Haematopoiesis

Question 1

What are the different white blood cells? Which is the most common type in the blood?

Answer 1

Basophils
Neutrophils
Eosinophils
Monocytes
B-lymphocytes
T-lymphocytes

There are also mast cells and natural killer cells.

Lymphocytes and neutrophils are the most common.

Question 2

What is haematopoiesis?

Answer 2

Process of making all blood cells from a single stem cell.

Question 3

Describe some roles of the fully differentiated myeloid cells?

Answer 3

Thrombocytes - clotting
Erythrocytes - oxygen carrying
Granulocytes (basophils, eosinophils, neutrophils) - inflammatory, allergic, anti-microbial, anti-parasites
Monocytes - phagocytosis

Question 4

Describe the role of fully differentiated lymphoid cells.

What does a fully differentiated B-cell become?

Answer 4

Both involved in immunity reactions.

B cell when differentiated is a plasma cell.

Question 5

Briefly, how does disruption of haematopoiesis result in leukemic disease?

Answer 5

• Genetic abnormality occurs
• the affected precursor cells is unable to differentiate into a mature cell and be released into the blood to do its job
• instead the result is rapidly dividing immature cells (blasts) which fill and overwhelm the marrow
  = bone marrow failure.

Question 6

What is the difference between chronic and acute leukaemia?

Answer 6

Chronic - slow growing, usually affects more mature cells so some function retained e.g. marrow overwhelmed with too many functional cells. No apoptosis.

Acute - rapid onset, more immature cells affected e.g. proliferation of blasts, immediately life threatening as marrow overwhelmed with non-functional blasts.

Question 7

What is the difference between leukaemia and lymphoma?

Answer 7

Leukaemia originates in the bone marrow/blood

Lymphoma originates in the lymphatic system

Question 8

Why can leukaemia’s be generally thought of as a disease of differentiation or apoptosis?

Answer 8

Chronic leuk - disease of apoptosis, failure of mature cells to die off. Chronic because some function retained.

Acute leuk- disease of differentiation, failure of immature cells to differentiate and end up with blasts which can’t function.

Question 9

Where does haematopoiesis take place in;
Fetus?
Infants?
Adults?

Answer 9

Fetus - yolk sac first, then liver and spleen and finally bone marrow.
Infants - bone marrow of most bones, production in liver and spleen finishes
Adults - marrow is replaced by fatty substance, production remains in central skeleton and proximal ends of femur and humerus. Under stress the liver and spleen can resume production.

Question 10

What should the white blood cell count of a normal adult be?

Answer 10

4-11 x 10^9 cells/L

Question 11

What could a very high white cell count be indicative of?

Answer 11

CML

Question 12

Should you see blasts in a blood film from a healthy person?

Answer 12

No - blasts are always indicative of leukaemia or some kind of abnormal bone marrow process.

Question 13

What is a pluripotent stem cell?

Answer 13

A stem cell that is able to become any cell in the body and is self renewing.

Question 14

What is a multipotent stem cell?

Answer 14

A cell that is slightly more limited in what kind of cell it can become, e.g. it is a haematopoietic cell that can differentiate into either myeloid or lymphoid cells.