Unit 1 Assignments

What is anemia and what could cause it?

Anemia is when the percentage of erythrocytes is lower than normal or the oxygen carrying capacity of the hemoglobin is reduced (not enough hemoglobin to carry around or the red blood cells are not functioning correctly). Some causes could be decreased/abnormal erythrocyte formation, heavy blood loss, such as a car accident, a deficiency of iron, vitamin B12, or folic acid, and genetic defects.

Describe how immune cells in the blood find their way to the site of infection/injury. Be sure to use the terms: margination, diapedesis and chemotaxis.

Immune cells in the blood find their way to the site of infection/injury by first, margination. This is when the CAMs on the white blood cells bind to CAMs on the endothelial cells, which brings the leukocytes closer to the capillary. During diapedesis, the immune cells leave the blood by squeezing through the capillary cells and into the part of the tissue that is infected. During chemotaxis, there is a movement of white blood cells along a chemical gradient until they reach the location of the infected/damaged tissue.

MHC class I molecules usually present self to lymphocytes. What has to have happened to the cell for an MHC class I molecules to present foreign antigens instead?

In order for an MHC class I molecule to present foreign antigens instead of self is if the cell in infected. This is because the infected cell gives of peptide fragments that are unfamiliar to the immune system. - If infected, the rough ER is no longer making proteins, they start making bacterial/viral proteins instead, MHC Class I grabs a fragment and stimulates cytotoxic T-cells, T-cells kill it off

What type of cell resides within the bone marrow and forms platelets? Explain platelet formation.

Megakaryocytes reside within the bone marrow and form platelets. They sit on top of the capillaries and get really big, producing more and more cytoplasm. One the weight gets too heavy the cytoplasm oozes down into the capillaries/blood stream which creates proplatelets. The small pieces that are sliced off are what become platelets.

List the benefits of a low-grade fever.

Some of the benefits of a low-grade fever are that it prevents the replication of the bacteria/viruses, it promotes activity of the interferons, the immune system increases its activity, tissue repair is sped up, and the lymphatic capillaries start to see an increase in CAMs on the endothelial cells.

What are T-cell Co-receptors need for? How do they differ between helper T cells and cytotoxic T cells?

T-cell co-receptors are needed for physical interaction with antigen presenting cells. The difference between helper T cells and cytotoxic T cells is that helper T cells contain CD4 proteins while cytotoxic T cells contain CD8 proteins.

What 4 things are required for the coagulation stage of hemostasis?

The 4 things that are required for the coagulation stage of hemostasis are calcium, clotting factors, platelets and vitamin K.

Explain how the Fc regions of an antibody aids in the immune response.

The Fc regions of an antibody can do one of 3 things. It can go through what is called a complement fixation, which is when the Fc region of IgG and IgM bind to complement proteins, causing the activation of the complement system. There is also opsonization, which is when the Fc region of IgG causes opsonization; some phagocytic cells have certain receptors that can swallow both antibodies and antigens. Lastly, there is the activation of natural killer cells, in which the Fc region of the IgG antibodies bind to specific natural killer cells that destroy foreign particles by the release of cytotoxic chemicals.

Explain the exogenous pathway used to bind an MHC class II molecules with a foreign antigen.

The exogenous pathway is when the phagocytic cell swallows bacteria/antigen and brings it into the cell. A lysosome then binds to that vesicle and breaks up the bacteria. Then a vesicle containing an MHC class II molecule comes from the Golgi apparatus and binds to the structure, picking up a fragment from the broken-down bacteria. It travels to the plasma membrane and lets the others know that it has swallowed bacteria and that there is a problem.

Which cells of the body use MHC class I molecules to present antigen to the lymphocytes? Which cells of the body are the only ones that can use MHC class II molecules?

All nucleated cells of the body (except red blood cells, sperm and ovum) use MHC class I molecules to present antigen to the lymphocytes. The only cells of the body that can use MHC class II molecules are dendritic cells, macrophages and B-cells (antigen presenting cells).

Define antigen. Explain how foreign and self-antigens interact with the immune system. What causes an autoimmune disorder?

An antigen is a substance found in the plasma membrane that binds with a component of the adaptive immune system (either lymphocytes or antibodies). Foreign antigens bind with one of these components because they are different from the human body's molecules and don't belong to the body. Self-antigens also bind but they do not activate the body's immune components. An autoimmune disorder can occur when lymphocytes get the components mixed and react with a self-antigen as if it was a foreign antigen.

What is an antigen presenting cell? Which cells of the body display self-antigens?

