Unit 6 - Red Cell Structure & Physiology Flashcards

1
Q

Size of RBC

A

7-9 um

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2
Q

RBCs can squeeze through small micro vessels as small as ___ in the spleen

A

3 micrometers

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3
Q

For normal function, the RBC structure must have

A

1) Intact, functioning membrane
2) Normal internal metabolism
3) No nucleus for repairs

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4
Q

RBC membrane structure components

A

Lipid Bilayer
Protein layers that transverse lipids
Protein cytoskeleton

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5
Q

Components of the lipid bilayer

A

Cholesterol
Phospholipids

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6
Q

Phospholipids composed of hydrophobic and hydrophilic parts

A

Hydrophobic tails - Interior
Hydrophilic heads - exterior

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7
Q

How much cholesterol on lipid bilayer is in proportion to plasma cholesterol

A

in equilibrium with plasma cholesterol

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8
Q

Components of proteins that transverse the lipid bilayer

A

Glycophorins
Band 3 protein

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9
Q

Glycophorin types

A

A, B, C

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10
Q

Three domains of the types of glycophorins

A

Cytoplasmic - Interior
Hydrophobic - Middle
Extracellular - Exterior

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11
Q

Where is glycophorin C in the membrane of the RBC?

A

Outside, its heavily glycosylated

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12
Q

What do extracellular glycophorins do

A

Carry RBC antigens
Negative charge (Zeta potential) that keeps RBCs apart

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13
Q

What does Band 3 protein do

A

Anion exchange protein 1
Channel for chloride <–> bicarbonate (CO2 exchange)

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14
Q

Components of membrane cytoskeleton

A

Spectrin
Ankyrin
Actin
Tropomyosin
Bands 4.1, 4.2, 4.9

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15
Q

Where is the RBC Cytoskeleton

A

Underneath the lipid bilayer

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16
Q

What does the RBC cytoskeleton do

A

Maintain RBC shape
Pliability to squeeze through capillaries and survive turbulence

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17
Q

What is the main protein of the cytoskeleton

A

Spectrin

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18
Q

What is spectrum composed of

A

alpha and beta chains twisted together

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19
Q

What is the shape of spectrin

A

Arranged in lattice of hexagons to allow it to recoil like a spring

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20
Q

Where is spectrin and what holds it there?

A

Attached to the bilipid layer by ankyrin and band 4.2

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21
Q

What does ankyrin do

A

Anchors spectrin

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22
Q

Another name for ankyrin

A

Band 2.1

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23
Q

What do actin and tropomyosin do

A

Muscle like filaments that stabilize RBC cytoskeleton

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24
Q

What do Bands 4.1, 4.2, 4.9 do

A

help with stabilization

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25
Q

Deformability of RBC depends on

A

1) Biconcave shape
2) Viscosity of internal solution (mostly hgb)
3) Elastic properties of RBC membrane

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26
Q

What does the lipid bilayer rely on for repair?

A

Plasma lipids

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27
Q

What does an increase of plasma lipids do to RBC

A

Changes the membrane

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28
Q

What are typical shape changes due to plasma lipids

A

Codocytes (target)
Acanthocytes (spur)

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29
Q

Anions and water flow freely across the membrane via what structures?

A

Protein band 3
Water channel protein

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30
Q

What do cations require for permeability?

A

Cation pump and ATP

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31
Q

What do cation pumps do

A

Sodium pumped out
Potassium drawn in

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32
Q

What are the main cation pumps in RBC membrane

A

Na/K
Ca-ATPase

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33
Q

Are calcium and magnesium intracellular or extracellular?

A

Intracellular

34
Q

What occurs if the cation pump fails?

A

Sodium builds up in the cell
Water accumulates in cell
Sphere shape
Hemolysis

35
Q

What is the cause of cell pump function decreasing

A

insufficient ATP from insufficient glucose metabolism

36
Q

Erythrocyte function in addition to O2 and CO2 transport

A

Membrane permeability to maintain ion balance
Buffer function of hgb via bohr effect
Bicarb formation and dissociation into carbonic acid and hydrogen

37
Q

Requirements for function of RBC

A

Energy supply
Membrane integrity
Normal hgb
Pyridine nucleotides (NAD/NADH)

38
Q

How do RBCs generate ATP?

A

Glycolysis

39
Q

What do pyridine nucleotides do

A

Prevent oxidant injury
Reduce methemoglobin to hemoglobin

40
Q

Red Cells perform their function without

A

Nucleus
Mitochondria
Protein synthesis

41
Q

Red cells are totally dependent on ___ for energy

A

Plasma glucose

42
Q

Red cells use oxygen to generate ATP

A

False, only anaerobic glycolysis

43
Q

When RBCs are chemically damaged, how are they repaired?

