Thermoregulation 2

nucelator

Ice crystal formation needs a trigger called a ________________

supercooling

a state where liquids don’t solidify even below their normal freezing point

-40C

Without a nucleator, water can remain liquid until a low of -__C

shrinks

If ice forms outside the cells, the water is drawn out, causing a hypertonic stress that _________ the cell, and may kill it

tolerance

a strategy for surviving freezing temps where animals can allow their tissues to freeze

avoidance

a strategy for surviving freezing temps where animals use behavioral and physiological mechanisms to prevent ice crystal formation

high

Endothermy is intertwined with low/high metabolic rate

more

High metabolic rate causes more/less heat production

regulate

Endothermy requires ability to _____________ temperature

thermogenesis

ability to generate heat

heterothems

exhibit temporal or regional endothermy

temporal

regional

2 types of heterotherms

basking

behavior that accentuates the warming effect of solar energy

huddling

behavioral strategy that reduces SA:V

birds

Shivering is unique to __________ & mammals

shivering

uncoordinated myofiber contraction that results in no gross muscle contraction

short

Shivering works for ________ periods of time

expensive

Shivering is ___________ and muscles are rapidly depelted of nutrients and become exhausted

locomotory

Shivering prevents the animal from using ___________ muscles for foraging or predator avoidance

piloerection

hair & feathers act as insulation and reduce thermal conductivity by standing up using erector muscles

vasomotor response

regulation of the amount of blood flowing into the vasculature

sympathetic

___________ nervous system controls normal body temp and (rapid involuntary responses) maintains tonic constriction of arterioles

adrenergic

Sympathetic nervous system is mediated by _____________ signals

relaxed endothermy

hypometabolic phase accompanied by a decrease in body temp

membranes

water, hypertonic, shinks

2 deleterious effects of ice crystal formation

Points and edges can pierce _________

Ice forming outside of the cells can draw ______ out → ________ stress, _________ the cell (and then may kill the cell)

nucleators

intracellular solutes

2 mechanisms of freeze tolerance

Produce __________ outside of the cell

Produce _______________ ___________ to balance the movement of water

urea, glucose, glycogen, glycerol

What are some examples of intacellular solutes that are used to balance the movement of water in freeze tolerant species?

osmotic

reduce

stabilize

When producing intracellular solutes to balance the movement of water in freeze tolerant species, the solutes

Increase the _________ pressure within the cells which increases/reduces the movement of water and cell shrinkage

AND it helps __________ the macromolecular structure (i.e. fats, proteins)

freeze avoidance

strategy that involves using behavioral and physiological mechanisms to prevent ice crystal formation

solutes

osmolarity

antifreeze

2 mechanisms of freeze-avoidance

Depress the freezing point by adding __________ to the liquid

As ___________ increases, freezing point decreases

______________ proteins which disrupt ice crystal formation by binding to small ice crystals and preventing growth

antifreeze

proteins that disrupt ice crystal formation by binding to small ice crystals and preventing growth

heterothermy

exhibiting temporal or regionally different body temps

temporal

heterothermy that changes over time

hibernating/torpor, fever response, sleep

examples of temporal heterothermy

regional heterothermy

priority on maintaining certain anatomical regions within very narrow thermal ranges

CNS and internal organs at a more constant temp, while allowing periphery to vary

birds in polar areas may allow their legs and feet to reach much lower temps than their body which is maintained at core temp

example of regional heterothermy

TNZ

in the ____ MR does not need to change to keep body temp constant

insulation

Having more ____________ means that the MR does not have to change as much to keep the animal at a constant temperature, having less means that the body is more susceptible to changes in ambient temp, and thus the MR must change more to account for these changes

basking

huddling

name 2 strategies displayed by animals experiencing cold

thermogenesis

creating heat

shivering thermogenesis

uncoordinated myofiber contraction that results in no gross muscle contraction

short

depleted

locomotry

shivering thermogenesis

works for ________ periods of time — muscles are rapidly ________ of nutrients and become exhausted

prevents the animal from using _____________ muscle for foraging or predator avoidance

brown adipose tissue

non-shivering thermogenesis uses what?

non-shivering thermogenesis (BAT)

important in thermogenesis for small mammals and newborns that live in cold environments

back & shoulder region

Where is BAT located?

adipocytes

mitochondria

thermogenin

BAT is different from white ___________ in that

it has higher levels of ___________

it produces the protein ____________

thermogenin

uncoupling protein that increases mitochondrial activity and uncouples the mitochondrial electron transport system and proton pumping from ATP synthesis

thyroid

In rodents, _________ hormones stimulate BAT thermogenesis

vasomotor response

regulation of the amount of blood flowing into the vasculature

hypothalamus

What controls the vasomotor response?

decrease

tonic

dilate

rabbit

Example of vasomotor response

When body temp is high there is a increase/decrease in _____ constriction of the arteriole and the vessels __________ to allow more blood flow

ex: blood flow increases to _______ ears when it’s hot in order to cool down

local

tissues

Vasomotor response

_______ control of blood flow can control the rate of heat loss in high surface area _______________

countercurrent system

arrangement of 2 flowing parallel systems so that their directions fo flow are opposite of one another

countercurrent system

most effective and simple way of insuring efficient exchange between the two flows (may exchange water, ions, gases, heat)

hairpin

turn

top

longer

A countercurrent system creates a thermal gradient along a ____________ loop.

it’s coolest at the ____ and warmest near the ____ of the hairpin

The ________ the loop the greater the gradient

relaxed endothermy

hypometabolic phase accompanied by a decrease in body temperature

hibernation torpor

examples of relaxed endothermy

saved

In relaxed endothermy, metabolic energy that would normally be used for thermoregulation is _______

specialized nose

dry feces

posture changes

high tolerance for dehydration

some of the ways that camels cope with high heat

fat

What do camels’ humps store?

cycle

evaporating

gain

When dehydrated, camels let their body temp _______

Instead of _________ to cool down, they store their heat and let their body temp cycle with ambient temp

increasing their body temp reduces the amount of heat ____ from the environment

warm receptors

the things that increase firing when hypothalamic temp rises above a certain setpoint

cold receptors

things that trigger heat production when the hypothalamic temp falls below a specific setpoint

peripheral

thermoreceptors that are secondry to the core receptors and brain regulation center