Animal Osmoregulation and Adaptations

The process by which animals regulate their internal solute concentration and water balance.

The removal of nitrogen-containing waste products of metabolism.

The movement of water across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration.

The measure of solute concentration per unit volume of solution.

Two solutions with the same osmolarity.

A solution with a higher solute concentration than another.

A solution with a lower solute concentration than another.

Organisms that maintain a constant internal osmolarity, regardless of their external environment.

The ability of some organisms to survive in a dormant state with almost no water in their bodies.

Tiny, resilient animals that can survive in a dehydrated state for extended periods.

A disaccharide sugar that helps protect cell membranes during dehydration by replacing water.

The process of losing water from the body, primarily through evaporation.

Adaptations that help organisms minimize or prevent water loss from their bodies.

Water produced during cellular respiration, a significant source of water for land animals.

The balance of water intake and loss in an organism.

Animals that have adapted to survive in arid environments and can go long periods without drinking water.

A type of tissue specialized for moving specific dissolved substances across cell membranes in controlled amounts and directions.

Water-impermeable junctions between epithelial cells that create a barrier between the tissue and the environment.

An internal body fluid that bathes the cells in animals with an open circulatory system.

The fluid that surrounds the cells in animals with a closed circulatory system.

Specialized structures within the body that regulate water balance and waste disposal.

A system of blood vessels that allows for efficient salt removal from the blood, such as in the salt-secreting glands of marine birds.

The breakdown of proteins and nucleic acids produces nitrogenous waste products, mainly ammonia, which is toxic and requires significant water for dilution.

Ammonia is highly soluble but toxic, making it suitable for excretion in watery environments where dilution is readily available.

Urea is a less toxic nitrogenous waste product, produced in the liver by combining ammonia with carbon dioxide, and excreted by the kidneys.

Urea is less toxic than ammonia, allowing it to be transported and stored at higher concentrations, reducing the water needed for excretion.

While less toxic, urea requires energy to produce from ammonia, making it a less efficient option in terms of energy expenditure.

Freshwater fishes, which gain water by osmosis, need to excrete nitrogenous wastes as ammonia to maintain their osmotic balance.

Marine animals, which lose water by osmosis, excrete urea as their primary nitrogenous waste, conserving water.

The type of nitrogenous waste an animal excretes is related to its evolutionary history (phylogeny) and its environment (habitat), reflecting adaptations for water balance and energy efficiency.

A nitrogenous waste product that is excreted by many aquatic organisms.

A nitrogenous waste product that is excreted by mammals and some amphibians.

A nitrogenous waste product that is excreted by birds, reptiles, and some insects.

The ability of organisms to maintain a stable internal environment, including water balance, despite changes in the external environment.

The process of converting ammonia to urea or uric acid, reducing water loss.

These animals primarily excrete uric acid, which helps them conserve water.

These animals often excrete urea and ammonia, due to their aquatic lifestyle.

The ascending limb of the loop of Henle is permeable to salt but not water, allowing salt to diffuse out into the interstitial fluid, increasing its osmolarity and making the filtrate more dilute.

The active transport of salt from the filtrate into the interstitial fluid in the thick segment of the ascending limb further increases the osmolarity of the medulla.

The distal tubule regulates K+ and NaCl concentrations in body fluids by controlling K+ secretion and NaCl reabsorption.

Like the proximal tubule, the distal tubule contributes to pH regulation by secreting H+ and reabsorbing bicarbonate (HCO3−).

The collecting duct plays a crucial role in determining salt excretion in urine by actively reabsorbing NaCl.

The collecting duct's epithelium is permeable to water, but not to salt or (in the renal cortex) urea, allowing water to move out and make the filtrate more concentrated.

The inner medulla of the collecting duct becomes permeable to urea, allowing some urea to diffuse out into the interstitial fluid, contributing to the high osmolarity of the medulla.

The mammalian kidney can excrete urine up to four times the concentration of blood, allowing for water conservation and the production of hyperosmotic urine.