Blood

Question 1

Outline the process of haemopoiesis

Answer 1

1) Proliferation: Starting with a stem cell, the cell divides into two. One to replace the original stem cell (self-renewal) and one that differentiates.
2) Differentiation: Haemopoietic progenitor will first differentiate to form either a myeloid blast (RBC, WBC, platelets) or a lymphoid blast (immunoresponse cells) -The progenitor will differentiate into a certain cell type under the influence of a particular cytokine. e.g. erythropoietin will cause differentiation into RBCs whilst thrombopoietin into platelets

N.B. Erythropoiesis is controlled by partial pressure of O2. decreased pO2 stimulates erythropoietin

Question 2

What type of nucleus do neutrophils have?

Answer 2

Multi-lobed

Question 3

What type of nucleus do eosinophils have?

Answer 3

Bi-lobed

Question 4

What type of nucleus do basophils have?

Answer 4

Bi/Tri lobed

Question 5

What type of nucleus do monocytes have?

Answer 5

Kidney shaped

Question 6

What type of nucleus do lymphocytes have?

Answer 6

Deep staining

Question 7

What is the function of neutrophils?

Answer 7

• they migrate out of circulation to infections site
• partake in phagocytosis
• granulocyte colony stimulating factor (G-CSF) increases neutrophil production

Question 8

What is the function of eosinophils?

Answer 8

• capable of phagocytosis

- release cytotoxic particles to damage larger particles

Question 9

What is the function of basophils?

Answer 9

-mediate acute inflammatory reactions using heparin and histamine

Question 10

What is the function of monocytes?

Answer 10

• they migrate out of cells to become macrophages in many organs of the body
• capable of phagocytosis and they interact with T-cells

Question 11

What is the function of lymphocytes?

Answer 11

B cells: humoral immunity/ stimulated by antigens which causes them to transform into plasma cells which secrete immunoglobins

Helper T cells: express CD4 on surface

Killer cells, permit the transformation of B cells into plasma cells

Question 12

Describe the structure and function of erythrocytes

Answer 12

• biconcave disc
• 4 globin chains (2 alpha, 2 beta)
• each molecule carries a haem
• carries oxygen to tissues
• carries carbon dioxide to the lungs

Question 13

Describe the structure and function of reticular cells

Answer 13

• synthesis reticular fibres and surround them with cytoplasm (structural function)
• Direct B and T lymphocytes to specific regions within the lymphatic tissues

Question 14

Describe the structure and function of platelets

Answer 14

• small round blue particles produced by megakaryocytes in the bone marrow
• complex surface membrane
• cytoplasm contains alpha and dense granules
• alpha granules: contains fibrinogen and Von Willebrand’s factor
• Dense: contain ADP and Ca2+
• involved in the clotting cascade, they adhere to damaged cell walls and aggregate together
• 8/9 day lifespan

Question 15

Describe some features of red blood cells

Answer 15

• 120 day lifespan

- Biconcave and flexible to facilitate passage through microcirculation

Question 16

Describe the process of red blood cell destruction and catabolism

Answer 16

• red blood cells broken down to release haemoglobin in blood
• haemoglobin broken down to release haem
• haem converted into bilirubin in plasma
• plasma bilirubin taken up by liver
• from the liver, bilirubin can go to the kidney, where urobilogen is excreted via urine
• from the liver it can also go to the gall bladder, then the small intestine, then the large intestine where stercobilin is excreted