Urinary System Anatomy and Nephron Function

Kidneys

The filtration organs of the body and blood that remove waste and toxins to regulate fluid volume, ion concentrations, and blood pH.

Excretion

The process of getting rid of metabolic waste via the urinary system, which is distinct from defecation.

Retroperitoneal

The anatomical position behind the peritoneum, describing the kidneys because they are covered by the serous membrane only on their anterior side.

Ureters

Tubes that convey urine from the kidneys down to connect to the posterior and inferior base of the urinary bladder.

Urethra

The muscular tube that transports urine from the urinary bladder out of the body through the external orifice, and also conveys semen in males.

Adrenal Glands

Glands located directly on top of each kidney whose cortex and medulla produce hormones such as aldosterone and cortisol.

Trigone

A triangular area at the base of the urinary bladder demarcated by the two ureteral openings and the internal urethral opening.

Detrusor Muscle

The smooth muscle forming bundles in the wall of the urinary bladder that contracts and squeezes to push urine into the urethra.

Hilum

The indented entry and exit region on an organ, such as the kidney, through which renal vessels and the ureter pass.

Fibrous Capsule

The outermost fibrous protective layer surrounding the kidney like shrink-wrap, positioned deep to the peritoneum.

Renal Cortex

The outer region or layer of the kidney where blood enters to be filtered and where cortical radiate arteries are found.

Renal Medulla

The inner region of the kidney located deep to the cortex, composed of the renal pyramids and renal columns.

Renal Pyramids

Triangular or conical tissue structures located within the renal medulla that house the microscopic collecting ducts.

Renal Columns

The spaces and tissue located between adjacent renal pyramids in the medulla.

Renal Papilla

The apex or tip of a renal pyramid that points toward and empties into a minor calyx.