REGULATION Reminders… 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.

REGULATION Excretory System How did the nervous system maintain homeostasis? The excretory system helps regulate the concentration of water and other components of body fluids.

Excretory System

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

Evolutionary Trends in Excretion Aquatic Invertebrates Excretory System Evolutionary Trends in Excretion Simple Complex Animal Taxon Aquatic Invertebrates Worms and Mollusks Insects Vertebrates 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

Major Organs of the Excretory System Kidneys: pair of organs that removes wastes *Note: renal=kidney receive blood via the renal artery Contain millions of filtering units called nephrons that remove wastes (excess salt and urea) from the blood and produce urine. Every 45 minutes kidneys filter all the blood in your body

Major Organs of the Excretory System 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 Excretory System Levels of Organization Nephrons Kidneys, Bladder, Ureter, Urethra Excretory

Interaction with other systems for Regulation Excretory System Interaction with other systems for Regulation Lungs of the respiratory system remove CO2 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.