Haematopoiesis

Question 1

What are platelets?

Answer 1

Cell fragments
Disc like structures circulating alone but forming clumps at sites of vessel injury
Role in clot formation

Question 2

What % of the blood is plasma and what %is erythrocytes?

Answer 2

55% plasma
45% erythrocytes
<1% buffy coat - leukocytes and platelets

Question 3

/What is haematopoiesis

Answer 3

the production of blood cells and platelets, which occurs in the bone marrow.

Question 4

What do all blood cells originate as?

Answer 4

Multipotential haematpoietic stem cell (haemocytoblast)

Question 5

What are haematopoietic stem cells?

Answer 5

Stem cells have the greatest ability of self renewal than any other cells
Able to differentiate into specialised cells dependent on stimuli
Can mobilise into the peripheral blood
Can undergo programmed cell death - apoptosis

Question 6

How many erythrocytes are made each second and how many are in 1 drop of blood? How long to they take to circulate?

Answer 6

2-3 mil made each second
Millions in 1 drop blood
One erythrocyte contains 1 bil molecules of oxygen
Takes 20s to circulate the body one time
Circulate for 120 days

Question 7

Describe erythrocytes

Answer 7

• Biconcave shape
• Lipid bilayer /..flexible
• No nucleus
• No organelles /..maximise space for carriage of Hb/O2/CO2

Question 8

Name the cells present in a 5 part differential count

Answer 8

Lymphocyte
Eosinophil
Neutrophil
Basophil
Monocyte

(See slid for images)

Question 9

What are the first line killers of the innate immune system?

Answer 9

Neutrophils Eosinophils Basophils Monocytes/macrophage
• Kill directly
• Smell organisms

Question 10

Briefly describe the 2 types of lymphocytes

Answer 10

• B Cells
– produce antibodies once faced with foreign
antigen
• T Cells
– Recognise foreign proteins and activate other cells
(e.g. neutrophils, monocytes, B cells) – Directly kill – Inhibit the immune response

Question 11

What are NK cells?

Answer 11

Natural Killer (NK) cells
– Stimulating sick cells to self destruct =

Question 12

What is the function of platelets?

Answer 12

Function of platelets
– Look for small breaks in blood vessels
– Primary plug
– Surface for clotting factors to make the definitive clot
– play a role in repair of the break

Question 13

How are stem cells transfused?

Answer 13

Bone marrow/stem cell transplantation

Use of recombinant growth factors

Question 14

What can result from abnormal full blood count results?

Answer 14

• Too much-high blood counts
– Polycythemia
– Leukaemia
– Thrombocythemia

• Too little-low blood counts
– Anaemia
– Leucopenia
– Thrombocytopenia

Question 15

What is pancytopenia?

Answer 15

Pancytopenia is a medical condition in which there is a reduction in the number of red and white blood cells, as well as platelets.

Question 16

What causes abnormal full blood count results?

Answer 16

Abnormal Full Blood Count results
• Mostly do NOT relate to primary bone marrow dysfunction
• Mostly are reactive to other conditions or treatment of these conditions

Question 17

What are some primary haematological disorders?

Answer 17

Haematological Malignancies
• Lymphomas
• Leukaemias
• Myelomas
• Myelodysplasia
• Myeloproliferative disorders
• Bone marrow failure syndromes

Primary haemostatic failure disorders (clotting/bleeding)

Red cell disorders (Haemoglobinopathies, enzyme,
membrane disorders)

Question 18

How would a test be performed to confirm diagnosis of primary haematological disorders?

Answer 18

Bone marrow biopsy - taken usually from iliac crest

Question 19

What is the cause of CML?

Answer 19

Chromosome translocation of 9 and 22 leading to creation of Philadelphia chromosome (new 22 with part of 9 attached)
Result - gene switched on and. A protein produced when and where it shouldnt be
This protein needs energy from atp to activate - atp in pocket - makes cells abnormal

Question 20

What is the bcr-abl gene?

Answer 20

A gene formed when pieces of chromosomes 9 and 22 break off and trade places. The ABL gene from chromosome 9 joins to the BCR gene on chromosome 22, to form the BCR-ABL fusion gene. The changed chromosome 22 with the fusion gene on it is called the Philadelphia chromosome. The BCR-ABL fusion gene is found in most patients with chronic myelogenous leukemia (CML), and in some patients with acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML).

Question 21

How does bcr-abl lead to cml?

Answer 21

Bcr-Abl plays a central role in the development of chromosome positive leukaemia. Chronic Myeloid leukaemia occurs due to increase proliferation and resistance to apoptosis by Bcr-Abl positive cells. Imatinib (STI571) is the first drug in the family of Bcr-Abl tyrosine kinase inhibitors