The Excretory System Do Now Excretory System Excretion

The Excretory System

Do Now:

Excretory System Excretion – removes cellular waste The process that collects & removes harmful or useless substances that form in the body or are taken into the body from the blood, tissues, and cells.

Excretory System Although the urinary system has a major role in excretion, other organs contribute to the excretory function.

Four Organs of the Excretory System The lungs in the respiratory system excrete some waste products, such as carbon dioxide and water. The skin is another excretory organ that rids the body of wastes through the sweat glands. The liver It converts nitrogenous waste from the break down of proteins into urea. The major task of excretion still belongs to the kidneys, the major organ in the urinary system. If it fails the other organs cannot take over and compensate adequately.

Cellular Waste Heat Water Salts CO 2 Urea W/O excretion poisonous wastes build up in blood, cells, and tissues. Could lead to serious illness & eventually DEATH!

Kidneys & Urinary System – excretes waste and maintains homeostasis of body fluids. – Kidneys (main organ of the system) – Ureters – Bladder – Urethra

Kidneys & Urinary System Kidneys – Two – Fist sized – Bean shaped

Urinary System - continued Ureters – Narrow muscular tubes – Connect Kidney Bladder Muscular sac Stores Urine Expand to fill Muscle relaxes : Urine squeezed into Urethra

Urinary System - endpoint Urethra – Tube leading from Bladder outside of body

Failures of Homeostasis Bladder & Kidney Infections caused by bacteria from colon/rectum entering urethra. Kidney Stones - crystallization of mineral salts & uric acid that block passage of urine Kidney Disease - caused by long term diabetes, infections, & chemical poisoning Gout – form of arthritis where excess production of uric acid leads to deposits of crystals in joints (esp. toes)