Excretory System Kidneys and the Urinary System Lungs

Excretory System Kidneys and the Urinary System, Lungs, Skin, & Liver (removing metabolic waste) AP Biology 2008 -2009

Unicellular Multicellular Warm, dilute ocean waters Limits cell size Must stay small Unicellular Multicellular • All cells in direct contact with environment • All cells can easily get nutrients in & waste out by diffusion Regents Biology • Internal cells not in direct contact with environment • Internal cells can’t get nutrients in & waste out • Need organ systems

What liquid waste do we make? § Digesting protein makes poison u nitrogen waste = ammonia = poison H O | || H N —C— C—OH | H H Regents Biology NH 2 = ammonia CO 2 + H 2 O AMINO ACIDs and Nitrogen Bases

Nitrogen waste § The kind of waste you make depends on where you live u Freshwater § Ammonia § Diffuse and dilute quickly u Land § Urea § Humans u Egg layer/Insects § uric acid § Solid – crystals § LEAST toxic Regents Biology

Human Excretory System § Mammals have a pair of bean-shaped kidneys u supplied with blood by a renal artery and a renal vein Nephron Organ system Tissue Organ Regents Biology

Bladder Regents Biology

Nephron = functional unit of kidney § Not filtered out u cells and proteins (too big) § Filtered out u “Bad” stuff § § u Urea (from liver) Salts H 2 O toxins from food “Good” stuff § simple sugars, aa § “Good” stuff reabsorbed; “Bad” stuff makes urine Regents Biology to bladder

Nephron Structure – functional unit Ball of capillaries Bowman’s capsule Renal FILTRATION Removes “good” and “bad” stuff NO Cells leave the blood vessels Renal Capillaries – wrapped around loop to increase surface area Regents Biology REABSORPTION Reabsorb “good” stuff” (ss, aa, some salt and some water to maintain water balance)

Also • Skin – removes salt, water, and urea • called sweat • Lungs – remove CO 2 and water • Liver – PRODUCES UREA Diseases/Disorders – failure to maintain homeostasis • Kidney Disease – failure of kidneys to filter toxins from blood; treatment =dialysis or transplant • Nephritis – inflammation of kidneys • Kidney stone – calcium deposit that blocks ureter • Gout – build up of uric acid in joints Regents Biology