Water & Electrolyte Balance

Flashcards for vocabulary review.

Electrolyte

A compound that dissociates into ions when dissolved in water (e.g., NaCl, HCl).

Osmosis

The movement of water down its concentration gradient across a semipermeable membrane.

Osmolarity

The concentration of solutes in solution (units: Osmoles/liter).

Osmotic Stress

A condition where the concentration of dissolved substances in a cell or tissue is abnormal.

Ionoregulatory Homeostasis

Main organs involved in animals: Fish & crustacean gills, insect Malpighian tubules, maxillary glands in barnacles, and kidneys in mammals.

Ionocytes

Mitochondrion-rich cells that actively pump ions to maintain osmotic, ionic, and acid-base levels.

Kidneys

Maintain water/salt balance, control blood volume and pH, produce RBCs, and activate Vitamin D.

Nephron

The functional unit of the kidney, consisting of tubules and blood vessels, and concentrates urine.

Glomerulus Pressure

High because the afferent arteriole is wider than the efferent arteriole, creating high pressure for filtration.

Glomerular Filtration

Forcing of liquid and solutes through capillary pores in the glomerulus, keeping blood cells in the blood.

Tubular Reabsorption

The process where most glomerular filtrate is reabsorbed by proximal tubule cells to prevent nutrient loss.

Aquaporins

They allow water to pass through cell membranes by osmosis.

Loop of Henle

Water reabsorbed in the descending limb; Na+ and Cl- are reabsorbed in the ascending limb (thin = passive, thick = active).

Tubular Secretion

Capillaries secrete substances like ammonia and drugs into the distal tubule for removal in urine.

ADH

It signals kidney collecting ducts to open aquaporins and reabsorb water into the body.

Caffeine and Alcohol Effect on ADH

They inhibit ADH release, leading to more water being lost in urine.

Deamination

The removal of an amino group from an amino acid, usually in the liver, producing ammonia.

Nitrogenous Waste Products

Ammonia (fish), urea (mammals), uric acid (birds and reptiles).

Osmoregulators

Maintain internal osmolarity different from their environment.

Osmoconformers

Match their internal osmolarity to their environment.

Alternative splicing in fish

Used to switch transport proteins in ionocytes for different salt and freshwater environments.