Circulation and respiration - Part 1 Flashcards Preview

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Blood flow in fish is ___________.



Give the direction of blood flow to the heart in fish.

Heart  ventral aorta  afferent branchial artery  gas exchange at gill lamellae  efferent branchial artery  dorsal aorta  head and body
• Head: dorsal aorta  carotid artery  head  anterior cardinal vein + jugular vein  common cardinal vein  heart
• Body: dorsal aorta  caudal artery, superior mesenteric artery, coeliac artery  caudal vein  common cardinal vein  heart


Where does oxygen exchange actually occur?

In the gill lamellae.


Lamellae are filled with ________ that are directly next to ______.

capillaries; water


Describe the counter-current exchange for gas exchange.

Blood flow through the capillaries goes in one direction while water flow over the gill lamellae goes in a different direction. This effectively concentrates oxygen into the capillaries.
At every point along the capillary flow in the lamellae, the blood PO2 is lower than that of the surrounding water.


Blood flow in fish is not _______.



What is meant by blood flow in fish is not 'fixed'?

Fish can control the amount of blood flowing through lamellae and can control which lamellae get blood and which ones do not.
If one of the filaments is damaged, can stop blood loss by stopping blood flow to the capillaries and send it to undamaged parts.


Describe the regulation of blood flow through the lamellae.

Part of the regulation is hormonal.
Epinephrine and Acetylcholine (Ach) act as complements.
Epinephrine in the fishes blood will increase the amount of blood flow.
Ach will decrease lamellar blood flow.


If it was nearing winter, what hormone would the fish most likely secrete regarding blood flow to the lamellae. Why?

If the fish knows winter is coming, needs less oxygen. Uses ACh to shut blood flow down.


Lamellae are _____ cell(s) thick

1 (or two)


More active fish will have ______ filaments and ______ lamellae per filament.

More; more


One can determine the relative amount of activity of a fish based on the number of _____ and ______.

filaments; lamellae


Each gill arch has ________ filaments on them.



Within a fish, water flow across the gills can be changed. How?

Can spread filaments out, bring them back together.
If more oxygen is needed, can flare filaments, let more water pass over lamellae or can close to have less water flow.


Often, we find that more _______ fish will have thicker lamellae.
What is the trade-off for this?

Give up efficiency in oxygen exchange to have increased durability in these lamellae.


Overall surface area for exchange is related to what?

Number of filaments
Number of lamellae
Thickness of lamellae


Active, pelagic fish will have _____ lamellae, benthic fish will have _______.

more; less


Where are pseudobranchs found?

Under the operculum


Many fishes have pseudobranchs, especially _______.



What is a pseudobranch?

Vestigial gill arch which functions as a partial gill.


What is the main probable function of a pseudobranch?
What is another possible function?

Special gill arch for blood supply to the eye.
May also function as a pressure detector


Why is it difficult for a fish to know at what depth it's at?

Difficult to do this without light cues.


Why does a swim bladder not work as a pressure detector?

It does, but only coarsely.
Not a precise measure, takes a large pressure change to change compression on the swim bladder.


How would a pseudobranch function as a pressure detector?

Small-scale changes in pressure might make small-scale compression changes to capillaries to determine pressure.


How does temperature affect DO concentration in the water?

DO in the water decreases as temperature increases.


Which carries more oxygen, all else being equal, freshwater or saltwater?



Describe how mixing affects DO content in the water.

Mixing of surface water with deeper water - upwelling
Mixing of water with air
Wave action
All increase DO


Describe the issues with Lake Erie in low oxygen content during the summer.

Low mixing in the summer for lake Erie since the winds die off.
Water also gets warmer.
Algae builds up and then gets digested by bacteria which further reduce oxygen content.


What is normoxia?

Water with normal oxygen concentrations for the fish, plenty of oxygen.


What is anoxia?

No oxygen. No fish can live in anoxic waters.