Homeostatis

homeostatis

maintained internal equilibrium in the body under varying external conditions (temp, blood pressure, pH, glucose, oxygen, energy)

regulation

perturbation to homeostasis requires an animal to expend energy to restore the set point in a process

negative feedback loop

antagonistic pairs where one part increases parameter, one part decreases parameter (panting/shivering)

two strategies of body heating

endotherm: produces adequate heat via metabolic processes to warm its own tissues
ectotherm: relies on heat from enviornment

homotherms

animals that keep their body temperature relatively constant; large body masses (low SA:volume ratio) would not change temp very quickly

poikilothermic

Animals whose body temperature changes over time (japanese honeybees warming around hornet at hives)

naked mole rats

between endo/ecto bc temp changes but environment is always cool underground)

torpor

reduction in metabolic rate and body temp

hibernation

torpor over weeks/months

estivation

torpor to escape over heating

counter-current heat exchange + example

when fluid flows through adjacent pipes in opposite directions to promote temp exchange, heat transfer between arteries and veins flowing in opposite directions

respiration

gas exchange between animal and its environment

two processes involved in respiration

diffusion (passive movement of uncharged solutes down their concentration gradient) + circulation (transport throughout body)

epithelia

Surface where air is in contact with internal structures to actually enter bloodstream (tissues that line an organ, gland, duct, body surface); high SA:volume ration, interface between internal/external enviornment

three structures used for respiration

lungs, gills (internal/external), trachea (all have high SA: volume ratio)

swim bladders

thought to have evolved from primitive lungs

osmolarity

concentration of solutes in a solution

osmoregulation

process where organisms control concentration of water + solutes in body

hypoosmotic vs hyperosmotive

lower solute concentration (loses water) vs higher solute concentration (absorbs water)

isosmotic

equal concentration of water and solutes

osmoconformer

solute concentrations similar to ambient conditions (jellyfish match environment)

osmoregulator

actively maintains osmolarity

ammonia

fish dilute it in water then excrete it as urine

urea

mammals/amphibians convert ammonia to urea then excrete it as urine

uric acid

birds/insects/reptiles convert ammonia to uric acid then excrete it as urine

kidneys

excrete nitrogenous waste as urine in mammals/amphibians, responsible for water/electrolyte balance

components of the autonomic nervous system

sympathetic (fight or flight) vs parasympathetic (rest and digest)

sympathetic activation

activation is divergence, so needs to return to baseline (homeostatis); not doing so causing high stress and health problems

HPA

Hypothalamus (releases CRH in seconds), pituitary (releases ACTH), adrenal (produces glucocorticoids)

lungfish

lungs vs gills thought to be diagnostic feature, originally giant amphibians