Regulating the

•Thermoregulation•Osmoregulation•Excretion

Regulators & Conformers

Regulation of Body Temperature

Direct transfer of heat

Transfer of heat by air or water movement

Emission of electromagnetic waves

Removal of heat fromthe surface of a liquid

Endotherms:High metabolic rate to maintain a high and very stable internal temperature

Ectotherms:Low metabolic rate, body temperature determined by environment

Thermoregulation

1. Adjusting the rate of heat exchange between the animal and its surroundings

• Vasodilation/vasoconstriction• Countercurrent heat exchanger

2. Cooling by evaporative loss (skin, breathing)3. Behavioral responses (basking, hibernation,

migration)4. Changing the rate of metabolic heat

production (endotherms only)

Countercurrent heat exchangers

Birdlegs

Marine mammal flippers

ENDOTHERMY

•Shivering•Movement•Brown fat•Insulation (hair, fat, feathers)•Goose bumps•Vasoconstriction•Vasodilation•Blubber•Sweat glands•Panting

FISHES

•Most conformers•Endothermic fishescirculatory adaptations

Invertebratesaquatic – thermoconformers; terrestrial – behavioralendothermic – many flying insects

Human Thermoregulation

Torpor – physiological state (low activity)Hibernation – long term torpor (winter)Estivation – summer torpor

WATER BALANCE & WASTE WATER BALANCE & WASTE DISPOSALDISPOSALOsmoregulation – management of body’s

water content & solute compositionContractile vacuolesTransport epithelium –

◦layer(s) of specialized cells that regulate solute movement

◦move specific solutes in controlled amounts in particular directions

◦joined by impermeable tight junctions forming a barrier at the tissue-environment boundary

Salt secreting glands in marine birds

Blood flow and salt flow counter current

Note tight junctions in epithelium

Ammonia – very soluble, very toxic, aquatic species

Nitrogenous wastes correlated to phylogeny & habitat

Urea – produced in the liver, land animals, less toxic, conserves water

Uric acid – largely insoluble, excreted as semi solid paste, minimal water loss, birds & reptiles

EXCRETORY SYSTEMS

Filtration – pressure filtering body fluid, largely nonselective, produces filtrate

Reabsorption – reclaims valuable substances by active transport

Secretion – extraction of toxins & excess ions from blood

Excretion – removal from body

Flame-Bulb System of a Planarian

Metanephridia of an Earthworm

Malpighian Tubules in Insects

HUMAN EXCRETORY SYSTEM

www.bioengineering.canterbury.ac.nz/graphics

http://www.lakemichigancollege.edu/liberal/bio/anat/urin.html

NEPHRON – functional unit of a kidney

•Glomerulus – ball of capillaries, very porous

•Bowman’s capsule – cup shaped swelling surrounding glomerulus

•Filtration – blood pressure provides the force, nonselective: glucose, aa, salts, ions, urea, H2O etc.

•Filtrate (essentially lymph) pathway – PCT, Loop of Henle, DCT, collecting duct•Cortical nephrons (cortex) – 80% of human’s

•Juxtamedullary nephrons – extend into medulla

•Blood vessels – afferent arteriole, efferent arteriole, peritubular capillaries, vasa recta

1. PROXIMAL TUBULE

Reabsorption:•of salt (most imp)•Active or passive•Nutrients •Bicarbonate ions

Active

Passive

Secretion:•H+ ions (pH)•Ammonia (pH)•Drugs, poisons

Epithelium:Exterior side smaller surface area, minimizes leakage

2. DESCENDING LIMB - LOOP OF HENLE Active

PassiveReabsorption of H2O continues

Epithelium not very permeable to salts

Interstitial fluid – osmolarity ↑ as fluid moves down from cortex to medulla

Active Passive

3. ASCENDING LIMB - LOOP OF HENLE

Transport epithelium permeable to salt NOT water

Thin segment – passive

Thick segment – active

Filtrate becomes more dilute as it moves into cortex

Active Passive4. DISTAL TUBULE

Secretion & reabsorption

Regulation of: K+ (secretion) and NaCl (reabsorption)

pH regulation (H+ & HCO3

-)

5. COLLECTING DUCT Active Passive

•Carries filtrate through medulla into pelvis•Actively reabsorbs NaCl•Epithelium (cortex) permeable to H2O but NOT salt, urea•High conc. of urea causes some to diffuse out

Concentration of urine in the human kidney based on urea & salt

Concentration of urine in the human kidney based on urea & salt

Concentration of urine in the human kidney based on urea & salt

REGULATION OF KIDNEYREGULATION OF KIDNEY

Antidiuretic hormone (ADH) – DCT & collecting duct

Juxtaglomerular apparatus (JGA) – near afferent arteriole, responds to low blood pressure or volume

Angiotensin II – activated by renin, constricts arterioles, reabsorption of NaCl in PCT, triggers release of aldosterone

Aldosterone – adrenal medulla, DCT reabsorption of NaCl

Renin-angiotensin-aldosterone system (RAAS)

Atrial natriuretic factor (ANF) – oppose RAAS

Hormonal control of the kidney by negative feedback circuits

ADH enhances fluid retention by making the kidneys reclaim more water

RAAS – JGA responds to in blood pressure/volume

Vampire bat excretesa)dilute urine while feeding (shedding

weight for flight home)b)concentrated urine while roosting