Excretory Systempp. 912-916

• Pre-Movie:http://kidshealth.org/kid/closet/movies/how_the_body_works_interim.html

• Major structures:– Kidneys– Ureters– Urinary bladder– Urethra

Excretory System Key Functions

• Removes wastes from blood• Regulates concentration of bodily fluids

Excretion of waste

• Excretion – the process that rids the body of toxic chemicals, excess water, salts, and carbon dioxide while maintaining osmotic and pH balance.

• Some wastes and their exits:– Carbon dioxide (and some water vapor) is transported to

your lungs by the circulatory system and excreted every time you exhale

– Excess water is excreted through the skin in sweat and through the kidneys in urine

– In the liver, ammonia is converted into a less toxic nitrogen waste called urea, which is carried by the bloodstream to the kidneys, where it is removed from the blood

Kidneys

• Two bean-shaped, reddish brown organs located in the lower back that are composed of microscopic blood-filtering tubes called nephrons

• Help regulate the amount of water and salts contained in blood

http://www.unckidneycenter.org/images/glomerulus.jpg

Urine Formation

• Urine – formed from the water, urea, and various salts that are left after the absorption and secretion processes.

• Collecting ducts receive fluid from several nephron segments and empty the urine into areas of the kidneys that lead to the ureters, tubes that carry the urine from the kidney to the urinary bladder.

• Urinary bladder- a hollow, muscular sac that stores urine• Urine leaves the bladder and exits through the body

through a tube called the urethra

Male: Female:

What is kidney dialysis?

• Also know as hemodialysis this is a procedure for filtering the blood by using a dialysis machine, which sorts small molecules in the blood, keeping some and discarding others

• Dialysis machines are sometimes used for kidneys that are damaged but either will eventually heal or be replaced by a kidney transplant

Excretory System Activities

• http://www.purposegames.com/game/human-excretory-system-quiz

• http://www.syvum.com/cgi/online/tgamem.cgi/squizzes/biology/excr.tdf?0

• http://www.whitman.edu/biology/vpd/excretory.html

• http://videos.howstuffworks.com/hsw/20550-human-body-systems-the-excretory-system-video.htm

• http://www.infovisual.info/03/video/excretory%20system.html