THE EXCRETORY SYSTEM

Controlling the Internal Environment

Gross Anatomy of System

• Pair of kidneys– Retroperitoneal

• Pair of ureters• Urinary bladder• Urethra

Gross Anatomy

Location of KidneysRetroperitoneal

Retroperitoneal Location

The Kidney

Cortex

Medulla

Calyx

PelvisUreter

Hilum

PapillaPyramid

Column

Functions of Excretory System

• Regulate body fluids– Volume, pH, composition

• Remove metabolic wastes from blood• Control rate of RBC formation• Regulate blood pressure• Regulate absorption of calcium

Nephron

Collecting duct

DCTPCT

Ascending tubuleDescending

Tubule

Bowman’scapsule

GlomerulusVasa recti

The Blood Supply to the Kidney

Renal Corpuscle

Renal Corpuscle

Podocyte and the Filtration Process

Renal Corpuscle

Function of Renal Corpuscle

• Bowman’s capsule• Glomerulus

– Filtration of blood• Water• Electrolytes• Glucose• Urea

Filtration Slits

Nephron

Tubules

Distal Tubule

Proximal Tubule

Function of Tubules

• Reabsorption of glucose– Proximal convoluted tubule

• Reabsorption of water– PCT, descending tubule, collecting duct

• Reabsorption of salts– PCT, ascending tubule, distal con. tub.

• Reabsorption of urea– PCT, collecting duct

Collecting Ducts

Cuboidal Epithelium lining ducts

Nepron with Vasa Recta

Function of Tubules

• Reabsorption of glucose– Proximal convoluted tubule

• Reabsorption of water– PCT, descending tubule, collecting duct

• Reabsorption of salts– PCT, ascending tubule, distal con. tub.

• Reabsorption of urea– PCT, collecting duct