

Innate Immunity

Does not require previous exposure and has innate responses to prevent us from getting sick or fight the pathogen when it enters the body. It has an immediate response. However, there is no immunologic memory and it does not remember the pathogen after it fights it. This includes physical and chemical barriers as the first line of defense, and inflammation and anti-microbial proteins as the second line of defense to fight the infection.

Physical barriers to infection

Intact skin is the first barrier that protects you from harmful microbes, but once it gets cut, there is a way for those pathogens to enter in. The same thing goes from the second barrier: mucous membranes. This lines the inner cavities in your body like your mouth, and if the inside of your cheek is cut, then you are also susceptible to infection.

Chemical barriers to infection

What is part of the first barrier is the chemical barriers, starting with sweat. Sweat cools down our body temperature and washes away microbes on our skin. Saliva in our mouth not only lubricates and dissolves food, but has lysozymes which break down any microbes in food that we eat. Tears wash away microbes in our eyes, and urine is acidic and keeps the urinary tract clear of microbes. Gastric juice is very caustic, and most microbes cannot survive it. Waste products made by the microbiome is a colony of bacteria living in the colon and small intestine where they provide us with fatty acids and vitamins. They also protect us from disease causing pathogens and compete with them in order to stay in our body.

Inflammation components and symptoms

If the barriers don't work and the microbe gets through, a mechanism your body employs is this. Neutrophils and macrophages are the cells which are part of the process, along with the chemicals histamine and cytokines. The symptoms are redness, heat, swelling, and pain.

Inflammation steps

First of all, there is histamine secretion. Next, there is a release of cytokine inflammatory chemical, then a diapedesis of neutrophils and macrophages. The capillary walls become leaky, so the WBCs leave the capillary and squeeze through the cells to go to the site of infection. The white blood cells leaving the system is called diapedesis. Finally, there is blood clotting and there is leakage of plasma into the area of damage. The interstitial fluid begins to rise, which causes swelling. The swelling pushes up against the nerves and causes pain.

Anti-microbial proteins

This is part of the first line of defense for our body. The complement system is a series of inactive proteins labeled C1 through C9 and activate to help boost the immune response. They trigger histamine release and attract phagocytes to come to the area of infection and help out with getting rid of the pathogen. The membrane attack complex (MAC) punctures a hole in the microbe, which leaks fluids and the cell ruptures and dies. It basically pokes a dart in the microbe to kill it. Another thing is Interferon, which helps uninfected cells to develop defense mechanisms against a virus.

Antigens

Self (cell markers) and non-self (pathogenic) antigens. They are usually protein based. Examples of non-self are portions of microbes, abnormal body proteins (a virus which modifies proteins and cancer cells which create non-self antigens).

Adaptive immunity

This is the third line of defense: it exhibits specificity and is custom tailored to the specific microbe. It is much stronger in responding in an infection and involves lymphocytes. The innate system in comparison uses non lymphocytic leukocytes. Two pathways of adaptive immune response: cell-mediated immunity with antigens within cells and T cells, and humoral immunity with antigens outside of cells and B cells.

Antibody-Mediated Immunity

The clonal selection model bindes an antigen to BCR, which activates a B cell. It will start rapidly proliferating (clonal expansion) and undergo mitosis. It will create two types of cells, plasma cells (pump out quantities of antibodies) and memory cells (not active during infection and will remember it). Apoptosis would be the death of unneeded cells. When infection is over, plasma cells die for cleanup because the antigen is gone. Overall, this type of immunity is good for antigens outside our body.

Antibody structure

Composed of four polypeptide chains: two are heavy and two are light. The heavy ones are longer and weigh more, and the light ones are shorter and weigh less. Antigen binding sites are at the ends of the chains. The antigen fits into the bonding site like a lock and key.

Antibody Classes

Five different genes for the classes determined by the constant region (labeled C). V region stands for variable, and will vary based on the antigen. The five classes are IgG, IgM, IgA, IgD, and IgE.

Functions of each antibody class

IgG is the main antibody in circulation binds to pathogens, IgM is an antibody found in circulation which is formed by a newborn and activates complement system and clumps cells. IgA is the main antibody in secretions, and prevents pathogens from attaching to epithelial cells in digestive and respiratory tracts. IgD is the antibody type found on the surface of immature B cells, and signifies the readiness of the B cell. IgE is an antibody found as antigen receptors on tissue cells, and is responsible for immediate allergic response and protection against parasitic worms.

Antibodies in Medicine

Monoclonal antibody development is where you fuse a plasma cell from the body and a cancerous cell, then you create a hybridoma. That hybridoma creates antibodies which are extracted and injected into the body. The antibodies are for diagnosis and therapy (cancer or autoimmune diseases).

Cell-mediated Immunity (antigen recognition)

T cell receptors cannot recognize cell markers. Instead, they want you to provide the antigen on an MHC (human leukocyte antigens) which are found on body's cells. They can bind to and present the antigen to the T lymphocytes. There are two types of MHCs, MHC I which is on all nucleated cells which bind to antigen from endogenous antigens (created from virally infected cells). The antigens are a sign that the cell needs to be destroyed by the T cell receptor because it is infected. MHC II is on antigen presenting cells (APCs) and will present the antigen from exogenous sources like bacteria. The antigen presenting cells can take the bacteria and chop it into pieces to display it.

Cell-Mediated Immunity (Fighting endogenous antigen)

The antigen binds to the TCR and is presented on MHC I by self cell. The TCR will secrete chemicals to kill the self cell: those chemicals being perforin and granzyme. Perforin pokes a hole in the cell, and granzyme goes through the hole and destroy the DNA of the target cell so it dies.

