L14 - Respiratory Pigments Flashcards
Why is having a left to right shunt in some reptiles useful?
If you increase the resistance of the pulmonary circulation, less blood passes this way therefore towards the body.
This is very useful in aquatic reptiles such as turtles who are not breathing all the time (diving).
Also useful as reptiles have a low metabolic rate.
Crocodiles have a fully separated right and left atriums and ventricles. But how is the circulation still connected?
The right aorta has a connection to the left aorta, therefore blood is mixed here - it is called the Foramen of Panizza
How is the connection between the oxygenated and deoxygenated blood flows useful to crocodiles?
Pressure changes in the pulmonary system can change the flow of blood into the right aorta.
High resistance in the pulmonary artery means more blood would go into the right aorta and vice versa.
This can be useful as the crocodile is still an aquatic species and can dive, so divert blood away from the lungs at this point
What colour is:
a) Haemoglobin
b) Haem-ertythrin
c) Haem-ocyanin
d) Chlorocruorins
a) Haemoglobin: colourless- reddish violet
b) Haem-ertythrin: colourless- reddish violet
c) Haem-ocyanin: colourless - blue
d) Chlorocruorins: green
In which animals is are each found:
a) Haemoglobin
b) Haem-ertythrin
c) Haem-ocyanin
d) Chlorocruorins
a) Haemoglobin: most phyla including vertebrates
b) Haem-ertythrin: Sipunculid worms, brachiopods, priapulida
c) Haem-ocyanin: arthropods and molluscs
d) Chlorocruorins: fan worms and feather worms
Describe the binding of the 4 O2 molecules to haemoglobin
The first molecule of O2 is difficult to bind to haemoglobin, but as the partial pressure of O2 is high when the deoxygenated blood first reaches the lungs, it binds.
After the first O2 is bound the affinity of haemoglobin for O2 increases up until the 4th one so it is easier and easier to bind
Describe why the oxygen dissociation curve is sigmoidal
The shallow gradient at first is due to the difficulty of binding the first 2 molecule to haemoglobin; a large increase is pO2 is needs for a small increase in saturation.
The steep rise is then due to the increased affinity of haemoglobin to O2 and the high partial pressure means a lot of O2 binds to haemoglobin so the saturation increases quickly
The final plateau is due to almost all the molecules of haemoglobin being full of O 2 at this point.
Describe the changed in affinity of saturated haemoglobin to O2 as it unloads it to the body and becomes deoxygenated
The release of the first O2 to the tissues is the hardest of all 4 to release (on the graph the plateau means a large drop in pO2 is needed for a small drop in saturation) but the pull from the tissues is high so it is released.
What kind of animals have a particularly high level of myoglobin and why?
Diving mammals such as seals and whales have very high myoglobin as myoglobin is a store of O2 therefore allows them to hold their breath for longer
What is the Bohr Effect?
This is the affect of pH on the affinity of haemoglobin for O2.
A decrease in pH (more H+) shifts the standard ODC to the right, meaning that O2 is released more readily. The BE means the body can adapt to changing conditions.
Why is the Bohr Effect useful in highly respiring animals?
Exercise/respiration produces CO2. High CO2 in tissues reacts and makes the ions HCO3- and H+.
The increase in H+ means that the more a tissue respires, the lower the pH and therefore the more really O2 is released it.
This is also true when muscles undergo anaerobic respiration and produce lactic acid, which acts almost like a super CO2 effect, and means that about 10% more O2 is released to tissues
What effect does temperature have on ODCs?
increased i temperatures shifts the ODC to the right meaning O2 is released more easily at higher temperatures
