osmo and thermoregulation

endotherm definition

able to produce heat through metabolic processes such as respiration

ectotherm definition

relies on external environment to produce heat

sweating to lose heat

evaporation of water requires heat E
latent heat for vaporisation of water is high for water, sweating releases a lot of E
lose heat by radiation

when cold/trapped etc. why do we lose heat

heat generated by metabolic rate - respiration, insufficient food to maintain high metabolic rate, no heat lost by radiation
(if small) large SA:Vol ratio, lose heat quickly)

heat and animal

muscle contraction/respiration releases heat energy
core temperature does not rise as much as skin temperature
blood temperature rise detected by hypothalamus from receptors of skin
vasodilation causes skin temperature to rise
water from sweat evaporates
evaporation removes heat so skin temperature rises and then levels off

positive feedback for cold

body cools, positive feedback makes it colder. bcs respiration is slower, enzymes have less kinetic E, metabolism releases less heat E

ultrafiltration process

endothelium of capillaries → epithelium of renal → glomerular filtrate
oncotic pressure is exerted by proteins
hydrostatic pressure is due to pressure of fluid on capillary walls
podocytes (foot like extensions projecting from the surface of the epithelium. they wrap around capillaries leaving filtration slits around 25nm wide)
pores are between endothelial cells in capillaries

water control

osmoreceptors detect that blood concentration is dilute. signal that ADH should stop being released. collecting duct is less permeable, less re-absorption of water, more urine produced

osmoreceptors detect that blood concentration is high, signals that more ADH should be released. the collecting duct is more permeable, more water is reabsorped, less urine produced

loop of henle

sodium ions are moved out of ascending limb via active transport, as ascending limb is impermeable to water
so the medulla has a lower water potential

descending limb is permeable to water, so water moves out from high to low water potential
loop of henle acts as counter current multiplier

urea production

deamination, as ammonia combines with CO2, during the ornithine cycle