Excretion Excretion is the process by which waste

Excretion • Excretion is the process by which waste products of metabolism and other non-useful materials are eliminated from an organism

• Organs include: – Lungs – Liver – Sweat Glands – Kidneys – Bladder

Lungs • CO 2 diffuses from the capillaries into the alveoli of the lungs • Excess water from AEROBIC respiration is also brought to the lungs • Both are removed from the body by the process of exhalation

Liver • Disposal of Hemoglobin – Old Red Blood Cells are destroyed – Hemoglobin is released which is then turned into bile pigments – These pigments are stored in the gall bladder and are later released into the small intestine where they can be removed from the body through feces

• Disposal of Nitrogenous wastes – Nitrogenous compounds are broken down and turned into UREA – Urea is then absorbed into the blood system and transported to the kidneys – Removed through URINARY SYSTEM

Sweat Glands • Structure – Small, coiled tubular glands in DERMIS of skin – Ducts lead to openings in the epidermis called PORES • Function – Water, salts, and urea diffuse into glands from blood – Eliminated from body, SWEAT – PERSPIRATION: The formation of sweat

• Temperature Regulation – Acts as a way of controlling our body temps – Sweat absorbs heat and carries the heat to the outside of our bodies – Sweat evaporates into the air, thereby cooling the body – Used in maintenance of homeostasis

Kidneys • Function – Remove UREA from blood – Excrete nitrogenous wastes – Regulate concentration of substances in the blood

Nephron • Functional unit of the kidney • Arteries turn into small balls of capillaries – GLOMERULUS • Glomerulus enclosed in cup like structure known as the BOWMAN’S CAPSULE • Extending from Bowman’s Capsule is a long, coiled tubule surrounded by capillaries

• Filtration – Water, Salts, Urea, Amino Acids, and Glucose diffuse out of blood in the Glomerulus and into Bowman’s Capsule • Re-absorption – After leaving Bowman’s Capsule, some of the water, salts, etc. enter back into the bloodstream through ACTIVE TRANSPORT

• URINE , made up of water, salts, and urea, is left over and travels to the URETER • The Urine travels through the Ureter into the BLADDER – Stores urine • Sphincter muscle leads to URETHRA – Leads outside the body

Diseases of the Excretory System • Kidney Disease – Variety of conditions where kidneys and nephrons are unable to do their jobs effectively – Unable to remove nitrogenous wastes – Can be caused by a high protein diet • Gout – Form of arthritis – Uric Acid crystals form and float in bloodstream – Get deposited in joints (Big Toe) – Cause pain and stiffness