BLood Physiology

Question 1

How do sites of haematopoiesis change as we age?

Answer 1

Yolk sac - embryo
Liver, spleen, lymph nodes - foetus 2-7 months gestation
Bone marrow - 7 months gestation onwards
All bones - birth - 5years
Axial skeleton - adult

Question 2

How are platelets formed?

Answer 2

Cytoplasmic fragments of megakaryocytes.

Question 3

How does pH, temperature and pCO2 affect O2 saturation of haemoglobin?

Answer 3

pH - More acidic = less O2 bound
temp - High temp less O2 bound
pCO2 = High = less O2 bound

Question 4

How is CO2 transported?

Answer 4

70% as bicarbonate
20% as Carbamino (Co2 combines with amino groups in haemoglobin)
10% as dissolved CO2

Question 5

Describe the lifecycle and recycling of RBCs/

Answer 5

Last about 120 days.
Old, damaged cells are removed by spleen, liver and bone marrow.

Iron is recycled.
Haemoglobin is converted into bilirubin.

Question 6

What does erythropoietin do?

Answer 6

Released by kidneys in response to hypoxia.

Stimulates HSCs to develop into proerythroblasts.

Question 7

Describe the maturation of HSCs into erythrocytes.

Answer 7

HSC -> Proerythroblast -> Erythroblast -> Normoblast -> Reticulocyte -> Erythrocyte

Question 8

What are the normal blood measurements of RBC count, haemoglobin and haematocrit in males/females?

Answer 8

RBC count

• 5 x 10^12 in males
• 4.8 x 10^12 in females

Haemoglobin

• 150g/L in males
• 135g/L in females

Haematocrit

• 0.45 males
• 0.42 females