An antigen presenting cell is an immune cell that functions specifically to communicate the presence of foreign antigen to both helper T cells and cytotoxic T cells. All cells in the body with a nucleus display self-antigens, unless they are infected.

Match the follow description with the correct complement outcome: A. Opsonization B. Inflammation C. Cytolysis D. Elimination of immune complex ___ Activation of mast cells and basophils, attraction of neutrophils and macrophages _____ Binding of immune complex to erythrocytes to be transported to liver and spleen _____ Binding of opsonin protein enhances pathogen for phagocytosis _____ Membrane attach complex forms holes in target cell causing fluid to enter and lysis of cell

B D A C

What exactly is complement and where does it come from?

Complement is a system of 30 plasma proteins that are produced by our liver and then released into the blood. It makes up just about 10% of the blood serum proteins. The reason why they are named that is because of how well they "complement" the antibodies.

For each of the following interferons, explain what types of cells would release them and what their function is. IFN-α and IFN-β IFN-γ

IFN-α and IFN-β Virus-infected cells release these interferons. Their function is to bind receptors of their neighboring cells, which triggers the synthesis of enzymes that destroy viral RNA or DNA and inhibit the process of viral proteins being made. After this process, these cells are protected from contracting the virus infection. IFN-γ IFN-y interferons are produced by natural killer cells, and they aid in the process of the stimulation of macrophages to destroy the virus-infected cells. These macrophages can also help clean up any viral infected cells/tissues

If an MHC class I molecule is presenting a foreign antigen, which type T-cell will respond and what will happen to the infected cell? If an MHC class II molecule is presenting a foreign antigen, which T-cell will respond?

If an MHC class I molecule is presenting a foreign antigen, it initiates a response from cytotoxic T-cells, which kill off and destroy the infected cell. If an MHC class II molecule is presenting a foreign antigen, it will initiate a response from the helper T-cells, which results in the stimulation of the adaptive immune system.

What is hematocrit and how can it be clinically used to help with diagnosis of a patient?

The clinical definition of hematocrit is the percentage of erythrocytes (RBC) within the blood. Hematocrit varies depending on age and gender. Young children and infants range from about 30%-60%, while older children range 35-50%. Adult females range a little lower in percentage than adult males (due to testosterone's influence on the release of EPO). A high percentage of hematocrit can mean dehydration (because blood becomes stickier and harder to get through) or blood-doping. Low percentages may mean anemia.

Explain the effector response of helper and cytotoxic T-cells.

The effector response of T-cells is that they leave after multiple days of exposure and move to the site of infection, releasing cytokines to regulate the immune cells. Helper T-cells function to activate the cytotoxic T-cells and B-cells and increase the formation of immune cells. Cytotoxic T-cells function to destroy the body cells that are infected (that show the antigen) by releasing perforin and granzymes. They have the same function as natural killer cells.

What causes the following signs of inflammation? Redness Heat Swelling Pain

Redness- increased amount of blood moving into tissue Heat- increased amount of blood flow and heightened metabolic activity in the area Swelling- increased amount of fluid lost from capillaries Pain- due to kinins, prostaglandins and substances that are released by the microbes, also compression of pain receptors

Why is local/acute inflammation good for us? What is exudate?

Local/acute inflammation is good for us because it shows that our body is fighting whatever infection our body has, and it is protecting us. Exudate is an increased movement of fluid, immune cells, and proteins that leave the capillary when there in an infection present.

Explain the function of natural killer cells. What are perforins and granzymes?

Natural killer cells function to destroy a huge variety of the cells that are unhealthy to us, such as those infected with viruses and bacteria. Perforins form pores in plasma membranes, and granzymes enter the cell and initiate the process of apoptosis. Both of these help the process of releasing cytotoxic chemicals.

What types of cells are phagocytic? Besides phagocytosis, what is the function of dendritic cells and macrophages? What happens to neutrophils after engulfing a microbe?

Neutrophils, macrophages and dendritic cells are phagocytic. The other function of dendritic cells and macrophages is to destroy infectious agents and then introduce little pieces of the microbe on the cell surface to activate the immune system. Soon after engulfing a microbe, neutrophils die and become a part of pus.

What two organs break down old erythrocytes? Why do erythrocytes need to be removed from the blood within about 120 days of their formation? Describe how the parts of hemoglobin are 'recycled'.

