Human Excretory System Name: ___________________ Date: __________________

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 (via the intestines) excretes bile pigments that result from the destruction of hemoglobin. It also 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!

Liver – Some Functions Functions in Excretion –Detoxifies Blood Filters Bacteria, alcohol, drugs, toxic substances Changes them into inactive or less toxic forms.  Excretes Bile  Contains  Worn-out RBC  Bile salts  Cholesterol

Liver Produces Urea Functions in Excretion – Forms Urea Changes toxic wastes (ammonia – from break down of amino acids) to Urea. Urea  Blood  Kidneys Filtered out & excreted in Urin e

Lungs –Main Function  Alveoli - Exchange O 2 & CO 2 between air and blood (through process of diffusion) Lungs excrete CO 2 when you EXHALE

Skin Sweat Glands –Help cool body: Heat escapes through millions of pores in skin surface –Excrete perspiration (evap. cooling) 99% H 2 O Mineral Salts Urea

Kidneys & Urinary System 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

Kidneys- Functional Units & Product Nephron (about one million per kidney) –Microscopic units that filter blood of wastes. –H 2 O and waste taken from blood into nephron Form URINE  Glomerulus (clump of capillaries)  At end of each nephron  Network of coiled tubes – diffusion of wastes - while useful substances & water are reabsorbed  Urine  Pale yellow solution  Urea, H 2 0, salts, other trace solutions (toxins…)

Urinary System - continued Ureters –Narrow muscular tubes –Connect Kidney  Bladder  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)