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 from the 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 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

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

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, H 2 O 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 – a fferent 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 Passive Reabsorption of H 2 O 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 4. DISTAL TUBULE Secretion & reabsorption Regulation of: K + (secretion) and NaCl (reabsorption) pH regulation (H + & HCO 3 - )

5. COLLECTING DUCT Active Passive Carries filtrate through medulla into pelvis Actively reabsorbs NaCl Epithelium (cortex) permeable to H 2 O 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