Blood cells and haempoesis

Question 1

Proliferation

Answer 1

Starting with a stem cell, the cell divides into two. One to replace the original stem cell (self-renewal) and one that differentiates.

Question 2

What is a haemopoietic progenitor?

Answer 2

A cell which differentiates into either a myeloid blast (RBC, WBC, platelets)or a lymphoid blast (immunoresponse cell).

Question 3

What cell influences the differentiation of the two blast cell?

Answer 3

Cytokines

Question 4

What is the name of the cell which causes the differentiation of a myeloid blast into an RBC?

Answer 4

Erythopoietin

Question 5

What is the name of the cell which causes the differentiation of a myeloid blast into a platelet?

Answer 5

Thrombopoietin

Question 6

How is erythropoiesis controlled?

Answer 6

By partial pressure of O2 in interstitial peritubular cells in kidney- low pO2 stimulates erythropoietin production, which influences differentiation of myeloid stemm cells into erythrocytes (rbc)

Question 7

What two things do lymphoid stem cells differentiate into?

Answer 7

Progenitors and thymus cells

Question 8

How are early blood cells held in the bone marrow?

Answer 8

By adhesion molecules, collagen and fibronectin.

Question 9

How many types of white blood cell are there?

Answer 9

5

Question 10

Give three functions of neutrophils

Answer 10

Neutrophil - Migrate out of circulation to site of infection (chemotaxis) - Phagocytosis - Increased production by G-CSF (Granulocyte Colony Stimulating Factor)

Question 11

Give two functions of eosinophils

Answer 11

Eosinophils - Capable of phagocytosis - Release cytotoxic particles to damage larger particles

Question 12

Give the main fucntion of basophils

Answer 12

Basophil - Mediate acute inflammatory reactions using heparin and histamine

Question 13

Give the two main fucntions of monocytes

Answer 13

Monocyte - Migrate to become macrophages in many organs of the body - Capable of phagocytosis and interact with T cells

Question 14

What are the two main functions of lymphocytes?

Answer 14

Lymphocytes - B: humoral immunity. Stimulated by antigens, transform into plasma cells, which secrete immunoglobins. - T: cellular immunity. Express CD4 or CD8 on cell surface. CD4 helper cells stimulate cytotoxic CD8 cells and permit transformation of B cells to plasma cells.

Question 15

What do megakaryoytes produce?

Answer 15

Megakaryocyte platelets

Question 16

What are the five structural features of an erythrocyte?

Answer 16

• Biconcave disc
• 4 globin chains (2 & 2)
• Each molecule carries a haem
• No nucleus
• No mitochondria, generate ATP via Embden Meyerhof pathway

Question 17

How is the structure of an erythrocyte adapted to its function?

Answer 17

• Structure allows it to change shape, in order to cooperatively modify its affinity with O2