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Homeostasis and temperature regulation (Endotherms (source of heat is…
Homeostasis and temperature regulation
Poikilotherms
allow body temp to conform to the environment
based on heat source
Homeotherms
based on a set point, regardless of external influencers
based on hear source
Endotherms
source of heat is internal (increasing metabilic rate or shivering )
advantages: sustained high energy activity
disadvantages: high metabolic rate required high and constant energy intake
effect of body size
INVERSE relationship: btwn body size and metabolic rate and O2 consumption
mechanisms for temperature homeostasis: evaporative cooling (sweating/panting ), dilating/constricting the BV to increase or decrease heat exchange
ectotherms
source of heat is external (the sun)
mechanisms for temperature homeostasis: behavior
low metabolic mate
heterotherms
in-between endo and ecto
Feed back
negative
gets it back to the set point
effectors act to change the value of the variable
positive
The effector drives the value of the controlled variable even farther from the set point
DO NOT HELP TO MAINTAIN HOMEOSTASIS. HIGHLY UNSTABLE
homeostasis
conditions that are constantly fluctuating and being monitored
Temperature
pH
Concentrations of glucose and oxygen
heat transfer mechanism used in animals
radiation:
transfer of heat by electromagnetic radiation, like the sun, does not require direct contact. Heat is trans. From hotter bodies to colder bodies by radiation
conduction
larger the surface area relative to overall mass, the greater the conduction of heat.
small organisms have a relatively larger surface area for their mass, and they gain or lose heat more readily to the surroundings
convection
trans. Of heat brought about by the movement of gas or a liquid. Maybe externally caused by the wind or due to density differences related to heating and cooling
evaporation:
all sub. Have a heat of vap. The amount of energy needed to change them from a liquid to a gas phase
Water has a high heat of vap, and many org use water as a cooling source
thermogenesis: 2 types shivering/non shivering
circulatory systems
Open
low pressure
organs bath in it
less well regulated
don't have a true body city
Closed
high pressure, rapid flow
blood conveyed directly to organs
Cephalopod, mollusk, annelids, vertebrates
gas exchange
countercurrent flow
meaning oxygenated water (which has a higher partial pressure for oxygen than the fish’s blood) and blood move in opposite directions.
The % saturation levels of oxygen in the fish’s blood will begin to increase but will never be higher that the % saturation levels of oxygen in the water. The % saturation level of oxygen will always be higher in the water
gills
concurrent flow
meaning oxygenated water and blood move in the same direction. This route allows for only a 50% maximum for oxygen
how nervous system regulates it
chemo. receptors pick up on excess CO2 and H+ in the blood, if too much this means to breathe
Lungs
frogs
The great increase in diffusion surface area that gills provide enables aquatic organisms to extract far more oxygen from water than would be possible from their body surface alone.
birds
a unique structure that affords birds the most efficient respiration of all terrestrial vertebrates. Unlike the mammalian lung, which ends in blind alveoli, the bird lung channels air through tiny air vessels called
parabronchi
, where gas exchange occurs. Air flows through the parabronchi in one direction only. This flow is similar to the unidirectional flow of water through a fish gill.
mammals
The alveoli in mammalian lungs provide a large respiratory surface area but do not permit countercurrent exchange. Inhaled fresh air contains some CO2, but levels are higher in the lungs, so more CO2 is exhaled than inhaled; similarly, O2 levels are higher in fresh air, leading to an influx of O2.
Hemo glogin vs. myoglobin
myo: higher affinity for O2
kidneys
loop oh henly: reabsorbtion
countercurrent multiplier effect
distal tube pumps out Na, proximal pumps out waters, in ions
until reaches maximizes urine concentration
ascending linb
distal convoluted tubule
ion permeable: pumps Na out
NOT water permeiable
descending limb
aka proximal convoluted tubule
water permeable: water exits bc of the {Na]
solute increases, increases[ions] inside
ADH