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Haematology > Normal Erythropoiesis > Flashcards

Normal Erythropoiesis Flashcards

1
Q

What are the properties of red blood cells?

A

Full of haemoglobin to carry oxygen
No nucleus or mitochondria
High surface area:volume ratio to allow gas exchange
Flexible to squeeze through capillaries

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2
Q

Why do red blood cells have no nucleus?

A

To allow more space for haemoglobin molecules and to make the cell more deformable

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3
Q

What are some issues caused by the adaptions of red blood cells?

A

High oncotic pressure and oxygen rich environment
Limited lifespan and can’t divide or replace damaged proteins
Can only produce energy by glycolysis

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4
Q

What are some features of the red blood cell membrane?

A

Complex structure = not just lipid bilayer

Protein spurs and anchors to make it flexible

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5
Q

What is required to allow red blood cells to keep water out?

A

Energy is needed to maintain specific ion concentrations

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6
Q

What maintains ion concentrations in red blood cells?

A

The sodium potassium pump = keeps water out but requires ATP

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7
Q

What is haemoglobin?

A

Tetrameric globular protein

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8
Q

What chains does adult haemoglobin consist of?

A

2 alpha and 2 beta chains

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9
Q

What does the heme group consist of?

A

Fe2+ in a flat porphyrin group = oxygen binds to Fe2+

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10
Q

How many heme groups are there per subgroup?

A

One heme per subgroup = 4 subgroups per haemoglobin molecule so 4O2 can bind

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11
Q

Where does red blood cell production occur?

A

In the bone marrow = result of HSC proliferation and differentiation

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12
Q

What regulates red blood cell production?

A

Erythropoietin

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13
Q

When is erythropoietin released by the kidneys?

A

When hypoxia is sensed by kidneys = releases erythropoietin to stimulate red blood cell production

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14
Q

Where does red blood cell destruction normally occur?

A

In the spleen

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15
Q

What is the average lifespan of a red blood cell?

A

120 days

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16
Q

What cells take up aged red blood cells?

A

Macrophages

17
Q

What happens when red blood cells are destroyed?

A

Contents are recycled = globin chains recycled to amino acids
Heme group broken down to iron and bilirubin

18
Q

What happens to the bilirubin produced by heme breakdown?

A

Taken to liver and conjugated then excreted in bile

19
Q

What are the steps in the breakdown of heme?

A

Heme - porphyrin - biliverdin - bilirubin

20
Q

What are reactive oxygen species?

A

Free radicals that have unpaired electrons (e.g hydrogen peroxide)

21
Q

Why are reactive oxygen species an issue?

A

They interact with other molecules and damage their structures

22
Q

What is the importance of glutathione?

A

Protect against hydrogen peroxide by reacting with it to form water and GSSG

23
Q

How is glutathione replenished by the body?

A

Using NADPH

24
Q

How is NADPH replenished?

A

Using the hexose monophosphate shunt

25
Q

What is the rate limiting step in glutathione production?

A

G6PD

26
Q

How is CO2 transported in the body?

A

10% dissolved in solution
30% bound directly to Hb as carbamino-Hb
60% as bicarbonate = red cells help in production

27
Q

What is bicarbonate exchanged for in red blood cells?

A

Exchanged for chlorine = HCO3- exported by facilitated diffusion

28
Q

How do red blood cells buffer the H+ produced by CO2?

A

Using deoxygenated haemoglobin

29
Q

What effect does chlorine entering the red blood cell in exchange for HCO3- have on the cell?

A

Preserves potential and causes cell to swell

30
Q

What shape is the oxygen-haemoglobin dissociation curve?

A

Sigmoidal

31
Q

How does red blood cells show co-operative binding?

A

As one O2 binds it changes the shape of Hb = makes it easier for next O2 to bind to another subunit

32
Q

Where on the oxygen-haemoglobin dissociation curve can venous pO2 be seen?

A

At the shoulder of the steep part of the curve = large reserve of spare capacity

33
Q

What effect to molecules that interact with Hb have on the dissociation curve?

A

Shift it to the right = examples include H+, CO2 and 2,3-BPG

34
Q

What does shifting the dissociation curve to the right do to oxygen delivery?

A

Increases the amount of oxygen being delivered

35
Q

What does glycolysis produce?

A

2 molecules of pyruvate, 2 ATP and 2 NADH

Haematology (24 decks)

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