thermoregulation Flashcards
how does core temp vary over the day?
varies 1-2 degrees over teh day by circadian rhytm
low at 6 am
what are the “Sensors” of body temp? what do they say?
thermoreceptors in skin, viscera, brain
tell the brain about body temp from different areas of body
what are the types of thermoreceptors?
thermoreceptors in core (brain and viscera)
cutaneous receptors
how are cutaneous thermoreceptors characterized?
bimodal to temp and touch
more cold than hot sensitive
tell us a bout environemental conditions
thermoreceptors in gut do what?
check for temp
threats to maintenance such as food ingested
tell hypothalamus about threats
where are thermoreceptors in hypothalamus, what do they do
preoptic and supraoptic regions
more warm sensitive , send information to other areas of hypothalamus to control temp
what is the controller of system?
hypothalamus,
has connections to control hormonal, autonomic and behavioral changes that are a part of thermoregulation
what is the role of hypothalamus in thermoregulation?
determine set point
receive info about current temp
decide what to do
what happens to core temp when sleeping?
decreases, decrease in set point
what happens to core temp when exercise?
increase, increase in set point
what part of hypothalamus responds if you cool down?
posterior hypothalamus, heat production
what part of hypothalamus responds if you heat up?
anterior hypothalamus, heat loss
how does the body produce heat?
autonomics (sympathetic)
endocrine
muscular activity
non shivering thermogenesis
what are the two ways muscular energy increases heat?
shivering
voluntary muscular movement
how does shivering happen?
dorsomedial posterior hypothalamus
sends axons to spinal cord motor neurons
increases excitability
how does voluntary action increase heat production
via cortex, any sort of motion
how does non shivering thermogenesis produce heat?
- hormonal influence via
thyroxin (increase metabolism)
and epinephrine - increase food intake for higher metabolism
- brown adipose tissue via adrenergic innervation
how is brown fat activated?
sympathetic fibers
by circulating epi
how does brown fat produce heat? in who
low efficiency hydrolysis of ATP
via uncoupling proteins
infants, white fat does the same in adults
how does heat loss work?
insensible ( respiratory)
sweating (Controlled)
conduction( transfer of eat between objects in contact with each other)
radiation (radiation transferring heat between 2 objects not in contact)
convection (movement of molecules away from contact)
how much blood do you send to vessels near skin if you want to lose heat?
alot
how is sweating initiated?
sympathetic innervation via aCH
muscarinic receptors
what is so special about sweat glands?
help you cool off and lose heat
lots of blood vessels surround it
whats the initial process of sweating
filtering the serum including ions (Na, Cl)
what happens in sweaing as it moves up duct?
water and sodium reabsorbed, taken back to blood
when your cold, theres low flow rate of sweat, what happens to the sweat?
most water is reabsorbed
sodium remains high in sweat
when your hot, theres high flow rate of sweat, what happens to the sweat?
little water reabsorbed
still sodium in sweat
what happens with acclimitization?
live in a hot place long enough
low sodium in sweat because of aldoserone, take sodiuum back but not water
what does fever do to temp?
controlled increase in set point
what increases temp due to fever?
prostaglandins
what happens when body temp goes down after fever?
apathy, anorexia
conduction/ convection
EHL
insensible heat loss