Old erythrocytes are broken down in the liver and the spleen by Kupffer cells (macrophages). Erythrocytes have to be removed from the blood within 120 days of formation because there is no nucleus, so the lost ones need to be replaced by new ones. The globin proteins are broken down into single amino acids. The heme is converted to bilirubin, which is a part of bile produced by the liver. Iron is stored in the liver or the spleen and bound to storage proteins called ferritin.

Describe what is occurring during each event of a fever.

Onset- The hypothalamus stimulates blood vessels to vasoconstrict, which causes the shivering to begin and the body temperature to increase. Stadium- The metabolic rate is increased to help the process of removing the harmful substance that is causing the sickness. Defervescence- This occurs once the illness is not completely gone but is under control. The hypothalamus will bot longer be run by pyrogens, and the amount of prostaglandin E2 releases decreases, setting the temperature set point back to normal. During this phase, the body releases heat which is what causes sweating.

What do plasma cells do?

Plasma cells only have a 5-day lifespan and stay in the lymph nodes the whole time. They are constantly producing and releasing antibodies to move throughout the body.

What do platelets stick to and what is the purpose of a platelet plug?

Platelets stick to collagen fibers which are exposed when the walls of blood vessels become damaged. The purpose of a platelet plug is to temporarily close off an injury.

What are the three types of lymphocytes that can form from the lymphoid stem cell? Where do each of the lymphocytes mature?

The 3 types of lymphocytes that can form from the lymphoid stem cell are B-lymphocytes, T-lymphocytes, and natural killer cells. B-lymphocytes mature in the bone marrow, T-lymphocytes mature in the Thymus, and natural killer cells come directly from lymphoid cells (there's no in between steps).

Which cells can act as pro-inflammatory cells? What chemicals are released by these cells?

The cells that act as pro-inflammatory cells are basophils and mast cells. The chemicals released by these cells include histamine (increases vasodilation and capillary permeability), heparin (anticoagulant that prevents from sticking together), and eicosanoids, which increase inflammation.

The chemicals released by platelets function to do what?

The chemicals released by platelets function to cause longer vascular spasms, attract more platelets, stimulate coagulation, and stimulate the replication of necessary cells to repair the damaged vessels.

For each of the following cells, describe what is occurring within each. Which one enters the blood? Erythrocyte Normoblast Reticulocyte

The erythroblast is where red blood cells start being formed. The erythroblast starts to produce hemoglobin in its cytoplasm and then ejects the nucleus once there has been enough transcription, which forms the normoblast The normoblast makes more hemoglobin and breaks down all of the remaining organelles (except ribosomes), then forming into a reticulocyte. The reticulocyte enters the blood stream and finishes the production of hemoglobin (although it is not functional yet; has to go through process of becoming an erythrocyte).

What are the three types of vascular changes that occur during inflammation?

The first type of vascular change that occurs during inflammation is the vasodilation of local arterioles (opening up of blood vessels going into damaged areas). The second is an increase in capillary permeability. This means that the simple squamous cells contract and make bigger openings between them, causing more fluid to move out of blood and into the capillaries, causing them to burst. The third type is the stimulation of capillary endothelium to display CAMs (cell adhesive molecules, which appear on simple squamous cells that make up the capillaries).

Where in the body are blood cells formed and what is the stem cell that all formed elements come from?

The formation of blood cells (hematopoiesis) occurs in the red bone marrow. The stem cell that all formed elements come from is the hemocytoblasts. There are 2 lines of blood cell formation within that; the myeloid line and the lymphoid line.

What are the four different types of T cells? What are their functions?

The four types of T cells are helper T cells, cytotoxic T cells, memory T cells, and regulatory T cells. Helper T cells are the main ones that coordinate the immune response. If helper T cells are not activated, none of the adaptive immune system cells will activate. Cytotoxic T cells act pretty much like natural killer cells; they release chemicals that are toxic to the cells which results in the destruction of them. Memory T cells do not do anything during the first infection. They stick around just in case the body comes across the same antigen a second time, and they create a quicker response to that antigen. Regulatory T cells function to suppress the immune response and make sure the replication does not get out of hand.

Myeloid stem cells can form into which of the formed elements? Which blood cell is the only one to form from the lymphoid stem cell?

The myeloid stem cells can form into erythrocytes (red blood cells), granulocytes, monocytes and platelets. The blood cell that is the only one to form from the lymphoid stem cell is lymphocytes.

The second line of defense, also known as the nonspecific internal defenses, includes what three types of defense?

The second line of defense (nonspecific internal defenses) include cellular defense, chemical defense, and physiologic processes. Cellular defense includes mast cells, macrophages, and natural killer cells. Chemical defense is the use of antimicrobial proteins (IFNs) and the complement system. Physiological processes include things like fever and inflammation.

