Chapter 44 ~ Chapter 44 ~ Regulating the Regulating the Internal EnvironmentInternal Environment

HomeostasisHomeostasis: regulation of internal : regulation of internal environmentenvironment

Thermoregulation Thermoregulation internal temperatureinternal temperature

Osmoregulation Osmoregulation solute and water balancesolute and water balance

Excretion Excretion nitrogen containing wastenitrogen containing waste

Regulator vs ConformerRegulator vs ConformerRegulator – moderates internal change is spite Regulator – moderates internal change is spite of environmental change (homeostasis)of environmental change (homeostasis)Conformer – allow some internal conditions to Conformer – allow some internal conditions to vary with environmental changevary with environmental change

Energy and Materials BudgetEnergy and Materials Budget

Thermoregulation – balancing heat Thermoregulation – balancing heat gained with heat lostgained with heat lost

Temperature can have an impact on the Temperature can have an impact on the following:following:– Enzymes – work in a certain temperature Enzymes – work in a certain temperature

rangerangeQQ1010 – the factor that enzyme rate increases with an – the factor that enzyme rate increases with an

increase of 10 degrees Cincrease of 10 degrees C

– Membrane fluidity – temp. affects the fluidity Membrane fluidity – temp. affects the fluidity of membranesof membranes

Lower temp. – organism needs to increase fluidityLower temp. – organism needs to increase fluidity

Calculating QCalculating Q1010

Rate of enzyme at T + 10C/rate of enzyme Rate of enzyme at T + 10C/rate of enzyme at Tat T

Types of Heat TransferTypes of Heat Transfer

Conduction Conduction ~ transfer of ~ transfer of heat between molecules of heat between molecules of body and environmentbody and environment

Convection Convection ~transfer of ~transfer of heat as water/air move heat as water/air move across body surfaceacross body surface

Radiation Radiation ~ transfer of heat ~ transfer of heat produced by organismsproduced by organisms

Evaporation Evaporation ~ loss of heat ~ loss of heat from liquid to gasfrom liquid to gas

Ectothermic vs EndothermicEctothermic vs Endothermic

Low metabolic rateLow metabolic rate

Generates minimal Generates minimal heat internallyheat internally

Less energy Less energy requirementsrequirements

High metabolic rateHigh metabolic rate

Heat generated Heat generated internally can heat the internally can heat the bodybody

Requires more Requires more energy to generate energy to generate this heatthis heat

Adaptations for heat regulationAdaptations for heat regulation

Insulation – fat, hair, feathersInsulation – fat, hair, feathers

Circulation – Circulation – – Vasodilation – blood vessels dilate (relax), Vasodilation – blood vessels dilate (relax),

blood flow increases, heat transfer increasesblood flow increases, heat transfer increases– Vasoconstriction – blood vessels contract, Vasoconstriction – blood vessels contract,

blood flow decreases, heat transfer decreasesblood flow decreases, heat transfer decreases– Countercurrent exchange – reduces heat lossCountercurrent exchange – reduces heat loss

Countercurrent exchangeCountercurrent exchange

Adaptations (cont.)Adaptations (cont.)

Evaporative cooling – sweating, pantingEvaporative cooling – sweating, panting

BehaviorBehavior– Basking in sun/cooling in shadeBasking in sun/cooling in shade– MigrationMigration– HibernationHibernation

Changing metabolic rate (heat production)Changing metabolic rate (heat production)

Increasing heat production Increasing heat production (metabolic rate) - endotherms(metabolic rate) - endotherms

Endotherms must counteract their heat Endotherms must counteract their heat loss to the environmentloss to the environmentMuscle activity – moving, shiveringMuscle activity – moving, shiveringNonshivering thermogenesis (NST) – Nonshivering thermogenesis (NST) – hormones released in the body can cause hormones released in the body can cause mitochondria to increase activity and mitochondria to increase activity and release heatrelease heatBrown fat – Tissue that can generate heat Brown fat – Tissue that can generate heat at a high rateat a high rate

Feedback mechanismsFeedback mechanisms

Regulation during environmental Regulation during environmental extremes – extreme hot or cold, no extremes – extreme hot or cold, no

food availablefood availableTorporTorpor~ low activity; decrease ~ low activity; decrease in metabolic ratein metabolic rate

1- Hibernation 1- Hibernation long long term or winter torpor (winter term or winter torpor (winter cold and food scarcity); bears, cold and food scarcity); bears, squirrelssquirrels

2- Estivation2- Estivation short term or summer torpor short term or summer torpor (high temperatures and water (high temperatures and water scarcity); fish, amphibians, scarcity); fish, amphibians, reptilesreptiles

Both often triggered by length Both often triggered by length of daylightof daylight

Ground SquirrelsGround Squirrels

Water balance and waste Water balance and waste disposaldisposal

Osmoregulation: Osmoregulation: management of the body’s water management of the body’s water content and solute compositioncontent and solute composition

Nitrogenous wastes: Nitrogenous wastes: breakdown products of proteins and breakdown products of proteins and nucleic acids; ammonia-very toxicnucleic acids; ammonia-very toxic

Deamination~Deamination~

Ammonia: most aquatic animals, Ammonia: most aquatic animals, many fishmany fish

Urea: mammals, most amphibians, Urea: mammals, most amphibians, sharks, bony fish (in liver; sharks, bony fish (in liver; combo of NHcombo of NH33 and CO and CO22))

