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MEH A > Session 5 Notes > Flashcards

Session 5 Notes Flashcards

1
Q

Define haemopoiesis?

A

The process by which blood cells are formed

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2
Q

How many different lineage pathways arise from the haemopoeitic stem cells?

A

5

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3
Q

What are the different lineage pathways that arise form the haemopoeitic stem cells?

A

Thrombopoiesis, granulopoiesis, monocytopoiesis, lymphopoiesis and erythropoiesis

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4
Q

What does thrombopoiesis result in?

A

Formation of platelets

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5
Q

What does the process of granulopoiesis result in?

A

Production of granulocytes

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6
Q

What are granulocytes?

A

Basophils, neutrophils and eosinophils

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7
Q

How are granulocytes produced?

A

Arise from myeloblast cells which in turn arise form common myeloid progenitor cells

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8
Q

What has inappropriate activation of eosinophils been associated with?

A

Asthma and allergy

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9
Q

What happens to monocytes after they are produced?

A

They circulate in the blood for 1-3 days before moving into tissues where they differentiate into macrophages or dendritic cells.

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10
Q

What does the final maturation of B cells require?

A

Exposure to antigen in the lymph nodes

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11
Q

Where do T cells mature?

A

Thymus gland

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12
Q

What is erythropoiesis?

A

The process by which red blood cells are produced in the bone marrow

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13
Q

What is the lifespan of an erythrocyte?

A

120 days

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14
Q

What commits progenitor cells in the bone marrow to the erythroid lineage?

A

The expression of transcription factors GATA1, FOG1 and PU.1

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15
Q

What happens once the progenitor cells are committed?

A

Further expansion of the erythroid precursors driven by the hormone erythropoietin

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16
Q

Where is erythropoietin produced?

A

Kidney

17
Q

What increased erythropoietin production?

A

Decreased level of oxygen in the bloodstream

18
Q

What is the main function of erythropoietin?

A

Inhibit apoptosis of CFU - E progenitor cells

19
Q

What does CFU-E stand for?

A

Colony forming units of the erythroid cell line

20
Q

What does reticulocyte count from a blood sample show?

A

Provides a good diagnostic estimate of the amount of erythropoiesis occurring in a patient’s bone marrow

21
Q

How are reticulocytes formed?

A

Activation of CFU-E progenitor cells causes them to develop, proliferate and differentiate. During this process nucleated erythroblastosis extrude their nucleus and mots of their organelles hence forming reticulocytes.

22
Q

What is the role of the reticuloendothelial system?

A

Remove dead or damaged cells and to identify and destroy foreign antigens in blood and tissues

23
Q

What role does the spleen play in the RES?

A

It filters blood to remove deformed and old cells from the circulation

24
Q

When might a spleen be removed?

A

In response to trauma or to treat diseases such as hereditary spherocytosis

25
Q

What issues can people who don’t have a spleen face?

A

Increased risk of sepsis

26
Q

Describe the red blood cell membrane

A

Lipid bilayer that contain proteins such as spectrum, ankyrin, band 3 and protein 4.2

27
Q

What do the proteins in the erythrocyte membrane do?

A

They facilitate vertical interactions its the cytoskeleton of the cell which are essential for maintaining the biconcave shape.

28
Q

What do gene mutations in the erythrocyte membrane proteins result in?

A

Diseases such as heriditary spherocytosis

29
Q

What deceases the affinity of haemoglobin for oxygen?

A

2,3 bisphosphoglycerate, fall in pH or increase in CO2.

30
Q

What happens to the oxygen dissociation curve if the affinity of haemoglobin for oxygen is decreased?

A

Rightward shift of the oxygen dissociation curve

31
Q

Why is free iron toxic to cells?

A

Because it acts as a catalyst in the formation of free radicals from reactive oxygen species

32
Q

Where does absorption of iron occur?

A

Duodenum and upper jejunum

33
Q

What facilitates the uptake of non-haem ferrous iron from the intestinal lumen?

A

Transporter protein divalent metal transporter 1 (DMT1)

34
Q

Where is DMT1 located?

A

On the apical surface of enterocytes

35
Q

What happens to ferric iron before uptake?

A

Reduced to ferrous iron

36
Q

What is responsible for reducing the ferric iron to ferrous iron?

A

Duodenal cytochrome B reductive (DcytB)

37
Q

What is the absorption of iron regulated by?

A

Small peptide called hepcidin

38
Q

What are the two forms in which iron can be stored?

A

Ferritin and its insoluble derivative haemosiderin

39
Q

What is ferritin?

A

It is a protein-rich complex which can be incorporated by phagolysosomes to form haemosiderin granules.

MEH A (19 decks)

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