In what two ways can the complement system become activated?

The two ways that the complement system can become activated are the classical pathway and alternative pathway. The classical pathway is composed of complement proteins that bind to antibodies that have previously attached to foreign substances. The alternative pathway consists of polysaccharides that are found on certain bacterial/fungal cell walls that bind with one of the complement proteins.

How do the variable and constant regions of an antibody differ in function?

The variable regions of an antibody are located at the end of the arms (top of Y shape) and that is where the antigen-binding sites are found. It is called a variable region because the antibody is specifically made to bind to bacteria that activated the B-cell. The constant region is considered the "stem" region of the antibody (the bottom of the Y shape, also called the Fc region), and it determines the function of the antibody and what type of immunoglobins are present.

What are vascular spasms and what causes them to occur?

Vascular spasms are a phase of hemostasis, and they occur when a blood vessel is damaged. The smooth muscle in the blood vessel contracts which causes vasoconstriction. This limits blood loss and can continue to occur even after the damage occurs.

What type of infection would interferons be used for?

Viral infections

Why is leukopoiesis stimulated during inflammation?

When GM-CSF is released, stimulating leukopoiesis, more white blood cells come out of the bone marrow. This is basically functioning to let the bone marrow know that it needs to make more white blood cells because they don't regenerate themselves.

Explain how the antigen-binding sites of an antibody aid in the immune response.

When an antibody binds to a pathogen, it can do one of three things. First, it could go through the process of neutralization, which is when the antibody covers every single antigen on the cell, causing the microbes to be ineffective and unable to infect the body. The second one is agglutination, which is when the antibody connects the foreign antigens to form a cluster, making it easier for phagocytes to come in and clean up the bacteria. The third would be precipitation, which is when the antibody takes all of the chemicals released by the pathogen and group them into a cluster, forming an insoluble antigen-antibody complex.

MHC class I and II molecules are both __________ made in the _______. MHC class I molecules attach to antigen through the __________ pathway while MHC class II molecules attach to antigen through the ________ pathway.

glycoproteins rough ER endogenous exogenous

The intrinsic pathway of coagulation initiation is caused by damage to the __________ of a blood vessel. This causes ___________ to release ____________. The extrinsic pathway of coagulation initiation is caused by damage to the ___________ of a blood vessel. This causes ____________ to release ___________. Both pathways eventually stimulate the common pathway which starts with the activation of ___________.

inside platelets factor XII outside damaged tissues factor III factor X

B cells will stay in the secondary structures and replicate into ... which make... which are then transported to...

plasma cells antibodies the site of infection

B cells mature in the ...

red bone marrow

Lymphocytes are formed in the ...

red bone marrow

Lymphocytes are housed and activated within ...

secondary lymphatic structures

Both ___________ and __________ provide physical, chemical and biological barriers to prevent pathogens from entering the body. _______ , __________, ________ and __________ contain lysozyme (an antimicrobial agent) while only _________ , __________ and ___________ contain IgA. Sebaceous gland secretions inhibit the growth of microbes by contributing to a _________ skin pH while the gastric juices within the stomach contain ____________ which can destroy microbes and toxins that enter through ingestion. If a microbe survives the gastric juices of the stomach _____________ and/or _____________ can expel the microbes from the body before they can be absorbed into the tissues.

skin mucosal membranes sweat mucus saliva tears mucus saliva tears low acid diarrhea vomiting

T cells mature in the ...

thymus

The __________ is the specific site of an antigen that is recognized by and can bind with an immune component, such as a __________ or an ____________. Poison ivy causes an immune response only after it releases small molecules called ___________ onto the skin. These poison ivy molecules then have to bind with _____________________ within our skin to be recognized by the immune system.

antigenic determinant lymphocyte antigen haptens carrier molecules

T cells will migrate out of the secondary structures to provide their effector response ... (where?)

at the site of infection

What are the five types of antibodies and where in the body would you find each of them?

1. IgG- These make up 75-85% of all antibodies and can be found in CSF (brain), lymph, serous fluid, peritoneal fluid, and joints. 2. IgM- These are mostly found in blood and are also made by immune cells 3. IgA- These are found in areas that are exposed to the outside environment, such as mucous membranes, mucus, saliva, tears, tonsils, and even breast milk. 4. IgD- They function as B-cell receptors. They are not released by the cell and do not float around; they are attached to B cells. 5. IgE- These antibodies are formed in response to parasitic infections and allergic reactions. They cause histamine to be released from basophils and mast cells and attract eosinophils.

