Red Blood cells

Question 1

Where do blood cells originate

Answer 1

bone marrow

Question 2

What are blood cells derived from

Answer 2

haemopoietic stem cells (HSC)

Question 3

Why are HSC described as “self-renewing”

Answer 3

some daughter cells remain as HSCs so the pool is not depleted

Question 4

What are the sites of haemopoiesis in foetus

Answer 4

Yolk sac (1-3wks) Liver (4-8wks) Bone marrow (8-adulthood)

Question 5

Where are progenitor and HSC distributed

Answer 5

Within the bone marrow amongst mesenchymal cells, endothelial cells and the vasculature

Question 6

What is haemopoiesis regulated by

Answer 6

genes, transcription factors, growth factors and the microenvironment

Question 7

What happens if haemopoiesis is not regulated

Answer 7

disturb balance between proliferation and differentiation

Question 8

What are irons main functions

Answer 8

oxygen transport in haemoglobin and mitochondrial proteins

Question 9

What does erythrocyte function depend on

Answer 9

Integrity of membrane, haemoglobin structure and function and cellular metabolism

Question 10

What is the red cell membrane made up of

Answer 10

made up of lipid bilayer supported by protein cytoskeleton and contains transmembrane proteins

Question 11

Why is the red cell membrane important

Answer 11

maintains the integrity, shape and elasticity of red cell

Question 12

What does disruption in the vertical links of red cell membrane cause

Answer 12

Hereditary spherocytosis

Question 13

What are spherocytes

Answer 13

cells that are spherical in shape and lack central pallor

Question 14

What causes spherocytes

Answer 14

loss of cell membrane without the loss of an equivalent amount of cytoplasm. This makes them less flexible and removed prematurely by the spleen (haemolysis)

Question 15

What does disruption in the horizontal links of red cell membrane cause

Answer 15

Hereditary elliptocytosis

Question 16

What is glucose-6-phosphate dehydrogenase

Answer 16

Important enzyme in the hexose monophosphate shunt which is couple to the Glutathione metabolism which protect red cells from oxidant damage

Question 17

What is 2,3-diphosphoglycerate and what does it do

Answer 17

allosteric effector produced by the Rapaport-Luebering shuttle. It binds to beta-globin chains in haemoglobin

Question 18

What are the effects of G6DP deficiency

Answer 18

Intravascular haemolysis associated with irregularly contracted cells

Question 19

What do irregularly contracted cells look like

Answer 19

Irregular in outline, smaller and lack central pallor. Contain denatured haemoglobin forming round inclusions called Heinz bodies

Question 20

What are the causes of mircocytosis

Answer 20

Defect in haem synthesis (iron deficiency). Defect in global synthesis called thalassaemia

Question 21

Types of macrocytosis

Answer 21

round, oval and polychromatic (young and immature)

Question 22

Causes of macrocytosis

Answer 22

Lack of vitamin B12 or folic acid, liver disease, haemolysis or pregnancy

Question 23

What is increased number of reticulocytes called

Answer 23

Reticulocytosis

Question 24

Why might reticulocytosis occur

Answer 24

response to bleeding or red cell destruction (body can’t keep up so produced immature cells)

Question 25

When might target cells occur

Answer 25

obstructive jaundice, liver disease, haemoglobinpathies or hyposplenism

Question 26

What do sickle cells result from

Answer 26

polymerisation of haemoglobin s which in the deoxygenation form is much less soluble than haemoglobin

Question 27

What are schistocytes

Answer 27

small fragments of red cells

Question 28

What does schistocytosis occur from

Answer 28

Shearing process caused by platelet Ruch blood clots in blood vessels