Blood (p2)

Question 1

What is fibrinolysis?

Answer 1

Removal of clot when its no longer needed

• key enzyme = plasmin (precursor is plasminogen, a plasma protein that gets incorporated into the clot)
• plasminogen is ctivated by tPA (tissue plasminogen activator) released by endothelial cells
• begins within 2 days at outer edges and continues until clot is fully dissolved

Question 2

What are the 2 homeostatic mechanisms to control the size of a clot?

Answer 2

1) swift removal of coagulation factors - procoagulation factions; ensures clotting doesnt occur where its not needed

2) inhibition of activated clotting factors - so clotting does not expand too far from the initial clot

Question 3

What are the different concentrations that clot formation requires?

Answer 3

[procoagulation factors] > [anticoagulation factors]

Question 4

What are some factors that limit clot growth/formation?

Answer 4

• normally flowing blood washes away procoagulants (importance of vascular spasms in response to injury - slowing down blood flow)
• as thrombin forms, it is adsorbed onto fibrin threads, to keep it in the vicinity of injury
• antithrombin III inactivates any escaping thrombin
• antithrombin III and protein C inaactivate many intrinsic pathway (slower) procoagulants (prevents clot from getting too large)
• heparin (basophils and mast cells) enhance activity of antithrombin III and inhibits intrinsic pathway
• smooth endothelial lining of undamaged blood vessels prevents undesirable clotting (no access to collagen)

Question 5

what is a thrombus?

Answer 5

clot that develops and pesists in an unbroken blood vessel - can block critical blood circulation to those tissues

Question 6

What might promote thrombus formation in an unbroken blood vessel?

Answer 6

Could be veins in someone on a plane who isnt moving around very much

Could be someone with atherosclerosis (slight damage to the inside in some areas of blood vessel walls - endothelial cells are more prone to peeling off)

Could have hypertension (increased blood pressure) which might increase peeling

Exposure to inner vessel to collagen triggering blood clotting

Question 7

What is an embolus ?

Answer 7

A thrombus which has broken free, can get stuck in a vessel of small diameter

• Completely blocks blood flow in smaller diameter veseels (pulmonary or cererbral emboli)

Question 8

Why is a low dose aspirin a good preventative therapy in heart attack risk patients?

Answer 8

Low does aspirin = blood thinner

• can interfere with production of prostaglandins that are prcoagulants
• prevents too much blood clotting in people who are at risk of excessive clotting without completely interfering with blodd clot formation inside and outside
• inside clotting = bruises

Question 9

What are some examples of bleeding disorders that interfere with normal clotting?

Answer 9

1) Thrombocytopenia = any condition harmful to bone marrow -> easy bruising due to internal hemorrhage

• ex. petechiae
• platelet count is below the normal range but there are still some
• whole blood transfusions are temporary -> bc lifespan of a platelet is only 10 days (short-lived)

2) Impaired liver function = liver disease also associated with reudced bile production - bile needed to adsorb vitamin K

• vitamin K = important in some factors involving the intrinsic pathways; fat soluble vitamin deficient in some procoagulants as a result

3) Hemophilias = hereditary bleeding disorders due to deficiencies in intrinsic pathway factors; sex-linked and require regular transfusions

• hemophilia A = lacking factor VIII
• hemophilia B = lacking factor IX

Question 10

What is donor blood mixed with?

Answer 10

Anticoagulant - citrate dextrose, a calcium chelator

• Ca+2 is a very important cofactor in the process of blood clotting, soaking it up will keep blood from coagulating, keeping it nice and fluid

Question 11

Why is type O the universal donor? Why is type AB the universal recipient?

Answer 11

Type O = RBCs have neither antigen ∴ will not induce antibodies

Type AB = Dont produce eihter antibodies

Question 12

Which blood type is the most common? the least common?

Answer 12

Most = O or A
Least = AB

Question 13

What do RBC antigens do?

Answer 13

Promote agglutination - antibodies that bind to antigens

Question 14

How are Rh antibodies formed?

Answer 14

Not spontaneously formed in blood of Rh- indivs

• indivs become sensitized upon first exposure to Rh antigens (tranfusions, carrying an Rh+ fetus)
• antibodies will attack donor RBCs in response to second and subsequent exposures

Question 15

What are Rh- mothers treated with if they are carrying an Rh+ fetus?

Answer 15

RhoGAM = an anti-Rh serum

• prevents erythroblastosis fetalis
• keeps her nbody from reacting to the Rh+ factor in fetus
• keeps her immune system from creating antibodies that attack the fetus

Question 16

In a transfusion reaction, why is the problem the recipients agglutinis (antibodies), not the donors?

Answer 16

If someone is given a mismatched transfusion there is a finite amount of antibodies (if any), it will get diluted in the recipients circulatory system

• then antibodies wont remain for long but may still cause agglutination

1) agglutination = clogs small blood vessels
2) clumped RBC s rupture/destroyed by phagocytes and Hb released

Question 17

What is an autolgous transfusion?

Answer 17

Someone can donate their own blood prior to a surgery that may need it and have that blood e stored and used when and if needed for them

• this is the best way to prevent agglutination/immune responses from blood of someone else

Question 18

What is blood typing?

Answer 18

Uses serum containing anti-A or anti-B agglutinins

• reacting with the anti-serums indicates that blood type is present
• Anti-B serum responds to type B blood and vice versa with Anti-A serum

A and B react = type AB
Only A reacts = type A
Only B reacts = type B
Neither A or B reacts = type O