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Haematology > Erythropoiesis > Flashcards

Erythropoiesis Flashcards

1
Q

structure that enables RBCs to function

A

Hb carries O2
no nucleus so deformable and more room for Hb
high SA/ volume ratio
specialised membrane makes it flexible

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2
Q

what does the high oncotic pressure of RBCs risk?

A

draws water in so risks lysis

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3
Q

what does the oxygen rich environment of the RBC risk?

A

oxidation

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4
Q

adverse of RBCs having no nucleus?

A

unable to divide and replace damaged proteins so limited life span

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5
Q

adverse of no mitochondria in the RBC

A

limited to glycolysis for energy

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6
Q

how does the RBC keep water out?

A

Na+/K+ pump (needs ATP)

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7
Q

what makes the RBC membrane flexible?

A

lipid bilayer with lots of proteins makes it flexible

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8
Q

which molecule is a tetrameric globular protein?

A

Hb

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9
Q

what chains are present in adult Hb?

A

2 alpha

2 beta

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10
Q

what does the haem group consist of?

A

Fe2+ in a flat porphyrin ring (one haem per subgroup)

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11
Q

how many oxygen molecules can bind to Fe2+

A

1

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12
Q

how many oxygen molecules are there per Hb?

A

4

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13
Q

how many ml of oxygen can 1g Hb carry when fully saturated?

A

1.34ml

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14
Q

can Fe3+ bind oxygen?

A

no

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15
Q

describe the steps in formation of the Hb molecules

A
  1. iron/Fe2+ is transported to RBC cytosol
  2. combines with porphyrin ring (now called haem)
  3. combines with globin chain (alpha or beta)
  4. subunits combine
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16
Q

role of Hb

A

delivers oxygen to tissues
acts as a buffer for H+ (H+ can stick to it)
CO2 transport

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17
Q

what regulates production of RBCs in the bone marrow?

A

erythropoietin

18
Q

what produces erythropoietin?

A

kidney

19
Q

where does RBC destruction occur?

A

spleen (and liver)

20
Q

average lifespan of a RBC?

A

120 days

21
Q

what takes up aged RBCs?

A

macrophages

22
Q

what are globin chains recycled to?

A

amino acids

23
Q

what is the haem group recycled to?

A

iron and bilirubin

24
Q

how is bilirubin excreted?

A

taken to the liver, conjugated and excreted in bile (colours faeces and urine)

25
Q

cascade of haem breakdown

A

haem > porphyrin > biliverdin > bilirubin

26
Q

what can free radicals do to Fe2+?

A

oxidise it to Fe3+ (metHb)

27
Q

what stops oxidation of Fe2+?

A

NADH in glycolysis

28
Q

examples of reactive oxygen species

A

superoxide

hydrogen peroxide

29
Q

what do reactive oxygen species have?

A

unpaired free electrons that are capable of interacting with molecules and damaging their structure

30
Q

where is glutathione (GSH) found?

A

in RBCs

31
Q

role of glutathione (GSH)?

A

protects from hydrogen peroxide by reacting with it to form water and an oxidised glutathione product (GSSG)

32
Q

what replenishes the oxidised glutathione product GSSG?

A

NADPH generated by the hexose monophosphate shunt

33
Q

what enzyme is involved in the hexose monophosphate shunt?

A

glucose-6-phosphate dehydrogenase (G6PD)

34
Q

is G6PD X-linked?

A

yes

35
Q

what happens if there is X-linked deficiency of G6PD?

A

boys will have low levels leading to impaired defence and oxidative damage

36
Q

what shape is the oxygen dissociation curve?

A

sigmoidal

37
Q

what is the allosteric effect?

A

when one oxygen binds to the Hb molecule it becomes easier for others to bind

38
Q

foetal Hb oxygen dissociation curve

A

saturates more pO2 so shifts curve to the left

39
Q

function of myoglobin?

A

in muscles it takes O2 from red cells

40
Q

what produces 2,3-BPG?

A

Rapapoport-Lubering shunt

41
Q

what increases 2,3-BPG?

A

chronic anaemia leading to increased oxygen release

Haematology (34 decks)

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