Lecture 16. October 13, 2008 - Swimbladders

1) How do fish get air into their swimbladders?

2) Why doesn’t it leak out?

We will read the Ah-King et al. paper for 10/20 instead of 11/5.

Choose a paper topic if you haven’t done so.

Take out a piece of paper. Do not put your name on it. Write a response to the following:

A group of 20+ students clambers down into a stream causing them to rapidly swim for a prolonged period of time.

A. Explain what changes are likely taking places at the fishes peripheral tissues and the effect that this has on uptake/release of O2 and CO2.

The students then take a few fish back to the lab. They were lucky enough to catcha salmon (active) and a madtom (less active).

B. What types of differences would you expect to see in the following traits: relative gill surface area, lamellae thickneess, p50 value, Bohr effect, Root effect? Explain the effects that these differences would have on O2 and CO2 uptake/release.

swimbladder

Questions for Review:1) Why bother trying to maintain neutral buoyancy? How do fish keep gas in their gas bladders? Give 2 ways that fish do this.

2) How does the counter-current exchange mechanism help keep gas in the gas bladder? What is the role of the “Root-effect” and “Bohr effect” in maintaining O2 in swimbladders?

3) The three things important for getting O2 into the gas bladder are (a) anaerobic respiration in the gas gland tissue, (2) counter current exchange in rete mirable, and (3) a slow “Root-on” effect. Explain how these 3 things allow O2 to get into the bladder.

4) How do the arterial and venous capillaries differ in O2 tension? in O2 content? in pH? in lactic acid? CO2?

5) How does lactic acid and bicarbonate help in “salting out” air? Does this help with loading all gases into the swimbladder or just O2?

6) How can the venous blood leaving the rete mirable have high pO2, and yet have lower total O2 content than the arterial blood leaving the rete mirable? Or did it actually gain O2 during this process?

7) How do fish deflate their swimbladders? Explain this for both physostomous and physoclistus swim bladders. Do fish with physostomous swimbladders ever resorb the gas into their blood? 8) Why have some fish lost their swim bladders? Have you read page 65?