A

RBC enzymes

44
Q

Major categories of RBC metabolism

A

Glycolysis –> ATP
NAD/NADH metabolism to reduce methemoglobin
Leubering Rapoport Shunt

45
Q

Two different glycolysis pathways for RBC ATP generation

A

Embden Meyerhoff Pathway
Hexose Monophosphate Shunt

46
Q

Two NAD/NADH metabolism routes for RBC metabolism

A

Hexose Monophosphate Shunt
Methemoglobin Reductase Pathway

47
Q

Anaerobic glycolysis for energy

A

Embden Meyerhoff Pathway
Hexose Monophosphate Shunt

48
Q

90% of cellular glucose processed using which pathway?

A

Embden Meyerhoff Pathway

49
Q

Glycolytic Pathway (embden meyehoff)

A

Glucose–>Pyruvate–> Lactate
ATP generated for energy
NADH generated for methemoglobin reduction

50
Q

Why is NADH important?

A

Methgb is oxidized hgb when exposed to Oxygen
Methgb can’t carry oxygen so reversal is important

51
Q

What generates NADH?

A

G-6PD

52
Q

5-10% of cell’s glucose processed through

A

Hexose monophosphate shunt

53
Q

Hexose monophosphate shunt produces

A

NADPH2

54
Q

NADPH function

A

Converts oxidized glutathione to reduced glutathione
Reduced glutathione neutralizes oxidation

55
Q

Methemoglobin Reductase Pathway

A

Enzyme takes NADH and reduces methemoglobin

56
Q

Diseases/Drugs that interfere with the methemoglobin reductase pathway cause what?

A

Cyanosis

57
Q

Leubering Rapoport Shunt

A

Generates 2,3 DPG
Needed for hgb to exchange oxygen

58
Q

G6PD deficiency

A

Glutahtione can’t be generated
Hgb is oxidized
Hgb denatures –> Heinz bodies –> removed by spleen

59
Q

What inclusion is associated with G6PD deficiency?

A

Heinz Bodies

60
Q

What stain allows us to see Heinz bodies

A

Supravital

61
Q

How much of hgb is methemoglobin normally

A

Normal for 2% of hgb to become methgb per day

62
Q

Without enzyme, how much does methemoglobin build up to?

A

20-40%

63
Q

Pyruvate kinase deficiency

A

Pyruvate can’t be converted to lactate
Less ATP generated
RBC weak (cation pumps)
Hemolytic anemia ensues

64
Q

WHy do infants get slight anemia after birth?

A

High RBC counts because Hypoxic in utero
High oxygen after birth –> low EPO
Slight anemia until EPO recovers

65
Q

Why do males have higher RBC counts

A

Testosterone magnifies EPO effect

66
Q

What hormones have an effect of EPO

A

Thyroid
Pituitary
Adrenals

67
Q

Chemical signal for senescence to phagocytes

A

Exposure of phosphatidylserine on RBC surface

68
Q

Extravascular hemolysis is what percent of normal destruction

A

90%

69
Q

Intravascular hemolysis is what percent of normal destruction

A

10%, old RBCs

70
Q

Where does most extravascular hemolysis take place

A

In spleen by phagocytes
also in marrow by phagocytes

71
Q

Hgb made up of

A

Heme + Globins

72
Q

Heme made up of

A

Iron and protoporphyrin ring

73
Q

Globins made up of

A

Amino acids

74
Q

HEme recyclin

A

Fe –> Transferrin –> marrow
Porphyrin ring –> bilirubin + urobilinogen

75
Q

Haptoglobin

A

Picks up free hemoglobin to prevent loss through kidneys

76
Q

Where does haptoglobin take hgb

A

Back to the liver for processing, same as extravascular

77
Q

What happens if haptoglobin is consumed and there is still excess free hemoglobin

A

Oxidized to methgb, broken down to heme + globin

78
Q

Hemopexin

A

Carries heme to liver for processing

79
Q

If hemopexin is all used up, what carries heme in its place?

A

Albumin, forms methemalbumin until hemopexin is produced

80
Q

IF hemolysis is beyond normal capacity, where is it going to go?

A

Hemoglobin shows up in urine

81
Q

Hemosiderinuria

A

when IV hemolysis sever, iron laden renal tubule cells can slough off
Stain cells in urine sediment with Prussian blue
Better indicator of sever IV hemolysis than hgb in urine