Uric acid: birds, insects, many Uric acid: birds, insects, many reptiles, land snailsreptiles, land snails

OsmoregulatorsOsmoregulatorsOsmoconformer: no active adjustment of internal osmolarity Osmoconformer: no active adjustment of internal osmolarity (marine animals); isoosmotic to environment(marine animals); isoosmotic to environment

Osmoregulator: adjust internal osmolarity (freshwater, marine, Osmoregulator: adjust internal osmolarity (freshwater, marine, terrestrial)terrestrial)

Freshwater fishesFreshwater fishes (hyperosmotic)- gains water, loses; excretes (hyperosmotic)- gains water, loses; excretes large amounts of urine salt vs. large amounts of urine salt vs. marine fishesmarine fishes (hypoosmotic)- loses (hypoosmotic)- loses water, gains salt; drinks large amount of saltwaterwater, gains salt; drinks large amount of saltwater

Excretory SystemsExcretory SystemsProduction of urine by 2 steps: • Filtration (nonselective) • Reabsorption Production of urine by 2 steps: • Filtration (nonselective) • Reabsorption (secretion of solutes)(secretion of solutes)

Protonephridia ~ flatworms (“flame-bulb” systems)Protonephridia ~ flatworms (“flame-bulb” systems)

Metanephridia ~ annelids (ciliated funnel system)Metanephridia ~ annelids (ciliated funnel system)

Malpighian tubules ~ Malpighian tubules ~ insects insects (tubes in digestive (tubes in digestive tract)tract)

Kidneys ~ vertebratesKidneys ~ vertebrates

Kidney Functional UnitsKidney Functional Units

Renal artery/vein: kidney blood Renal artery/vein: kidney blood flowflow

Ureter: urine excretory ductUreter: urine excretory duct

Urinary bladder: urine storageUrinary bladder: urine storage

Urethra: urine elimination tubeUrethra: urine elimination tube

Renal cortex (outer region)Renal cortex (outer region)

Renal medulla (inner region)Renal medulla (inner region)

Nephron: functional unit of kidneyNephron: functional unit of kidney

Cortical nephrons (cortex; 80%)Cortical nephrons (cortex; 80%)

Juxtamedullary nephrons Juxtamedullary nephrons (medulla; 20%)(medulla; 20%)

Nephron StructureNephron StructureAfferent arteriole: supplies blood to Afferent arteriole: supplies blood to nephron nephron from renal arteryfrom renal artery

Glomerulus: ball of capillariesGlomerulus: ball of capillaries

Efferent arteriole: blood from Efferent arteriole: blood from glomerulusglomerulus

Bowman’s capsule: Bowman’s capsule: surrounds glomerulussurrounds glomerulus

Proximal tubule: Proximal tubule: secretion & reabsorptionsecretion & reabsorption

Peritubular capillaries: Peritubular capillaries: from efferent arteriole; from efferent arteriole; surround proximal & distal tubulessurround proximal & distal tubules

Loop of Henle: water & salt balanceLoop of Henle: water & salt balance

Distal tubule: secretion & reabsorptionDistal tubule: secretion & reabsorption

Collecting duct: Collecting duct: carries carries filtrate to renal pelvisfiltrate to renal pelvis

Basic Nephron FunctionBasic Nephron Function

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Nephron Function, INephron Function, IProximal tubule: secretion and reabsorptionProximal tubule: secretion and reabsorption

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Nephron Function, IINephron Function, IILoop of Henle: reabsorption of water and saltLoop of Henle: reabsorption of water and salt

Distal tubule: secretion and reabsorptionDistal tubule: secretion and reabsorption

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Nephron Function, IIINephron Function, IIICollecting duct: reabsorbs water, salt, some ureaCollecting duct: reabsorbs water, salt, some urea

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Kidney regulation: hormonesKidney regulation: hormonesAntidiuretic hormone (ADH)Antidiuretic hormone (ADH) ~ secretion ~ secretion increases permeability of distal tubules increases permeability of distal tubules and collecting ducts to water (H2O back and collecting ducts to water (H2O back to body); inhibited by alcohol and coffeeto body); inhibited by alcohol and coffee

Juxtaglomerular apparatus (JGA)Juxtaglomerular apparatus (JGA) ~ ~ reduced salt intake--->enzyme renin reduced salt intake--->enzyme renin initiates conversion of angiotension initiates conversion of angiotension (plasma protein) to angiotension II (plasma protein) to angiotension II (peptide); increase blood pressure and (peptide); increase blood pressure and blood volume by constricting capillaries blood volume by constricting capillaries

Angiotension IIAngiotension II also stimulates adrenal also stimulates adrenal glands to secrete aldosterone; acts on glands to secrete aldosterone; acts on distal tubules to reabsorb more sodium, distal tubules to reabsorb more sodium, thereby increasing blood pressure (renin-thereby increasing blood pressure (renin-angiotension-aldosterone system; RAAS)angiotension-aldosterone system; RAAS)

Atrial natriuretic factor (ANF)Atrial natriuretic factor (ANF) ~ walls of ~ walls of atria; inhibits release of renin, salt atria; inhibits release of renin, salt reabsorption, and aldosterone releasereabsorption, and aldosterone release

Hormonal ControlHormonal Control

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