Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Ch49WaterBalance - Environmental
Document related concepts
no text concepts found
Transcript
Regulating the Internal Environment AP Biology 2006-2007 Conformers vs. Regulators 2 evolutionary paths for organisms regulate internal environment maintain relatively constant internal conditions conform to external environment allow internal conditions to fluctuate along with external changes osmoregulation thermoregulation regulato r AP Biology conformer regulato r conformer Homeostasis Keeping the balance animal body needs to coordinate many systems all at once AP Biology temperature blood sugar levels energy production water balance & intracellular waste disposal nutrients ion balance cell growth maintaining a “steady state” condition Regulating the Internal Environment Water Balance & Nitrogenous Waste Removal AP Biology 2006-2007 Animal systems evolved to support multicellular life aa O2 CH CHO CO2 aa NH3 CHO O2 O2 CH aa CO2 aa NH3 CO2 NH3 CH CO2 CO2 NH3 NH3 CO2 AP Biology NH3 NH3 CO2 CO2 aa O2 NH3 NH3 CO2 O2 intracellular waste CO2 CHO CO2 aa Diffusion too slow! extracellular waste Solving exchange problem Evolve of exchange systems for distributing nutrients circulatory system removing wastes excretory system CO2 CO2 aa CO2 CO2 O2 NH3 CO2 overcoming the limitations of diffusion CO2 CO2 NH3 NH3 CO2 CH AP Biology NH3 NH3 NH3 CO2 aa O2 NH3 NH3 CHO CO2 aa Osmoregulation Water balance freshwater hypotonic water flow into cells & salt loss saltwater hypertonic water loss from cells land dry environment need to conserve water may need to conserve salt Why do all land animals have to conserve water? always lose water (breathing & waste) AP may lose life while searching for water Biology Waste disposal What waste products? Animals poison themselves from the inside by digesting proteins! what do we digest our food into… carbohydrates = CHO CO2 + H2O lipids = CHO CO2 + H2O proteins = CHON CO2 + H2O + N nucleic acids = CHOPN CO2 + H2O + P + N relatively small amount in cell cellular digestion… cellular waste NH2 = AP Biology ammonia H| O || H N –C– C–OH | H R CO2 + H2O Nitrogenous waste disposal Ammonia (NH3) very toxic carcinogenic very soluble easily crosses membranes must dilute it & get rid of it… fast! How you get rid of nitrogenous wastes depends on who you are (evolutionary relationship) where you live (habitat) AP Biology Nitrogen waste Aquatic organisms can afford to lose water ammonia most toxic Terrestrial need to conserve water urea less toxic Terrestrial egg layers need to conserve most water uric acid AP Biology least toxic Freshwater animals Water removal & nitrogen waste disposal surplus of water can dilute ammonia & excrete it need to excrete a lot of water anyway so excrete very dilute urine pass ammonia continuously through gills or through any moist membrane loss of salts reabsorb in kidneys or active transport across gills AP Biology Land animals Nitrogen waste disposal on land evolved less toxic waste product need to conserve water urea = less soluble = less toxic kidney filter wastes out of blood reabsorb H2O excrete waste urine = urea, salts, excess sugar & H2O AP Biology urine is very concentrated concentrated NH3 would be too toxic Urea Larger molecule = less soluble 2NH2 + CO2 = urea combined in liver H Requires energy to produce worth the investment of energy Filtered out by kidneys AP Biology collected from cells by circulatory system N H H C N H O Egg-laying land animals Nitrogen waste disposal in egg no place to get rid of waste in egg need even less soluble molecule uric acid = bigger = less soluble = less toxic birds, reptiles, insects itty bitty living space! AP Biology Uric acid Polymerized urea And that folks, is why a male bird doesn’t have a penis! large molecule precipitates out of solution doesn’t harm embryo in egg white dust in egg adults excrete white paste no liquid waste white bird “poop”! O H H N N O O N N AP Biology H H Mammalian System blood filtrate Key functions filtration fluids from blood collected includes water & solutes reabsorption selectively reabsorb needed substances back to blood secretion pump out unwanted substances to urine excretion remove excess substances & toxins from body AP Biology urine Mammalian Kidney inferior vena cava aorta adrenal gland kidney nephron ureter renal vein & artery epithelial cells bladder urethra AP Biology Nephron Functional units of kidney 1 million nephrons per kidney Function filter out urea & other solutes (salt, sugar…) Process blood plasma filtered into nephron selective reabsorption of valuable solutes & H2O greater flexibility & control AP Biology why selective reabsorption & not selective filtration? “counter current exchange system” How can different sections allow the diffusion of different molecules? Mammalian