Excretory System learning the ways of waste…

 Animal cells move material across the cell membrane by diffusion  nutrients and fuels for energy  from digestive system  oxygen in  from respiratory system  waste out  CO 2  leaves by respiratory system  urea from cells, leaves by excretory system What Do Animal Cells Do To Stay Alive? O2O2 sugar nutrients CO 2 urea nutrients O2O2

Unicellular  Multicellular All cells in direct contact with environment All cells can easily get nutrients in & waste out by diffusion Internal cells not in direct contact with environment Internal cells can’t get nutrients in & waste out Need organ systems UnicellularMulticellular

Keeping An Animal Alive  Had to evolve organ systems for:  getting materials in & around  digestive system  respiratory system  circulatory system  removing wastes  respiratory system  excretory system

What Liquid Waste Do We Make?  Digesting protein makes poison  nitrogen waste = ammonia = poison H CO 2 + H 2 O NH 2 = ammonia H H N C—OH || O H | —C— |

 The kind of waste you make depends on where you live  Freshwater  ammonia  Land  urea  Land egg layer  uric acid Nitrogen Waste

Nitrogen Waste Disposal In Water  Freshwater animals  If you have a lot of water you can dilute the waste before it poisons you  excrete ammonia through gills and as urine Yes, fish pee in the water!

Nitrogen Waste Disposal On Land  Land animals  need to save H 2 O  evolved less poisonous waste product  urea  excrete urea & H 2 O as urine

Urea and Skin….  Did You Know:  Urea in its pure form is a powder  This powder is very good for your skin  Its even found in most make-up!

Human Kidney  Mammals have a pair of bean-shaped kidneys  supplied with blood by a renal artery and a renal vein

Proximal tubule Distal tubule Glomerulus Collecting duct Loop of Henle Amino acids Glucose H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O Na + Cl - Mg ++ Ca ++ Bowman’s capsule Na + Cl - kidney’s filtering unit

Kidneys: -contains millions of nephrons -nephrons filter the blood -removes wastes by diffusion Ureters: -brings waste to bladder Urethra: -brings waste from bladder to outside world Urinary Bladder: -holds waste from kidneys -make of special tissue that allows for expansion

Nitrogen Waste Disposal in Egg  Egg-laying land animals  no place to get rid of waste while in egg  needs waste that doesn’t dissolve in water inside egg  uric acid  stays a powder inside egg  birds, reptiles, insects

Uric Acid  Bird & reptile waste  large molecule that doesn’t dissolve in water inside egg  stays as a white powder  doesn’t harm embryo in egg  adults excrete white paste not liquid waste  white bird poop is really their pee!  this is why male birds don’t have a penis! Getting a little personal, aren’t we!

So Why Do Humans Dave Two Kinds of Waste? O2O2 CO 2 urea nutrients