Regulation within animal systems requires maintaining homeostasis- the ability of the body or a cell to seek and maintain a stable internal environment when dealing with external changes There are several organ systems that work together to maintain an organism’s internal environment, despite changes that occur in its external environment. The nervous system maintains homeostasis by controlling and regulating the other parts of the body. The excretory system helps regulate the concentration of water and other components of body fluids.

The Excretory System Maintains Homeostasis In 3 Steps: 1.Filtration- Filters substances from the blood 2.Reabsorption- Regulate the chemical composition of body fluids by retaining the proper amounts of water, salts, and nutrients 3.Secretion- Elimination of wastes in the form of urine

Evolutionary Trends in Excretion Animal Taxon Aquatic Invertebrates Worms and Mollusks InsectsVertebrates Release Wastes By… diffusion to remove waste across their cell membranes directly into the water Use of nephridia- tiny pores along the body excrete waste Using malpighian tubules to collect and excrete wastes Use of kidneys, ureters, and a bladder to collect and excrete waste Picture of system Examples Sponges, jellyfish, planaria Earthworm, clam, octopus Grasshopper, ants, bees mammals, birds, reptiles, fish, amphibians Simple Complex

Kidneys (renal = kidney)-  Paired organs that receive blood via the renal artery  Contain millions of filtering units called nephrons that remove wastes from the blood and produce urine.  Every 45 minutes kidneys filter all the blood in your body  Filtered blood leaves kidneys and returns to circulation carrying nutrients, salts, and water via the renal vein  Excess water and toxic waste in the form of urine leave the kidney via the ureter  Sometimes excess salts or minerals in the urine crystallize and form kidney stones. When kidney stones block the ureters, they cause great pain.

 Ureters—tubes that carry urine from kidneys to urinary bladder  Bladder—muscular sac where urine is stored temporarily before being excreted  Urethra—tube that carries urine from bladder to the outside

Levels of Organization Nephrons Kidneys, Bladder, Ureter, Urethra Excretory

3/4 Pick up old quiz Get out Excretory System notes If you missed the Urine Analysis Lab – make ups will be tomorrow before/after school.

Interaction with other systems for Regulation  Lungs of the respiratory system remove CO 2 from blood.  The circulatory system brings wastes to the lungs, kidneys, and skin for excretion.  Skin of the integumentary system excretes water, urea, salts, and other wastes through sweat.

Think-Pair-Share: Explain how a Big Mac and a large French fry could disrupt normal homeostasis within your excretory system?