•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