Gas Exchange: Fish Flashcards
What type of circulatory system does a fish have?
A single circulatory system.
Why do fish only need a single circulatory system rather than a double circulatory system?
They are less active than other animals so do not require oxygen at as great a rate.
The single circulatory system is a simple loop, what is the direction of blood flow in this circuit?
Heart > Gills > Body > Heart.
What limits the rate of blood flow in the fish’s circulatory system?
The delicate nature of the blood capillaries in the gills.
What happens to the pressure of blood as it leaves the gills?
It decreases dramatically.
What is the structure of the fish’s heart?
It has only one atria and one ventricle.
Where is blood oxygenated in the fish?
The gills.
Where is blood circulated in the fish?
The heart.
What does it mean that fish have a single circulatory system?
Blood flows through the heart only once for each complete circuit of the body.
How does blood enter and leave the heart?
Enters through the atria and leaves through the ventricle (it is always de-oxygenated).
Why cannot the fish’s gills tolerate a large air pressure?
Because they have a thin membrane to ensure a small diffusion distance, lots of pressure on the thin membrane will break it.
Gas exchange occurs in fish via the _____.
Gills.
What is important about the direction of water flow and direction of blood flow in a fish?
They are opposite to each other (countercurrent).
How is a countercurrent flow ensured?
Through the structure of the gill filaments and lamellae.
What is the significance of the countercurrent flow?
It maintains a concentration gradient throughout the module.
What are the many protrusions on a gill filament called?
gill lamellae.
What supports the folds of the gills and maintains their moisture?
The water that is continuously pumped through the mouth over the gills.
How are the gills adapted to increase surface area?
The gill filaments are at right angles to the gill lamellae.
How are the gills adapted to maintain a large concentration gradient?
The filaments have a dense capillary network.
What does it mean that the fish has a countercurrent flow?
The direction of blood and the direction of water are in opposite directions.
How are the gills adapted to provide a short diffusion distance?
The gill lamellae and filaments are thin.
Compare the efficiency of a concurrent and countercurrent flow:
A countercurrent flow extracts oxygen at three times the rate of a concurrent flow.
Suggest why the fish need a high adaptive gas exchange system:
Because the oxygen concentration in water is much less than in air.
What is special about cartilaginous fish?
They have no opercula and have to swim the whole time to circulate water through the gills and stop them from sticking.
