Tuesday, 4-12-Thermoregulation (Karius) Flashcards
Describe the graphical presentation of warm sensitive receptors regarding discharge rate and environmental temperature:
As temperature increases, the discharge rate of the warm-sensitive receptors increases. After a certain point, it levels off and begins to decrease which is due to “burning” and the point at which firing rate falls steeply, you have burned off the warm-sensitive receptors
TRPM8 (CMR-1) and TRPA2 are __-sensitive receptors
Cold
-Also activated by menthol
Cold-sensitive receptors open as the temperature decreases and allows for ___ influx
Na or Ca
Describe the graphical presentation of cold-sensitive receptors regarding discharge rate and environmental temperature:
Discharge of cold-sensitive receptors increases as temperature falls. At really high temperatures, the discharge rate of these can actually increase. At extremely low temperatures, there is a steep decrease in discharge rate because of damage to the skin and cold-sensitive receptors
The __ has the connections to control the hormonal, autonomic, and behavioral changes that are part of thermoregulation
Hypothalamus
Which part of the hypothalamus responds to cooling through heat-production behaviors?
Which part of the hypothalamus responds to heat through heat-loss behaviors?
Posterior
Anterior
When is body temperature usually at its lowest?
In the early AM
__ determines the set-point for core temperature
Hypothalamus
__ thermoreceptors are often bimodal (temp and touch-sensitive), may be warm or cold sensitive (10x as many cold sensitive), and tell us about ENVIRONMENTAL conditions
Cutaneous
Central thermoreceptors are location in these regions of the hypothalamus:
- pre-optic
- superoptic
___ thermoreceptors are located in the pre-optic and superoptic region of the hypothalamus. They have neuron cell bodies sensitive to changes in temperature–> 3x as many warm-sensitive and relay their information to other areas of the hypothalamus
Central
What are the roles of the hypothalamus and thermoregulation?
- integration of afferent input
- determination of “set-point”
- compare core temp to “set-point” (if different: generate response)
- respond to environment
Sympathetics and hormonal release of thyroxine and epi/norepi are mechanisms of __ production
Heat
Muscular activity through shivering is done by the __ which increases motor neuron excitation
Muscular activity that is done by increased voluntary activity is via the ___ (i.e., jumping, running)
- dorsomedial posterior hypothalamus
- cortex
List mechanisms to induce non-shivering thermogenesis:
- hormonal influence–> thyroxin increase metabolic rate, epi
- Increase food intake -> increase metabolism
- Brown adipose tissue
Utilization of Brown adipose tissue requires:
- exposure to cold (acute)
- sympathetic activation
What are the 2 kind of heat loss?
1) insensible (respiratory)
2) sweating (controlled)
___ -movement of molecules away from contact (air heating and rising)
___- transfer of heat between objects in physical contact with 1 another
___- transfer of heat between 2 objects not in physical contact
Convection
Conduction
Radiation
In response to INCREASED CORE TEMPERATURE, we can decrease heat production through ___. We can increase heat loss through ___.
Decrease heat production: apathy/inertia, anorexia
Increase heat loss: blood to skin, evaporative heat loss (sweat), insensible heat loss (pant)
Increased core T= Tb > Tsetpoint
What is the innervation of a sweat gland?
- Sympathetic-CHOLINERGIC
- Ach binds to a muscarinic receptor
Describe the concentration of water and sodium when there is a:
Low flow rate: ___
High flow rate: ___
Low flow rate=Low water, High Na
High flow rate=High water, low Na
In response to DECREASED CORE TEMPERATURE, we can increase heat production through ___. We can decrease heat loss through ___.
Increase heat production: shivering, non-shivering thermogenesis
Decrease heat loss: blood away from the skin, decrease sweating
Describe the process of a FEVER:
1) Endotoxin + Immune cells (PGE2) –> INCREASED HYPOTHALMIC SET POINT FOR TEMP
2) Tb is less than Tsetpoint: Increase heat production and decrease heat loss
3) Tb=Tsetpoint –> “COMFORT” in a relative sense
4) No endotoxin + No IS activation –> In absence of endotoxins, etc., hypothalamic set point returns to normal: Tb > Tsetpoint
5) Tb > Tsetpoint –> Decrease heat production and increase heat loss
6) Tb=Tsetpoint –> REAL COMFORT
TRP-V1-4 are ___ -sensitive receptors
Warm
- Sensitive over different ranges
- V=Vanilloid=capsaicin (hot peppers)
