Thermoregulation Flashcards
What are the relative temperatures of the body from hottest to coldest?
Core>oral>average skin>hands>feet
When is the core temperature the lowest during the day?
6 AM
When is the core temperature the highest during the day?
Early afternoon
Where are thermoreceptors found?
Skin, viscera, and brain
Cutaneous thermoreceptors are bimodal. What does this mean?
They are both temperature and touch sensitive
Are there more warm or cold sensitive cutaneous thermoreceptors?
Cold sensitive (10x more)
What do cutaneous thermoreceptors tell us about?
Environmental conditions
What do visceral thermoreceptors sense?
Core temperature and threats to maintenance of the core temperature.
What does the visceral thermoreceptors contact about threats to maintenance of core temperature?
The hypothalamus
What is an example of a threat to core temperature?
Food intake (ice cream, hot soup, etc)
Where are thermoreceptors located in the brain?
Pre-optic and superoptic region of hypothalamus.
Are there more warm or cold sensitive brain thermoreceptors?
Warm sensitive (3x more)
What is the core temperature of most humans in the morning?
36.7C
The hypothalamus has the connections to control the _______, _______, and _______ changes that are part of thermoregulation.
hormonal; autonomic; behavioral
The hypothalamus is the controller for body temperature:
1) Determining _____ ______.
2) Receiving info about ______ _______.
3) __________ ______ _____ ____.
set point;
current temperature;
deciding what to do
What 3 things change set point?
sleep, exercise, and fever
Sleep _____ set point.
decreases
Exercise _______ set point.
increases
Fever ______ set point.
increases
The ______ part of the hypothalamus responds to heat and causes heat loss behaviors.
anterior
The ______ part of the hypothalamus responds to cooling and causes heat production behaviors.
posterior
What are the 4 mechanisms of heat production?
1) ANS
2) endocrine
3) muscular activity
4) non-shivering thermogenesis
Muscular activity increases body temperature by _____ and increasing ______ ______ via the _____.
shivering; voluntary activity; cortex
What is shivering mediated by?
the dorsomedial posterior hypothalamus by increasing motoneuron excitation
Non-shivering thermogenesis produces heat by a strong ______ ______, increasing _____ _____, and by _____ adipose tissue.
hormonal influence; food intake; brown
The hormones that influence non-shivering thermogenesis, are _____, which is stimulated by cold and increases metabolic rate, and ______.
thyroxin; epinephrine
Another mechanism of non-shivering thermogenesis is increasing food intake which leads to an _______ ___ ______.
increase in metabolism
Brown adipose tissue increases heat production in non-shivering thermogenesis by _______ ________ for initiation.
adrenergic innervation
Brown adipose tissue produces heat by ____ _______ ______ of ATP via uncoupling proteins leads to more heat production.
low efficiency hydrolysis
What are the two kinds of evaporative heat loss?
Insensible (respiratory) and sweating (controlled)
_______ is movement of molecules away from contact.
Convection
_______ is the transfer of heat between objects in physical contact with one another.
Conduction
______ is the infrared _____ transferring head between 2 objects not in physical contact.
radiation
How much blood is sent to the ____ determines how much heat moves from blood to external environment.
skin
Innervation of sweat glands is ________ _______.
sympathetic cholinergic (Ach binding to a muscarinic receptor)
The sweat gland duct removes ___ followed by ___.
Na+; H2O
When there is a high flow rate of sweating, the sweat has a high concentration of ____.
water
When there is a low flow rate of sweating, the sweat has a high concentration of ____.
Na+
What happens when there is a decreased core temperature?
Increased heat production (shivering & non-shivering thermogenesis) and decreased heat loss (blood away from skin & decrease evaporative heat loss).
A _____ is a controlled increase in body temperature.
fever
A set point increase is the body temperature doing what the _____ is telling it to do.
hypothalamus
Secretion of _______ by “the bug” and _____ by immune cells cause _______ to be released.
endotoxins; cytokines; prostaglandins
Prostaglandins _______ the hypothalamic set point for temperature.
increase
When one has a fever, the body temperature is _____ ____ the set point temperature.
less than
When one is breaking their fever, the endotoxins and cytokines are no longer being released so the hypothalamus tells the set point to _____ ____ ____.
return to normal
When one is breaking their fever, the body temperature is _____ _____ the set point temperature.
greater than
When one is breaking their fever, their body ______ heat production and _____ heat loss.
decreases; increases
In order to decrease heat production, the body becomes _____ and _____.
apathetic and anorexic
In order to increase heat loss, the body uses ______, ______, _______ heat loss (sweating and _____ heat loss (panting)).
conduction; convection; evaporative; insensible
