Red Blood Cells: Production and Function Flashcards

1
Q

What nutrients do red blood cells require for their function?

A

Iron

Folate

Vit B12

EPO

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2
Q

What is the normal lifespan of RBCs?

A

120 days

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3
Q

How much Hb does each red blood cell contain?

A

640x10^6 molecules of Hb

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4
Q

What is haemoglobin made up of?

A

Haem containing Fe2+ and 4 globin polypeptide chains.

2 alpha subunits and 2 beta subunites

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5
Q

Where is Haem made?

A

Mitochondria

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6
Q

What conditions are caused by defects in globin?

A

Sickle cell anaemia

Thalassaemia

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7
Q

Where is erythropoietin produced?

A

In the kidneys

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8
Q

Where do red cell precursors develop?

A

In the Bone Marrow

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9
Q

What is nuclear maturation?

A

Chromatin condenses and is then extruded when RBC is maturing.

Cytoplasm then undergoes haemoglobinisation

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10
Q

What are the parts of the bone marrow where red blood cells are produced called?

A

Erythroid islands which are located radially. They are surrounded by macrophages which deliver iron to them from storage form (ferritin).

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11
Q

What happens to the colour of the RBC as it is undergoing its formation?

A

It goes from orthchromatic (many colours) to becoming red like the haemoglobin molecules it contains.

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12
Q

What are the stages of erythropoiesis called?

A

Proerythroblast

Basophilic normoblast

Polychromatic normoblast

Orthochromatic normoblast

Reticulocyte

RBC

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13
Q

What is RBC membrane composed of?

A

Phospholipids with proteins

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14
Q

What does haemoglobin do?

A

Transports O2 from lungs to tissues

Returns CO2 to the lungs

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15
Q

What are normal Hb levels in infants?

A

110 - 140 g/L

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16
Q

What are normal Hb levels in adult females?

A

115 - 155 g/L

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17
Q

What are normal Hb levels in adult males?

A

130 - 180 g/L

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18
Q

What is the normal RBC count?

A

3.8 - 6 x 10^12/L

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19
Q

What does Hb look like in normal adults?

A

Consists of 2 alpha and 2 non-alpha globin chains.

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20
Q

What chains does Hb contain in fetal and adult haemoglobin?

A

In fetal haemoglobin there are 2 gamma chains and 1 gamma chaina nd 1 beta chain. This is called haemoglobin F

At birth there is an increase in beta chains which start to replace gamma chains until adulthood where there are 2 alpha and 2 beta chains.

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21
Q

What chains can’t be made in thalassemia?

A

Beta chains

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22
Q

What is the stimulus for EPO release in the kidneys?

A

Renal O2 tension and hypoxia(anaemia or low atmospheric O2)

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23
Q

What nutrients are required to make RBCs?

A

Iron, Cobalt

Vitamin B12, folate, thiamine

Amino acids; Other cytokines (SCF; IL3)

24
Q

Which cells of the kidney produce EPO?

A

Juxtaglomerular cells

25
Q

What does iron do?

A

Integral part of haemoglobin,

26
Q

How much of our dietary iron do we absorb?

A

5 - 10% in upper small bowel (in alkaline environment)

27
Q

How is iron transported to bone marrow?

A

Bound to transferrin protein and excess is stored in macrophages and liver as ferritin

28
Q

How much iron do we require daily?

A

1 - 2 mg/day

Varies by age and gender

29
Q

What increases needs for iron?

A

Pregnancy increases needs too as well as menstruation and times of growth.

30
Q

How do we lose Iron?

A

Sweating

Faeces

Blood loss

31
Q

What is vitamin B12 needed for?

A

required for nuclear maturation

32
Q

Where is vitamin B12 absorbed?

A

Absorbed in the ileum (requires intrinsic factor)

33
Q

Which food sources contain vitamin B12?

A

Animal products

34
Q

Is vitamin B12 stored?

A

Yes can be stored for years

35
Q

What does folate do?

A

Needed to prevent macrocytic anaemia

36
Q

Where can folate be consumed?

A

Fruit and vegetables

37
Q

Where is folate absorbed?

A

Upper small bowel

38
Q

Are folate stores large?

A

No they are small and are stored for 3 months

39
Q

Where are the genes for alpha globin located?

A

2 alpha genes on each 16 chromosome

Each is responsible for 25% of the normal total alpha chain synthesis

40
Q

Where are the non-alpha globin genes located?

A

one beta gene on each chromosome 11

beta gene is part of a complex containing the delta and gamma genes

41
Q

What gives red blood cells their tensile strength?

A

Peripheral proteins which include:

Spectrin

Actin

Protein 4.1

42
Q

What binds spectrin proteins through bilayer?

A

Integral proteins (Band 3 and glycoprotein)

43
Q

How does a red blood cell make ATP?

A

Embden-Meyerhof pathway

44
Q

How is glucose metabolised in RBCs?

A

Anaerobic glycolysis (requires no mitochondria and no oxygen)

45
Q

How much ATP is produced by the Embden-Meyerhof pathway?

A

1 glucose molecule = 2 ATP

46
Q

Why do RBCs need ATP?

A

To become more flexible and deformable.

47
Q

What else is produced besides ATP in the Embden-Meyerhof pathway?

A

2 molecules of lactate

48
Q

What features do normal cells have that RBCs don’t have?

A

No nucleus

Can’t reproduce

Have no organelles

Have no synthetic activities

Are easy to deform reversibly

49
Q

What is haem broken down into?

A

Bilirubin and excreted by the liver in bile

50
Q

What is haemolysis?

A

Reduced RBC lifespan / increased rate of red cell destruction

51
Q

What happens to byproducts of RBC destruction?

A

Globin is broken down to constituent amino acids

Iron is bound to transferrin

Protoporphyrin is broken down into bilirubin (producing CO2) and then excreted in bilirubin

52
Q

What causes anaemia?

A

Reduced BM production

Increased loss of RBCs

Premature destruction (haemolysis)

53
Q

What are symptoms based on in anaemia?

A

Speed of onset and patient age

54
Q

What are primary causes of reduced BM production of RBCs?

A

Bone marrow failure

Red cell aplasia

55
Q

What are secondary causes of reduced BM production of RBCs?

A

Infection

Drugs

Infiltration

Absence of ingredients

BM hypoxia

Ineffective erythropoiesis

56
Q

What causes increased RBC loss?

A

Bleeding, haemorrhage

Haemolysis: premature RBC breakdown (reduced red cell lifespan through cell destruction)

57
Q

Summary

A

Describe the process by which RBC are produced

Understand the components required for erythropoiesis