33. Thermoregulation: responses and adaptations to heat Flashcards
how does the hypothalamus respond when theres a rise in core temperature? 3 steps
- vasodilation
- sweat glands activated
- fall in core temperature
how does the hypothalmus respond to a fall in core temperature? 3 steps
- vasoconstriction
- skeletal muscles activated
- rise in core temperature
what are the four ways an mammal gains and looses heat with the thermal environment?
- conduction
- convention
- radiation
- evaportion
what is radiation?
the transfer of heat by electromagnetic radiation - without direct conatct with objects
what is conduction?
the transfer of heat between objects with direct contact with each other
what is convection?
a specialised for of conduction - the transfer of heat contined in gas or liquid
what is evaportation?
the energy required to change a liquid to a gas
what are the three ways of rate of heat transfer as mechanims for temperature control?
- surface area - the size of the animal of how much heat they transfer
- temperature differences - altering the temperature gradient
- specific heat conductance - eg fur trapping air and conducts heat, blubber is low at conducting heat
what is perpheral heterthermy?
localised changes in heat.
the core is more closely controlled nad variation in the ‘shell’ is peripheral heterthermy
what is the thermonetural zone?
where body temperature is mainated without changing the BMR, so no energy expenditure
what are four features that alter body temperature?
- smooth muscle around artioles
- sweat gland
- skeletal muscle
- endocrine glands
what are four temperature decreasing mechanisms?
- vasodilation
- sweating
- decrease in heat production
- behavioural thermoregulation
what is vasodilation and how does it decrease temperature?
letting muscles relax and widening of arteries = higher blood flow. lots of blood to periphery which menas heat can be lost
what is a sweat gland and how does it reduce tempertaure?
an exocrine gland that produces sweat. eccrine gland produces the sweat. evaportation of sweat allows cooling
what are three examples of behaviroual mechanisms to decrease body temperature? not in the thermoneutral zone
- panting
- taking off clothes
- seeking shade
- going near water
how does the hypothalamus act as a mammals thermostat?
neuron sin the preoptic area generate a nerve impule at a high frequency which temp increases
low frequency when body temp decreases
how have different species of animals evolved to deal with heat?
to deal with the limiting water availability
evaporation to remove excess heat
why is opening and closing of blood vessels important for thermoregulation?
the concentration gradient helps be more effiecent
what is the lower and upper critical temperature?
lower - body is colder than the external environemnt
upper - body is hotter than the external envionrment (evaportaion)
both use energy to thermoregulate
which zone does panting come into place and why?
in the upper crtiical zone because it is using evaporation to reduce heat and is above the BMR due to moving the diaphram
