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Explore the two evolutionary paths for organisms to regulate their internal conditions. Learn how conformers allow internal conditions to fluctuate with external changes, while regulators maintain relatively constant internal conditions. Discover the importance of homeostasis and the systems involved in regulating temperature, blood sugar levels, energy production, water balance, intracellular waste disposal, nutrients, ion balance, and cell growth.
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Conformers vs. Regulators • Two evolutionary paths for organisms • ______________________________________ • maintain relatively constant internal conditions • ______________________________________ • allow internal conditions to fluctuate along with external changes osmoregulation thermoregulation regulator regulator conformer conformer
Homeostasis • Keeping the balance • animal body needs to coordinate many systems all at once • temperature • blood sugar levels • energy production • water balance & intracellular waste disposal • nutrients • ion balance • cell growth • maintaining a “steady state” condition
Regulating the InternalEnvironment Water Balance & Nitrogenous Waste Removal
aa O2 CH CHO CO2 aa NH3 CHO O2 CH O2 aa CO2 CO2 O2 NH3 aa NH3 CO2 NH3 CO2 CO2 NH3 NH3 O2 CO2 CO2 CO2 NH3 aa NH3 NH3 CHO CO2 CO2 aa CH Animal systems evolved to support multicellular life intracellular waste extracellular waste Diffusion too slow!
CO2 CO2 O2 NH3 aa NH3 CO2 NH3 CO2 CO2 NH3 NH3 O2 CO2 CO2 CO2 NH3 aa NH3 NH3 CHO CO2 CO2 aa CH Overcoming limitations of diffusion • Evolution of exchange systems for • distributing nutrients • _________________ • removing wastes • _________________ systems to support multicellular organisms
hypotonic Osmoregulation • Water balance • freshwater • _________________ • water flow into cells & salt loss • saltwater • _________________ • water loss from cells • land • dry environment • need to conserve water • may also need to conserve salt hypertonic Why do all land animals have to conserve water?
H O H | | | –C– C–OH N | H R Animalspoison themselvesfrom the insideby digestingproteins! Intracellular Waste • What waste products? • what do we digest our food into… • carbohydrates = CHO • lipids = CHO • proteins = CHON • nucleic acids = CHOPN CO2 +H2O lots! CO2 +H2O verylittle CO2 +H2O + N CO2 +H2O + P + N cellular digestion…cellular waste CO2 + H2O NH2= ammonia
Nitrogenous waste disposal • Ammonia (NH3) • ______________________ • carcinogenic • ______________________ • 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) aquatic terrestrial terrestrial egg layer
Nitrogen waste • ____________________ • can afford to lose water • _________________ • most toxic • ____________________ • need to conserve water • _________________ • less toxic • ________________ ________________ • need to conserve water • need to protectembryo in egg • _________________ • least toxic
Freshwater animals • Water removal & nitrogen waste disposal • remove surplus water • use surplus water to dilute ammonia & excrete it • need to excrete a lot of water so dilute ammonia & excrete it as very dilute urine • also diffuse ammonia continuously through gills or through any moist membrane • overcome loss of salts • reabsorb in kidneys or active transport across gills
H H H H N N C O Land animals • Nitrogen waste disposal on land • need to conserve water • must process ammonia so less toxic • _____ = larger molecule = less soluble = less toxic • 2NH2 + CO2 = urea • produced in liver • _______________ • filter solutes out of blood • reabsorb H2O (+ any useful solutes) • excrete waste • _____ = urea, salts, excess sugar & H2O • urine is very concentrated • concentrated NH3 would be too toxic Ureacosts energyto synthesize,but it’s worth it! mammals
Egg-laying land animals • Nitrogen waste disposal in egg • no place to get rid of waste in egg • need even less soluble molecule • _________ = BIGGER = less soluble = less toxic • birds, reptiles, insects itty bittyliving space!
O O O N N N N H H H H And that folks, is why a male birddoesn’t have a penis! Uric acid • Polymerized urea • large molecule • __________________________ • doesn’t harm embryo in egg • white dust in egg • adults excrete N waste as white paste • no liquid waste • urea = white bird “poop”!
