Osmoregulation and Excretion

Maintaining balance of water

• Osmoregulation

– Regulate solute concentrations

– Balance the gain and loss of water

• Excretion

– The disposal of mostly nitrogenous waste products of metabolism

Salt 20%

Salt 70%

Water 80% Water 30%

How does the solvent move through a permeable membrane?

Osmosis is the spontaneous net movement of solvent molecules through a partially permeable membrane into a region of higher solute concentration (hypo to hyperosmotic solution), in the direction that tends to equalize solute concentrations (Isoosmotic sol.)on two sides by osmotic pressure.

A B hypo hyper

Get the answer!

Then in case of fish, what do you think?

Saltwater fish

Freshwater fish

Saltwater fish

Hypoosmotic solution

Freshwater fish

Hyperosmotic solution

Osmoregulation

Kidney play a large role by regulating the amount of water reabsorbed from glomerular filtrate in kidney tubules

Physiology of osmoregulation and excretion

Osmoregulation is controlled by…

Angiotensin II: Increases Na+ and water reabsorption. Causes vasoconstriction to increase blood pressure.

Aldosterone: Increases Na+ and water reabsorption

Regulation of blood volume

& pressure

BP decreased; JG cell produce Renin

Renin-angiotensin system

If the Na conc. of the blood is high, the osmoreceptors secrete ADH. If the Na conc. of the blood is low, they don't

secrete ADH.

Regulation of ECF osmolarity

and volume

sense the Na conc. of the blood.

Excretory process

• The process of separation and elimination of waste products (esp. nitrogenous waste)

• Waste products are formed due to catabolism of amino acid, glucose, glycerol, fatty acids.

• Maintain homeostasis within organism and prevent damage to the cell body.

The elimination of waste products

Function of kidney

I.

II.