Thermoregulation

Question 1

Patient in a coma body temperature is 33C, no infection, for 16 hours What is normal temperature, and how does it change with outside temp How does pt body respond to this Temp

Answer 1

36.3-37.1C/98.6F Stays the same in many different environmental temperatures (core)= constant control (SET POINT) These change and need to be adjusted by the body from least to most Oral, Skin, hands, feet Lower in the morning

Question 2

Reason Hands and feet get cold fast

Answer 2

To keep the core temperature steady and the same (the control)

Question 3

What influences core temperature and how does it change

Answer 3

Circadian rhythm Waxing and waning by 1C HIGH=Evening LOW= morning

Question 4

Sensors of thermoregulation name and location

Answer 4

Thermoreceptors in skin , viscera, brain Some warm sensitive and some cold sensitive

Question 5

Cutaneous Thermoreceptors

Answer 5

Tell us about environmental temperature located on skin Are temp. And touch sensitive= bimodal

Question 6

Core Thermoreceptors

Answer 6

Found in viscera and brain and tell me about core temperature And viscera can tell me about the environmental temp also (eating and breathing in air)

Question 7

Warm vs cold receptors

Answer 7

10x more cold receptors on skin (cutaneous Thermoreceptors) 3x more warm receptors in brain (core Thermoreceptors)

Question 8

Thermoreceptors in gut why (Visceral)

Answer 8

Injected food can be a threat (Usually cold food can cool blood in that area) Cold food can increase metabolism in response to heat the core

Question 9

Thermoreceptors of core (brain) specific location

Answer 9

Pre-optic and superoptic region of hypothalamus ——> other parts of hypothalamus to process info

Question 10

What controls and sets the set point for thermoregulation

Answer 10

Hypothalamus Can control ANS, behavioral, and hormonal for body temperature Gets info about temp. , sets a set point, and generates response to what I should do ——> other parts of brain (ex. Increase ANS)

Question 11

How does the hypothalamus set temperature right

Answer 11

Gets into from how many cold and warm sensory neurons are firing and compare it to how many should be firing them MEASURE APs numbers : set point neurons APs should = thermoreceptors APs

Question 12

When does set point increase or decrease

Answer 12

Decrease: during sleep Increase: during exercise (since ATP making makes enzymes more effective)

Question 13

What does the hypothalamus do in response to increase in core temperature or environmental temp

Answer 13

Anterior Hypothalamus causes heat loss (sweating, ANS)

Question 14

What does the hypothalamus do in response to decrease in core temperature or environmental temp

Answer 14

Posterior Hypothalamus causes heat production behavior (goosebumps)

Question 15

Adipose does what when it comes to heat And how is it in infants

Answer 15

Great insulation (1/5 heat loss compared to skin) Babies SA is higher then adults compared to size= they have higher heat loss and need more fat (chubby cheeks)

Question 16

Using energy for metabolism and other body functions causes

Answer 16

A LOT of heat,

Question 17

How is heat produced specifically

Answer 17

ANS (sympathetic) Endocrine (Thyroxine, Epinephrine) 1. Muscle activity (voluntary and shivering) 2. Thermogenesis like (increase metabolism not due to muscles Ex: brown adipose, Hs)

Question 18

Shivering signal is from where Involuntary muscle movement

Answer 18

Post. Hypothalamus——>Dorsomedial posterior Hypothalamus——> down the spinal cord to alpha-motor n. + VOLUNTARY muscle movement ——> causes shivering Voluntary = breathing, moving a certain way, to actually cause shivering

Question 19

Increase voluntary muscle movement for heat is from where and how

Answer 19

Post. Hypothalamus signals ——> cortex ——> jumping, running

Question 20

Non-shivering thermogenesis happens how and where

Answer 20

1. Thyroxin increases metabolic rate (cold stimulates TRH) Epinephrine 2. Food intake= increase metabolism 3. Brown adipose = stimulated by ANS

