Urinary System 10-15

Renal Capsule

A tough fibrous shell that surrounds each kidney.

Renal Cortex

The outer portion of the kidney.

Renal Medulla

The inner portion of the kidney where filtration takes place.

Medullary Pyramids

Cone-shaped masses of tissue in the renal medulla.

Kidney Papilla

The location where medullary pyramids empty into the minor calyx.

Renal Columns

Structures between the pyramids that anchor the cortex.

Minor Calyx

Located directly below the renal papillae; collects urine from the pyramid.

Major Calyx

Formed by the convergence of several minor calyces; collects urine to pass into the renal pelvis.

Renal Pelvis

The center of the kidney where urine collects before moving to the ureter.

Ureters

Tubes that transport urine from the kidneys to the urinary bladder.

Urinary Bladder

An expandable muscular sac that stores urine.

Trigone

A triangular region at the base of the urinary bladder.

Pathway of urine from nephron to excretion

Glomerular capsule → Proximal convoluted tubule → Loop of Henle → Distal convoluted tubule → Collecting duct → Papillary duct → Minor calyx → Major calyx → Renal pelvis → Ureter → Urinary bladder → Urethra.

Internal Urethral Sphincter

Regulates involuntary control of urine release.

External Urethral Sphincter

Regulates voluntary control of urine release.

Micturition

The process by which urine is expelled from the urinary bladder to the outside of the body.

Role of the Loop of Henle in Urine Concentration

The descending limb is permeable to water, allowing water reabsorption; the ascending limb is impermeable to water but allows ion reabsorption, contributing to urine concentration.

Function of the Distal Convoluted Tubule (DCT)

Responds to hormones like ADH and aldosterone to make homeostatic changes in ion and water balance.

Effect of ADH on Collecting Ducts

ADH causes aquaporins to open in the collecting ducts, increasing water reabsorption.