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TOB > Blood Cells And Haemopoesis > Flashcards

Blood Cells And Haemopoesis Flashcards

0
Q

In haemopoiesis what two cell lines derive from stem cells?

A

Myeloid blasts - precursors of erythrocytes, megakaryocytes, granulocytes and monocytes
Lymphoblasts - precursors of lymphocytes

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1
Q

Where are blood cells made in the developing foetus?

A

Initially by the mesoderm of the yolk sac, then by the liver and spleen, then eventually by the bone marrow.

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2
Q

What is the fate of lymphocytes on leaving the bone marrow?

A

Some pass through the thymus and go to form T lymphocytes- involved in cell mediated immunity
Others are B cells - produce antibodies for humoral immunity.
Further division may occur in lymph nodes and lymphoid aggregates.

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3
Q

What regulates the release of blood cells from the bone marrow?

A

Early blood cells are held in the bone marrow by adhesion molecules (collagen and fibronectin)
As the blood cells mature the expression of adhesion molecule receptors on the cell surfaces leading to release into the blood.

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4
Q

What regulates the production of erythrocytes?

A

The peritubular endothelial cells of the kidney release erythropoietin in response to hypoxia. This increases rate of production and release of erythrocytes.

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5
Q

How long does the average erythrocyte remain in the circulation?

A

120 days

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6
Q

Where are erythrocytes broken down?

A

Liver and spleen.

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7
Q

What happens to haem when red blood cells are broken down?

A

Iron is recycled, protoporphyrin ring is metabolised to bilirubin.

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8
Q

What are the three polymorphonuclear granulocytes?

A

Neutrophils
Eosinophils
Basophils

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9
Q

What are the agranulocytes?

A

Monocytes

Lymphocytes

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10
Q

What is the appearance of a neutrophil?

A

Multilobed nucleus

Small granules in the cytoplasm

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11
Q

What is the function of a neutrophil?

A

Migrate to site of infection by chemotaxis, destroy foreign material by phagocytosis.

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12
Q

What chemotactic substances cause neutrophils to migrate?

A

Substances released by bacteria or other white blood cells already present.

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13
Q

How long does an average neutrophil survive?

A

10 hours

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14
Q

What is the role of G-CSF. What does it stand for?

A

Granulocyte colony stimulating factor.

Increases neutrophil production and increases chemotaxis and phagocytosis.

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15
Q

What are the granules in a neutrophil?

A

Lysosomes containing digestive enzymes

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16
Q

What is a accumulation of neutrophils?

A

Pus

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17
Q

What is the appearance of eosinophils?

A

Bilobed nucleus, orange granules.

18
Q

What is the function of eosinophils?

A

Weakly phagocytic, ingest antigen - antibody complexes.

19
Q

In what group of patents is the blood level of eosinophils high?

A

Those with allergic conditions such as hay fever and asthma.

20
Q

How can eosinophils damage larger particles?

A

Release cytotoxic enzymes onto their surfaces.

21
Q

What is the appearance of basophils?

A

Granules stain blue

22
Q

Are basophils common?

A

No, least common of all blood cells.

23
Q

What is the function of basophils?

A

Mediate inflammation by secreting antihistamine - vasodilation, and increased permeability of capillaries leads to oedema
serotonin
heparin - anticoagulant.

24
Q

What is the appearance of monocytes?

A

Large cell with folded nucleus and grey/blue cytoplasm.

Occasional vacuoles.

25
Q

What is the function of monocytes?

A

Migrate into the tissue after 20-40 hours and act as macrophages.
Kupffer cells in liver
Glial cells in brain

26
Q

Do monocytes exhibit chemotaxis, and if so what do they move towards?

A

Yes - infection, neoplasm, inflammation.

27
Q

What is the name of a monocyte that has migrated into surrounding tissue?

A

Histiocyte

28
Q

What is the appearance of lymphocytes?

A

Small cells, round nucleus and rim of pale blue cytoplasm.

29
Q

What proportion of lymphocytes are T lymphocytes?

A

75%

30
Q

What property must lymphocytes have in order to be released into the blood stream?

A

Must recognise HLA (self histocompatability molecules -human leukocyte antigens) antigens but not react against them.

31
Q

What lymphocytes express CD4? What do they do?

A

T helper cells.
Recognise antigens bound to HLA class 2 molecules and:
Stimulate cytotoxic T cells which recognise and kill virally infected host cells
Permit B cells to transform into plasma cells and produce antibodies (immunoglobulin)

32
Q

What lymphocytes express CD8?

A

Cytotoxic T cells

33
Q

What happens to a b lymphocyte stimulated by antigens?

A

Transform into immunoblasts then plasma cells which secrete immunoglobulins.

34
Q

What are platelets produced from?

A

The cytoplasm of megakaryocytes

35
Q

What does the cytoplasm of a platelet contain?

A

Alpha granules - fibrinogen, von willebrands factor
Delta granules - calcium ions and ADP, Serotonin - vasoconstriction
Factor 3 - activates prothrombin.

36
Q

What is the appearance of platelets.

A

Small, purple staining

37
Q

What is the role of activated platelets in blood clotting?

A

Adhesion to damaged cell wall and aggregation with other platelets
Presents phospholipid surface - binding site for clotting factors.

38
Q

How do you classify blood?

A

Loose connective tissue

39
Q

What is the total blood volume, and what proportion is made up of plasma?

A

6 litres, 55%

40
Q

What proportion of body weight is blood?

A

7%

41
Q

What is the name of a newly formed red blood cell?

A

Reticulocyte.

42
Q

How do lymphocytes return to the circulation?

A

Lymphatic system.

43
Q

What proteins are found in plasma?

A

Include albumins, globulins, and fibrinogen.

TOB (14 decks)

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