Tuesday, 4-12-Thermoregulation (Karius)

Question 1

Describe the graphical presentation of warm sensitive receptors regarding discharge rate and environmental temperature:

Answer 1

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

Question 2

TRPM8 (CMR-1) and TRPA2 are __-sensitive receptors

Answer 2

Cold

-Also activated by menthol

Question 3

Cold-sensitive receptors open as the temperature decreases and allows for ___ influx

Answer 3

Na or Ca

Question 4

Describe the graphical presentation of cold-sensitive receptors regarding discharge rate and environmental temperature:

Answer 4

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

Question 5

The __ has the connections to control the hormonal, autonomic, and behavioral changes that are part of thermoregulation

Answer 5

Hypothalamus

Question 6

Which part of the hypothalamus responds to cooling through heat-production behaviors?

Which part of the hypothalamus responds to heat through heat-loss behaviors?

Answer 6

Posterior

Anterior

Question 7

When is body temperature usually at its lowest?

Answer 7

In the early AM

Question 8

__ determines the set-point for core temperature

Answer 8

Hypothalamus

Question 9

__ 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

Answer 9

Cutaneous

Question 10

Central thermoreceptors are location in these regions of the hypothalamus:

Answer 10

• pre-optic

- superoptic

Question 11

___ 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

Answer 11

Central

Question 12

What are the roles of the hypothalamus and thermoregulation?

Answer 12

• integration of afferent input
• determination of “set-point”
• compare core temp to “set-point” (if different: generate response)
• respond to environment

Question 13

Sympathetics and hormonal release of thyroxine and epi/norepi are mechanisms of __ production

Answer 13

Heat

Question 14

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)

Answer 14

• dorsomedial posterior hypothalamus

- cortex

Question 15

List mechanisms to induce non-shivering thermogenesis:

Answer 15

• hormonal influence–> thyroxin increase metabolic rate, epi
• Increase food intake -> increase metabolism
• Brown adipose tissue

Question 16

Utilization of Brown adipose tissue requires:

Answer 16

• exposure to cold (acute)

- sympathetic activation

Question 17

What are the 2 kind of heat loss?

Answer 17

1) insensible (respiratory)

2) sweating (controlled)

Question 18

___ -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

Answer 18

Convection

Conduction

Radiation

Question 19

In response to INCREASED CORE TEMPERATURE, we can decrease heat production through ___. We can increase heat loss through ___.

Answer 19

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

Question 20

What is the innervation of a sweat gland?

Answer 20

• Sympathetic-CHOLINERGIC

- Ach binds to a muscarinic receptor

Question 21

Describe the concentration of water and sodium when there is a:

Low flow rate: ___

High flow rate: ___

Answer 21

Low flow rate=Low water, High Na

High flow rate=High water, low Na

Question 22

In response to DECREASED CORE TEMPERATURE, we can increase heat production through ___. We can decrease heat loss through ___.

Answer 22

Increase heat production: shivering, non-shivering thermogenesis

Decrease heat loss: blood away from the skin, decrease sweating

Question 23

Describe the process of a FEVER:

Answer 23

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

Question 24

TRP-V1-4 are ___ -sensitive receptors

Answer 24

Warm

• Sensitive over different ranges
• V=Vanilloid=capsaicin (hot peppers)