Lecture 11: haemopoiesis, spleen, BM

Question 1

What is haemopoiesis?

Answer 1

Production of blood cell formation in BM by specification of blood cell lineages then proliferation.

Question 2

Where does haemopoiesis occur in adults and infants?

Answer 2

Adults: BM in skull, sternum, ribs, pelvis, vertebrae

Infants: BM throughout skeleton

Question 3

Which cells drive haemopoiesis?

Answer 3

Haemopoietic stem cells

Question 4

5 major lineage pathways arise from the haemopoietic stem cells.

Identify all 5 pathways.

Answer 4

• erythropoiesis
• lymphopoiesis
• thrombopoiesis
• granulopoiesis
• monocytopoiesis

Question 5

What factors determine the differentiation of the haemopoietic stem cells?

Answer 5

• hormones
• transcription factors
• interactions with non-haemopoietic cell types

Question 6

Which hormones stimulate erythropoiesis and thrombopoiesis?

Answer 6

• erythropoietin

- thrombopoietin

Question 7

Where are erythropoietin and thrombopoietin produced then secreted from?

Answer 7

Erythropoietin produced & secreted from kidneys.

Thrombopoietin produced in liver & secreted from kidneys.

Question 8

Briefly describe thrombopoiesis and its role.

Answer 8

1. Multipotential haematopoietic stem cell
2. Common myeloid progenitor cell
3. Megakaryocyte
4. Platelets are fragments of cytoplasm budding off

Role: produce platelets for clot formation

Question 9

Describe erythropoiesis and its role.

Answer 9

1. Haematopoietic stem cell
2. Common myeloid progenitor cell
3. Reticulocytes
4. Erythrocytes

Role: RBCs produced in BM for transport purposes.

Question 10

Describe granulopoiesis and name the 3 granulocytes produced.

Answer 10

1. haematopoietic stem cell
2. common myeloid progenitor
3. myeloblast
4. granulocytes

Basophil, Eosinophil, Neutrophil

Question 11

Describe monocytopoiesis.

Answer 11

1. haematopoietic stem cell
2. common myeloid progenitor cell
3. myeloblast
4. monocyte
5. macrophage/ dendritic cells

Question 12

Describe lymphopoiesis and its role.

Answer 12

1. haematopoietic stem cell
2. common lymphoid progenitor cell
3. small lymphocyte
4. B/T lymphocyte, natural killer cells

Role: produce B/T lymphocytes & natural killer cells for immune response.

Question 13

Compare T and B lymphopoiesis.

Answer 13

T lymphopoiesis occurs mainly in the thymus.

B lymphopoiesis finishes in the BM.

Question 14

Tell me the main roles of each of the granulocytes.

Answer 14

Basophil: involved inflammatory + allergy responses by releasing histamines, heparin

Eosinophil: involved allergy responses and certain diseases

Neutrophil: 1st line of defence that phagocytoses & destroys pathogens in the circulation

Question 15

Tell me the main role of monocytes.

Answer 15

Monocytes circulate the blood before differentiating into macrophages or dendritic cells.

Macrophage: phagocytoses pathogens inside tissues.

Dendritic cells: APCs that help initiate the immune response.

Question 16

Why is erythropoiesis a continuous process?

Answer 16

Erythrocytes have a finite lifespan (120 days) and they lack the ability to divide so erythropoiesis needs to continue occurring in order for there be enough RBCs for transport & exchange.

Question 17

Where would be a source of haemopoietic stem cells for transplantation?

Answer 17

• BM
• Umbilical cords
• Granulocyte colony stim. factor (GCSF)

Question 18

Name 3 macrophages that are part of the reticuloendothelial system and where they are found.

Answer 18

• Kupffer cell (liver)
• Red pulp macrophage (spleen)
• Langerhans cells (skin + mucosa)
• Peritoneal macrophage (peritoneal cavity)
• microglia (CNS)
• tiss. histiocyte (connective tiss.)

Question 19

What is the purpose of the RES?

Answer 19

Remove dead/damaged cells and destroy foreign antigens.

Question 20

Which organs are mainly involved in the RES?

Answer 20

liver and spleen