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•Thermoregulation •Osmoregulation •Excretion Regulators & Conformers Regulation of Body Temperature Transfer of heat by air or water movement Emission of electromagnetic waves Removal of heat from the surface of a liquid Direct transfer of heat 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 Bird legs Marine mammal flippers ENDOTHERMY •Shivering •Movement •Brown fat •Insulation (hair, fat, feathers) •Goose bumps •Vasoconstriction •Vasodilation •Blubber •Sweat glands •Panting FISHES •Most conformers •Endothermic fishes circulatory adaptations Invertebrates aquatic – thermoconformers; terrestrial – behavioral endothermic – many flying insects Human Thermoregulation Torpor – physiological state (low activity) Hibernation – long term torpor (winter) Estivation – summer torpor WATER BALANCE & WASTE DISPOSAL Osmoregulation – management of body’s water content & solute composition Contractile vacuoles Transport 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 Nitrogenous wastes correlated to phylogeny & habitat Ammonia – very soluble, very toxic, aquatic species 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 Secretion: •H+ ions (pH) •Ammonia (pH) •Drugs, poisons Epithelium: Exterior side smaller surface area, minimizes leakage Active Passive 2. DESCENDING LIMB - LOOP OF HENLE Reabsorption 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 Passive Active Passive 4. 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 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 excretes a)dilute urine while feeding (shedding weight for flight home) b)concentrated urine while roosting