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3.3 identify the role of the kidney in the excretory system of fish and mammals
identify the role of the kidney in the excretory system of fish and mammals
- The kidney is an organ of the excretory system of both fish and mammals. It plays a central role in homeostasis, forming and excreting urine while regulating water and salt concentration in the blood. It maintains the precise balance between waste disposal and the animal’s needs for water and salt.
- The role of the kidney in fish is dependant on the environment of the fish.
- In marine (salt water) environments, the kidneys excrete small quantities of isotonic (same concentration as sea water) urine. This helps conserve water and excrete the excess salt they gain from their hyperosmotic environment.
- In freshwater fish, the kidneys work continuously to excrete copious quantities of dilute urine, which also has a very low salt concentration. This helps to remove excess water gained from the hypo-osmotic environment.