Aim: Excretory System Enter Date Warm-up: HW: 2008-2009

What do animal cells do to stay alive? Animal cells move material across the cell membrane by diffusion nutrients in from digestive system oxygen in from respiratory system waste out CO2, urea from cells to respiratory system, excretory system O2 sugar nutrients CO2 urea

Unicellular → Multicellular Warm, dilute ocean waters Warm, dilute ocean waters Unicellular Multicellular Internal cells not in direct contact with environment Internal cells can’t get nutrients in & waste out Need organ systems All cells in direct contact with environment All cells can easily get nutrients in & waste out by diffusion

What liquid waste do we make? Digesting protein makes poison nitrogen waste = ammonia = poison C—OH || O H | —C— CO2 + H2O H N H NH2 = ammonia

Nitrogen waste The kind of waste you make depends on where you live Freshwater ammonia Land urea Egg layer uric acid Mode of reproduction appears to have been important in choosing between these alternatives. Soluble wastes can diffuse out of a shell-less amphibian egg (ammonia) or be carried away by the mother’s blood in a mammalian embryo (urea). However, the shelled eggs of birds and reptiles are not permeable to liquids, which means that soluble nitrogenous wastes trapped within the egg could accumulate to dangerous levels (even urea is toxic at very high concentrations). In these animals, uric acid precipitates out of solution and can be stored within the egg as a harmless solid left behind when the animal hatches.

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 dilute urine If you have a lot of water you can urinate out a lot of dilute urine. Predators track fish by sensing ammonia gradients in water. Transport epithelia in the gills of freshwater fishes actively pump salts from the dilute water passing by the gill filaments.

Nitrogen waste disposal on land Land animals need to save H2O evolved less poisonous waste product urea excrete urea & H2O as urine The salt secreting glands of some marine birds, such as an albatross, secrete an excretory fluid that is much more salty than the ocean. The salt-excreting glands of the albatross remove excess sodium chloride from the blood, so they can drink sea water during their months at sea. The counter-current system in these glands removes salt from the blood, allowing these organisms to drink sea water during their months at sea.

Sweat Glands The body removes wastes through sweating. Small amounts of urea leave the body Sweating also acts as a way to cool the body

Bladder

Kidney An organ designed to filter blood. It removes all wastes from blood and helps regulate water levels in the body If the body needs water, the kidney pulls water out from blood and puts it back into the body.

Human kidney Mammals have a pair of bean-shaped kidneys supplied with blood by a renal artery and a renal vein In humans, the kidneys account for less than 1% of body weight, but they receive about 20% of resting cardiac output

Nephron = Kidney’s filter Not filtered out cells proteins Filtered out urea sugars salts H2O toxins from food Makes urine Filtrate from Bowman’s capsule flows through the nephron and collecting ducts as it becomes urine. Filtration occurs as blood pressure forces fluid from the blood in the glomerulus into the lumen of Bowman’s capsule. The porous capillaries, along with specialized capsule cells called podocytes, are permeable to water and small solutes but not to blood cells or large molecules such as plasma proteins. The filtrate in Bowman’s capsule contains salt, glucose, vitamins, nitrogenous wastes, and other small molecules. ↓ to bladder

Ureter Tubes that bring urine from the kidney to the bladder

Bladder Stores urine

Urethra The tube which urine travels during excretion

Nitrogen waste disposal in EGG LAYERS Getting a little personal, aren’t we! Bird & reptile waste called uric acid Excrete white paste not liquid waste Birds don’t pee. This is why male birds don’t have penises. Both male and female birds have cloaca (Greek for sewer)

Urinary Tract Infection E. Coli can inhabit the urinary tract and cause an infection. The bacteria eats at the walls of the tract causing discomfort when urinating and blood in the urine.

Disease of Excretory System 1) Kidney Stones - Collections of solid material that may block the kidney, ureters, or bladder

3) Skin problems 2) Gout -Elevated levels of uric acid in the blood 3) Skin problems -Blackheads & acne due to clogging of skin pores

3) Cirrhosis -Disease of liver caused by damage to its cells -Mostly caused by drinking large amount of alcohol