Erythropoiesis Flashcards

STILL NEEDS COMPLETING especially with clinically relevant lecture content.

1
Q

Erythropoiesis

A

formation of erythrocytes from stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Haematopoiesis

A

formation of the blood’s cellular components. This is a continuous process of replenishment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Erythropoietin

A

a.k.a. EPO.

An enzyme with various roles; activates the development of erythroid cell precursors to proerythroblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sites of EPO production/release in the foetus

A
  • Yolk sac
  • Liver
  • Kidney
  • Spleen
  • Bone marrow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Sites of EPO production/release in the adult

A
  • Renal interstitium (kidney)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the stimulus for EPO secretion?

A

The tissue needs for oxygen.

This is identified as renal hypoxia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What factors might lead to renal hypoxia and thus erythropoietin secretion?

A
  • Normal oxygen levels but low delivery e.g. circulatory failure/anaemia
  • Low oxygen levels = hypoxia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Outline the steps that follow renal hypoxia

A
  • Increased renal secretion of erythropoietin
  • EPO transported by the blood to the bone marrow
  • EPO binds to receptors on CFU-E (erythroid cell precursors)
  • EPO also accelerates the release of reticulocytes into the blood
  • This aims to increase the number of circulating erythrocytes and thus restore oxygen transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

True/false: the lifespan of compatible transfused erythrocytes is shorter than that of erythrocytes produced within that animal’s body.

A

True.

e.g. in dog, transfused erythrocyte lifespan = 21 days compared to normal 120 days.

This is due to the process of blood taking and transport into another animal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to erythrocytes as they age?

A
  • They become more fragile
  • They may become swollen due to failure of the normal membrane function
  • They lose sialic acid residues from their surface, exposing galactose moieties that induce their phagocytosis.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the average lifespan of erythrocytes in dogs?

A

120 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the average lifespan of erythrocytes in horses?

A

145 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the average lifespan of erythrocytes in cattle?

A

160 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the average lifespan of erythrocytes in cats?

A

70 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When erythrocytes reach the end of their lifespan, the iron in them is released from haemoglobin. What happens next?

A

2 options:

  • Iron is conveyed to bone marrow by transferrin
  • Iron is stored as insoluble iron in macrophages and hepatocytes as ferritin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which species are these erythrocytes from?

A

These are equine erythrocytes.

There is characteristic rouleaux formation (clustering of RBCs in standing blood) - this is a normal finding in horses.

17
Q

Which species are these erythrocytes from?

A

These are bovine erythrocytes.

There is characteristic crenation and variation in size.

18
Q

Which species are these erythrocytes from?

A

These are camelid erythrocytes.

They have a characteristic ellipsoid shape.

19
Q

Which species are these erythrocytes from?

A

These are canine erythrocytes.

They are of uniform size and show central pallor, indicating their concave shape.

20
Q

Which species are these erythrocytes from?

A

These are feline erythrocytes.

They are smaller than other species and show anisocytosis (variation in size).

They show scarce central pallor (less concave than other species).

21
Q

Which species are these erythrocytes from?

A

These are avian erythrocytes.

They are larger and nucleated.

The earlier stages are more rounded and may be binucleate.

Occasionally cells lose their nucleus and are termed erythroplastids.

22
Q

Which species are these erythrocytes from?

A

These are reptile erythrocytes.

They are larger and nucleated.

The earlier stages are more rounded and may be binucleate.

Occasionally cells lose their nucleus and are termed erythroplastids.

23
Q

Erythrocytes are metabolically active (they need to maintain an electrolyte gradient); how do they obtain energy for this?

A

Via anaerobic metabolism of glucose.

This avoids the need for mitochondria and also avoids consumption of any of the oxygen they are carrying.