Urinary System Overview

Overview

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

Kidneys

• 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

Nephrons

• 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, Bladder, and Urethra

• 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 and Regulation

• 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

Renal System

• Produces, stores, and eliminates urine
• Composed of two kidneys, two ureters, bladder, and urethra

Kidney Structure and Function

• 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

Nephron Structure and Function

• 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, Bladder, and Urethra

• 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 and Regulation

• 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)