Red blood cells- creation, function and destruction Flashcards

Aidan

1
Q

What is haematocrit?

A

the packed cell volume or the amount of RBC’s in the total blood volume.

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2
Q

What is generally the make up of the blood in people with anaemia?

A

less RBC’s in proportion to WBC’s and plasma than usual but normally the same amount of blood volume.

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3
Q

Describe the structure of RBC’s

A

A biconcave disc with a high surface areas to volume ratio.

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4
Q

What are the main functions of RBC’s?

A

Transport of O2 and CO2 and maintaining the acid/base balance of the blood.

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5
Q

Brief description of RBC’s?

A

Bag of Haemoglobin (Hb) and enzymes for glycolysis- unable to divide and create new proteins.

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6
Q

How does bone marrow move from birth to adulthood.

A

Widespread throughout body after birth but redistributed to the axial skeleton by adulthood.

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7
Q

Name the stroma of the bone marrow

A

Fibroblasts, macrophages, endothelium and fat cells.

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8
Q

What other cells do red blood cells develop around?

A

Red blood cells mature and develop around macrophages in the bone marrow

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9
Q

What is the function of the macrophages in the bone marrow?

A

Macrophages are the main store of iron in the bone marrow and feed this to developing RBC’s.

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10
Q

What is reticulin?

A

remnants of mRNA left once the nucleus of a maturing RBC has been extruded, removed by the spleen within 1-2 days.

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11
Q

what form must iron be in to be absorbed and used?

A

ferrous form

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12
Q

when is there a higher need for iron?

A

During pregnancy/Blood loss

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13
Q

What does hepcidin do in the body?

A

It regulates iron absorption and release from macrophages- increased in inflammatory disease so less available iron.

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14
Q

What are some causes of iron loss from the body?

A

Blood sampling, menstrual loss, minor trauma, GI approx 1ml per day, very small amounts in urine/skin shedding.

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15
Q

what is the role of transferrin?

A

Transport/recycling, transferrin receptors increased when iron is deficient.

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16
Q

What is ferritin?

A

The insoluble storage form of iron (it is a better measure of iron stores).

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17
Q

What are B12 and folate(folic acid) involved in?

A

They are important in the production of RBC’s

18
Q

When is erythropoetin produced?

A

Tissue hypoxia and anaemia, high altitude and certain epo producing tumours (renal).

19
Q

What is produced when at low oxygen levels?

A

erythropoetin (epo).

20
Q

What is the most important driver of RBC production?

A

Erythropoetin (epo)

21
Q

What is spectrin and what properties does it give to RBC’s?

A

It gives RBC’s their flexibility and ability to return to shape after squeezing through tiny capillaries etc.

22
Q

What does haem do and where are they found?

A

It binds to oxygen and one is found per globin chain.

23
Q

What does haemoglobin need? (adults)

A

Two alpha chains and two beta chains

24
Q

What does haemoglobin need? (foetal)

A

Two alpha chains and two gamma chains

25
Q

What is Thalassaemia in relation to globin chains?

A

An inherited defect in globin chain production.

26
Q

What is sickle cell anaemia in relation to globin chains?

A

One amino acid change in the beta chain.

27
Q

What does the glycolytic pathway ending in lactate and pyruvate supply energy for?

A

Maintaining membrane integrity, Prevent oxidation of enzymes and Fe++, Maintain gradients of of K+ and Ca++

28
Q

what can cause anaemia by increased haemolysis (increased rate of RBC breakdown).

A

Enzyme deficiencies e.g; pyruvate kinase.

29
Q

What will acidosis and increased temperature cause?

A

will cause more oxygen to be delivered to the cells.

30
Q

what causes an increase of 2,3 DPG?

A

Exercise, anaemia and high altitude.

31
Q

What happens with the buildup of 2,3 DPG?

A

It works its way in between the globin strands and forces the chains apart to allow more oxygen to be released.

32
Q

Where is Myoglobin located?

A

In skeletal muscle.

33
Q

What is Myoglobin used for?

A

A ‘last ditch’ store of O2 for immediate use in cases of extreme exertion.

34
Q

What is the acid-base balance?

A

The regulation of H+ ions in the body fluids

35
Q

Why is the acid-base balance important?

A

Enzymes work optimally at physiological pH, Cell membranes become leaky in acidosis and Neurones become less able to transmit in acidosis and hyperactive in alkalosis.

36
Q

What are buffer systems used for?

A

Used to regulate the amount of hydrogen ions in the body by providing a buffer against extreme changes in hydrogen ions

37
Q

which buffer system accounts for 60% of the available buffer?

A

Bicarbonate reaction using carbon anhydrase as the catalyst.

38
Q

Which buffer system accounts for 30% of the available buffer?

A

Haemoglobin binds to H+ ions after the loss of oxygen and then Hb reacts with CO2 (more H+ ions are buffered and absorbed than are released in this reaction).

39
Q

What happens as red blood cells age?

A

Membrane becomes more rigid, loses glycolytic enzymes and neoagents are exposed on the cells surface

40
Q

Examples of RBC loss or destruction?

A

Some RBC loss into GI/menstrual loss/into soft tissues and some RBC’s are destroyed within the body

41
Q

How does the spleen/liver recycle RBC’s?

A
  • Free Hb “mopped up” by haptoglobin- cleared by liver. (Any excess can appear in urine).
  • Globin chains broken up into amino acids
  • Iron bound to transferrin and returned to macrophages
  • Porphyrin ring becomes bilirubin- bound to albumin and “conjugated” to glucuronide- excreted in bile