Urinary System Overview

Study Notes

The renal system, also known as the urinary system, produces, stores, and eliminates urine
Consists of two kidneys, two ureters, bladder, and urethra

Location: lower back, one on each side of the spine
Functions:
- Filter waste and excess substances from blood
- Regulate electrolyte and water balance
- Produce hormones that help control blood pressure and produce red blood cells
Structure:
- Outer cortex and inner medulla
- Nephrons: functional units of the kidney, consisting of glomerulus and renal tubule

Glomerulus:
- Cluster of capillaries surrounded by Bowman's capsule
- Filtration: blood pressure forces water and small molecules out of capillaries into Bowman's space
Renal tubule:
- Proximal convoluted tubule (PCT): reabsorption of water, ions, and nutrients
- Loop of Henle: concentration of urine
- Distal convoluted tubule (DCT): further reabsorption and secretion
- Collecting duct: final concentration and transport of urine to renal pelvis

Ureters:
- Muscular tubes that transport urine from kidneys to bladder
- Peristalsis: rhythmic contractions propel urine downward
Bladder:
- Storage organ for urine
- Detrusor muscle: contraction and relaxation control urination
Urethra:
- Tube that carries urine out of the body
- Internal urethral sphincter: involuntary muscle that controls urine flow

Urine formation:
- Glomerular filtration rate (GFR): rate of fluid filtered from blood
- Tubular reabsorption and secretion: regulate electrolyte and water balance
Regulation:
- Renin-angiotensin-aldosterone system: regulates blood pressure and electrolyte balance
- Antidiuretic hormone (ADH): regulates water reabsorption in collecting ducts

Located in the lower back, one on each side of the spine
Functions: filter waste and excess substances from blood, regulate electrolyte and water balance, produce hormones to control blood pressure and produce red blood cells
Consists of outer cortex and inner medulla
Nephrons are the functional units, comprising glomerulus and renal tubule

Glomerulus: cluster of capillaries surrounded by Bowman's capsule, responsible for filtration
Renal tubule: composed of proximal convoluted tubule (PCT), loop of Henle, distal convoluted tubule (DCT), and collecting duct
Proximal convoluted tubule (PCT): reabsorption of water, ions, and nutrients
Loop of Henle: concentration of urine
Distal convoluted tubule (DCT): further reabsorption and secretion
Collecting duct: final concentration and transport of urine to renal pelvis

Ureters: muscular tubes that transport urine from kidneys to bladder, using peristalsis for propulsion
Bladder: storage organ for urine, with detrusor muscle controlling urination
Urethra: tube that carries urine out of the body, with internal urethral sphincter controlling urine flow

Urine formation involves glomerular filtration rate (GFR) and tubular reabsorption and secretion
Regulation involves the renin-angiotensin-aldosterone system (blood pressure and electrolyte balance) and antidiuretic hormone (ADH) (water reabsorption)