Osmoregulation and Renal Physiology

Comprehensive vocabulary definitions regarding biological osmoregulation, waste excretion strategies, and kidney function based on the lecture transcript.

Osmolarity

The total concentration of all solute particles per liter of solution.

Osmoconformers

Animals that match their internal salt and water concentrations to the environment around them.

Osmoregulators

Animals that actively maintain a constant internal solute concentration regardless of the environment.

Hypotonic Regulation

Maintaining an internal fluid concentration that is lower (more dilute) than a highly salty environment.

Hypertonic Regulation

Maintaining an internal fluid concentration that is higher (more concentrated) than a dilute environment.

Nasal Salt Glands

Specialized secretory tubules in marine birds that actively pump out excess dietary salt, draining it right out of the beak.

Ammonotelic

Animals (like aquatic fish) that flush out toxic, raw ammonia waste using vast amounts of water.

Ureotelic

Animals (like mammals) that convert toxic ammonia into water-soluble, less dangerous urea for disposal.

Uricotelic

Animals (like birds and reptiles) that convert ammonia into water-saving, insoluble uric acid paste.

Protonephridia

A simple invertebrate filter network where beating ciliated flame cells pull in and filter body fluid (found in flatworms).

Metanephridia

Open-ended tubes that pull fluid in through a ciliated opening (nephrostome) to process it segment by segment (found in earthworms).

Vasa Recta

Straight capillary loops that run deep into the medulla parallel to the loops of Henle to preserve the salt gradient.

Malpighian Tubules

Blind-ended tubes in insects that pump uric acid and salt into the gut, recycling water to leave a dry waste paste.

Estivation

A state of dormant, low-energy survival during extreme droughts, sometimes aided by storing water in the bladder.

Nephron

The functional filtering unit of the kidney that builds urine using filtration, reabsorption, and secretion.

Glomerulus

A high-pressure ball of leaky capillaries where blood plasma is packed and filtered.

Bowman's Capsule

The cup-like structure of the nephron that catches the freshly leaked fluid filtrate from the glomerulus.

Podocytes

Specialized cells in Bowman's capsule that wrap around the glomerular capillaries to form fine filtration slits.

Afferent Arterioles

The small blood vessels that bring blood directly into the high-pressure glomerulus.

Efferent Arterioles

The small blood vessels that carry filtered blood out of the glomerulus toward the surrounding tubules.

Peritubular Capillaries

A blood vessel network that wraps around the convoluted tubules in the kidney cortex to exchange items.

Proximal Convoluted Tubule (PCT)

The first stop in the nephron; it immediately reabsorbs over $75\%$ of water, salt, glucose, and nutrients back into the blood.

Countercurrent Multiplier

Fluid flowing in opposite directions through parallel tubes to build and maintain a steep concentration gradient in the tissue.

Descending Limb (Loop of Henle)

A segment that is highly permeable only to water, concentrating the urine as fluid moves down into the salty medulla.

Ascending Limb (Loop of Henle)

A waterproof segment that actively pumps only salt out into the tissue, making the kidney core extremely salty.

Aquaporins

Specialized membrane protein channels that selectively allow water molecules to flow right through.

Antidiuretic Hormone (ADH)

A brain hormone released when dehydrated that forces the collecting ducts to insert aquaporins to maximize water reabsorption.

Uremic Poisoning

A toxic and dangerous buildup of urea waste in the blood caused by renal failure.

Acidosis

A life-threatening drop in blood pH that occurs when failing kidneys cannot excrete excess hydrogen ions.