Cells & Blood Flashcards

Question

What is a thrombus and how is it formed?

Answer 1

A thrombus is a blood clot It is formed by HEAMOSTASIS: 1) INJURY: a blood vessel is damaged 2) VASCULAR SPASM: the smooth muscle in the vessel wall contracts to reduce blood loss 3) PLATELET PLUG FORMATION: Platelets are activated and stick to each other at the wound site 4) COAGULATION: fibrinogen is converted to fibrin which forms a mesh that tracks platelets and erythrocytes, forming a clot

Answer 2

Extrinsic: usually triggered by trauma Intrinsic: begins in the bloodstream, triggered by internal damage to the wall of the blood vessel

Answer 3

The liver secretes oat of the 12 clotting factors and it requires vitamin K to produce many of them

Answer 4

Catalysed prothrombin to throw in, the active form, which subsequently converts fibrinogen to its active form, fibrin, to form the mesh that traps platelets and erythrocytes to produce a cross linked fibrin clot

Answer 5

Fibrin is in the final common pathway of coagulation. When activated at the site of vessel damage, the fibrin acts as a mesh to trap erythrocytes and platelets in order to form a cross linked fibrin clot

Answer 6

Vitamin K is needed by the liver to synthesise the clotting factors

Answer 7

Calcium activates an enzyme complex which activates the Factor X in the extrinsic pathway of blood clotting, which then feed into the common pathway

Answer 8

ABO and rhesus status

Answer 9

The blood type is determined by the antigens present upon the surface of the erythrocytes. If antigen A is present they will be blood type A, if antigen B is present they are blood type B, if both are present they are blood type AB. If neither are present they are O A & B are codominant. A & B are dominant over O

Answer 10

There are 3 rhesus antigens inherited in a set from the parents. CDE antigens carried on the erythrocytes. The rhesus status is determined by D. If absent, you are rhesus negative, if present you are rhesus positive.

Answer 11

- Production and maturation of lymphocytes - Filtering of the lymph fluid at lymph nodes and organs (spleen, thymus) to remove microbes and other materials - Pass filtered lymph back into the blood near the heart

Answer 12

If a mother is rhesus negative, they do not have any D antigens on the surface of the erythrocytes. When their foetus is rhesus positive, the body will produces antibodies to the D antigens presenting on the surface of the foetal erythrocytes. In the primary exposure, a first pregnancy with a baby that is rhesus positive, there is rarely a response. In subsequent pregnancies with a foetus possessing rhesus positive erythrocytes, the material antibodies will cross the placenta, leading to haemolysis and foetal anaemia which can be fatal. The mother can be treated with anti D immunoglobulin therapy to bind any rhesus positive cells in the maternal circulation, to prevent the body responding to them and to stop the mother creating attacking D antibodies.

Answer 13

You can only donate blood to those who have a blood type who do not carry the antibodies to the antigens presenting on the erythrocytes being donated. O is the universal donor because it has no antigens on the surface of its erythrocytes so can be given to anybody, as whichever antibodies the recipient has they will not react to the foreign blood. AB is the universal recipient because they possess no antibodies, so will not react to any donated blood, no matter the type.