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Undeleted > Erythrocytes > Flashcards

Erythrocytes Flashcards

1
Q

mammalian shape of RBC

A

discocyte (biconcave disc)

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2
Q

Which in general have a higher RBC mean cell volume: mammals or nonmammals?

A

nonmammals

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3
Q

Increased total RBC count –> MCV? (In general)

A

decreases. As number of RBCs increases, they usually also decrease in size

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4
Q

“drepanocyte” means:

A

sickle shaped. i.e. - deer blood

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5
Q

“dacrocyte” means:

A

tear shaped. i.e. - goat blood

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6
Q

Camelids have what shape RBC?

A

elliptocytes

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7
Q

Birds have what shape RBC?

A

ovalocyte

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8
Q

pigs have what shape RBC?

A

echinocyte

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9
Q

What causes sickling of RBC?

A

Single amino acid substitution. Also, a pH drop and oxygen can potentiate sickling

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10
Q

What can cause echinocyte shape in RBC?

A

1) excess anticoagulant in sample
2) ATP depletion with prolonged storage
3) addition of fatty acids, bile acids, certain drugs
4) disease states

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11
Q

Is echinocyte shape in RBC reversible?

A

yes

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12
Q

erythrocyte functions

A

1) transport of oxygen
2) transport of carbon dioxide
3) buffering of H+ ions

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13
Q

blood oxygen content is dependent on:

A

1) Hb content
2) pO2
3) Hb oxygen affinity (P50)

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14
Q

What is the advantage of releasing O2 to tissues at a higher pO2? (Hb is unloading sooner)

A

creates a greater gradient for O2 delivery to the tissues

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15
Q

What is the DISadvantage of releasing O2 to tissues at a higher pO2? (Hb is unloading sooner)

A

won’t be able to fully load the oxygen in the lungs and some of the animal’s Hb won’t even get used

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16
Q

Increased 2,3 DPG –> Hb’s affinity for O2

A

decreases. Hb releases O2 sooner

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17
Q

How does 2,3 DPG, temperature, CO2, and H+ effect Hb affinity for O2?

A

If any of them increase, Hb’s affinity for O2 decreases

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18
Q

How do anemic dogs compensate for low Hb?

A

have higher 2,3-DPG lvls

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19
Q

products of oxidative metabolism at the tissues?

A

CO2 and acids

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20
Q

Where is binding of O2 to Hb maximized and minimized?

A

Maximized at the lungs, minimized at the tissues

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21
Q

P50 represents

A

oxygen affinity. High p50 means lower O2 affinity

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22
Q

Why do smaller animals have higher p50 than larger animals?

A

they have higher metabolic rates, therefore need more O2 released to tissues rapidly

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23
Q

Why is there higher Hb affinity for O2 in fetal blood than maternal blood?

A

potentiates O2 delivery from mother to fetus. Fetus normally lives in a hypoxic environment, so it’s ok for their Hb to have a higher affinity for O2

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24
Q

Where is majority of CO2 in body?

A

bicarbonate in the blood. Acts as a buffer and increases CO2 carrying capacity of blood

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25
Q

Which binds more CO2: deoxyHb or oxyHb?

A

deoxyHb. Is triggered to bind CO2 once O2 is released

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26
Q

Where is carbonic anhydrase located? what does it do?

A

In erythrocytes. Catalyzes formation of bicarbonate from CO2 and H2O

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27
Q

major protein buffer in blood

A

Hb

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28
Q

which is stronger acid: deoxyHb or oxyHb?

A

OxyHb

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29
Q

what buffers organic acids produced by metabolism?

A

Hb

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30
Q

What are Heinz bodies?

A

oxidative denatured Hb

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31
Q

What is glucose ultimately converted to during the process of carbohydrate metabolism?

A

lactate, with production of ATP. 2,3-DPG is also produced in a side reaction.

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32
Q

What does pentose phosphate pathway generate? Why is it important?

A

NADPH. It keeps glutathione in a reduced state, which ultimately protects the RBC from oxidative injury

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33
Q

What will glutathione do if its oxidized?

A

become GSSG by reduction of H2O2

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34
Q

fx of reduced glutathione (GSH)?

