Flashcards in Temperature Regulation Deck (24):
What is body temperature regulation?
Homeostatic regualation of normal body temperature within narrow limits (36.9-37) and involved complex processes that continually interplay between physiological and environmental factors
What is the basic principle in thermoregulation?
Heat Input (absorbed from environment) + Heat produced/conserved= Heat loss
What are the 5 ways in which heat can be produced?
1. Metabolic Activity
2. Non-shivering thermogenesis
4. Muscle Activity
Which heat production method is the most efficient and produces the most heat?
What is non-shivering thermogenesis?
Heat production due to metabolic energy transformation processes that do not involve contraction of skeletal muscles
-releasing noradrenalin or thyroxin via the SNS which causes metabolism to increase
What are the 4 forms of heat loss?
1. Radiation- before touching something
2. Conduction- direct contact transfer of heat
3. Convection- Heating up air molecules around you and fanning them away
4. Evaporation- Sweat on skin being evaporated off
In all the ways heat is lost form our body, what are their %?
Conduction 1% (not very effective
Other 3% (urination/deification)
What are thermoreceptors?
Sensory receptors that codes for relatively e changes in temperature (no hot or cold specific sensors).
Sensors that are sensitive to hot and cold respond best to either modality within the skin are located in the dermis
Where are the areas that thermoreceptors are found in high concentrations ?
What are the 2 types of thermoreceptors and where are they located?
Peripheral receptors: Anything outside of the CNS
Central thermoreceptors (hypothalamic): Located in the anterior and posterior hypothalamic nuclei
How are the central thermoreceptors activated?
Temperature of the blood (professing through to the anterior) turns on the receptors.
-responds to core body temperature through blood
How do the anterior and posterior work together?
Thermoreceptors are only present in the anterior, NOT in the posterior.
Posterior and anterior need to work together by anterior receiving the change, and posterior responding to commands and information from the anterior
What can the posterior do that the anterior can not?
Able to both release heat and conserve heat
For both anterior and posterior, do they increase or decrease BP/temperature control?
Anterior: Decreases BP and body temp by controlling the PSNS (dilating blood vessels so more hot blood goes to extremities to release heat)
Posterior: Increases BP and body temp by controlling the SNS (turns on neurons that increase sympathetic nerve activity causing vessels mot constrict to conserve energy)
How does regulation of endocrine secretion and ANS activity maintains homeostasis?
By a direct action of the internal environment itself
How does regulation of emotions and motivated behaviour maintains homeostasis?
By acting indirectly through interactions with the external environments
What are the 3 physiological responses to cold?
1. Hypothalamus responds through drop of temp. TRH released, to release TSH to release thyroxine which act on cells to increase the basal metabolic are and this increases heat production and temp
2. Hypothalamus stimulates SNS leads to constriction of blood vessels in the skin. Less blood flow reduces heat loss. Increased SNS activity stimulates shivering which increases heat production.
3. Cold is a stimulus for goal direction motivated behaviours like seeking shelter, putting on a sweater, turning up thermostat. All behaviours lead to reduced heat loss
When there is high environmental temperature what is the anterior responsible for doing?
Maximizing heat loss
-behavioural responses (use of fans, removing clothes)
Minimizing heat production
-diminish food intake
-decrease physical activity
When there is low environmental temperature what is the posterior responsible for doing?
Minimizing heat loss
-Lack of sweating
-Behavioural response (adding layers, curling up)
Maximize heat production
-Shivering thermogenesis (most effective
-Non-shivering thermogenesis (releasing hormones)
-behavioural response (stomping feet)
What happens when you place a bacterial pyrogen into the anterior hypothalamic/preoptic region?
Toxin from bacterial cell attracts immune system (white blood cells). WBC produce interluken 1 protein which its in the hypothalamus and binds to anterior region receptors. Doesn't want anterior to sense the increase in body temperature (increasing temp to kill/denature bacterial proteins so they can't harm us)
-shutting down he anterior hypothalamic region or can reset the set point temperature in our body
Where is the best most accurate place to take body temperature?
What is heat exhaustion?
Result of thermoregulating effectively but you are still losing fluids and causing you to sweat (wet skin)
What is heat stroke?
Occurs when you are no longer thermoregulating (dry skin)