Thermoregulation Flashcards
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
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
Reason Hands and feet get cold fast
To keep the core temperature steady and the same (the control)
What influences core temperature and how does it change
Circadian rhythm Waxing and waning by 1C HIGH=Evening LOW= morning
Sensors of thermoregulation name and location
Thermoreceptors in skin , viscera, brain Some warm sensitive and some cold sensitive
Cutaneous Thermoreceptors
Tell us about environmental temperature located on skin Are temp. And touch sensitive= bimodal
Core Thermoreceptors
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)
Warm vs cold receptors
10x more cold receptors on skin (cutaneous Thermoreceptors) 3x more warm receptors in brain (core Thermoreceptors)
Thermoreceptors in gut why (Visceral)
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
Thermoreceptors of core (brain) specific location
Pre-optic and superoptic region of hypothalamus ——> other parts of hypothalamus to process info
What controls and sets the set point for thermoregulation
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)
How does the hypothalamus set temperature right
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
When does set point increase or decrease
Decrease: during sleep Increase: during exercise (since ATP making makes enzymes more effective)
What does the hypothalamus do in response to increase in core temperature or environmental temp
Anterior Hypothalamus causes heat loss (sweating, ANS)
What does the hypothalamus do in response to decrease in core temperature or environmental temp
Posterior Hypothalamus causes heat production behavior (goosebumps)
Adipose does what when it comes to heat And how is it in infants
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)
Using energy for metabolism and other body functions causes
A LOT of heat,
How is heat produced specifically
ANS (sympathetic) Endocrine (Thyroxine, Epinephrine) 1. Muscle activity (voluntary and shivering) 2. Thermogenesis like (increase metabolism not due to muscles Ex: brown adipose, Hs)
Shivering signal is from where Involuntary muscle movement
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
Increase voluntary muscle movement for heat is from where and how
Post. Hypothalamus signals ——> cortex ——> jumping, running
Non-shivering thermogenesis happens how and where
- Thyroxin increases metabolic rate (cold stimulates TRH) Epinephrine 2. Food intake= increase metabolism 3. Brown adipose = stimulated by ANS
How does brown adipose make heat
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
Heat loss types
Evaporative Convection Conduction Radiation
Evaporative Heat Loss
Energy(heat) lost at water evaporates INSENSIBLE: Panting(breath in cold air), CONTROLLED: sweating, only at right conditions
Convection Heat loss
Molecules move away from contact Hot Air raises away from the body
Conduction heat loss
Heat transferred form objects in contact
Radiation hear loss
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)
How we control heat loss in our bodies
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)
How does sweating occur and one good thing about it
Evaporative heat loss It works in all environments when the body is colder then outside even
Innervation to the sweat glands
Sympa cholinergic ——> ACH binds to muscarinic receptor
Coiled region of sweat gland
Start sweat production = sweat gland
Duct to skin of sweat gland
Modifies sweat as it goes on Depending on how fast and much sweat you need H2O and Na+ flows back to the blood
How sweat is made
- 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
Low flows rate for sweat (I am warm)
Resbsorb ALOT of water Not Na+ (Can cause high NA+ loss) (SWEAT= low H2O, high Na+)
High sweat flow rate (I am really hot)
Aldosterone causes high Na+ reabsorption (SWEAT= high H2O, low Na+)
Aldosterone function
Increase Na+ reabsorption in sweat gland duct Increase K+ secretion from urine
PT comes in with 33C core temperature Core< set point (36C) What is happening inside her body
trigger heat production 1. Non-shivering thermogenesis 2. Shivering 3. Blood moves away from skin (pale)
Patient high fever , he is 40F, What is the fever (what happens)
CONTROLLED increase in body temperature Hypothalamus increased the set point for the core body temp. Body acts accordingly
What triggers fever
Pathogen= secretion of endotoxins Immune Cells= release cytokines PROSTAGLANDIN EP3 This increases the set point by the hypothalamus
When fever is about to break
Body temperature > set point You sweat , conduction convection, pant
I feel hot
Body temp> set point
I feel cold
Body temp < set point
Hyperthermia vs Fever 1. Set point 2. Thermoregulation response 3. Signs 4. Perception 5. Cause
Core temperature in increase for both Set point > body - fever Body> set point - hyperthermia Hyperthermia= dehydration can be a cause
How does hypothalamus send signal for ANS
Paraventricular Nucleus (of hypothalamus) ——-> 1. Dorsal motor nucleus of vagus 2. Nucleus Ambiguous 3. Parasympathetic and Sympathetic neurons in spinal cord
Inflow to Hypothalamus for ANS stimulation
- DLF (dorsolateral fasciculus) 2. Medial forebrain bundle (from nucleus tractus solitaries) -visceral thermoreceptors 3. Mammillotegmental tract —> hypo—-> mammillary bodies—> ANS
