Hb-O2 Affinity Flashcards

1
Q

Plasma O2 carriage ___ at cold temp

A
  • increases
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2
Q

Antarctic ice fish live at ____ deg. C and have a ____ MO2. Why?

A
  • (-1.5)
  • low
  • low activity
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3
Q

What % dissolved plasma O2 do notothenioid ice fish have?

A
  • 12% (solubility) relatively high
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4
Q

What adaptations do crocodile ice fish have to compensate for lack of haemoglobin? (3)

A
  • low metabolic rate
  • sluggish lifestyle with abundant prey (large volume of blood)
  • large heart and low resistance circulatory system (lg diameter vessels and low viscosity blood0
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5
Q

What is myoglobin?

A
  • buffers O2 in tissues (muscle)
  • high affinity
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6
Q

When are lampreys and hagfish monomeric?

A
  • when oxygenated
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7
Q

What is a polymorphism?

A
  • variation in sequences (2+)
    –> difference in amino acid sequences
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8
Q

What may polymorphisms reflect?

A
  • different functional demands associated in different environments, activity level, life history
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9
Q

How many polymorphisms do trout have

A
  • 4
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10
Q

How many polymorphisms do goldfish have?

A
  • 3 (temp sensitive)
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11
Q

How many polymorphisms do american eel have

A
  • 2 (SW and FW)
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12
Q

Seawater has ___ O2 available and ___ solubility

A
  • less, lower
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13
Q

What is P50?

A
  • PO2 where hemoglobin is 50% saturated
  • measure of affinity
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14
Q

P50 is ____ proportional to Hb-O2 affinity

A
  • inversely
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15
Q

Low P50 = ____ affinity. it is important during what?

A
  • high
  • hypoxia/warm stagnant water (loading)
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16
Q

High P50 = ____ affinity. What does this promote?

A
  • low
  • promotes O2 unloading at tissues
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17
Q

When P50 is low, it shifts saturation ____ on the dissociation curve.

A
  • left
18
Q

When P50 is high, it shifts saturation ____ on the dissociation curve.

A
  • right
19
Q

What is a “T” state?

A
  • tense/de-oxy state = low affinity for O2
20
Q

What is a “R” state?

A
  • relaxed/oxy state = high affinity for O2
21
Q

What is the Bohr effect?

A
  • decreased Hb-O2 affinity
  • rightward shift
22
Q

What is the bohr effect important for?

A
  • O2 unloading at tissue
    –> Hb-O2 –> O2 release = PO2 diffusion to tissue
23
Q

What is the equation for Bohr effect? What does it mean?

A
  • CO2 + H2O <–> HCO3 + H+
  • increase PCO2 = decrease pH
24
Q

What is the bohr factor?

A

= (delta)logP50/(delta)pH

25
Q

Blackfish are ____ fish. What does this mean in regard to P50?

A
  • hypoxic
  • small P50 = high affinity Hb-O2
26
Q

Trout are ____ fish.

A
  • normoxic
27
Q

What is the root effect?

A
  • exaggerated bohr effect
  • decreased Hb-O2 CARRYING CAPACITY
28
Q

What is the difference between bohr and root effect?

A
  • bohr is shifting right (affinity
  • root shifts down (carrying capacity)
29
Q

What does H+ production lead to?

A
  • jettisoning of O2 (greater unloading)
30
Q

What is the root effect important for?

A
  • O2 supply to eye (O2 demanding) and swimbladder inflation (req. high PO2)
31
Q

What do organic phosphates cause?

A
  • conformational change in Hb
32
Q

What cascade effect does ATP + GTP cause?

A
  • ATP,GTP –> lower Hb-O2 affinity –> improved O2 unloading
33
Q

What cascade effect does a depletion of ATP + GTP cause?

A

–> improved O2 loading by RBC

34
Q

How long does it take for hypoxia to decrease RBC ATP and GTP levels?

A
  • 15 min
35
Q

A higher temp =

A

–> lower Hb-O2 affinity (greater P50)

36
Q

What is the relevance of higher temp causing lower affinity?

A
  • improved O2 unloading at working muscle
  • impaired oxygen uptake
37
Q

Why is impaired oxygen uptake not an issue for billfish?

A
  • lower water temp at gill
38
Q

What is the Haldane effect?

A
  • shift in opposite direction than bohr effect
  • Hb-O2 affects Hb-CO2 affinity
39
Q

What is carbaminohemoglobin?

A
  • CO2 carried by Hb (Hb-CO2 - small fraction of total CO2)
40
Q

When is Hb-CO2 affinity lowered?

A
  • when Hb is oxygenated
41
Q

When is haldane effect the largest?

A
  • in fish living in stagnant, high PCO2 water
42
Q

Hb-CO2 =

A
  • increased PCO2 = diffusion out of gill into water