Physiology Term 1 Final Midterm (December 7) Flashcards
Define humoral immunity.
Immunity conferred by antibodies present in the blood plasma and other bodily fluids.
What do antibodies do?
Though they are produced by lymphocytes, antibodies circulate freely in the blood and lymph, where they bind primarily to extracellular targets—bacteria, bacterial toxins, and free viruses— inactivating them temporarily and marking them for destruction by phagocytes or complement.
Define cellular immunity.
Immunity conferred by activated T cells, which directly kill infected or cancerous body cells or cells of foreign grafts and release chemicals that regulate the immune response. Also called cell-mediated immunity.
What four key characteristics sets the adaptive immune system apart from the innate immune system?
- The adaptive immune system involves lymphoyctes called the T and B lymphocytes.
- It is specific
- It is systemic
- It has memory.
Define antigen.
Large organic molecules, usually a protein, stuck in a cell membrane which could be self or foreign.
Define MHC proteins.
Major histocompatibility complex. Molecules on the outer surface of the plasma membrane of all cells; help the immune system distinguish self from nonself. T cells recognize antigens only when combined with these proteins.
What marks a cell as “self” instead of non-self?
Self-antigens, particularly MHC proteins, mark a cell as self.
Which cells oversee humoral immunity?
B cells
Define T cells.
Non-antibody producing lymphocytes that constitute the cellular arm of adaptive immunity.
Define immunocompetence.
The ability of the body’s immune system to recognize (by binding) specific antigens; reflects the presence of plasma membrane-bound receptor.
Define self-tolerance.
Each lymphocyte must be relatively unresponsive to self-antigens so that it does not attack the body’s own cell.
Define antigen-presenting cell (APC)
A specialized cell (dendritic cell, macrophage, or B cell) that captures, processes, and presents antigens on its surface to T lymphocytes.
What two types of cells are involved in adaptive immunity?
T lymphocytes and B lymphocytes
Where are both T cells and B cells produced?
Bone marrow
Where do T cells mature?
thymus
Where do B cells mature?
Bone marrow. Then they go to the blood and lymph nodes.
What is the name of one of the important self-antigens contained on the cells?
MHC glycoprotein (major histocompatibility complex); also known as human leukocyte antigens - HLAs
What is the role of the MHC protein?
To present fragments of either your own proteins or foreign antigens.
What are the two main classes of glycoproteins?
Class 1 and Class 2.
Where are Class 1 found?
They are found on just about all cells in the body. (any cell with a nucleus)
Where are Class 2 found?
They are found on B cells, dendritic cells and macrophages.
How are B cells activated?
By an antibody challenge that usually happens in the spleen or the lymph node.
Describe what happens when a B cell comes into contact with an antigen.
Once it is bound onto the antigen, it is stimulated to start dividing. The cells it produces are known as clones. Keeps dividing and dividing and creating cells that identical to the parent cells.. After a while these clone cells start to differentiate and start to form plasma cells and occasionally a memory B cell.
Structurally, what do antibodies consist of?
Four looping polypeptide chains linked together by disulfide bonds.
Describe antibody class IgM
The first immunoglobulin class secreted by plasma cells during the primary response. Readily fixes and activates complement. Numerous binding sites make it a potent agglutination agent. (pentamer)
Describe antibody class IgA
Referred to as secretory IgA, is found in body secretions such as saliva, sweat, intestinal juice and milk. Helps stop pathogens from attaching to epithelial cell surfaces. (dimer)
Describe antibody class IgD
Found on B cell surface
Functions as a B cell antigen receptor (as does IgM) (monomer)
Describe antibody class IgG
Most abundant antibody in plasma, accounting for 75%-85% of circulating antibodies
Main antibody of both secondary and late primary responses
Readily fixes and activates complement
Crosses the placenta and confers passive immunity to the fetus. (monomer)
Describe antibody class IgE
Stem end binds to mast cells or basophils. Antigen binding to its receptor end triggers these cells to release histamine and other chemicals that mediate inflammation and an allergic reaction. (monomer)
What is the most common event in all antibody-antigen interactions?
Formation of antigen-antibody complexes.
List the defense mechanisms used by antibodies.
Neutralization, agglutination, precipitation and complement fixation.
What are the main functions of blood? Please give an example of each.
Transport (delivering oxygen from the lungs), regulation maintaining normal pH in body tissues), and protection. (preventing infection - antibodies, complements proteins and leukocytes drift in the blood).
What does ADP do as part of hemostasis?
A potent aggregating agent that causes more platelets to stick to the area and release their contents
Define antibody.
A protein molecule that is released by a plasma cell (a daughter cell of an activated B lymphocyte) and that binds specifically to an antigen; an immunoglobulin.
