Red Blood Cells and Haemoglobin

Question 1

What are the proportions of the comments that make up blood?

Answer 1

55% plasma

45% cells

Question 2

What are the adaptations that enable it to carry to O2?

Answer 2

biconcave, no nucleus to maximise space for haemoglobin

flexible = can collapse in the narrowest capillaries, reduce diffusion distance and keeps viscosity low

Question 3

What happens to blood cells when flow is ceased?

Answer 3

RBC’s aggregate and bind loosely to one other

As you increase flow, blood gets less viscous

Question 4

What are reticulocytes?

Answer 4

immature red cells released from bone marrow

Question 5

What is 2,3-DPG? How does it affect Hb?

Answer 5

2,3 - diphosphoglycerate
Binds in pocekt on complete deoxygenation
Stabilises de-oxy conformation (lowers affinity for O2)
Ejected on binding first O2 molecule –> higher affinity for O2

Question 6

How is foetal Hb different to adult Hb?

Answer 6

Adult = 2 x alpha, 2 x beta
Foetal = 2 x alpha, 2 x gamma

Question 7

Where in health would you find nucleated RBC’s?

Answer 7

in the newborn

Question 8

Briefly describe the stages of erythropoiesis

Answer 8

Red cells produced in bone marrow 
Pronormoblast
Normoblast (nucleated, non circulating)
Reticulocyte --> circulation
In circulation --> mature red cell

Question 9

Describe how how erythropoesis is controlled?

What is anaemia of chronic kidney disease?

Answer 9

EPO from kidney (erythropoeitin)
Under feedback control from O2 delivery
EPO is released from the kindeys when they detect low O2 content
Anamia of chronic kidney disease, cannot produce EPO, erythropoiesis not stimulated

Question 10

What is the lifespan of a red blood cell?

How are they removed when they die?

Answer 10

120 days

Removed by reticuloendothelial system ie. macrophages in spleen, liver, lungs, marrow

Question 11

What is anaemia?

Answer 11

low level of Hb in blood
Due to:
- impaired production of cells or haemoglobin
- increased red cell destruction

Question 12

What is the opposite of anaemia?

Answer 12

polycythaemia

overproduction of RBC’s, increases viscosity of blood, headache, dizziness, weakness, thrombosis

Question 13

What are the 2 major causes of anaemia. What classification of anaemia fit under these headings?

Answer 13

1. Impaired production of cells or haemoglobin
   - Decreased erythropoeisis e.g. iron deficiency, chronic disease, reduced EPO
   - Inneffective erythropoiesis e.g. VitB12 deficiency, haemiglobinopathy (thalassemia)
2. Increased destruction
   - haemolytic anaemia e.g. sickle cell, malaria
   - blood loss
   - immune mediated e.g. hypersplenism, RE phagocytosis

Question 14

What are the consequences of anaemia?

Answer 14

Reduced oxygen carrying capacity (note that sats are likely to be normal)
Haematocrit and blood viscosity low
Cardiac output may be high