Circulation 8 Flashcards
1
Q
carbonic anhydrase (2)
A
- essential enzyme for many different systems/processes
- found in almost all living things
2
Q
CA reaction
A
- catalyzes CO2 + H2O <–> H+ + HCO3-
3
Q
what is CA’s role in respiratory gas exchange in the RBC (2)
A
- CO2 excretion in RBCs
- converts CO2 into H+ and HCO3- at tissues and converts these back into CO2 at the gills
4
Q
what is unique about sharks and CO2 excretion (2)
A
- sharks don’t need their blood
to maintain normal CO2 excretion - hagfish and chondrichthyans have CA outside the RBC at the gills
5
Q
what is CA’s role in respiratory gas exchange (2)
A
- facilitates CO2 excretion in gills and RBC
- facilitates O2 delivery in the heart and red muscle (aerobically-demanding tissues)
6
Q
what environmental condition drives O2 offloading (2)
A
- hemoglobin pH sensitivity/Bohr effect
- O2 saturation (O2 binding affinity) decreases when pH decreases
7
Q
root effect (2)
A
- describes how telosts experience a decrease in binding affinity AND binding capacity when pH decreases
- membrane bound CA and root effect help with O2 offloading at tissues
8
Q
betaNHE (2)
A
- protects O2 binding at gills
- moves H+ out of Hb in low pH stress to maintain O2 binding at the gill
9
Q
how do the sequences in fish with gill CA differ from those without
A
- histidine substitution (his-64) with a different amino acid occurs
10
Q
how does his-64 contribute to activity (2)
A
- RBC CA activity is significantly lower in fish with gill CA
- CA activity is driven by His-64
11
Q
how has the pattern of CA evolved in fish with and without gill CA
A
- CA isoform types are mutually exclusive; only those without gill CA have high activity RBC CA
12
Q
why was the red drum used to study CA in teleosts (4)
A
- has root effect
- has betaNHE
- has membrane-bound CA
- has high-activty RBC CA
13
Q
does RBC CA activity impact O2 offloading rate
A
- yes, CA addition increases O2 offloading from baseline and vice versa
14
Q
how much does CA impact O2 offloading
A
- CA inhibition decreases O2 offloading 1:1
- CA addition increases O2 offloading 1:1
15
Q
red blood cell CA: activity (2)
A
- dictated by amino acid His-64
- may have evolved with O2 delivery capabilities