Cell-Mediated Immunity (Fighting exogenous antigen)

The antigen binds to the T cell receptor and is presented on MHC II by APCs. There will be clonal expansion where the helper T cell secretes cytokines, and the memory T cell remembers the infection so you have a more effective way of getting rid of the pathogen when it comes back. When infection is over, apoptosis happens and the T cells kill themselves as they are not needed.

Active Immunity

Individual produces antibodies after infection or after immunization. The primary response is the first time we're exposed to the pathogen, and the secondary is any subsequent times we're exposed to the same one. Level of immunity is measured with an antibody titer. This type of immunity is better for long-term.

Passive Immunity

These are individual given antibodies through the placenta, breast milk given to babies through mother's breastfeeding, and injecting antibodies.

Allergies

People who have this are hypersensitive to allergens you normally don't response to. There are two types of responses: immediate (IgE induced with histamine release, anaphylactic shock needing EpiPen if severe) and delayed type. For immediate, EpiPens contain norepinephrine injected into the body so the airways open up for BP and heart rate to go up. The delayed response is cytotoxic T cell induced and releases cytokine.

Immunodeficiencies

A weakness of the immune system where the body cannot protect itself against disease. An example is SCID, which is genetic and there is a lack of humoral and cell mediated immune systems. While you have first and second barriers of defense, you lack the third one line of defense. People with this are very susceptible to illness and should be secluded from other people who have microbes. AIDS is HIV infection which targets helper T cells which boost the innate immune response. Without the T helper cells, you do not have an innate or adaptive system. People don't die from AIDS solely, but the diseases that they contract because of their inability to fight off infection.

Autoimmunity

Fighting against one's own tissues (self cells) instead of fighting foreign ones. The process becomes confused and your body thinks your own cells are foreign, and depending on what it views as foreign determines the disease. There is one where cytotoxic T cells and antibodies attack self cells, and the cause is unknown. Men are more likely to get this disease than women, so it may have to do with hormones. Risk factors are certain HLA antigens (self markers) and being female is also a risk factor.

Autoimmunity examples

Examples are rheumatoid arthritis, where auto reactive cells attack your own joints until patients lose all mobility. Systemic lupus erythematosus are severely anemic, and their spleen and liver become enlargened and they may display rashes. It is very severe. There is also myasthenia gravis, where the antibodies binds to the receptor and there's no signal telling the muscle to contract. Ultimately, it leads to muscle paralysis. The last example is multiple sclerosis. Neurons are wrapped by myelin, but the auto reactive cells start to attack the myelin and leave scars. Scarred neurons do not function, so they start dying off and your hands and feet will tingle, and you will lose speech, vision, and motor function.

Organ Transplantation

Organ rejection can be controlled by carefully selecting the

organ to be transplanted and administering immunosuppressive

drugs. It is best if the transplanted organ has the same type of

MHC antigens as those of the recipient, because cytotoxic T cells

recognize foreign MHC antigens. Rejection of transplanted tissue results

because the recipient’s immune system recognizes that the trans-

planted tissue is not “self.” Cytotoxic T cells respond by attacking

the cells of the transplanted tissue. Alternatives is transplanting from animals with similar organs (like pigs) or tissue engineering organs in labs.

Microbes

Microscopic organisms with much smaller structures than eukaryotic cells. Most of them are useful to humans, such as in bread, cheese, or drugs. A bacteria can create a drug and be injected into humans. They also work as decomposers to get rid of dead tissue. Only some of them are considered pathogens.

Bacteria

Single-celled and prokaryotic, and come in different shapes: coccus (sphere), bacillus (rod), spirillum (spiral)

Bacterial Anatomy

It has no nucleus and has one chromosome, a circular chromosome called a plasmid. Not all of these have plasmids. It has a plasma membrane, a cell wall, and is inside a capsule. A flagellum (tail) is attached to it, and there are also fimbriae (looks like hair), and a pillus (conjugation).

Bacterial Physiology: Conjugation

Conjugation is when two cells, one with a plasmid one, one without a plasmid. The one with a plasmid copies itself and transfers the plasmid to the other one so they are both F positive. It has basically transferred its own genes to the other one, and now the one without a plasmid is resistant to antibiotics because it gained one plasmid.

Bacterial Physiology: Binary fission

A bacterial cell splits in half to create two new cells which are a perfect copy of the original.

Viruses

They are acellular (not a living organism characteristic), they cannot acquire and use nutrients. Their structure is an outer capsid with proteins, an inner core with nucleic acid with DNA or RNA. Viruses dock to a host cell in a human body, empty their viral contents and integrate into the genetic material of the host, then make copies of itself. After that, the host cell releases it. While replicating itself, the virus will destroy the host cell.

Prions

Infectious proteins which are not living, and are transmitted by eating infected nervous tissue. It causes neurodegenerative diseases like CJD, BSE, and scrapie (sheep).

Tuberculosis

A disease which affects the lungs. The causative agent is mycobacterium tuberculosis, and it has a waxy coat to live for weeks outside the body. Transmission is by airborne droplets, for they can float for several hours and be breathed in. The likelihood of getting sick is dependent on how long someone is exposed to the bacterium. The symptoms are coughing, chest pain, blood in sputum. Incubation can be 1-3 months so you can be asymptomatic for a while. Tubercles form and have bacteria and macrophages.

Tuberculosis Infection types

Latent infection means that the bacteria are in your body but are dormant. They are not currently making you sick. Active infection means you are symptomatic and need treatment.

Tuberculosis treatment

There is a combination of multiple antibiotics to be effective, and it is a 6 month course. The best way to prevent tuberculosis is to isolate patients, monitoring for drug compliance (do not create antibiotic resistant tuberculosis bacteria), and treat anyone exposed to active tuberculosis.