Erythropoiesis Flashcards

1
Q

Properties of mature RBCs

A

packed with Hb
no nucleus or mitochondria
no DNA/RNA - no cell division

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2
Q

Life span of a RBC

A

120 days

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3
Q

which organ removed fragile old RBCs from circulation

A

the spleen

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4
Q

where are new cells produced

A

red bone marrow

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5
Q

what are new RBCs produced from

A

pluripotent stem cells

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6
Q

what are RBCs broken down to

A

globular haemoglobin proteins are broken down to amino acids
Haem group is converted to bilirubin
Iron binds to transferrin in the blood and is recycled

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7
Q

where does bilirubin go

A

transported to the liver and secreted into bile

it’s breakdown products colour urine and faeces

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8
Q

what regulates erythrocyte production

A

EPO- erythropoietin, released by the kidneys

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9
Q

what causes the kidney to release EPO

A

hypoxia

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10
Q

steps of erythropoiesis

A
  1. pro erythroblast (derived from myeloid stem cells)
  2. polychromatic erythroblast (Hb appears in cytoplasm)
  3. orthochromatic erythroblast (nucleus shrinks, full complement of Hb in cytoplasm)
  4. erythroblast extrudes nucleus
  5. reticulocyte into circulation
  6. mature erythrocyte
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11
Q

structure of a RBC and its importance

A

Biconcave disc:

  • increased surface area
  • Flexible membrane so that cells can squeeze through capillaries in single file
  • decreased diffusion distance
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12
Q

what is the largest component of blood

A

plasma (55%)

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13
Q

what % of blood composition do platelets + white blood cells make up

A

1%

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14
Q

what % of blood is made up of RBCs in males, and in females

A

males- 40-50%

famles- 36-46%

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15
Q

what is haematocrit

A

the volume of RBCs as a % of total blood volume

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16
Q

how is RBC ion balance and cell volume regulated

A

Na+/K+ ATPases (the sodium pump) energy dependent process

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17
Q

through what route does a RBC synthesise ATP

A
Anaerobic glycolysis
(no mitochondria in RBC so cannot do aerobic glycolysis)
18
Q

what component from glycolysis keeps iron in Fe2+ state

19
Q

what is produced when Oxygen is low in order to release oxygen from haemoglobin

A

2,3 biphosphoglycerate

20
Q

what is glutathione

A

tripeptide consisting of glutamate, cysteine and glycine

21
Q

what other mechanism is some glucose metabolised through

A

hexose monophosphate shunt

22
Q

another name for the hexose monophosphate shunt

A

pentose phosphate pathway

23
Q

what does the pentose phosphate pawthay produce

A

nucleic acids and NADPH

24
Q

role of glutathione

A

combats oxidative stress (i.e. it is an anti-oxidant)

25
what are free radicals
highly reactive molecules with unpaired electrons
26
what happens if there is excessive free radicals or inadequate antioxidant defence mechanisms?
damage of cellular structures and enzymes
27
what is the importance of glutathione
helps protect against the toxic effects of free radicals | essential to de-toxify hydrogen peroxide
28
what is needed to produce glutathione
NADPH from pentose phosphate pathway
29
which condition causes a lack of glutathione
glucose 6-phosphate dehydrogenase deficiency
30
which form of glutathione acts as an anti-oxidant
the reduced form
31
how is CO2 carried to the lungs
1. dissolved in solution 2. bound to Hb (carbamino-haemoglobin) 3. as bicarbonate (60%)
32
how is the movement of CO2 facilitated
by carbonic anhydrase
33
what is haemoglobin comprised of
4 globin (protein) sub-units, each containing a single haem molecule
34
what does each haem molecule contain
single Fe2+ Ion | porphyrin ring
35
what can each haem group bind to
one O2 molecule
36
what does haemoglobin synthesis require
synthesis of globin chains- 4 per molecule of Hb synthesis of porphyrin ring (haem group) insertion of Fe2+ into haem
37
normal Hb concentration for male and females
male- 130-180 g/l | female- 115-165 g/l
38
differences between fetal and adult Hb
fetal Hb has a higher affinity for O2 has a lower affinity for 2,3 BPG Facilitates the transfer of O2 from the mother to the foetus
39
factors that shift the oxygen haemoglobin curve to the right
Increased 2,3 DIphosphoglycerate, increased temperature, increased H+
40
what does a shift to the right mean
more oxygen released at tissues
41
what pathway generates 2,3 diphosphoglycerate
Rapapoport-Lubering Shunt
42
name of the pathway that generates ATP and NADH by anaerobic glycolysis
Embden-Myerhof pathway