A

free radical scavenger, electron donor for reductive enzyme reactions

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35
Q

What reduces GSSG back to GSH?

A

NADPH-dependent glutathione reductase

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36
Q

how does selenium act as an antioxidant?

A

It is incorporated into protective enzymes

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37
Q

how does catalase act as antioxidant?

A

degrades H2O2

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38
Q

how does ascorbate act as antioxidant?

A

donates electrons

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39
Q

how does vitamin E act as antioxidant?

A

membrane free radical scavenger

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40
Q

catalase reaction

A

H2O2 –> H2O + O2

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41
Q

What happens to H+ released from deoxyHb with CO2?

A

Combines with HCO3- to form H2CO3, which reversibly forms CO2 and H2O

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42
Q

How does pH change when Hb binds CO2?

A

only slightly lowers. Hb allows for transport of CO2 with only a slight change in pH

43
Q

Describe composition and orientation of erythrocyte membrane lipids

A

phospholipid bilayer with hydrophobic hydrocarbon chains of fatty acids directed to the center of the bilayer. Unesterified cholesterol intercalated with FA chains. Glycolipids in the outer layer containing blood group antigens

44
Q

Integral vs. skeletal membrane proteins on erythrocytes

A

integral memb. proteins are transmembrane glycoproteins that include receptors, transport proteins, and erythrocyte antigens.

Skeletal memb. proteins form a lattice-like arrangement on inner surface of membrane that allow for a fluid lipid bilayer

45
Q

where are blood group antigens produced? What are they composed of and why are they important?

A

erythroid cells. Composed mainly of carbs. important for animal ID and parentage testing. Most blood group antigens are the same across members of a species

46
Q

clinically significant blood group antigens in horses

A

A and Q factors

47
Q

clinically significant blood group antigens in dogs

A

DEA (dog erythrocyte antigen), and Dal (lacking in some Dalmations)

48
Q

clinically significant blood group Ag in cats

A

AB group, Mik group

49
Q

what are natural antibodies?

A

antibodies present BEFORE you give a transfusion. Most likely arise from carbs present on gut flora seen by the immune system, however they have never had exposure to the foreign RBC!

50
Q

Erythrocyte method of metabolism

A

in absence of ribosomes, mitochondria, and ER, they utilize glucose in glycolysis and pentose phosphate pathway for energy.

51
Q

Does DPG cycle generate net ATP gain?

A

NO

52
Q

What are RBC’s energy requirements?

A

1) maintain Na and K concentrations
2) maintain shape and deformability
3) maintain 2,3-DPG concentrations
4) MetHb reduction
5) pentose phosphate pathway to protect against oxidant injury

53
Q

oxidant damgae to Hb/enzymes/membrane unsaturated lipids can result in:

A

MetHb, heinz bodies, increased phagocytosis, intravascular hemolysis

54
Q

difference between MetHb and Hb

A

MetHb has Fe in +3 state instead of +2 state, so it can’t bind O2. This is a natural product of neutrophil activation

55
Q

What converts MetHb back to normal Hb?

A

Cb5R. FAD is a cofactor for this process

56
Q

What is majority of Fe in the body used for? **

A

RBC production. Majority of the body’s iron is located in the RBCs ***

57
Q

where is transferring produced?

A

liver

58
Q

Where does majority of recycled Fe come from?

A

Macrophages, which break down old RBCs

59
Q

True or False: Fe is highly conserved in the body

A

True

60
Q

What brings Fe to developing RBCs?

A

transferrin

61
Q

What stores Fe absorbed from the intestine?

A

interocytes. Stores Fe as ferritin

62
Q

Fe+3 =

A

ferric iron

63
Q

Fe+2 =

A

ferrous iron

64
Q

What solubilizes Fe from food in the stomach?

A

HCl. Mucin helps keep it solubilized

65
Q

2 mechanisms to absorb Fe into a RBC

A

1) Fe is reduced, then transported into cell via DcytB and divalent transporter
2) Heme carrier protein takes heme molecule in with bound Fe. Heme oxidase then breaks down and releases Fe into the cell

66
Q

What converts Fe+2 to Fe+3?

