Lecture 25

Question 1

Describe the makeup of blood

Answer 1

blood = connective tissue
plasma = 25% of ECF
cellular elements = erythrocytes (RBC), leukocytes (WBC), thrombocytes (platelets)

Question 2

Define hematocrit

Answer 2

% of total blood volume composed of RBC

Question 3

What is hematopoeisis

Answer 3

synthesis of new blood cells
this is done in the bone marrow of the spine/ribs, proximal end of long bones, cranium
25% is RBC, 75% is WBC due to the difference in lifespan
starts from pluripotent stem cells then goes to erythroblasts to reticulocyte (loss of nucleus) to erythrocyte for RBC.
megakaryocyte will fragment to form platelets

Question 4

What are cytokines and why are they important?

Answer 4

proteins released from a cell that influence activity of another
ex. EPO and TPO (erythropoietin from kidneys and thrombopoietin from the liver) lead to formation of erythrocytes and thrombocytes after there is low O2 sesned
EPO used in blood doping

Question 5

What is leukemia?

Answer 5

cancer of the bone marrow, results in production of abnormal WBC, not enough RBC or normal WBC

Question 6

Describe the structure of the RBC

Answer 6

made up of 4 globin chains (2 alpha and 2 beta), each chain has a heme group within it. the heme group contains an iron atom which reversibly binds with O2

Question 7

Describe anemia and its factors

Answer 7

decreased hemoglobin content, reduced O2 carrying capacity
caused by either decreased RBC production (aplastic anemia from drugs/radiation or not enough vitamins/nutrients) or increased RBC loss (loss of blood, hemolytic anemia (more RBC degraded than produced) can be hereditary (sickle cell) or acquired (malaria))

Question 8

How is tissue repaired? describe the entire pathway

Answer 8

tissue damage leads to 4 responses
1) vasoconstriction (natural tourniquet)
2) platelet plug formation
3) coagulation (formation of clot)
4) dissolution of clot
collagen exposed means that the endothelium isn't producing chemicals to prevent platelet adhesion, platelets adhere to the wound and undergo positive feedback loop that increases recruitment of platelets. leads to intrinsic activation of coagulation cascade

damaged tissue also releases tissue factors that cause lead to extrinsic pathway to coagulation cascade. this cascade leads thrombin to change fibrinogen to fibrin which cross links in a mesh to form the clot and support the platelet plug.

the clot is later dissolved by plasmin

Question 9

Describe the different blood types

Answer 9

every persons’ RBC has different antigens on it (none, A, B, AB, and possibly Rh) and has antibodies for all of the other cells. If it has antibodies, then it will react with those antigens and cause the RBC to clump

people with Rh- blood don’t have the Rhesus factor, but they won’t produce Rh antibodies until they come into contact with Rh blood