Mammalian System blood filtrate • Filter solutes out of blood & reabsorb H2O + desirable solutes • Key functions • ____________________ • fluids (water & solutes) filtered outof blood • ____________________ • selectively reabsorb (diffusion) needed water + solutes back to blood • ____________________ • pump out any other unwanted solutes to urine • ____________________ • expel concentrated urine (N waste + solutes + toxins) from body concentratedurine
Mammalian Kidney inferiorvena cava aorta adrenal gland kidney nephron ureter renal vein& artery epithelialcells bladder urethra
Nephron • Functional units of kidney • 1 million nephronsper kidney • Function • filter out urea & other solutes (salt, sugar…) • ________________________into nephron • high pressure flow • ________________________of valuable solutes & H2O back into bloodstream • greater flexibility & control whyselective reabsorption& not selectivefiltration? “counter current exchange system”
How candifferent sectionsallow the diffusionof different molecules? Mammalian kidney • Interaction of circulatory & excretory systems • Circulatory system • _______________ = ball of capillaries • Excretory system • __________________ • __________________ • __________________ • proximal tubule • descending limb • ascending limb • distal tubule • __________________ Proximal tubule Distal tubule Bowman’s capsule Glomerulus Glucose H2O Na+ Cl- Amino acids H2O H2O Na+ Cl- H2O Mg++ Ca++ H2O H2O Collecting duct Loop of Henle
Nephron: Filtration • At glomerulus • filtered out of blood • H2O • glucose • salts / ions • urea • not filtered out • cells • proteins high blood pressure in kidneysforce to push (filter) H2O & solutes out of blood vessel BIG problems when you start out with high blood pressure in systemhypertension = kidney damage
Descendinglimb Ascendinglimb Nephron: Re-absorption • Proximal tubule • reabsorbed back into blood • NaCl • active transport of Na+ • Cl– follows by diffusion • H2O • glucose • HCO3- • bicarbonate • buffer for blood pH
Descendinglimb Ascendinglimb Nephron: Re-absorption structure fitsfunction! • Loop of Henle • ________________ • __________________________________ • ____________________________________ • low permeability to salt • few Na+ or Cl– channels • reabsorbed • H2O
Descendinglimb Ascendinglimb Nephron: Re-absorption structure fitsfunction! • Loop of Henle • ________________ • low permeability to H2O • _________________ • __________________________________ • different membrane proteins • reabsorbed • salts • maintains osmotic gradient
Nephron: Re-absorption • Distal tubule • reabsorbed • salts • H2O • HCO3- • bicarbonate
Descendinglimb Ascendinglimb Nephron: Reabsorption & Excretion • Collecting duct • reabsorbed • H2O • excretion • concentrated urine passed to bladder • impermeable lining
Osmotic control in nephron • How is all this re-absorption achieved? • tight osmotic control to reduce the energy costof excretion • use diffusioninstead of active transportwherever possible the value of acounter current exchange system
whyselective reabsorption& not selectivefiltration? Summary • _____________________ • cells u proteins • remain in blood (too big) • Reabsorbed: __________________ • Na+u amino acids • Cl–u glucose • Reabsorbed: __________________ • Na+u Cl– • H2O • Excreted • urea • excess H2O u excess solutes (glucose, salts) • toxins, drugs, “unknowns”
Regulating the InternalEnvironment Maintaining Homeostasis
high low Negative Feedback Loop hormone or nerve signal lowersbody condition (return to set point) gland or nervous system sensor specific body condition sensor raisesbody condition(return to set point) gland or nervous system hormone or nerve signal
high low Nervous System Control Controlling Body Temperature nerve signals brain sweat dilates surfaceblood vessels body temperature brain constricts surfaceblood vessels shiver nerve signals
nephron high low Endocrine System Control Blood Osmolarity ADH increasethirst increasedwaterreabsorption pituitary blood osmolarity blood pressure ADH = AntiDiuretic Hormone
Maintaining Water Balance Get morewater intoblood fast • High blood osmolarity level • too many solutes in blood • dehydration, high salt diet • stimulates thirst = drink more • release ADH from pituitary gland • antidiuretic hormone • increases permeability of collecting duct & reabsorption of water in kidneys • increase water absorption back into blood • decrease urination H2O H2O Alcohol suppresses ADH… makes youurinate a lot! H2O
high low JGA adrenalgland nephron Endocrine System Control Blood Osmolarity Oooooh,zymogen! JGA = JuxtaGlomerular Apparatus blood osmolarity blood pressure increasedwater & saltreabsorption in kidney renin aldosterone angiotensigen angiotensin
adrenalgland Maintaining Water Balance Get morewater & salt intoblood fast! • Low blood osmolarity level or low blood pressure • 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 Why such arapid responsesystem? Spring a leak?
increasethirst pituitary nephron high JuxtaGlomerularApparatus low adrenalgland nephron Endocrine System Control Blood Osmolarity ADH increasedwaterreabsorption blood osmolarity blood pressure increasedwater & saltreabsorption renin aldosterone angiotensinogen angiotensin
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