Define B-cells.
Also called B lymphocytes. Oversees humoral immunity; their descendants differentiate into antibody-producing plasma cells.
Define buffy coat.
Layer contains leukocytes (leuko = white), the white blood cells that act in various ways to protect the body, and platelets, cell fragments that help stop bleeding.
Define coagulation.
Process in which blood is transformed from a liquid to a gel; blood clotting.
Define diapedesis.
Passage of white blood cells through intact vessel walls into tissues.
Define erythropoeisis.
Refers to the production of red blood cells. Find them in flat bones like the pelvic girdle, sternum, skull or shoulder blades.
What is fibrin?
Fibrous insoluble protein formed during blood clotting.
What is fibrinogen?
A soluble blood protein that is converted to insoluble fibrin during blood clotting.
Define hematocrit. What is its normal value?
The percentage of total blood volume occupied by erythrocytes. It is normally about 45%.
List two protective functions of blood.
Blood can prevent blood loss by forming clots when a blood vessel is damaged. Blood can prevent infection because it contains antimicrobial proteins and white blood cells.
What is the chemical composition of plasma?
Blood plasma is a straw-colored, sticky fluid
Although it is mostly water (about 90%), plasma contains over 100 different dissolved solutes, including nutrients, gases, hormones, wastes and products of cell activity, proteins, and inorganic ions (electrolytes)
Electrolytes (Na+, Cl−, etc.) vastly outnumber the other solutes.
What are formed elements?
erythrocytes, leukocytes (white blood cells), and platelets
True/False: All formed elements are true cells?
False. 2 out of 3 are not (RBCs have no nucleus and platelets are fragments).
If you put blood in a centrifuge, what would the breakdown be?
RBCs (45%), Buffy coat (< 1%), plasma (55%)
How many molecules of oxygen can each hemoglobin molecule transport? What part of the hemoglobin binds the oxygen?
Each hemoglobin molecule can transport four O2. The heme portion of the hemoglobin binds the O2.
List the differential white blood cell count from most to least and outline their percentages.
Neutrophils (50-70%), Lymphocytes (25 - 45%), Monocytes (3-8%), Eosinophils (2-4%), Basophils (0.5 - 1 %) (think Never Let Monkeys Eat Bananas)
Define hemostasis.
Hemostasis is the prevention of blood loss by the three mechanisms of vascular spasm, the formation of a platelet plug and coagulation.
Define innate immunity.
Innate immunity refers to the type of immunity that does not have memory and that responds to a pathogen the same way every time - no specificity.
When infected by a virus a cell may respond by producing ____________.
Interferon
True or false, please correct if false: The chemical ADP causes vascular constriction.
False. It attracts more platelets to the forming platelet plug. Serotonin and thromboxane A2 cause vascular constriction in addition to attracting more platelets.
You have been infected by a bacterial infection; list all the innate mechanisms which will attempt to eliminate this.
Phagocytes and phagocytosis, natural killer cells, inflammation, antimicrobial proteins and fever.
(I didn’t include surface barriers as the question stated that I have been infected by a bacterial infection - so that mechanism failed)
Compare (2 similarities) and contrast (2 differences) the intrinsic and extrinsic blood clotting pathways (do not give details of all the factors involved)
2 similarities:
Both pathways are trying to produce prothrombin activator
Both pathways use clotting factors as well as the ion calcium
Crucial components in both pathways are negatively charged membranes.
2 differences:
The intrinsic pathway has more steps and is slower than the extrinsic pathway
The intrinsic pathway has the factors needed for clotting present within the blood while the extrinsic pathway requires tissue factor which is outside of blood.
How does histamine cause the 3 signs of inflammation?
Redness: Histamine causes vasodilation which leads to increased blood flow to the area. This results in redness.
Swelling (pain): Histamine increases vascular permeability, so plasma leaks into surrounding tissues causing the swelling. Swelling causes the pain.
Heat: Histamine causes vasodilation which leads to increased blood flow to the area. This results in redness.
Define myeloid cell
a stem cell that gives rise to all other formed elements
You have unfortunately been in a car accident and lost a large amount of blood. Explain in terms of homeostasis how the body will respond and why.
Your body will detect a drop in blood oxygen, which will put an imbalance in homeostasis. The kidney acts as the receptor and control centre in this case and releases erythropoietin. The erythropoietin will stimulate the red bone marrow (the effector) and the resulting enhanced erythropoiesis increases the RBC count. The blood can now carry more oxygen, thereby trying to return the body to homeostasis.
