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Regulating the Internal Environment Water Balance & Nitrogenous Waste Removal AP Biology 2006-2007 Conformers vs. Regulators Two evolutionary paths for organisms regulate internal environment conform to external environment osmoregulation thermoregulation regulator regulator AP Biology conformer conformer Osmoregulation A What are the challenges faced by an osmoregulator living in freshwater? B What are the challenges faced by an osmoregulator living in the sea? AP Biology Osmoregulation hypotonic Water balance freshwater hypotonic water flow into cells & salt loss saltwater hypertonic water loss from cells Land need to conserve water AP Biology hypertonic Nitrogenous waste disposal Ammonia (NH3) very toxic very soluble must dilute it & get rid of it aquatic AP Biology terrestrial terrestrial egg layer Nitrogen waste Aquatic organisms Ammonia Terrestrial urea less toxic Terrestrial egg layers uric acid least toxic AP Biology Mammalian System Filter solutes out of blood & blood filtrate reabsorb H2O + desirable solutes Key functions Filtration reabsorption selectively reabsorb secretion pump out unwanted solutes excretion expel concentrated urine AP Biology concentrated urine Mammalian Kidney inferior vena cava aorta adrenal gland kidney ureter bladder urethra AP Biology nephro n renal vein & artery epithelial cells Mammalian kidney Interaction of circulatory & excretory systems Circulatory system Glomerulus Bowman’s capsule Proximal tubule Distal tubule Glomerulus Excretory system nephron Bowman’s capsule Proximal tubule loop of Henle descending limb ascending limb AP Biology Distal tubule collecting duct Glucose Amino acids H2O Mg++ Ca++ H2O Na+ ClH2O H2O Na+ Cl- H2O H2O Loop of Henle Collecting duct Nephron: Filtration At glomerulus filtered out of blood H2O glucose salts / ions urea not filtered out cells proteins AP Biology high blood pressure in kidneys force to push (filter) H2O & solutes out of blood vessel Nephron: Re-absorption Proximal tubule reabsorbed back into blood NaCl active transport of Na+ Cl– follows by diffusion H2O Glucose, amino acids HCO3 Bicarbonate (pH) AP Biology Descending limb Ascending limb Nephron: Re-absorption Loop of Henle descending limb structure fits function! high permeability to H2O many aquaporins low permeability to salt reabsorbed H2O AP Biology Descending limb Ascending limb Nephron: Re-absorption Loop of Henle ascending limb structure fits function! low permeability to H2O Cl- pump Na+ follows by diffusion reabsorbed salts maintains osmotic gradient AP Biology Descending limb Ascending limb Nephron: Re-absorption Distal tubule reabsorbed salts H2O HCO3- AP Biology Nephron: Reabsorption & Excretion Collecting duct reabsorbed H2O concentrated urine passed to bladder Descending limb AP Biology Ascending limb Summary Not filtered out cells proteins remain in blood (too big) Reabsorbed: active transport Na+ Cl– amino acids glucose Reabsorbed: diffusion Na+ H2O Cl– excess solutes (glucose, salts) Excreted AP Biology urea excess H2O toxins, drugs Endocrine System Control Blood Osmolarity ADH pituitary increased water reabsorption increase thirst nephron high blood osmolarity low AP Biology ADH = AntiDiuretic Hormone Endocrine System Control Blood Osmolarity/Blood Pressure JGA = JuxtaGlomerular Apparatus high blood pressure adrenal gland low increased water & salt reabsorption in kidney nephron renin aldosterone AP Biology JGA angiotensinogen angiotensin Don’t get batty… Ask Questions!! AP Biology