form + function pt 2 (thermoregulation -> torpor)

thermoregulation

maintaining internal temperatures within a tolerable range

what qualities can change due to thermoregulation being affected by temperature?

biochemical + physiological processes are sensitive to changes in temperature

the cell membrane fluidity can also change due to varying temperatures

how do ectotherms thermoregulate?

behavioral thermoregulation → basking on rocks, in the sun, seeking shade

→ they can tolerate wider internal temperature ranges compared to endotherms

what are some examples of behavioral thermoregulation?

• bugs flapping their wings in the cold to warm up their thorax so they can fly

• doing jumping jacks before running in the cold so you can stay warm

endo and ectotherms exchange heat with their environment through 4 physical processes. what are they?

1) conduction

2) convection

3) radiation

4) evaporation

conduction

direct transfer of heat between objects in direct contact

→ holding a cup of hot chocolate makes your hands warm because of the transfer of heat between both objects

convection

transfer of heat by the movement of air or liquid past a surface

→ if you stick your hand in a moving stream of cold water and your hand becomes cold, it’s because the warmth is moving out of your hand into the stream

radiation

emission of electromagnetic waves by all objects warmer than absolute zero

→ placing your hand close to someone’s forehead while they have a fever transmits their heat to your hand by radiation

→ standing outside in the sun transmits heat from the sun to your skin by radiation

evaporation

removal of heat from the surface of a liquid that is losing some molecules as gas

transfer of heat between objects in direct contact

conduction

movement of air or liquid past a surface to transfer heat

convection

emissions of heat waves by all objects warmer than absolute zero

radiation

liquid turning into a gas

evaporation

insulation is a thermoregulatory adaptation of ________ and _____ (endotherms)

mammals + birds

→ hair, feathers, fat → how well these structures insulate depends on the amount of AIR trapped between the layers

how have marine mammals developed their thermoregulation?

they developed an even thicker layer of fat insulation (blubber) because heat transfer to water (convection) occurs 100x faster than heat transfer to air

circulatory adaptation

altering blood flow to the surface of the skin to help regulate internal temperature

→ vasodilation + vasoconstriction

vasodilation

increase the diameter of blood vessels → more blood flows through → heat releases more quickly out of the core of the body

vasoconstriction

decreases the diameter of blood vessels → reduces blood flow → keeps warm blood close to the core of the body

countercurrent heat exchanger

blood vessels are closer to the core of the body

→ this allows the heat not to be lost as easily between the core and the skin so the blood stays warm when leaving the heart and entering the heart

*this happens in geese, dolphins, fish, and sharks !!

how do animals cool off to maintain homeostasis?

behavioral thermoregulation

evaporation

torpor

when temperatures reach extremes or food sources are unavailable, some animals go into a physiological state where activity is low and metabolism decreases

hibernation

a long-term torpor

→ advantageous in winter where animals will shut their bodies down and go into a deep sleep BECAUSE there isn’t enough food to sustain their energy expenditures

estivation

summer torpor

→ animals decrease metabolic rate + activity when temperatures are too hot, water supplies are low, or food is scarce

→ frogs do this !!

daily torpor

carried out by small animals + birds based on their feeding patterns of 24 hours or less

→ shrews and bats go into daytime torpor

→ chickadees and hummingbirds go into night time torpor

shrews and bats go into what kind of torpor?

daytime torpor → these animals are diurnal (day-active)

chickadees and hummingbirds go into what kind of torpor?

night time torpor → these animals are nocturnal (night-active)

why is it so important that small animals go through a DAILY torpor?

they are using most of the metabolism to thermoregulate because their bodies release heat faster

so they NEED to conserve energy by doing a mini-hibernation by lowering their metabolic rate daily through torpor

→ if they don’t do this, they will die :(

how is torpor related to humans?

torpor was helpful during our evolution

we are big enough that we can sustain our own thermoregulation that we don’t need to have a mini-hibernation anymore