Question 21

How does brown adipose make heat

Answer 21

Low ATP hydrolysis by uncoupling proteins = heat (not ATP) Innervation by ANS nerves and Epinephrine from blood HIGH in infants or in adults due to acute cooling

Question 22

Heat loss types

Answer 22

Evaporative Convection Conduction Radiation

Question 23

Evaporative Heat Loss

Answer 23

Energy(heat) lost at water evaporates INSENSIBLE: Panting(breath in cold air), CONTROLLED: sweating, only at right conditions

Question 24

Convection Heat loss

Answer 24

Molecules move away from contact Hot Air raises away from the body

Question 25

Conduction heat loss

Answer 25

Heat transferred form objects in contact

Question 26

Radiation hear loss

Answer 26

Infrared heat transferred between objects not in contact The walls are cold transferring heat to you Reason we put on sweaters (change behavior to prevent change in temperature) = FEEBBACK FORWARD mechanism = prevent change (not fix change)

Question 27

How we control heat loss in our bodies

Answer 27

Control amount of blood sent to skin 1. Not a lot of blood sent to the skin = less heat loss (they get pale) 2. A lot of blood sent to the skin = higher heat loss (they get flushed skin)

Question 28

How does sweating occur and one good thing about it

Answer 28

Evaporative heat loss It works in all environments when the body is colder then outside even

Question 29

Innervation to the sweat glands

Answer 29

Sympa cholinergic ——> ACH binds to muscarinic receptor

Question 30

Coiled region of sweat gland

Answer 30

Start sweat production = sweat gland

Question 31

Duct to skin of sweat gland

Answer 31

Modifies sweat as it goes on Depending on how fast and much sweat you need H2O and Na+ flows back to the blood

Question 32

How sweat is made

Answer 32

1. BF increases with heat 2. Filtration starts: high Na+ and Cl- (low K+) into the sweat gland (same as plasma except proteins= serum) 3. Na+ and H2O flows back to the blood in the duct

Question 33

Low flows rate for sweat (I am warm)

Answer 33

Resbsorb ALOT of water Not Na+ (Can cause high NA+ loss) (SWEAT= low H2O, high Na+)

Question 34

High sweat flow rate (I am really hot)

Answer 34

Aldosterone causes high Na+ reabsorption (SWEAT= high H2O, low Na+)

Question 35

Aldosterone function

Answer 35

Increase Na+ reabsorption in sweat gland duct Increase K+ secretion from urine

Question 36

PT comes in with 33C core temperature Core< set point (36C) What is happening inside her body

Answer 36

trigger heat production 1. Non-shivering thermogenesis 2. Shivering 3. Blood moves away from skin (pale)

Question 37

Patient high fever , he is 40F, What is the fever (what happens)

Answer 37

CONTROLLED increase in body temperature Hypothalamus increased the set point for the core body temp. Body acts accordingly

Question 38

What triggers fever

Answer 38

Pathogen= secretion of endotoxins Immune Cells= release cytokines PROSTAGLANDIN EP3 This increases the set point by the hypothalamus

Question 39

When fever is about to break

Answer 39

Body temperature > set point You sweat , conduction convection, pant

Question 40

I feel hot

Answer 40

Body temp> set point

Question 41

I feel cold

Answer 41

Body temp < set point

Question 42

Hyperthermia vs Fever 1. Set point 2. Thermoregulation response 3. Signs 4. Perception 5. Cause

Answer 42

Core temperature in increase for both Set point > body - fever Body> set point - hyperthermia Hyperthermia= dehydration can be a cause

Question 43

How does hypothalamus send signal for ANS

Answer 43

Paraventricular Nucleus (of hypothalamus) ——-> 1. Dorsal motor nucleus of vagus 2. Nucleus Ambiguous 3. Parasympathetic and Sympathetic neurons in spinal cord

Question 44

Inflow to Hypothalamus for ANS stimulation

Answer 44

1. DLF (dorsolateral fasciculus) 2. Medial forebrain bundle (from nucleus tractus solitaries) -visceral thermoreceptors 3. Mammillotegmental tract —> hypo—-> mammillary bodies—> ANS