Chapter 25 Part B: The Urinary System - Human Anatomy and Physiology

These flashcards cover key vocabulary and concepts related to the urinary system, specifically the processes of tubular reabsorption and secretion.

Tubular Reabsorption

A process whereby most tubular contents are reclaimed and returned to the blood.

Transcellular Route

Pathway where solute enters apical membrane of tubule cells, travels through cytosol and exits basolateral membrane into blood.

Paracellular Route

Pathway between tubule cells, limited by tight junctions, allowing some ions and water to move into the blood.

Na⁺-K⁺ ATPase

An active transport pump that moves Na⁺ ions into the interstitial space to facilitate Na⁺ reabsorption.

Obligatory Water Reabsorption

Water reabsorption that occurs in the proximal convoluted tubule and is not regulated by hormones.

Facultative Water Reabsorption

Water reabsorption that occurs in collecting ducts, regulated by the presence of Antidiuretic Hormone (ADH).

Transport Maximum (Tm)

The maximum rate at which a substance can be reabsorbed by the renal tubules, limited by the number of carriers available.

Aldosterone

A hormone that increases Na⁺ reabsorption in the distal convoluted tubule and collecting duct.

Countercurrent Mechanism

A mechanism that helps the kidneys adjust urine concentration, involving fluid flow in opposite directions in renal tubules.

Urea Recycling

The process by which urea is reabsorbed in the collecting duct, contributing to the medullary osmotic gradient.

Diuretics

Chemicals that increase urinary output, affecting the reabsorption of water and solutes.

Antidiuretic Hormone (ADH)

A hormone released by the posterior pituitary that promotes the reabsorption of water in the kidneys.