Controlling the Internal Environment ThermoregulationOsmoregulationExcretion

Thermoregulation Ectothermic Endothermic Poikilothermic Homeothermic

Heat Exchange

Conduction - direct transfer of heat Convection - transfer of heat by the movement of air or water across a surface Radiation - emission of electromagnetic waves Evaporation - loss of heat from changing a liquid into a gas

Body Temp vs. Ambient Temp

Thermoregulation Adjustments Adjusting the rate of heat exchange –vasodilation/vasoconstiction –countercurrent heat exchange Cooling by evaporation Behavioral responses Changing the rate of metabolic heat production

Endothermic Animals Invertebrates –Large flying insects –Honeybees

Endothermic Animals Fish –Bluefin tuna –Swordfish –Great white shark Countercurrent heat exchange

Amphibians and Reptiles Most are ectothermic –regulate temperature by behavior

Mammals and Birds Contraction of muscles –moving –shivering Nonshivering thermogenesis –triggered by hormones

Feedback Mechanisms High body temperature –hypothalamus activates skin blood vessels to dilate and the sweat glands to produce sweat Low body temperature –hypothalamus activates skin blood vessels to constrict and the skeletal muscles to shiver

Temperature Range Adjustments Slow changes –acclimatization (enzymes and membranes) Fast changes –heat-shock proteins

Metabolic Cycles Torpor Hibernation Aestivation

Osmoregulation Osmoconformers vs. Osmoregulators

Osmoregulation Marine Fish –hypoosmotic –lose water to environment –must excrete salt –small amounts of urine Freshwater Fish –hyperosmotic –gain water from environment –must take in salt –large amounts of urine

Functions of the Excretory System Filtration Reabsorption Secretion Excretion

Excretion of Nitrogenous Waste Ammonia Urea Uric Acid

Invertebrate Structures Protonephridia (flame cells) network of closed tubules used mostly for osmoregulation found in platyhelminthes, some annelids, mollusk larvae

Invertebrate Structures Open tubules surrounded by a nephrostome Osmoregulation and excretion Found in annelids

Invertebrate Structures Malpighian Tubules Open into the digestive tract Osmoregulation and excretion Insects and terrestrial arthropods

Excretory Systems Origins in Vertebrates Pronephros, Mesonephros, Metanephros

Vertebrate Excretory Systems Pronephros –adult hagfish, embryonic fish, amphibians, reptiles, birds, mammals Mesonephros –adult lamprey, fish, amphibians, embryonic reptiles, birds, mammals Metanephros –adult reptiles, birds, mammals

The Human Excretory System Kidneys Ureters Urinary Bladder Urethra

Blood Filtrate to Urine Bowman’s Capsule and the Glomerulus –(filters the blood) Proximal tubule –reabsorbed (NaCl, Potassium, Water, Nutrients) –secretes ( ammonia) –regulates (pH)

Blood Filtrate to Urine Loop of Henle –Descending loop reabsorbed (water) –Ascending loop reabsorbed (NaCl)

Blood Filtrate to Urine Distal tubule –reabsorbed (NaCl, Water) –secrete (potassium) –regulate (pH) Collecting duct –reabsorbed (NaCl, Water, Urea)

Control of the Kidney Antidiuretic hormone (ADH) –water reabsorption Renin-angiotensin- aldosterone system (RAAS) –water reabsorption Atrialnatiuretic Factor (ANF) –inhibits the release of renin