Hb-O2 Affinity

Question 1

Plasma O2 carriage ___ at cold temp

Answer 1

• increases

Question 2

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

Answer 2

• (-1.5)
• low
• low activity

Question 3

What % dissolved plasma O2 do notothenioid ice fish have?

Answer 3

• 12% (solubility) relatively high

Question 4

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

Answer 4

• 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

Question 5

What is myoglobin?

Answer 5

• buffers O2 in tissues (muscle)
• high affinity

Question 6

When are lampreys and hagfish monomeric?

Answer 6

• when oxygenated

Question 7

What is a polymorphism?

Answer 7

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

Question 8

What may polymorphisms reflect?

Answer 8

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

Question 9

How many polymorphisms do trout have

Answer 9

• 4

Question 10

How many polymorphisms do goldfish have?

Answer 10

• 3 (temp sensitive)

Question 11

How many polymorphisms do american eel have

Answer 11

• 2 (SW and FW)

Question 12

Seawater has ___ O2 available and ___ solubility

Answer 12

• less, lower

Question 13

What is P50?

Answer 13

• PO2 where hemoglobin is 50% saturated
• measure of affinity

Question 14

P50 is ____ proportional to Hb-O2 affinity

Answer 14

• inversely

Question 15

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

Answer 15

• high
• hypoxia/warm stagnant water (loading)

Question 16

High P50 = ____ affinity. What does this promote?

Answer 16

• low
• promotes O2 unloading at tissues

Question 17

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

Answer 17

• left

Question 18

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

Answer 18

• right

Question 19

What is a “T” state?

Answer 19

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

Question 20

What is a “R” state?

Answer 20

• relaxed/oxy state = high affinity for O2

Question 21

What is the Bohr effect?

Answer 21

• decreased Hb-O2 affinity
• rightward shift

Question 22

What is the bohr effect important for?

Answer 22

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

Question 23

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

Answer 23

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

Question 24

What is the bohr factor?

Answer 24

= (delta)logP50/(delta)pH

Question 25

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

Answer 25

- hypoxic - small P50 = high affinity Hb-O2

Question 26

Trout are ____ fish.

Answer 26

- normoxic

Question 27

What is the root effect?

Answer 27

- exaggerated bohr effect - decreased Hb-O2 CARRYING CAPACITY

Question 28

What is the difference between bohr and root effect?

Answer 28

- bohr is shifting right (affinity - root shifts down (carrying capacity)

Question 29

What does H+ production lead to?

Answer 29

- jettisoning of O2 (greater unloading)

Question 30

What is the root effect important for?

Answer 30

- O2 supply to eye (O2 demanding) and swimbladder inflation (req. high PO2)

Question 31

What do organic phosphates cause?

Answer 31

- conformational change in Hb

Question 32

What cascade effect does ATP + GTP cause?

Answer 32

- ATP,GTP --> lower Hb-O2 affinity --> improved O2 unloading

Question 33

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

Answer 33

--> improved O2 loading by RBC

Question 34

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

Answer 34

- 15 min

Question 35

A higher temp =

Answer 35

--> lower Hb-O2 affinity (greater P50)

Question 36

What is the relevance of higher temp causing lower affinity?

Answer 36

- improved O2 unloading at working muscle - impaired oxygen uptake

Question 37

Why is impaired oxygen uptake not an issue for billfish?

Answer 37

- lower water temp at gill

Question 38

What is the Haldane effect?

Answer 38

- shift in opposite direction than bohr effect - Hb-O2 affects Hb-CO2 affinity

Question 39

What is carbaminohemoglobin?

Answer 39

- CO2 carried by Hb (Hb-CO2 - small fraction of total CO2)

Question 40

When is Hb-CO2 affinity lowered?

Answer 40

- when Hb is oxygenated

Question 41

When is haldane effect the largest?

Answer 41

- in fish living in stagnant, high PCO2 water

Question 42

Hb-CO2 =

Answer 42

- increased PCO2 = diffusion out of gill into water