Describe the structure of hemoglobin. What part of the hemoglobin does O2 and CO2 bind with it?

A hemoglobin molecule is composed of four globin proteins (2 alpha chains and 2 beta chains). Each globin has a heme group, which is an organic ringed molecule with an iron ion in its center. Oxygen forms weak bonds with iron ions, and carbon dioxide forms bonds with the globin proteins (alpha and beta).

What is a pyrogen and how does it induce a fever? (explain what is happening in the hypothalamus)

A pyrogen is a molecule/chemical that cause a fever to start. This happens due to the pyrogens causing the hypothalamus to release prostaglandin E2 that increases the temperature set point. The more E2 released, the higher the set point is going to be reset.

After T cells have completed both positive and negative selection, they must complete the maturation process by going through differentiation. What is differentiation and how does if define which cells become helper T cells and which ones become cytotoxic T cells?

Differentiation is the last step in T-lymphocyte selection (only 2% of cells survive the selection process in the thymus). The t-cells become Helper T-cells if they lose the CD8 protein; they become Cytotoxic T-cells if they lose the CD4 protein. They then migrate out of the thymus to their secondary lymphatic structures. They are immunocompetent which means they can bind to an antigen and respond to it but still considered naive because they have not yet been exposed to their antigen

Explain what is being tested for during both positive and negative selection. Which cells would go through apoptosis?

During positive selection, immature t-cells bind with cells that have MHC molecules. T-cells that bind with MHC molecule survive, where they travel to the medulla of the thymus, ready to go to the next stage. T-cells that do not bind with MHC molecules go through the process of apoptosis because they will not help the immune system in any way. During negative selection, dendritic cells present self-antigens with MHC class I and II molecules to immature t-cells. Those that ignore the self-antigen survive and those that bind to the self-antigen go through apoptosis.

Each lymphocyte is specific for recognizing how many antigens? How do B-cell receptors and T-cell receptors differ in regards to how they recognize an antigen?

Each lymphocyte is specific for recognizing 1 antigen (this is why we have so many lymphocytes: they are all specialized). B-cell receptors will make direct contact with the antigen, while T cell receptors will not react until the antigen is process and shown in the plasma membrane of an antigen presenting cell.

What are eosinophils primarily responsible for and how do they do this?

Eosinophils are primarily responsible for the targeting of multicellular parasites. They release enzymes and other things that are deadly to the parasite. These enzymes that are released form pores in the plasma membranes of parasitic cells.

Explain the common pathway. What is trapped by the fibrin mesh to form the clot?

Factor X combines with both Factors II and V, and Ca2+ and PF3 form into the prothrombin activator. This causes the activation of prothrombin (Factor II) forming into thrombin. Then, the thrombin converts Factor I (fibrinogen) into fibrin; Ca2+ and Factor XIII cross-link together and help stabilize the fibrin fibers, forming a mesh network. This mesh network then traps the formed elements and plasma proteins to form a clot.

About how long does it take for an erythrocyte to form (from myeloid stem cell to functioning erythrocyte)? How does EPO influence this production? What two organs secrete EPO and why would they do so?

From myeloid stem cell to the reticulocyte, it takes about 5 days. Once all the hemoglobin is made and the ribosomes have broken down, the erythrocyte is made, which takes about 2 days. This means that it takes about 7 days from myeloid stem cell to functioning erythrocyte. EPO influences this production by speeding up the rate of red blood cell formation (erythrocytes). The kidneys and the liver secrete this hormone when there is a decrease in blood oxygen levels.

Myeloid stem cells will form into a progenitor cell due to the release of ________. This progenitor cell will then form into a ___________ due to the release of __________ and will eventually form into one of the granulocytes. It can also form into a ____________ due to the release of __________ and will eventually form into a monocyte.

GM-CSF myeloblast G-CSF monoblast M-CSF

How do hemophilia and thrombocytopenia differ? Be sure to include what is missing from each and what causes them.

Hemophilia is a lack of certain clotting factors. There are 2 types: hemophilia A and hemophilia B. In hemophilia A, factor VII is missing, this is the most common type. In hemophilia B, factor IX is missing. Hemophilia occurs in an X-linked recessive pattern (males show full-blown disease while females carry the genes and are not actually affected by it). Thrombocytopenia, on the other hand, is a platelet deficiency. It is caused by an increased breakdown or decreased production of platelets. This may occur in cancer or bone marrow infections.