Haemopoiesis

Question 1

What is haemopoiesis?

Answer 1

Regulated process that forms blood cells.

Question 2

Where are blood cells manufactured?

Answer 2

Bone marrow.

Question 3

What is 45% of blood made of?

Answer 3

Blood cells; erythropoiesis, leucopoiesis and thrombopoiesis.

Question 4

What is 65% of blood made of?

Answer 4

Plasma which contains dissolved nutrients and plasma.

Question 5

What is erythropoeisis (RBC)?

Answer 5

Responsible for transporting oxygen from lungs to tissues.

Question 6

What is leucopoiesis (WBC)?

Answer 6

Responsible for defending the body against infection.

Question 7

What is thrombopoiesis (PLATELETS)?

Answer 7

Responsible for preventing blood loss at site of injury.

Question 8

What are the production of blood cells regulated by?

Answer 8

Growth Factors
Cytokines
Environmental Factors
Apoptosis (cell death)

Question 9

Where does haemopoiesis take place in adults?

Answer 9

Bone Marrow of Vertebrae
Ribs
Sternum
Skull
Sacrum
Pelvis

Question 10

Where does haemopoiesis take place in infants?

Answer 10

Bone Marrow (all bones)

Question 11

Where does haemopoiesis take place in foetus?

Answer 11

0-2 months - Yolk Sac Of Embryo
2-7 months - Liver, Spleen
5-9 months - Bone Marrow

Question 12

What is haemopoiesis that takes place in the bone marrow called?

Answer 12

Intramedullary

Question 13

What is extramedullary disease?

Answer 13

Pathological condition in which bone marrow is unable to meet demands of the body. Myeloma cells form tumours outside the bone marrow.

Question 14

What is red bone marrow?

Answer 14

Contains blood stem cells that can become red blood cells, white blood cells or platelets.

Question 15

What is yellow bone marrow?

Answer 15

Mostly made up of fat and contains stem cells that can become cartilage, fat or bone cells.

Question 16

How does the blood stem cells differentiate?

Answer 16

1) Begins with the pluripotent stem cell (mother stem cell). It has the ability to replicate, proliferate and differentiate into any of the different lineages.
2) Pluripotent stem cells give rise to the common myeloid progenitor cell which enables red cells, white cells and platelets.
3) Common lymphoid progenitor cell gives rise to B and T cells and natural killer cells.

Question 17

What does the bone do?

Answer 17

Provides support and pivotal points for muscles, ligaments and tendons. This includes lungs, hearts, brain and spinal cord. It also gives support for body organs such as liver and spleen.

Question 18

Where does haemopoesis take place in the bone ?

Answer 18

Hollow spaces within the bone that are not being used for structural reasons.

Question 19

What is homing?

Answer 19

Attracts any haemopoietic stem cells and keep them in the blood marrow until optimum proliferation can take place.

Question 20

What is cell mobolisation?

Answer 20

The release of haempoietic stem cells. Happens in times of injury, in which platelet production is triggered.

Question 21

What are examples of growth factors?

Answer 21

-Interleukins (ILs)
-Colony Stimulating Factors (CSFs)
-Other Factors

Question 22

Interleukins ?

Answer 22

IL-1 stimulates the production of GM-CSF, G-CS, M-CSF and IL-6 from a variety of cells within the bone marrow.
IL-3, IL-4 and IL-6 act on early multipotent cells.
IL-5 is an eosinophil CSF.

Question 23

Colony Stimulating Factors ?

Answer 23

Granulocyte CSF stimulates the differentiation of granulocyte precursors and also the activity of mature granulocytes.

Granulocyte-macrophage CSF stimulates the differentiation and maturation of granulocytes and macrophages, and also the function of these cells once mature.

Question 24

Other Factors ?

Answer 24

Stem cell factors act on pluripotent stem cells, causing them to differentiate further. It has effects on the later maturation of several cell lineages.

Erythropoietin is released mostly from the kidney and travels in the blood to the bone marrow where it acts on erythroid precursors to stimulate red blood cell production.

Thrombopoietin (produces by the liver) stimulates megakaryocytic maturation and therefore platelet production.

Question 25

What is apoptosis ?

Answer 25

-Programmed cell death.
-Individual cells are triggered to activate intracellular proteins that lead to the death of the cell.
-Characterised by cell shrinkage, condensation of nuclear chromatin, cleavage of DNA at internucleosomal sites and fragmentation of the nucleus.

Question 26

Erythropoiesis ?

Answer 26

-Formation of red blood cells.
-RBC transports oxygen from the lungs to the tissues.
-Red due to high levels of haemoglobin.
-Centre of pallor which takes up 1/3 of the blood cell.
-2 microns in diameter.
-Normal concentration in the blood is 3.0-6.5 X 10^12L.