thermoregulation in endotherms

are endotherms warm or cold blooded?

warm

do endotherms temps change or stay constant?

• their body temps stay constant, despite changes in the temp of their environment

where do endotherms get their heat?

use heat generate internally from their metabolic processes to maintain a stable ore body temp regardless of the environmental temp

what are some advantages of being an endotherm?

enzymes are able to continuously work at their optimum rate so chemical reactions continue continuously at a steady rate so the endotherm can remain active even when its cold outside (can always hunt or run away)

what are the 2 types of temp receptor?

• peripheral temp receptors in the skin

• receptors in the hypothalamus

what do the peripheral temp receptors in the skin do?

detect change in temp in environment

where are the peripheral temp receptors located?

in the skin

what do the receptors in the hypothalamus contain?

thermoregulatory centre

what do the receptors in the hypothalamus do?

detect any change in temp of blood

how are the peripheral temp receptors and receptors in hypothalamus used?

• The brain uses the information from the peripheral temperature receptors to anticipate whether or not our core body temperature might be about to decrease or increase.

• The hypothalamus contains the thermoregulatory centre and therefore controls the responses that maintain the core body temperature at around 36.5°C

what is our usual body temp?

36.5°C

what type of responses do endotherms mainly use?

physiological

what are some physiological responses endotherms use to keep body temp constant?

• Vasodilation

• Sweating

• Hair lies flat against skin

• Vasoconstriction

• Shivering

• Raising body hair or feathers

what are the physiological responses endotherms use if body temp increases too much?

• Vasodilation

• Increased sweating

• Hairs lay flat

what are some behavioural responses endotherms?

• Wallowing in mud (e.g. hippos)

• Huddling (e.g. penguins in Antarctic)

• Basking in the sun

what are some anatomical adaptions some endotherms have to help keep body temp constant?

• Very large ears to lose heat

• Small ears so they don't lose too much heat

• Layers of blubber so that they stay warm

what is vasodilation?

• Vasodilation is when the arterioles dilate (they do not move closer to the skin)

how does vasodilation occur and how does this help cool us down?

• Arteriovenous shunt vessels constrict

• Blood is therefore forced through capillaries close to the surface of the skin

• Blood plasma carries heat around the body

• If the blood flow to the surface of the skin is increased, more heat is lost through the skin's surface by: radiation, conduction (if a cool surface is pressed against the skin)

how does sweating help cool us down?

• Sweat glands secrete sweat

• The water from the sweat then evaporates off the skins surface using energy from the body, which cools the blood

• In this way, endotherms lose heat energy and cool down

• This is also why our skin tastes salty

how do hair erector muscles help us cool down?

• Hair erector muscles, the erector pili muscles relax

• Hair lies flat along the skin

• This thin layer of air traps very little heat

what are our physiological responses if core body temp decreases?

• Vasoconstriction

• Decreased sweating

• Hairs stand on end

• Shivering

what is vasocontriction?

Vasoconstriction is when the arterioles near the surface of the skin contract

how does vasoconstriction occur and how does this help warm us up?

• Arteriovenous shunt vessels dilate

• Both of the physiological responses mean that very little blood flows to the surface of the skin (our skin looks pale)

• This means that heat is conserved inside the body

• Blood (plasma) carries heat around the body, this means if blood flow to the surface if the skin is decreased, less heat is lost by radiation

how does sweating change when core body temp decreases?

rate of sweating decreases

how do hair erector muscles help warm us up?

• When endotherms are cold, hair erector muscles (erector pili muscles) contract, pulling the hairs on the skin upright

• This traps a layer of insulating air next to the skin

• Air is a good insulator

• Less heat is lost from the body by radiation

what is shivering?

This is rapid, involuntary contracting and relaxing of the large voluntary (skeletal) muscles in the body

how does shivering help us warm up?

rapid contraction of muscles require a higher metabolic rate (rate of respiration increases), and this generates heat(releases heat energy), which is used to warm the body

what are some disadvantages of being an endotherm?

A steady respiration rate means that regular food is needed which is then respired to release energy