L24: Temperature regulation

Question 1

Normal body temperature

Answer 1

36-38 C (96.8-101.4)

Question 2

consequences of increased body temp

Answer 2

hyperthermia, heat stroke, organ failure, brain lesions

Question 3

consequences of decreased body temp

Answer 3

hypothermia, impairment of temperature regulation, cardiac fibrillation

Question 4

core body temp is lowest when

Answer 4

sleeping

Question 5

core body temp spikes during _____ of the menstrual cycle

Answer 5

ovulation

after ovulation?

Question 6

thermal flux

Answer 6

can be adjusted to compensate and maintain thermal balance

Question 7

Radiation

Answer 7

Energy goes through a medium or space via electromagnetic radiation

Question 8

heat moves down its

Answer 8

thermal gradient

Question 9

Conduction

Answer 9

transfer of thermal energy through solid matter
2 solids or the body and still air
(minor route of heat transfer to environment)

Question 10

Convection

Answer 10

process of losing heat through air/water moving across skin

Question 11

Evaporation

Answer 11

water vaporizing from skin/respiratory passages

Question 12

radiation emission from the body is via

Answer 12

infrared photons

Question 13

infrared photons may represent up to 50% of heat loss during

Answer 13

low physical activity

Question 14

rate of heat loss in convection depends on

Answer 14

rate of fluid movement

Question 15

how many calories does it take to evaporate 1g of H2O?

Answer 15

580 calories

Question 16

Eccrine glands

Answer 16

all over body
clear odorless sweat
innervated by SNS, use ACh

Question 17

Apocrine glands

Answer 17

axial, genital areas

odor from bacterial activity

Question 18

when is sweating less effective?

Answer 18

as air is saturated with water vapor (increased humidity)

Question 19

most passive transfer of heat from core to skin occurs by

Answer 19

convection in the vascular circulation
(some by conductance)
requires a temperature gradient

Question 20

Tcore vs Tskin

Answer 20

Tcore>Tskin

Question 21

Active heat transfer from core to skin

Answer 21

increased by vasodilation

decreased by vasoconstriction

Question 22

conduction of water vs air

Answer 22

conduction of water is higher

Question 23

heat loss from skin surface

Answer 23

radiation + convection + evaporation

Question 24

on a dry summer day, most heat is lost by

Answer 24

evaporation (most)
convection
(radiation
conduction)

Question 25

on a humid day, most heat is lost by

Answer 25

convection (almost entirely)
radiation
(conduction
evaporation)

Question 26

warmth receptors respond to the range

Answer 26

44-46 C

Question 27

cold receptors respond to the range

Answer 27

24-28 C

Question 28

peripheral receptors on the skin

Answer 28

send info to hypothalamus

allow body to anticipate changes before they affect core temperature

Question 29

Central (intrinsic) thermoreceptors are found in 2 places

Answer 29

1. preoptic area (POA)
2. abdominal organs
   Measure core body temperature

Question 30

integrates thermal information

Answer 30

preoptic area

Question 31

Anterior (rostral) hypothalamus

Answer 31

stimulates heat dissipation via parasympathetic response

decreased muscle tone, voluntary actions, increased vasodilation, sweating

Question 32

Posterior (caudal) hypoathalamus

Answer 32

stimulates heat production and conservation via sympathetic response

increased muscle tone, shivering, brown fat, skin vasoconstriction

Question 33

heat is regulated by

Answer 33

1. shiver
2. vasomotor command
3. sweat glands
4. postural changes that change surface area of the body

Question 34

cardiovascular and temperature control the same arterioles, which takes precedence?

Answer 34

TEMPERATURE

always

Question 35

When it’s hot, blood pressure

Answer 35

may drop (vasodilation)

Question 36

Thermoneutral zone

Answer 36

temperatures at which minimal changes in metabolic rate can regulate core temperature

Question 37

metabolic rate at cold temperatures

Answer 37

increases a lot: shivering

Question 38

metabolic rate at hot temperatures

Answer 38

increases some: sweating

Question 39

feel too hot

Answer 39

hyperthyroidism

Question 40

feel too cold

Answer 40

hypothyroidism

Question 41

increase temperature sensitivity

Answer 41

thyroid hormone disorders

Question 42

thyroid hormone increases

Answer 42

vasodilation

Na+-K+ATPase

O2 consumption

Brown adipose tissue: deiodinase 2 (T3 signaling)

Question 43

Leptin

Answer 43

signals pre-optic area to increase body temperature

by activation of beta receptors in brown fat (synergistic with thyroid hormone): decoupling enzyme

Question 44

Excessive catecholamines

Answer 44

increase core body temperature

alpha1 receptors reduce blood flow to the surface of the skin

Question 45

mean skin temperature when exercising

Answer 45

doesn’t change due to evaporation

Question 46

body core temperature when exercising

Answer 46

increases until compensation by evaporation and convective heat loss
Core body temp increases 1 C

Question 47

trained individuals

Answer 47

during exercise:
more skin perfusion
sweats more

Question 48

Heat acclimation occurs in a few days:

Answer 48

1. Lower HR
2. Lower threshold for skin vasodilation
3. Increased sweat
4. Plasma volume increased
5. Better control of core body temps

Question 49

Infection causes macrophages to release

Answer 49

endogenous pyrogens: cytokines

Question 50

cytokines cause release of

Answer 50

prostaglandins

Question 51

prostaglandins are release from

Answer 51

organum vasculosum laminae terminalis (OVLT)
in the hypothalamus
where cytokines can reach bc no BBB

Question 52

prostaglandins stimulate

Answer 52

pre-optic area to increase hypothalamic set point

Question 53

aspirin targets

Answer 53

cyclooxygenase needed for prostaglandin synthesis