Functions and Anatomy of the Urinary System

Main functions of the urinary system

Regulation of ECF volume and blood pressure, regulation of osmolarity, maintenance of ion balance, homeostatic regulation of pH, excretion of wastes, production of hormones.

Organs of the urinary system

Kidneys, ureters, urinary bladder, urethra, renal arteries and veins.

Most superficial layer of the kidney

Renal cortex.

Region of the kidney containing renal pyramids

Renal medulla.

Part of the kidney continuous with the ureter

Renal pelvis.

Function of the minor and major calyces in the kidney

They collect urine from the papillae of renal pyramids.

Nephrons

The functional units of the kidneys.

Components of the renal corpuscle

Bowman's capsule + glomerulus.

Parts of the nephron in order

Bowman's capsule → Proximal convoluted tubule → Loop of Henle (descending and ascending limbs) → Distal convoluted tubule → Collecting duct.

Function of collecting ducts

They drain into the renal pelvis.

Cortical nephrons

The most common type of nephron; responsible for standard filtration and reabsorption.

Juxtamedullary nephrons

Nephrons with long loops of Henle; responsible for creating concentrated urine.

Where filtration occurs in the nephron

In the renal corpuscle (Bowman's capsule + glomerulus).

Where reabsorption occurs in the nephron

In the peritubular capillaries (from tubule to blood).

Secretion in renal physiology

Movement of substances from blood to tubule; more selective than filtration.

Excretion in the urinary system

The removal of substances from the body in the form of urine.

Micturition

The voiding of the bladder (urination).

Daily fluid processed by kidneys

Kidneys process ~180L of fluid daily; only ~1.5L exits the body as urine.