7. Red Cells 1

Question 1

Haemopoiesis in Fetus

Answer 1

0-2 months (yolk sac) 2-7 months (liver, spleen) 5-9 months (bone marrow)

Question 2

Haemopoiesis Infants

Answer 2

bone marrow (practically all bones)

Question 3

Haemopoiesis in Adults

Answer 3

vertebrae

ribs

sternum

sacrum

pelvis

proximal ends of femur

Question 4

Growth Factors

Answer 4

Act on stromal cells = TNF

Act on pluripotential stem cells = SCF

Act on multipotential progential cells = GM-CSF, G-CSF

Act on committed progenitor cells = G-CSF, Erythropoietin

Question 5

G-CSF

Answer 5

Stimulate granulocyte differentiation

Question 6

Erythropoietin (Epo)

Answer 6

Stimulates late BFUE, CFUE and proerythroblasts

Produced in the peritubular interstitial cells of the kidney (90%)

↓O2 tension in the renal tissue stimulates Epo production = Anaemia, Hypoxia

↑ O2 tension in the renal tissue reduces Epo production = Primary polycythaemia

Question 7

Genetic disorders affecting globin synthesis

Answer 7

amino acid substitution of a global chain = HbS → sickle cell disease

Reduced rate of synthesis of either α or β global chain = thalassaemia

Question 8

Red cell shape

Answer 8

biconcave disc

Question 9

Energy Metabolism

Answer 9

Hexose monophosphate pathway

NADPH maintains Hb in a reduced state

Requires glucose-6-phosphade dehydrogenase (G6PD)

Red cells are susceptible to oxidant stress in G6PD deficiency

Question 10

Red cell membrane layers

Answer 10

1) Lipid bilayer
2) Integral membrane proteins
3) Membrane skeleton proteins - Spectrin

Question 11

Normal red cell destruction

Answer 11

Red cell lifespan 120 days

End-product = unconjugated bilirubin

Globin → recycled Iron → recycled

Question 12

Haemolytic anaemias

Answer 12

Result from an increase in the rate of red cell destruction

Lifespan <120 days

↑ bilirubin → jaundice

↑ requirement of red cells → ↑ red cell synthesis → ↑ reticulocytes in blood ↓ Hb