8.3 Osmoregulation

Osmoregulation is the maintenance of constant osmotic conditions (water and solute concentration) in the body. Animals may be either osmoregulators or osmo-conformers with respect to their external environment.

Definition

Osmoregulation: The maintenance of constant osmotic conditions (water and solute concentration) in the body is called osmoregulation.

Osmoconformers: Those animals that change the osmotic concentrations of the body fluids according to that of surrounding medium are called osmo-conformers. These are isotonic to their external environment.

Osmoregulators: Those animals that can maintain internal osmotic concentrations different from the surrounding medium are called osmoregulators. Such animals are hypotonic or hypertonic to their environment.

Main Idea

• Osmoregulation is the maintenance of constant osmotic conditions.
• It involves water and solute concentration.
• Animals may be either osmoregulators or osmo-conformers.
• Osmoconformers change their osmotic concentrations according to the environment.
• Osmoregulators maintain internal osmotic concentrations different from the environment.
• Osmoregulators are hypotonic or hypertonic to their environment.

Core Concept

• Osmoregulation = maintenance of constant osmotic conditions
• Osmoconformers = change osmotic concentrations with environment
• Osmoconformers = isotonic to environment
• Osmoregulators = maintain internal osmotic concentrations different from environment
• Osmoregulators = hypotonic or hypertonic to environment
• Examples of osmoconformers = all marine invertebrates, some freshwater invertebrates, some marine vertebrates (Myxine, elasmobranchs)
• Examples of osmoregulators = almost all freshwater animals, most marine vertebrates
• Osmolytes = organic substances that increase osmotic concentration

Detailed Explanation

Osmoregulation

• The maintenance of constant osmotic conditions (water and solute concentration) in the body is called osmoregulation.
• Animals may be either osmoregulators or osmo-conformers with respect to their external environment.