Osmoregulation – AP Biology Flashcard

Osmoregulation is the process of maintaining the balance of water and electrolytes in an organism's body to ensure homeostasis.

Osmosis is the movement of water across a semipermeable membrane from a region of low solute concentration to high solute concentration.

Osmotic pressure is the pressure required to stop water from moving across a semipermeable membrane by osmosis.

Osmoreceptors detect changes in osmotic pressure and signal the body to adjust water and electrolyte balance.

Osmoconformers are organisms that match their internal osmolarity with the surrounding environment.

Marine invertebrates like jellyfish and starfish are osmoconformers.

Osmoregulators actively regulate their internal osmotic pressure, independent of the external environment.

Freshwater fish and humans are examples of osmoregulators.

Seawater is hypertonic to human body fluids, causing dehydration as the body loses water to balance the salt concentration.

Freshwater fish excrete large amounts of dilute urine to get rid of excess water and actively absorb salts through their gills.

Marine fish drink seawater and excrete excess salt through their gills to retain water and maintain internal balance.

Antidiuretic hormone (ADH) helps the kidneys reabsorb water and reduce urine output, maintaining the body's fluid balance.

When ADH is released, the kidneys increase water reabsorption, producing concentrated urine to conserve water.

Euryhaline organisms can tolerate a wide range of salinities, such as salmon, which live in both fresh and saltwater.

Stenohaline organisms can only tolerate a narrow range of salinities, like goldfish.

Plants regulate water loss through stomata, and in dry conditions, they store water in vacuoles and have thick cuticles to reduce water loss.

Bacteria use transport mechanisms to adjust their internal solute concentration and produce osmoprotectants during osmotic stress.

The kidney is the main organ responsible for osmoregulation in humans, filtering blood and regulating water and electrolytes.

Aldosterone regulates sodium reabsorption in the kidneys, influencing water retention and blood pressure.

Sharks accumulate urea in their tissues to become isotonic with seawater and use a rectal gland to excrete excess salt.

Ureotelic animals excrete urea as their primary nitrogenous waste, such as sharks and mammals.

Desert animals produce highly concentrated urine and minimize water loss through adaptations like reduced sweating and thick skin.

Mitochondria-rich cells in fish gills actively absorb salts from the surrounding water to maintain electrolyte balance.

Marine invertebrates are typically osmoconformers, meaning their body fluids are isotonic with seawater, matching its osmolarity.

Osmoregulation ensures the proper balance of fluids and solutes, preventing dehydration or overhydration, which is vital for maintaining homeostasis.