kidney Interaction of circulatory & excretory systems Circulatory system glomerulus = ball of capillaries Bowman’s capsule Proximal tubule Distal tubule Glomerulus Excretory system nephron Bowman’s capsule loop of Henle Glucose Amino acids H2O Mg++ Ca++ H2O AP Biology collecting duct H2O H2O descending limb ascending limb Na+ ClNa+ ClH2O 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 H2O & solutes out of blood vessel BIG problems when you start out with high blood pressure in system hypertension = kidney damage Nephron: Re-absorption Proximal tubule reabsorbed NaCl active transport Na+ Cl- follows by diffusion H2O glucose HCO3 bicarbonate buffer for blood pH AP Biology Descending limb Ascending limb Nephron: Re-absorption structure fits Loop of Henle function! descending limb high permeability to H2O many aquaporins in cell membranes low permeability to salt reabsorbed H2O AP Biology Descending limb Ascending limb Nephron: Re-absorption structure fits Loop of Henle function! ascending limb low permeability to H2O Cl- pump Na+ follows by diffusion different membrane proteins reabsorbed salts maintains osmotic AP Biology gradient Descending limb Ascending limb Nephron: Re-absorption Distal tubule reabsorbed salts H2O HCO3 bicarbonate AP Biology Nephron: Reabsorption & Excretion Collecting duct reabsorbed H2O excretion urea passed through to bladder AP Biology Descending limb Ascending limb Osmotic control in nephron How is all this re-absorption achieved? tight osmotic control to reduce the energy cost of excretion use diffusion instead of active transport wherever possible the value of a counter current exchange system AP Biology why selective reabsorption & not selective filtration? Summary Not filtered out remain in blood (too big) cells proteins Reabsorbed: active transport Na+ Cl- amino acids glucose Reabsorbed: diffusion Na+ H2O Cl- Excreted AP Biology urea (highly concentrated) excess H2O excess solutes (glucose, salts) toxins, drugs, “unknowns” Any Questions? AP Biology 2006-2007 Regulating the Internal Environment Regulation of Homeostasis AP Biology 2006-2007 Negative Feedback Loop Maintaining homeostasis Response Return to set point Perturbing factor Stimulus deviation from set point Negative feedback loop completed Sensor constantly monitors conditions AP Biology Effector causes changes to compensate for deviation Integrating center compares conditions to set point Negative Feedback Model hormone 1 lowers body condition gland (return to set point) high sensor specific body condition sensor raises body condition gland (return to set point) AP Biology low hormone 2 Nervous System Control Controlling Body Temperature nerve signals brain sweat high body temperature low brain constricts surface shiver blood vessels AP Biology nerve signals dilates surface blood vessels Endocrine System Control Blood Osmolarity ADH pituitary increased water reabsorption nephron high blood osmolarity blood pressure low AP Biology increase thirst Maintaining Water Balance High blood osmolarity level too many solutes in blood Get more water into blood fast dehydration, high salt diet stimulates thirst = drink more release ADH from pituitary gland anti-diuretic hormone increases permeability of collecting duct & reabsorption of water in kidneys H2O H2O increase water absorption back into blood decrease urination AP Biology Alcohol suppresses ADH… makes you urinate a lot! H2O Endocrine System Control Blood Osmolarity ADH increased water reabsorption pituitary increase thirst nephron high blood osmolarity blood pressure adrenal gland low increased water & salt reabsorption JuxtaGlomerular Apparatus nephron renin aldosterone AP Biology angiotensinogen angiotensin Maintaining Water Balance Low blood osmolarity level or low blood pressure Low solutes renin (from JGA) activates angiotensinogen angiotensin triggers aldosterone aldosterone increases absorption of NaCl & H2O in kidney AP Biology Oooooh, zymogen! Maintaining Water Balance Low blood osmolarity level or low blood pressure Get more water & salt into blood fast! JGA releases renin in kidney renin converts angiotensinogen to angiotensin angiotensin causes arterioles to constrict increase blood pressure angiotensin triggers release of aldosterone from adrenal gland increases reabsorption of NaCl & H2O in kidneys puts more water & salts back in blood AP Biology Why such a rapid response system? Spring a leak? adrenal gland Don’t get batty… Ask Questions!! AP Biology 2006-2007 Homeostasis Osmoregulation solute balance & gain or loss of water Excretion elimination of nitrogenous wastes Thermoregulation AP Biology maintain temperature within tolerable range Maintaining Water Balance Monitor blood osmolarity amount of dissolved material in blood High solutes in brain AP Biology ADH = anti-diuretic hormone