Relate structure to function for the erythrocyte
Anucleate biconcave disc allows for higher surface-to-volume ratio; this facilitates more gas diffusion. Additionally, it means that the no point within the cytoplasm is far from the surface.
Because erythrocytes lack mitochondria and generate ATP by anaerobic mechanisms, they do not consume any of the oxygen they carry, making them very efficient oxygen transporters
A blood sample taken from a patient indicates a large amount of eosinophils. How do you identify eosinophils and what might be the reason for the large numbers?
Eosinophil can be identified as it has a bilobed nucleus that has the appearance of earmuffs and red cytoplasmic granules. There may be large numbers because the patient has a parasitic worm.
A blood sample taken from a patient indicates a large amount of neutrophils. How do you identify neutrophils and what might be the reason for the large numbers?
Neutrophils can be identified by their multilobed nucleus and pale red and blue cytoplasmic granules. They are bacteria slayers so the large number may be due to the fact that the patient has a bacterial infection.
A blood sample taken from a patient indicates a large amount of basophils. How do you identify basophils and what might be the reason for the large numbers?
Basophils can be identified as it is similar to a mast cell and has a bilobed nucleus and purplish-black cytoplasmic granules. The granules are histamine containing. Someone may have an infection.
A blood sample taken from a patient indicates a large amount of monocytes. How do you identify monocytes and what might be the reason for the large numbers?
They are the largest leukocyte and have abundant pale-blue cytoplasm and a darkly staining purple nucleus, which is often U or kidney shaped. Because they can differentiate into highly mobile macrophages, the person may have a viral infection.
A blood sample taken from a patient indicates a large amount of lymphocyte. How do you identify lymphocytes and what might be the reason for the large numbers?
The nucleus is usually spherical but may be slightly indented, and it is surrounded by a thin rim of pale-blue cytoplasm.
How do cells of the innate immune system detect infection?
They have Toll Like Receptors (TLRs) either on the surface of their membranes or within the cell. These identify specific components of microorganisms that enter the body.
Why might fever be beneficial to the body in terms of the effect on microorganisms?
Most microorganisms work best at normal body temperature; increasing temperature decreases their replication rate.
How does interferon fight viruses?
Interferes with viral replication
Modulates inflammation
Activates immune cells
Explain how the leukocytes are produced.
Hematopoietic stems cells divide early on into myeloid stem cells and lymphoid stem cells. The myeloid stem cells divide into eosinophils, basophils and neutrophils (granulocytes) as well as monocytes (agranulocyte). The lymphoid cell divides into lymphocytes (agranulocyte). Lymphocytes are then divided until T and B lymphocytes.
Explain the difference between T and B lymphocyte production.
T cells mature in the thymus while B cells mature in the red bone marrow.
T cells differentiate when they come out of the thymus.
B and T cells then enter the lymph nodes
Define platelets
A formed element that is a fragment of a larger cell called a megakaryocyte. They play a major role in the formation of the platelet plug and in coagulation.
A hormone called _____________ regulates the formation of platelets.
thrombopoietin
Explain the three mechanisms involved in hemostasis.
Vascular spasm involves the vasoconstriction of the blood vessel. The smooth muscle contracts and restricts the flow of blood. Reduces blood loss for 20-30 minutes.
During platelet plug formation the site injury exposes collagen fibers, which enables the platelets to stick to the site of injury. Three chemicals are released (serotonin, ADP and thromboxane A2) that increase platelets sticking and vasoconstriction. This leads to the formation of a platelet plug that slows the loss of blood. Builds up the plug within one minute.
During coagulation, fibrin proteins form a mesh that traps red blood cells and platelets and forms the clot. Both the intrinsic and extrinsic paths can build the fibrin mesh.
What factors trigger vascular spasm?
Direct injury to vascular smooth muscle
Exposure to underlying collagen fibers
Metal or glass can activate it (a lot of negative charges will activate the pathways)
True or false: Capillaries are able to have vascular spasm.
False: They cannot because they don’t have smooth muscle.
What are the functions of the immune system?
Fights off pathogens and invaders Prevents the spread of damaging agents to nearby tissues Disposes of cell debris and pathogens Alerts the adaptive immune system Sets the stage for repair
What are four cardinal signs of inflammation?
Redness
Heat
Swelling
Pain
Describe the first line of defense for the innate immune system.
The first line of defense consists of surface barriers. The skin and mucosae are part of this line of defense. In addition to being a mechanical barrier, there are a number of chemicals that they use in their defense arsenal: Acid Enzymes Mucin Defensins Other chemicals (lipids in sweat)
List the mucous membranes involved in the first line of defense of the innate immune systems.
Respiratory - nose
Urinary
Reproductive
Digestive (mouth and anus)
