Thermoregulation (karius)

Question 1

what kind of system is thermoregulatino

how does it work?

Answer 1

feed-forward system

-prevents changes in the controlled variable

Question 2

definition of thermoreceptor

Answer 2

neurons which change their firing rate in response to changes in local temperature

Question 3

what kind of nerve endings do thermoreceptors have

Answer 3

bare nerve endings

Question 4

describe warm sensitive thermoreceptors

• channel names
• also activated by what

Answer 4

TRP-V!-V4 detect different levels of temp range
also activated by capsaicin (hot peppers)
-binding of receptor allows sodium and or calcium in

Question 5

cold senstitive receptor called

Answer 5

TRPM8 or CMR-1

Question 6

what else is cold sensitive thermoreceptors activated by

Answer 6

menthol

Question 7

at very low temperatures what causes the falling off of cold sensitive neurons from firing

Answer 7

actually damage to the skin

Question 8

at very high temperatures why do cold sensitive neurons fire

Answer 8

body protection mechanism

-warm receptors can stop working gradually but cold ones cannot

Question 9

where are the thermoreceptors located

Answer 9

skin, viscera, and brain

Question 10

what is the main controller of thermoreg

Answer 10

hypothalamus

Question 11

anterior hypothalamus responsible for what

Answer 11

responding to heat

heat loss behavior

Question 12

posterior hypothalamus responsible for what

Answer 12

response to cooling

heat production behaviors

Question 13

how does body temp change with activity

Answer 13

sleep–> Temp decreases, circadian influence
with exercise–> T increases
-increase heat production and set point

Question 14

when is body temp lowest based on circadian rhythm

Answer 14

6 am

Question 15

thermoreceptors in the core

Answer 15

brain

viscera

Question 16

thermoreceptors not in the core

Answer 16

cutaneous thermoreceptors

-axons located in the skin

Question 17

cutaneous thermoreceptors

Answer 17

bimodal (temp and touch sensitive)

• warm or cold sensitive
• 10X as many cold sensitive
• tell us about environmental conditions

Question 18

location of central thermoreceptors

Answer 18

pre-optic and superoptic region of hypothalamus

-in anterior part of hypothal but help whether hot or cold

Question 19

more warm or cold sensitive receptors in the central thermoreceptors

Answer 19

3x as many warm ones

Question 20

where do central thermoreceptors relay info

Answer 20

to other areas of the hypothalamus

Question 21

heat production mechanisms

Answer 21

ANS: sympathetic
hormonal: thyroxin, epinephrine/norepi

Question 22

ways of producing heat

Answer 22

muscular activity (involuntary or conscious)
non shivering thermogenesis (non-muscular)
-heat being produced by other cells than muscle

Question 23

center of shivering location

Answer 23

dorsomedial posterior hypothalamus

Question 24

muscular activity has 2 mechanisms

Answer 24

shivering
-dorsomedial posterior hypothal
-increase in motorneuron excitation
increase in voluntary activity 
-via cortex
-jumping, running

Question 25

non-shivering thermogenesis

Answer 25

hormonal influence increase food intake brown adipose tissue

Question 26

hormonal non shivering thermogen

Answer 26

thyroxin increases metabolic rate stiumulus for TRH release is cold epinephrine

Question 27

increase in food intake non shivering thermogenesis

Answer 27

increases metabolism

Question 28

brwon adipose tissue

Answer 28

uncoupling enzyme hydrolyzes ATP to uses this as heat instead of energy sympathetic: innervation of brown fat, circulating epinephrine

Question 29

heat loss: evaporative (2 kinds)

Answer 29

evaporative heat loss 1) insensible (respiratory) 2) sweating (controlled)

Question 30

convection

Answer 30

losing heat to cooler air than skin

Question 31

conduction

Answer 31

losing heat to objects in contact with our skin

Question 32

radiation

Answer 32

infrared radiation transferring heat btwn 2 objects not in physcial contact -losing heat to cooler wall in room

Question 33

response to increased core temp

Answer 33

decreased heat production - apathy/inertia - anorexia increase heat loss: - blood to skin - sweat

Question 34

sweating innervation

Answer 34

sympathetic but ach binding to muscuranic receptors

Question 35

low flow rate: sweat composition

Answer 35

high in salt low in water

Question 36

high flow rate: sweat composition

Answer 36

high water low sodium

Question 37

response to decreased core temp

Answer 37

increase heat produciton - shivering - non-shivering thermogenesis decrease heat loss - blood away from skin - decrease sweat

Question 38

how is fever produced

Answer 38

when "bug" releases endotoxins it causes immune cells to release prostaglandin E2 -this tells the hypothalamus to increase set point for temp above normal

Question 39

in absence of endotoxins what happens

Answer 39

hypothalamic set point returns to normal

Question 40

hyper and hypothermia

Answer 40

uncontrolled changes in body temperature - set point remains normal - environmental stresses exceed body's ability to regulate temp - at extremes: hypothalamic regulation may be lost