Function of fish kidney? (1 Viewer)

[RishBonjour]

In some books, e.g. heinmann - and also many places on the net - it says fish kidney's only role is osmoregulation - wastes are released via gills

some other books e.g. bio in focus I think - also many places on the net - say fish releases "urine" with ammonia - I'm assuming its a product of the kidney

which one is accepted in HSC?
any ideas?

 

[jamesischool]

doesnt osmoregulation include releasing ammonia? that keeps the osmotic balance intact?

 

[RishBonjour]

I think it more directly refers to the regulation of water and solutes
ammonia/urea etc fall under excretion :/
Also, the heinmann explicitly says ammonia released through gills

this and the enanstiostasis are presented differently in different textbooks..

 

[Leffife]

Well, I'll give a good quick overview on the function of the fish kidney. I'm only going to deal with the balance between salt & water concentrations since it's in the syllabus but the other function of the kidney is hematopoiesis (don't worry about this one)

The main function of the kidney is osmoregulation.
In freshwater fish, the kidney saves ions (salts) & excretes water to maintain homeostasis.
In marine fish (saltwater fish), the kidney excretes ions (salts) and conserves water.
Most of the nitrogenous wastes are excreted through the gills.

Why does freshwater fish kidney retain salts in the blood?
Freshwater fish is hyper-osmotic to its surroundings (environment) - salts diffuse out & water moves into the fish.

Why do marine fish kidney retain water in the blood?
Marine fish is hypo-osmotic to its surroundings (environment) - salts moves into the fish & water diffuses out.

KEY TO REMEMBER: OSMOREGULATION

Hope that helped

 

[RishBonjour]

Well, I'll give a good quick overview on the function of the fish kidney. I'm only going to deal with the balance between salt & water concentrations since it's in the syllabus but the other function of the kidney is hematopoiesis (don't worry about this one)

The main function of the kidney is osmoregulation.
In freshwater fish, the kidney saves ions (salts) & excretes water to maintain homeostasis.
In marine fish (saltwater fish), the kidney excretes ions (salts) and conserves water.
Most of the nitrogenous wastes are excreted through the gills.

Why does freshwater fish kidney retain salts in the blood?
Freshwater fish is hyper-osmotic to its surroundings (environment) - salts diffuse out & water moves into the fish.

Why do marine fish kidney retain water in the blood?
Marine fish is hypo-osmotic to its surroundings (environment) - salts moves into the fish & water diffuses out.

KEY TO REMEMBER: OSMOREGULATION

Hope that helped

thanks! but I was asking about the excretion bit - I'm aware of the hypertonic and hypotonic fresh and salt water fish

Also - isn't hematopeisis how blood cells are created? (was looking that up yday while doing WBC)


What would you say about the function of fish kidney and excretion of ammonia? (since you seem to know your stuff )