Comparative Anatomy and Physiology in Animals
Lecture 6 Respiration in Vertebrates 28/10/20
Respiration
- Permits the completion of aerobic components of cellular respiration (glycolysis, Kreb’s cycle
and oxidative phosphorylation) so as to release ATP.
- No oxygen- only glycolysis is possible and small amounts of ATP produced.
- Conversion of pyruvate to lactate allows glycolysis to continue but high levels inhibit
glycolysis.
Oxygen
- Delivered to cells via blood, from the respiratory surfaces.
- Water 1%, air ~21%
Oxygen in water
- Oxygen dissolves in water from the air and then is distributed by diffusion
- Still water – high O2 at the surface but rapidly declines as the distance increases from the air
- Turbulence increases rates of solution and breaks down diffusion gradients
- Gas solubility decreases with increasing temperature – as tap water warms it releases
dissolved gases
- Warm water O2 < Cold water O2
- Freshwater can dissolve 25% more O2 than seawater
Oxygen transport
- Limited oxygen solubility restricts its penetration into deep tissue.
- Haemoglobin is the iron-containing oxygen-transport metalloprotein in all vertebrates.
- Mammalian haemoglobin can carry 4 oxygen
- Oxygen binding capacity of 1.34mL oxygen per gram of haemoglobin
- Increases the total blood oxygen capacity seventy-fold compared to dissolved oxygen in
blood plasma.
Oxygen transport- ice fish
- Crocodile icefish (Channichthyidae) of Antarctic waters lack any haemoglobin or red blood
cells in their blood
- Oxygen instead dissolves in the plasma.
- Fish can live without haemoglobin because of their low metabolic rates and the high
solubility of oxygen in water at low temperatures.
- Oxygen carrying capacity is less than 10% that of their relatives with haemoglobin.
Fish gills
- Gill arches support the primary lamellae. This forms a curtain through which water flows
from the buccal cavity to the opercular cavity. Secondary lamellae run perpendicular to the
primary lamellae surface. This causes a massive increase in surface area.
- Gills able to exchange water and ions and contribute to osmotic pressure.
- Lifestyle and metabolism of a species corresponds with gill area.
- Suction pump phase and pressure pump phase, or ram ventilation.
- Gills exchange respiratory gases.
- Blood flows through the lamellae in a counter-current flow.
- Deoxygenated blood from the heart passes through lamellae and is oxygenated.
Fish gills – Elasmobranchs
- Gill support is different- septa create structural difference compared with teleost fish.
- Principles of water and blood flow are the same.
Lecture 6 Respiration in Vertebrates 28/10/20
Respiration
- Permits the completion of aerobic components of cellular respiration (glycolysis, Kreb’s cycle
and oxidative phosphorylation) so as to release ATP.
- No oxygen- only glycolysis is possible and small amounts of ATP produced.
- Conversion of pyruvate to lactate allows glycolysis to continue but high levels inhibit
glycolysis.
Oxygen
- Delivered to cells via blood, from the respiratory surfaces.
- Water 1%, air ~21%
Oxygen in water
- Oxygen dissolves in water from the air and then is distributed by diffusion
- Still water – high O2 at the surface but rapidly declines as the distance increases from the air
- Turbulence increases rates of solution and breaks down diffusion gradients
- Gas solubility decreases with increasing temperature – as tap water warms it releases
dissolved gases
- Warm water O2 < Cold water O2
- Freshwater can dissolve 25% more O2 than seawater
Oxygen transport
- Limited oxygen solubility restricts its penetration into deep tissue.
- Haemoglobin is the iron-containing oxygen-transport metalloprotein in all vertebrates.
- Mammalian haemoglobin can carry 4 oxygen
- Oxygen binding capacity of 1.34mL oxygen per gram of haemoglobin
- Increases the total blood oxygen capacity seventy-fold compared to dissolved oxygen in
blood plasma.
Oxygen transport- ice fish
- Crocodile icefish (Channichthyidae) of Antarctic waters lack any haemoglobin or red blood
cells in their blood
- Oxygen instead dissolves in the plasma.
- Fish can live without haemoglobin because of their low metabolic rates and the high
solubility of oxygen in water at low temperatures.
- Oxygen carrying capacity is less than 10% that of their relatives with haemoglobin.
Fish gills
- Gill arches support the primary lamellae. This forms a curtain through which water flows
from the buccal cavity to the opercular cavity. Secondary lamellae run perpendicular to the
primary lamellae surface. This causes a massive increase in surface area.
- Gills able to exchange water and ions and contribute to osmotic pressure.
- Lifestyle and metabolism of a species corresponds with gill area.
- Suction pump phase and pressure pump phase, or ram ventilation.
- Gills exchange respiratory gases.
- Blood flows through the lamellae in a counter-current flow.
- Deoxygenated blood from the heart passes through lamellae and is oxygenated.
Fish gills – Elasmobranchs
- Gill support is different- septa create structural difference compared with teleost fish.
- Principles of water and blood flow are the same.
