Red Blood Cells

Question 1

What is haemopoesis?

Answer 1

The formation and development of blood cells

Question 2

What are HSC’s?

Answer 2

Haemopoieitic Stem Cells, which give rise to lymphoid stem cells and myeloid stem cells- from which red blood cells arise.

Question 3

Two essential characteristics of HSC’s?

Answer 3

They can self-renew and differentiate to mature progeny

Question 4

Sites of haemopoesis in the fetus?

Answer 4

Yolk sac (mesoderm), then liver and then bone marrow

Question 5

4 factors required for erythropoiesis?

Answer 5

Iron, Vitamin B12, Folate and erythropoietin (regulator)

Question 6

Microcytic vs macrocytic anaemia?

Answer 6

Iron deficiency vs B12/folate deficiency

Question 7

Where is erythropoietin synthesised?

Answer 7

The kidney

Question 8

Two major functions of iron?

Answer 8

• Oxygen transport in haemoglobin
• Mitochondrial proteins cytochromes a,b and c, ATP production (vital co-factor for many enzymes and proteins involved in metabolism)

Question 9

What synthesis are Vitamin B12 and folate used for?

Answer 9

dTTpP which is used in thymidine. Therefore, lack of Vitamin B12 and folate inhibits DNA synthesis and cell divison.

Question 10

What factor does B12 combine with?

Answer 10

Intrinsic Factor (IF) made in the gastric parietal cells

Question 11

Autoimmune disorder due to inadequate secretion of IF?

Answer 11

Pernicious anaemia

Question 12

Where is folic acid absorbed?

Answer 12

small intestine

Question 13

Erythrocyte life span?

Answer 13

120 days

Question 14

3 factors that affect erythrocyte function?

Answer 14

• Integrity of the membrane
• Haemoglobin structure and function
• Cellular metabolism

Question 15

What shape are erythrocytes and how does this help them?

Answer 15

Biconcave which helps their maneuverability through small blood vessels

Question 16

What is hereditary spherocytosis?

Answer 16

When RBC’s are spherical in shape due to a genetic defect that causes disruption of vertical linkages in the membrane. They are less flexible and are removed prematurely by the spleen (haemolysis)

Question 17

What does the disruption of horizontal linkages in the membrane produce?

Answer 17

Hereditary Elliptocytosis

Question 18

What two things are RBC metabolism highly adapted for?

Answer 18

• Generation of ATP to meet energy requirements

- Maintenance of haemoglobin, membrane integrity and RBC volume

Question 19

RBC sizes?

Answer 19

• Microcytic- smaller RBC’s due to iron deficiency, anaemia or defects in globin synthesis (alpha or beta thalassaemia)
• Normocytic- normal RBC’s
• Macrocytic- larger RBC’s (round, oval or polychromatic-blue tinged) due to Vitamin B12 and folic acid deficiency, liver disease, haemolysis or pregnancy. Cells grow in size as they cannot undergo cell division or DNA synthesis.

Question 20

RBC colour

Answer 20

• Normal RBC’s have a third of the diameter that is pale due to the centre having less haemoglobin
• Hypochromia- when RBC’s have a larger lighter area due to having a flatter shape and lower haemoglobin content. Goes with microcytosis
• Polychromasia- describes a blue tinge to the RBC’s, indicating that the cell is young. Causes macrocytosis

Question 21

What is poikilocytosis?

Answer 21

When RBC’s show more variation in shape than normal