Osmoregulation

This set of flashcards covers key concepts related to osmoregulation, the urinary system, kidney function, and the role of hormones in maintaining fluid and electrolyte balance.

What are the two main compartments in an animal's body where water is distributed?

Intracellular and extracellular compartments.

What is osmotic pressure?

A measure of concentration difference that balances the pressure created by the movement of water.

Define 'osmoconformers'.

Organisms that have body fluids isotonic to seawater and maintain osmotic equilibrium with their environment.

What is the main difference between osmoregulators and osmoconformers?

Osmoregulators maintain a constant blood osmolarity, while osmoconformers match their osmolarity to their environment.

How do freshwater vertebrates deal with their hypertonic body fluids?

They prevent excess water from entering by excreting a large volume of dilute urine and actively transporting ions back into their bodies.

What type of nitrogenous waste do mammals produce?

Urea, which is less toxic than ammonia.

Why do reptiles, birds, and insects excrete uric acid instead of urea or ammonia?

Uric acid is less soluble in water, which conserves water.

What role does the loop of Henle play in the nephron?

It creates a gradient of increasing osmolarity from the cortex to the medulla, allowing water reabsorption in the collecting duct.

Explain the function of antidiuretic hormone (ADH).

ADH increases the permeability of the collecting ducts to water, promoting water reabsorption back into the bloodstream.

What triggers the release of aldosterone?

A decrease in blood sodium concentration and blood volume.

What is the renin-angiotensin-aldosterone system?

A hormonal system that regulates blood pressure and fluid balance by controlling sodium and water reabsorption.

How do marine bony fishes maintain osmotic balance?

They drink large amounts of seawater and actively excrete excess ions through their kidneys and gills.

What is the general structure of the nephron?

It consists of a long tubule and associated blood vessels, including a glomerulus for filtration.

What happens when blood glucose levels exceed 180 mg/100 mL?

Excess glucose appears in the urine, indicating diabetes mellitus.

What is the countercurrent multiplier system in the kidney?

A system that enhances the osmotic gradient for water reabsorption by having fluid flow in opposite directions in the loop of Henle.

What is the primary function of the kidneys?

To maintain homeostasis by regulating water and electrolyte balance, removing waste, and controlling blood pressure.