Thermoregulation - 4/12 Karius Flashcards
What do thermoreceptors change their firing rate in response to?
Changes in local temperature
Thermoreceptors are presumed to be what?
Bare nerve endings (neurite complex)
Warm or cold sensitive
What are the warm sensitive ion channels?
TRP-V1 to V4 (cover different temperature range)
What activates Vanilloid?
Capsaicin (hot peppers)
What are the cold sensitive receptors?
Activated by what?
When?
TRPM8 and TRPA2
Menthol
Open as Temp Decreases
Where are thermoreceptors located?
Skin
Viscera
Brain
What does the hypothalamus control?
Hormonal, autonomic, and behavioral changes that are part of thermoregulation
Responses to cooling occur where?
To heat?
Posterior hypothalamus
Anterior hypothalamus
What happens to temperature with sleep?
Exercise?
Decreases
Increases (set point increases)
Describe the characteristics of cutaneous thermoreceptors:
10x as many as cold sensitive
Where are the central thermoreceptors in the hypothalamus?
Special characteristic?
Pre-optic and supraoptic
3x as many as warm sensitive
What hormones increase heat production?
What ANS system?
Thyroxin (inc BMR)
Epi/NE
Symp
What other ways can the body produce heat?
Muscular activity
Non-shivering thermogenesis
Where does shivering occur?
Increases what?
Dorsomedial posterior hypothalamus
Motor neuron excitation
What ways can heat inc with non-shivering thermogenesis?
Increase food intake
Brown adipose tissue
What drives the brown fat low efficiency hydrolysis of ATP?
Symp innervation
circulating Epi
What is the main way to lose heat?
What kinds?
Evaporation (heat lost as water evaporates)
Insensible (respiratory)
Sweating (controlled)
What is convection?
Conduction?
Movement of molecules away from contact (air is heated and rises)
Transfer of heat between objects in physical contact with one another
What is radiation heat loss?
Example?
In fared radiation transferring heat between 2 objects not in physical contact
You and the walls
If there is increased core T, how does the body increase heat loss?
Blood to skin
evaporative heat loss (sweat)
Insensible (panting)
If there is increased core T, how does the body decrease heat production?
Apathy/inertia
Anorexia
What is the innervation of sweating?
What nt?
What receptor?
Sympathetic
ACh
Muscarinic
What is the composition of sweat at low flow rates when it is not hot?
High flow rates when it is very hot?
Little water, high sodium
High water, low sodium
With a decreased core temperature how do you decrease heat loss?
Blood away from skin
Decrease evaporative heat loss
With a decreased core temperature how do you increase heat production?
Shivering
Non-shivering thermogenesis
Definition of fever?
Implication of it?
Controlled increase in body temperature
Set point increases via direction from hypothalamus
What is the major play in making a fever?
PGE2
Increasing set point
What is the definition of hyper and hypothermia?
Uncontrolled changes in body temperature
In a feed-forward system, how is information used to change the controlled the variable?
Example?
Prevent changes
Putting on a sweater when feeling cold when walking from house to outside