A

hephaestin

67
Q

what transports Fe out of RBC?

A

ferroportin

68
Q

Why is too much Fe in blood bad?

A

Can be toxic and act as a free catalyst

69
Q

If there is too much Fe entering a RBC, how is this compensated for?

A

Fe is stored as ferritin (a protein shell filled with Fe+3). This protects cell from damage

70
Q

hepcidin fx

A

Inhibits ferroportin from depositing Fe into the body from the RBC. Increases when there is too much Fe in the body. Cell with excess Fe will then slough in the GI tract

71
Q

inflammation –> iron absorption

A

decreases

72
Q

increased erythropoiesis –> hepcidin release

A

decreased. Erythropoiesis requires more Fe to be available

73
Q

Can hepcidin be increased even if Fe is low?

A

Yes.

74
Q

Total iron binding capacity is a measure of:

A

transferrin concentration

75
Q

Almost all Fe is bound to:

A

transferrin

76
Q

Which binds Fe better: diferric or monoferric transferrin?

A

diferric. It can also deliver Fe to the body more efficiently

77
Q

Majority of plasma iron is utilized for:

A

Hb synthesis. It mostly comes from macrophage release

78
Q

where is heme formed?

A

inside mitochondria of RBC

79
Q

Where is Hb formed?

A

in cytoplasm of RBC (heme leaves mitochondria and combines with globin)

80
Q

Do reticulocytes have mitochondria?

A

Yes

81
Q

What does hepsidin control?

A

How much Fe is present in the whole body. Master regulator of Fe homeostasis

82
Q

apoferritin fx

A

intracellular Fe storing protein

83
Q

TfR =

A

transferrin receptor. Carrier protein for transferrin that imports Fe into the cell

84
Q

When is TfR expression promoted?

A

under conditions of low Fe content inside the cells

85
Q

ceruplasmin fx

A

copper containing plasma protein that converts Fe from +2 to +3 state. (+3 state binds to transferrin)

86
Q

Increased hepcidin –> Fe absorption

A

inhibited

87
Q

hemosiderin

A

aggregates of protein and iron in lysosomes in a macrophage

88
Q

increased intracellular Fe concentration –> apoferritin synthesis

A

increases

89
Q

3 mechs of transporting Fe into the cytoplasm

A

1) DMT1 (used by duodenal enterocytes)
2) phagocytized erythrocytes (used by macrophages)
3) transferrin endocytosis (used by RBCs and other cells)

90
Q

1 Hb binds ___ O2 molecules?

A

4

91
Q

1st step in heme synthesis

A

formation of ALA. Occurs in the mitochondria

92
Q

last step of heme synthesis

A

insertion of Fe into the heme group. Occurs in the mitochondria

93
Q

Synthesis of globin monomers is promoted by:

A

increased free heme

94
Q

increased free heme –> iron uptake by erythroid cells

A

inhibits

95
Q

RBC lifespan in large vs. small animals

A

longer in large animals. Slower metabolism doesn’t acquire as much damage to RBCs as quickly

96
Q

Eryptosis

A

apoptosis in anucleated cells

97
Q

band 3

A

an anion transporter that clusters to form a senescent antigen in old RBCs and mark them for destruction by macrophages

98
Q

Signs of an aging RBC

A

1) altered phospholipids (increased surface PS)
2) altered carbs
3) altered proteins (partially degraded band 3)

99
Q

High lvl of CO in the body indicates:

A

high lvl of RBC destruction

100
Q

Where/how is CO produced in the body?

A

Inside macrophage when heme is broken down into biliverdin

101
Q

biliverdin reductase

A

converts biliverdin to bilirubin

102
Q

physiologic anemia

A

normal dropoff in Hb lvl post-partum. Animal can become anemic and Fe deficient

103
Q

why does erythropoietin decrease post-partum?

A

at birth there are high red cells, oxygen, and 2,3-DPG due to recent transfusion of cord blood. Therefore, additional RBCs are not needed. (this short-lived however with increasing growth)

104
Q

lifespan of adult vs. fetal RBCs

A

adult RBCs have longer lifespan

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