Lecture 24- salinity and osmoregulation

Question 1

what affects the salinity of lakes and oceans regionally?

Answer 1

temperature, rainfall and evaporation

Question 2

define osmotic regulators:

Answer 2

they work to maintain an internal ion concentration that differs from the environment

Question 3

stenohaline fishes:

Answer 3

fishes are limited to a narrow salinity range (most fishes) and not able to tolerate wide changes in sality

Question 4

euryhaline fishes:

Answer 4

can tolerate a wide range of salinities ex.) mollies

Question 5

marine fishes are ————

Answer 5

hypoosmotic: because the surrounding seawater has a higher ion concentration than the fish causing water to move out of the fish and ions to move in. most fish have to deal with this by drinking a tan of salt water and pump Nacl out their gills and get rid of the other ions through feces.

white arrows are diffusion, black is what they are actively doing

Question 6

freshwater fishes are ———-

Answer 6

hyperosmotic: the fish has a higher ion concentration than the surrounding water so water moves in the fish and ions move out. Have exact opposite problem than marine. freshwater fish have to take in Nacl and has o urinate a lot to get rid of the water! If they dont they will die by having their cell bursts!

remember black is what they are actively doing and white is via diffusion

Question 7

describe the function of nephron is kidneys?

Answer 7

to remove water, salts, waste metabolites and foreign substances. In most fish the blood is filtered through the glomerulus. Here we see a difference between freshwater and marine based on what they decide to keep.

Question 8

after the blood enters the bowmans capsule it is called ultrafiltrate. what is ultrafiltrate?

Answer 8

is blood minus blood cells and larger molecules. ultrafiltrate is then further processes in the renale tube to return metabolites and water to the blood stream..

Question 9

freshwater fish adaptations:

Answer 9

1. the fishes body surfave has low permeability to water and ions- most ion loss and water gain occurs across the gills.
2. to compensate for water gain the kidneys produce a large volume of urine. they do not drink!
3. to reduce salt loss- salts are reabsorbed from the urine

Question 10

salt water fish adaptations:

Answer 10

1. produce very little urine to minimize water loss
2. to compensate for water loss they drink
3. to get ride of salt they have chloride cells (in the gills) that pump Na+ and Cl- ions outward
4. body surface has low permeability to water and ions- most ion loss and water gain occurs across the gills

Question 11

what are some adpatation euryhaline fish have?

Answer 11

1. capable of changing urine concentration according to the salinity of the environemnt (dramatic change in the function of they kidneys)
2. chloride cell number can increase or decrease and the cells can reverse direction

Question 12

how does the copious amount of water available to fish directly impact nitrogenous waste excretion?

Answer 12

excrete nitrogenous waste as ammonia! ammonia is toxic and must be dilluted with large amunts of water and fish have lots of that in their disposal!

Question 13

salinity decreases ——- availability

Answer 13

oxygen; fish that live in relatively high salinity environments must have adaptations to handle the lower O2

Question 14

salinity also increases water denisty, which impacts what?

Answer 14

buoyanc and the seed of sound transmission!