AP Biology 2008-2009

Excretory SystemKidneys and the Urinary

System, Lungs, Skin, & Liver

(removing metabolic waste)

Regents Biology

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

Warm, diluteocean waters

Warm, diluteocean waters

Unicellular Multicellular

Limits cell size - Must stay small

Regents Biology

What liquid waste do we make?

Digesting protein makes poison nitrogen waste = ammonia = poison

H

CO2 + H2O

NH2 = ammonia

H

HN C—OH

|| O

H|

—C—| AMINO ACIDs and

Nitrogen Bases

Regents Biology

The kind of waste you make depends on where you live Freshwater

Ammonia Diffuse and dilute

quickly Land

Urea Humans

Egg layer/Insects uric acid Solid – crystals LEAST toxic

Nitrogen waste

Regents Biology

Human Excretory System Mammals have a pair of bean-shaped

kidneys supplied with blood by a renal artery

and a renal vein

Organ system

Organ

Tissue

Nephron

Regents Biology

Bladder

Regents Biology

Nephron = functional unit of kidney Not filtered out

cells and proteins (too big) Filtered out

“Bad” stuff Urea (from liver) Salts H2O toxins from food

“Good” stuff simple sugars, aa

“Good” stuff reabsorbed; “Bad” stuff makes urine

to

bladder

Regents Biology

Nephron Structure – functional unit

Renal

Renal

FILTRATIONRemoves “good” and

“bad” stuffNO Cells leave the

blood vessels

REABSORPTIONReabsorb “good”

stuff” (ss, aa, some salt and some water

to maintain water balance)

Capillaries – wrapped around loop to

increase surface area

Ball of capillariesBowman’s capsule

Regents Biology

Also• Skin – removes salt, water, and urea

• called sweat• Lungs – remove CO2 and water• Liver – PRODUCES UREA

Diseases/Disorders – failure to maintain homeostasis

• Kidney Disease – failure of kidneys to filter toxins from blood; treatment =dialysis or transplant

• Nephritis – inflammation of kidneys• Kidney stone – calcium deposit that blocks ureter • Gout – build up of uric acid in joints