Blood And Blood Components

Question 1

What are the constituents of blood

Answer 1

55% of plasma, <1% of leukocytes white blood cells and thrombocytes (platelets), 45% of erythrocytes

Question 2

What is the function of red blood cells

Answer 2

Carry haemoglobin, a protein which carries O2, carries some CO2, no nucleus and organelles

Question 3

Describe erythropoiesis

Answer 3

Starts in bone marrow as pluripotent stem cell > differentiates into a pro erythroblast > synthesis of haemoglobin and nucleus expelled to make a reticulocyte > reticulocyte matures over 1-2 days after leaving bone marrow to make an erythrocyte

Question 4

Identify the factors important in erythropoiesis

Answer 4

Low O2 levels, vitamin B12 (cobalamin), folic acid

Question 5

What is a leukocyte

Answer 5

Has a nucleus, is a white blood cell

Question 6

Describe the function of leukocytes

Answer 6

Detect foreign and abnormal material by becoming an antigen presenting cell, and digest and destroy them by Phagocytosis
Examples: macrophages, neutrophils

Question 7

Describe the production of leukocytes

Answer 7

Granulocytes: myeloblast > myelocyte > differentiate into 3 types, neutrophil with multilobed nuclei
Agranulocytosis: pluripotent stem cell in red bone marrow > lymphoblast in lymphatic tissue > lymphocytes

Question 8

Describe the structure and function of thrombocytes (platelets)

Answer 8

Cytoplasm packed with granules as no nucleus which is essential for blood clotting by forming a platelet plug, which causes haemostasis

Question 9

Describe how thrombocytes are formed

Answer 9

Buds of cytoplasm of megakaryocytes under the influence of thrombopoietin in red bone marrow

Question 10

Describe blood group A, B, AB and O

Answer 10

Has surface antigen A
Has surface antigen B
Has surface antigen C
Has no surface antigens

Question 11

Describe Blood group compatibility between donor and recipient

Answer 11

The plasma will contain antibodies of the surface antigen it doesn’t have,
A= anti-B antibodies
B= anti-A antibodies
AB= neither
O both Anti-A and B
So O is a universal donor and AB Is the universal recipient

Question 12

Explain the rhesus system

Answer 12

Can be Rh neg or Rh pos
Pos has the Rh antigen and neg has no antigens so make anti-D

Question 13

Explain rhesus incompatibility in pregnancy and blood transfusions

Answer 13

Pregnancy: mum is Rh neg and foetus is Rh pos
Mum makes anti D so the antibodies will attack and haemolyse the Fetal erythrocytes as they have antigen D
Causes Fetal anemia, can lead to jaundice,

Question 14

Outline blood clotting,

Answer 14

1. Vessel damage causes blood and components to flow out into surrounding tissues
2. When platelets come into contact with vessel injury then they stick to the site which causes vasoconstriction as they release serotonin. Smooth muscles contract, reducing/ stopping blood flow
3. The platelets clump together attracting other platelets by releasing ADP forming a tempo plug
4. Coagulation: clotting cascade occurs, enzymes activating each other e.g. thrombin converts soluble fibrinogen into an insoluble mesh of fibrin, trapping RBCs and platelets to form a stronger clot

Question 15

Describe coagulation in more depth

Answer 15

Extrinsic > thromboplastin realised by damaged tissue cells enter the blood
Intrinsic > platelets stick to damaged blood vessel lining
Prothrombin activator > prothrombin >thrombin > fibrinogen > loose fibrin threads > stronger fibrin clot