Karius Thermoregulation Flashcards Preview

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Flashcards in Karius Thermoregulation Deck (63):
1

Normal body temperature

36.3 - 37.1 degrees C

2

How is controlled variable measured

sensor ex. thermostat

3

Sensor of controlled variable system

ex. thermostat if it's cooler that set point then the the heater will turn on, if thermostat is warmer than the set point then the air conditioning will turn on

4

Feed-Forward system

information is used to prevent changes in the controlled varible

5

Example of feed forward system

1. sun an change room temperature, the actual room never changed
2. bodies in a room make the room warmer but the actual temperature of the room never changes
3. If it's cold outside, you put on a sweater, body temperature didn't change but you know it would if you didn't but a sweater on

6

Is thermoregulation feed forward or negative feedback

Negative feedback with some feed forward aspects

7

Thermoreceptors

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

8

Warm sensitive thermoreceptors

4 channels - TRP V1-4 which all cover different temperature ranges
V = vanilloid = capsaicin

9

Warm sensitive thermoreceptors at low temperatures

not a lot of action potentials

10

Warm sensitive thermoreceptors at high temperatures

lots of action potentials -- except it can plateau and that means the skin is burning

11

Cold sensitive thermoreceptors activated

as temperature decreases

12

Ions involved in cold sensitive thermoreceptors

Na and Ca++ influx

13

Where are thermoreceptors found

skin, viscera, and the brain (hypothalamus)

14

Hypothalamus invovled in thermoregulatory system

controls hormonal, autonomic, and behavioral changes

15

Location for response to heat

anterior - heat loss behaviors

16

Location for response to cooling

posterior - heat production behaviors

17

Most controlled temperature place in the body

brain and abdomen

18

Least controlled temperature place in the body

hands and feet

19

Body temp change with sleep

temp decreases b/c of circadian influence

20

Body temp change with excercise

temp increases b/c of increase in heat production and set point increase

21

What determines set point

hypothalamus determines set point for core temp

22

Set point

desired temp value

23

Temperature influence on body

changes enzyme activity and cellular function

24

Change in environment temperature

can threaten body temperature

25

Cutaneous themoreceptors

*these tell us about environmental conditions
axons located in skin
often bimodal
may be warm or cold - 10x as sensitive to cold

26

Visceral thermoreceptors

*threats to maintenance due to food intake (eat scoop of ice cream or hot pepper)

27

Central thermoreceptors location

pre-optic and superoptic region of hypothalamus

28

Central thermoreceptors function

tells me about temperature in the brain b/d neuron cell bodies are sensitive to change in temp
relay info to hypothalamus
3x as many warm receptors

29

Heat production mechanism

sympathetic system, hormonal control

30

Hormonal heat production mechanism

thyroxin and epinephrine/NE

31

Ways of producing heat

muscular activity - can be voluntary or involuntary (shivering)
Non-shivering thermogenesis (jumping up and down when at gas station)

32

Shivering sensory to hypothalamus

dorsomedial posterior hypothalamus to increase motorneuron excitation

33

Non-shivering thermogenesis

hormone influence, food intake, brown adipose tissue

34

Increase food intake on thermogenesis

non-shivering thermogenesis
increase metabolism

35

Brown adipose tissue

use ATP without directing it towards somewhere
low efficiency = lots of heat production
strong in infants and not adults

36

Evaporative heat loss

energy lost as water evaporates

37

Two kinds of evaporative heat loss

sweating (controlled) and insensible (respiratory)

38

Convection

heat loss
movement of molecules AWAY from contact

39

Conduction

heat loss
transfer of heat between objects in contact with one another
depends on the object being colder than body temp

40

Radiation

heat loss
infrared radiation transferring heat between 2 objects NOT in physical contact
ex. a wall

41

How to respond to changes in core temperature

hypothalamus will adjust to both heat loss and heat production

42

Hypothalamus response to increased core temp

decrease heat production - less likely to eat and exercise
increase heat loss - blood to skin (flushing), sweat, insensible heat loss (panting)

43

How to increase convection and conduction

send more blood to the skin to send more heat from blood to external environment

44

Sweat gland innervation

**sympathetic** CHOLINERGIC- **Ach** is the NT binding to a muscarinic receptor

45

Primary secretion of sweat

high in water and sodium
*when you sweat a little bit

46

Low flow rate of sweat

concentrated- little water, high sodium

47

High flow rates

diluted- lots of water, little sodium

48

What happens along the sweat duct

reabsorb sodium, chloride, and water

49

Fever

controlled increase in body temperation

50

Hypothalamus during fever

causes a increase in set point
telling body to change to accommodate for the set point change

51

How to make a fever

Secretion of endotoxins --> Immune cells activated --> prostaglandin E2 --> increase hypothalamic set point

52

Body temp to set point temperature during fever

body temp

53

Body response to making a fever

increase heat production and decease heat loss

54

Increasing heat production during fever

shivering and non-shvering thermogenesis

55

Decreasing heat loss during fever

decrease conduction/convection and decrease sweat

56

Getting rid of fever

no endotoxins, no more immune activation, set point goes back to normal

57

Body temp to set point temperature when getting rid of fever

Tb > Tset point

58

Fever breaking

decrease heat production, increase heat loss

59

Decreasing heat production when breaking a fever

eat less, do less

60

Increasing heat loss when breaking a fever

conduction/convection, sweat, pant

61

Hyper and Hypothermia

uncontrolled changed in body temperature

62

Implications for hypo and hyperthermia

set point is normal, environmental stresses exceed bodies ability to regulate temp
hypothalamic regulation may be lost

63

Hypothalamic tumor

can't thermoregulate