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Regulation of body temperature Four physical process account for heat gain or loss:
Conduction-the direct transfer of thermal motion between molecules of objects in direct contact w/ each other
Convection- transfer of heat by the movement of air or liquid past a surface
Radiation- the emission of electromagnetic waves by all objects warmer than absolute zero, including the animal’s body, the environment, and the sun
Evaporation- the removal of heat from the surface of a liquid that is losing some of its molecules as gas
ENDOtherms& Ectotherms Ectotherms-=cold-blooded; has low metabolic rate that amount of heat generates is too small to have effect on body temp ex. Invertebrates, fishes, amphibians, and reptiles Endotherms=warm-blooded; high metabolic rate generates heat to keep body warm than environment ex. Mammals, birds, some fishes, a few reptiles, and numerous insects Ssss! I’m an Ectotherm RAWR! I’m an Endotherm
Four general categories of adaptations help animals thermoregulate: Adjusting the rate of heat exchange btwn the animal and its surroundings. Vasodilation- increase in the diameter of superficial blood vessels triggered by nerve signals that relax the muscles of the vessel walls. In Endotherms, vasodilation usually warms the skin, increasing the transfer of body heat to cool environment by radiation, conduction, and convection Vasoconstriction- (reverse process) reduces blood flow and heat transfer by decreasing the diameter of superficial vessels Countercurrent heat exchanger- helps trap heat in the body core and is important in reducing heat loss in many endotherms.
Cont. 2. Cooling by evaporative heat loss Terrestrial animals lose water by evaporation from the skin and when they breathe Water absorbs heat when evaporates (Sweating or bathing also enhances evaporative cooling) 3. Behavioral responses Changes in posture or movement Hibernation or migration to a more suitable climate 4. Changing the rate of metabolic heat production Only endotherms(mammals&birds) Increase metabolic heat production when exposed to cold
ex: some aquatic invertebrates living in temporary ponds and films of water around soil particles can lose almost all body water and survive in a dormant state when habitats dry up. Terrestrial Animals
Transport Epithelia pumps out salts for reabsorption, &dilute urine is excreted through nephridiopores
TUBULAR SYSTEMS CONT.
Malpighian Tubules in Insects
Remove nitrogenous wastes from the hemolymph; function in osmoregulation
The insects excretory system very important because to them conserving water is essential to live on land
Kidneys mayne! -Excretory tubules arranged into compact organs (Kidneys) **IMPORTANT FOR THE EXCRETORY SYSTEM Nephron- functional unit of the kidney
Mammalian excretory system Ex. Humans -Excretory tubules=consist of nephrons and collecting ducts -Blood vessels and excretory pack the kidney -Fluid from nephrons flow into collecting duct -Collecting ducts passes urine to the renal pelvis -Ureter conveys urine from the renal pelvis to the urinary bladder -Nephrons control composition of blood by filtration, secretion, and reabsorption
Kidney has the ability to conserve water is a key terrestrial adaption for mammals
Collecting duct (permeable to water but not to salt) carries filtrate through kidney’s osmolarity gradient and more water exits by osmosis.
Urea diffuses out of tubule with salt and forms osmotic gradient that enables the kidney to make urine that is hyperosmotic to blood
Osmolarity of urine regulated by nervous system and hormonal control of water and salt reabsorption