Homeostasis - Buoyancy control

Question 1

What are the general strategies fish employ to avoid sinking?

Answer 1

Hydrodynamic lift
Skeletal changes
Lipid accumulation
Swimbladders

Question 2

Both ______ and _______ affect density in water. Which is more important?

Answer 2

Temperature and salinity

Salinity is more important

Question 3

Describe how hydrodynamics aid in buoyancy control.

Answer 3

Hydrodynamic aid when fish swim in the water causing water to flow over them and create a negative pressure zone, essentially lifting them up the water column.

Question 4

Describe how skeletal changes can aid in buoyancy control.

Answer 4

In fish, many bones are small and not relatively thick to reduced weight.
Trade off of protection for reduced density.

Question 5

How does lipid accumulation reduce density?

Answer 5

Fats are lighter than water, easier to float.

Question 6

How does a swim bladder aid in buoyancy?

Answer 6

Bubble of gas basically, bladder filled with air.

Air is lighter than gas and allows fine scale control of position in water column without needing to swim.

Question 7

Describe an example of lipid accumulation, the most common.

Answer 7

Sharks accumulate fats in their liver, larger liver.

This is stored as squalene, an intermediate of cholesterol synthesis.

Question 8

What are the four layers, from outside in, of the teleost swimbladder?

Answer 8

Tunica externa
Submucosa
Muscularis mucosa
Epithelium

Question 9

The swim bladder probably first evolved for what purpose?

How do we know it is evolutionarily separate from lungs?

Answer 9

Respiration

Dorsal structure that was and can still be an offshoot from the esophagus.

Question 10

Describe the tunica externa.

Answer 10

Provides structural integrity.

Hard shell to reduce stretching and not permeable to gas.

Question 11

Describe the submucosa.

Answer 11

Under the tunica externa, generally impermeable to gas, moreso with more guanine crystals.

Question 12

Describe the muscularis mucosa.

Answer 12

Ring of muscles around the interior of the swim bladder that help regulate its size.

Question 13

Describe the epithelial layer of the swim bladder.

Answer 13

Site of gas exchange.

Bunch of capillaries near it for gas exchange.

Question 14

What are the two designations for the two general types of swim bladders and what is specific about them.

Answer 14

Physostomes - has a stoma (tube) between esophagus and swim bladder.

Physoclists - do not have a tube connecting the esophagus and swim bladder.

Question 15

How can physostomes increase the amount of gas in their swim bladder?
Whats the issue with this?

Answer 15

Gulping air at the surface.

Need to go to the surface.

Question 16

How do swim bladders fill up in physoclists?

Answer 16

Anaerobic respiration produces lactic acid and H+.
H+ functions in the Root Shift and Bohr effect to decrease Hb affinity for oxygen, increasing the partial pressure of oxygen for diffusion into the swim bladder.
Increased hydogen ions pushes the respiration equation in the reverse direction to form CO2 and water, increasing carbon dioxide pressure to once again fill up the gas gland.
Finally, the increased lactate in the blood causes a salting out effect whereby more particles in the blood increase volatility and thus less gas is dissolved, increasing partial pressure and diffusion into the swim bladder.
Last way is through the rete mirable, a countercurrent exchange system with the capillaires supplying the gas gland which functionally concentrate gas, generally oxygen, to fill up the swim bladder.

Question 17

How did Dr. Higgs lie to us?

Answer 17

i dunno really.