Thermoregulation Flashcards
Define: thermoregulation
homeostasis of core body temperature
What is the main purpose of thermoregulation?
To ensure enzymes are at the correct temperature to carry out chemical reactions that are necessary for survival.
Name the 4 physical processes of heat transfer
Evaporation
Convection
Conduction
Radiation
Define: evaporation
Heat energy converts liquid water to vapour, taking heat with it.
Can evaporation cause heat gain?
NO. it only causes heat loss
List processes in which water can be lost from evaporation (B-SPLUT)
Breathing? Sweating Panting Urinating on themselves (squirrel monkey) Licking, Thermal gaping (crododile)
Why is sweating more effective in dry air than humid air?
Humid air cannot hold/remove as much water as dry air
Define: radiation
heat transfer from warm object to cold object, without physical contact
Gained: body environment
Define: convection
heat transer caused by the mass movement of air or water (currents) to areas of the body of different temperatures
In convection, what is the amount of heat transfer caused by?
The rate of movement of the current.
Define: conduction
Heat transfer from a warm object to a cold object via immediate physical contact.
Is heat transfer from conduction limited to the body parts that touch it?
Yes
Define: core body temperatue
The temperature of the organs and deep tissues. (NOT peripheral surface temperatures)
What is the average core body temperature in humans and the narrow range?
37 degrees, 36-39 degrees
Define: endothermic
Body temperature comes from internal metabolic heat, instead of from external sources.
Define: ectothermic
Body temperature is reliant on external sources of heat
What groups of animals are endothermic?
Mammals and birds
Does the cbt of ectotherms match the environment?
No, but they fluctuate with it.
When does hypothermia occurs?
When the cbt drows below 35 degrees.
Hypothermia stimulus?
Drop in cbt
Hypothermia receptors?
Thermoreceptors in the skin, organs and hypothalamus
Hypothermia modulator?
The hypothalamus, which sends nerve and hormonal messages
Hypothermia response?
increased thyroxine production (which boosts metabolic rate), shivering, vasoconstriction, piloerection, behavioural changes
When does hyperthermia occur?
WHen the cbt is over 39 degrees.
Hyperthermia stimulus?
Increase in CBT
Hyperthermia receptor?
Thermoreceptors in the skin, organs and hypothalamus
Hyperthermia modulator?
Hypothalamus which sends nerve and hormonal messages
Hyperthermia effectors?
Arterioles of blood vessels near skin, sweat clands
Hyperthermia response?
Vasodilation, sweating
Define: shivering
Involuntary contraction and relaxation of skeletal muscles controlled by the hypothalamus, which produces heat
Is shivering sustainable?
No, because it drains energy reserves of muscle tissue.
Define: vasoconstriction
Narrowing of the arterioles near the skin
How does vasoconstriction work?
Ring of muscles surrounding the arterioles near the skin contracts. Blood must travel through a shunt vessel which is further from the skin, causing less heat loss.
Define: vasodilation
Relaxation of muscles surrounding the arterioles near the skin, resulting in more heat loss
Define: piloerectoin
An organism’s hair stands on end, due to muscles tensing (controlled by nerve impulses from hypothalamus) at the hair follicle.
How does piloerection conserve heat?
Traps a layer of air between the fur and skin - thus conserving heat
Explain how the metabolic rate is increased, after cbt decreases.
Hypothalamus detects fall in blood temperate and produces thyrotropin-releasing hormone (TRH)
TRH stimulates pituitary gland to release thyroad stimulating hormone (TSH)
TSH stimulates the thyroid gland to release thyroxine (produced in greater quantities in response to cold body temp)
Name behavioural activities for altering heat gain/loss (SSSUBH-CE)
Saliva spreading Shade/sun Sprawling (thermal window) Urinating into hands and splashing themselves Burrowing Huddling Clothes Exercise
Define: saliva spreading
lick parts of body with less fur and more blood vessels which can be more easily evaporated
