Lec 15 Respiration Flashcards
How do fishes obtain oxygen?
Through a continuous flow of water over the gills.
What do gills do in particular to obtain air?
They remove oxygen that’s dissolved in water
What does the unidirectional oxygen flow of water do?
The unidirectional flow pattern eliminates the waste associated with dead air space and make it possible to maintain a constant gradient for oxygen to diffuse from the water into the blood by way of gills
Where is does the water enter and exit?
enter through the water and exit by the opercular opening on the side of the head.
What is the cycle of respiration that can be divided in phases?
- opercular suction pump
- pressure is reduced
- buccal pressure pump
- pressure is reversed
What happens in Opercular suction pump
Water is sucked into the mouth due to the high negative pressure.
What happens during the reduced pressure?
Mouth closes and buccal cavity contracts, creating positive pressure in the buccal cavity
What occurs during the buccal pressure pump?
Pressure is positive in both cavities. Water is pushed out of the opercular opening.
What occurs during the buccal cavity?
It expands while opercular cavity is still being compressed.
How does time duration vary among fishes?
Depends on speed and oxygen availability in the environment.
What pump dominates in slowly swimming fishes?
the opercular pump predominates
What pump dominates in faster swimming fishes?
the buccal pump predominates
What happens in pelagic forms with the buccal and opercular cavities?
pumps may not be used as all. Water flow in and through the buccal and opercular cavities is enough to supply adequate oxygen to the gills.
Stream of water can be regulated simply the degree of mouth opening
What phase is increased in bottom living fishes?
Increase of opercular pump phase.
What is the gill structure like?
Sieve like structure that’s in path of respiratory flow
each gill arch has gill filaments or holobranches which is made up of two halves called hemibranches
What does the gill lamellae do?
It’s beared by the hemibranch, and forms major part of sieve to which water is passed.
responsible for creaing resistance to water flow
Capillaries in the gill lamellae are more involved in what than gill filaments?
gas exchange
What is the counter current principle?
Blood with higher oxygen content meets water with highest oxygen content so that oxygen diffuses into the blood along length of lamellae.
Allows for efficient interchange of oxygen and CO2 between water and blood.
Where is deoxygenation common?
Shallow and stagnant waters. When water is slow moving, covered with vegetation and heavily shaded.
How does oxygen get to where deoxygenation is frequent?
by diffusion from the air
Can gills be used for air breathing?
No because gill lamellae is not stiff enough to support themselves and collapse when out of water. SA is lost and fish suffocates.
Does air breathing organs have anything to do with CO2?
No, just absorbs oxygen. Gill/ skin take care of CO2 excretion.
what happens to the scales as skin is used for CO2 discharge?
Scales are reduced.
What is the biological sig of air breathing?
- survival in oxygen poor habitats
- utilize terrestrial food resources
- able to search for better habitat
- invade new territories, enhance distribution.
How does oxygen get to where deoxygenation is frequent?
by diffusion from the air
Can gills be used for air breathing?
No because gill lamellae is not stiff enough to support themselves and collapse when out of water. SA is lost and fish suffocates.
Does air breathing organs have anything to do with CO2?
No, just absorbs oxygen. Gill/ skin take care of CO2 excretion.
what happens to the scales as skin is used for CO2 discharge?
Scales are reduced.
