Week 4 Blood cells

Question 1

What is the origin of all blood cells?

Answer 1

Haemocytoblasts (multipotent haematopoietic cells)

Question 2

What are the sites for haematopoiesis?

Answer 2

Foetus: yolk sac -> foetal liver

Around time of birth: red bone marrow & lymphatic tissue

Question 3

What is the main constituent of yellow bone marrow?

Answer 3

Adipose cells

Question 4

Percentage constituents of blood

Answer 4

55% plasma (water, proteins, others)

45% formed elements (erythrocytes, leukocytes, platelets)

Question 5

Types of leukocytes

Answer 5

1. Neutrophils
2. Basophils
3. Eosinophils
4. Lymphocytes
5. Monocytes

Question 6

Steps of erythropoiesis

Answer 6

1. pluripotent haematopoietic stem cell
2. colony-forming unit (CFU)
3. erythroblast
4. Reticulocyte (with leftover organelles)
5. Erythrocytes

Question 7

Where are red bone marrows found in adults?

Answer 7

Axial skeleton (e.g. ribs, sternum, pelvis)

Question 8

Hormone that stimulates erythropoiesis

Answer 8

Erythropoietin

Question 9

What nutrients does erythropoiesis require?

Answer 9

1. Iron
2. vitamin B12
3. Folate (vitamin B9)

Question 10

When does death of erythrocyte occur? How?

Answer 10

after ~120 days

1. broken up by liver & spleen
2. cell fragments are phagocytized
3. Haemoglobin is broken into heme and globin

Heme: further broken into biliverdin & iron
Biliverdin -> bilirubin -> Bile -> faeces
Iron: stored/reused/loss through menstruation or injury

Globin: hydrolyzed into amino acids

Question 11

5 Functions of platelets

Answer 11

1. Secrete vasoconstrictors
2. Secrete chemicals that attract neutrophils and monocytes
3. Form temporary platelet plugs
4. Secrete clotting factors
5. Secrete growth factor to help maintaining and repairing blood vessels

Question 12

4 Types of lymphocytes

Answer 12

1. T lymphocytes
2. B lymphocytes
3. Natural killer cells
4. Dendritic cells (antigen-presenting)