Hb-O2 Affinity Flashcards
Plasma O2 carriage ___ at cold temp
- increases
Antarctic ice fish live at ____ deg. C and have a ____ MO2. Why?
- (-1.5)
- low
- low activity
What % dissolved plasma O2 do notothenioid ice fish have?
- 12% (solubility) relatively high
What adaptations do crocodile ice fish have to compensate for lack of haemoglobin? (3)
- 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
What is myoglobin?
- buffers O2 in tissues (muscle)
- high affinity
When are lampreys and hagfish monomeric?
- when oxygenated
What is a polymorphism?
- variation in sequences (2+)
–> difference in amino acid sequences
What may polymorphisms reflect?
- different functional demands associated in different environments, activity level, life history
How many polymorphisms do trout have
- 4
How many polymorphisms do goldfish have?
- 3 (temp sensitive)
How many polymorphisms do american eel have
- 2 (SW and FW)
Seawater has ___ O2 available and ___ solubility
- less, lower
What is P50?
- PO2 where hemoglobin is 50% saturated
- measure of affinity
P50 is ____ proportional to Hb-O2 affinity
- inversely
Low P50 = ____ affinity. it is important during what?
- high
- hypoxia/warm stagnant water (loading)
High P50 = ____ affinity. What does this promote?
- low
- promotes O2 unloading at tissues
When P50 is low, it shifts saturation ____ on the dissociation curve.
- left
When P50 is high, it shifts saturation ____ on the dissociation curve.
- right
What is a “T” state?
- tense/de-oxy state = low affinity for O2
What is a “R” state?
- relaxed/oxy state = high affinity for O2
What is the Bohr effect?
- decreased Hb-O2 affinity
- rightward shift
What is the bohr effect important for?
- O2 unloading at tissue
–> Hb-O2 –> O2 release = PO2 diffusion to tissue
What is the equation for Bohr effect? What does it mean?
- CO2 + H2O <–> HCO3 + H+
- increase PCO2 = decrease pH
What is the bohr factor?
= (delta)logP50/(delta)pH
Blackfish are ____ fish. What does this mean in regard to P50?
- hypoxic
- small P50 = high affinity Hb-O2
Trout are ____ fish.
- normoxic
What is the root effect?
- exaggerated bohr effect
- decreased Hb-O2 CARRYING CAPACITY
What is the difference between bohr and root effect?
- bohr is shifting right (affinity
- root shifts down (carrying capacity)
What does H+ production lead to?
- jettisoning of O2 (greater unloading)
What is the root effect important for?
- O2 supply to eye (O2 demanding) and swimbladder inflation (req. high PO2)
What do organic phosphates cause?
- conformational change in Hb
What cascade effect does ATP + GTP cause?
- ATP,GTP –> lower Hb-O2 affinity –> improved O2 unloading
What cascade effect does a depletion of ATP + GTP cause?
–> improved O2 loading by RBC
How long does it take for hypoxia to decrease RBC ATP and GTP levels?
- 15 min
A higher temp =
–> lower Hb-O2 affinity (greater P50)
What is the relevance of higher temp causing lower affinity?
- improved O2 unloading at working muscle
- impaired oxygen uptake
Why is impaired oxygen uptake not an issue for billfish?
- lower water temp at gill
What is the Haldane effect?
- shift in opposite direction than bohr effect
- Hb-O2 affects Hb-CO2 affinity
What is carbaminohemoglobin?
- CO2 carried by Hb (Hb-CO2 - small fraction of total CO2)
When is Hb-CO2 affinity lowered?
- when Hb is oxygenated
When is haldane effect the largest?
- in fish living in stagnant, high PCO2 water
Hb-CO2 =
- increased PCO2 = diffusion out of gill into water
