Controlling the Internal Controlling the Internal EnvironmentEnvironment

ThermoregulationThermoregulation

OsmoregulationOsmoregulation

ExcretionExcretion

ThermoregulationThermoregulation

• Ectothermic• Endothermic

• Poikilothermic• Homeothermic

Heat ExchangeHeat Exchange

Heat ExchangeHeat 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 Body Temp Temp

vs. vs. Ambient Ambient

TempTemp

Thermoregulation AdjustmentsThermoregulation 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 Endothermic AnimalsAnimals

• Invertebrates– Large flying insects– Honeybees

Endothermic Endothermic AnimalsAnimals

• Fish– Bluefin tuna– Swordfish– Great white shark

• Countercurrent heat exchange

Amphibians and ReptilesAmphibians and Reptiles

• Most are ectothermic– regulate temperature by behavior

Mammals and Mammals and BirdsBirds

• Contraction of muscles– moving– shivering

• Nonshivering thermogenesis– triggered by

hormones

Feedback MechanismsFeedback 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 Temperature Range AdjustmentsAdjustments

• Slow changes– acclimatization (enzymes and membranes)

• Fast changes– heat-shock proteins

Metabolic CyclesMetabolic Cycles

• Torpor

• Hibernation

• Aestivation

OsmoregulationOsmoregulation

• Osmoconformers vs. Osmoregulators

OsmoregulationOsmoregulation

• 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 Functions of the Excretory SystemExcretory System

• Filtration• Reabsorption• Secretion• Excretion

Excretion of Excretion of Nitrogenous Nitrogenous

WasteWaste

• Ammonia• Urea• Uric Acid

Invertebrate StructuresInvertebrate Structures

• Protonephridia (flame cells)

• network of closed tubules

• used mostly for osmoregulation

• found in platyhelminthes, some annelids, mollusk larvae

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

Invertebrate StructuresInvertebrate Structures• Malpighian

Tubules• Open into the

digestive tract• Osmoregulation

and excretion• Insects and

terrestrial arthropods

Excretory SystemsExcretory SystemsOrigins in VertebratesOrigins in Vertebrates

• Pronephros, Mesonephros, Metanephros

Vertebrate Excretory SystemsVertebrate 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 SystemThe Human Excretory System

• Kidneys• Ureters• Urinary Bladder• Urethra

Blood Filtrate to UrineBlood 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 UrineBlood Filtrate to Urine

• Loop of Henle – Descending loop

• reabsorbed (water)

– Ascending loop• reabsorbed (NaCl)

Blood Filtrate to UrineBlood Filtrate to Urine

• Distal tubule– reabsorbed (NaCl, Water)– secrete (potassium)– regulate (pH)

• Collecting duct– reabsorbed (NaCl, Water, Urea)

Control of the Control of the KidneyKidney

• Antidiuretic hormone (ADH)– water reabsorption

• Renin-angiotensin-aldosterone system (RAAS)– water reabsorption

• Atrialnatiuretic Factor (ANF)– inhibits the release of renin