Physiology of thermoregulation

explain core temp and skin temp and their changes

core temp remains stable and protects the functions of the internal organs

skin temp rises and falls with the surrounding temperature

What is considered a fever for adults and children

adults: 99.9F

children: 100.4F

How does body temp change throughout the day?

it is lowest in the morning and increases throughout the day and late afternoon

• this must be taken into account when determining if someone has a fever or not

How does sex, age, weight, and height affect body temp?

sex: higher temp in women

age: body temp decreases with age (little old ladies be cold)

weight: higher temp with higher weight

height: lower temp with taller height

explain heat exchange with the environment:

conduction, convection, radiation, and evaporation

conduction: tranfer heat through direct contact

convection: lose heat through movement of air or water (like an oven)

radiation: transfer heat through electromagnetic waves

evaporation: lose heat through water evaporation (sweating)

explain the idea behind a basal/resting metabolic rate

heat is produced by your metabolism literally doing nothing special like exercising, just by keeping your organs functioning

this is why you burn calories throughout the day even when you are watching tv on the couch

metabolic rate is proportional to _____

how does infancy, pregnancy, and gender affect metabolic rate?

proportional to body surface area

metabolic rate is highest in infancy (to sustain growth)

metabolic rate is high in pregnancy (to sustain fetal growth)

metabolic rate is higher in males even if they are the same height and weight as a female

metabolic rate and catecholamines, thyroxine, and progesterone

catecholamines: pheochromocytoma (weight loss and heat intolerance)

thyroxine

• hyperthyroidism: weight loss, heat intolerance

• hypothyroidism: weight gain, cold intolerance

progesterone: increase in body temp after ovulation

explain the thermic effect of food

metabolic rate and body heat increase when you digest

fats and proteins increase it more than sugars/carbs do

explain heat production during external work and exercise

skeletal muscle becomes the main source of heat, and can increase metabolic rate up to 10 fold

working muscles can warm the blood by 1-2F

which one goes with what?

adrenergic and cholinergic

vasodilation and vasocontriction

adrenergic: vasoconstriction (you tense up with adrenalin)

cholinergic: vasodilation

explain the regulation of cutaneous blood flow when you are hot vs cold

hot = vasodilation → so more blood goes to the surface of skin and can be cooled by radiation

cold = vasoconstriction → so the warm blood stays in the core of the body (not the periphery) and keeps us warm

explain the two segments of the eccrine glands and their functions

bottom/deep part: coil (subdermal) that produces the primary secretion

top part: duct (in the dermis and epidermis) which reabsorbs the sodium and chloride ions that were in the primary secretion so they aren’t all lost to the sweat

swaet glands are innervated by the post-ganglionic ______ neurons

cholinergic sympathetic

explain the relationship of acclimation to heat, swaeting, aldosterone, and salt levels

more acclimated = more sweat BUT more aldosterone so = more salt reabsorption

less acclimated people will lose more salt with their sweat than acclimated people

skin thermoreceptors: describe them, what types, what’s more?

these are the free nerve endings in the skin that sense temperature in the environment

hot and cold receptors

there are more cold receptors than hot so we are more sensitive to cold

explain thermal sensing and how the skin thermoregulators work in tandem with the hypothalamic temperature-sensitive neurons

skin thermoreceptors sence a change in ambient temp and send info to the hypothalamic temperature-sensitive neurons so they can keep the core temp steady even as the environmental temp changes

explain chemical thermogenesis

brown adipose tissue (not white) produces heat and activates lypolysis → then this activates the mitochondria uncoupling protein 1 (UCP1) and there is uncoupling of the electrochemical proton gradient of electrochemical proton gradient and ATP synthesis → energy dissipates as heat

exaplin the shivering thermogenesis

you have an increase in basal skeletal muscle tone → involuntary clonic rhythmic contractions → mote neurons innervated

this can impair voluntary movements like talking or fine motor function becuase the shivering takes over

what is the hierarchy of the thermoregulatory response?

1st: behavioral responses (go inside, take off or put on clothes, etc.)

2nd: autonomic responses (swaeting, shivering, vasodilation or constriction

3rd: endocrine responses: hormones

explain fever, chills, and crisis

pyrogens (IL-1, IL-6, TNF, IFN) all increase the set point, so then we have fever and our set point threshold is higher so our body thinks that its normal is now too cold so we try to get warm and vasoconstrict → makes our skin cold so we shiver

then with crisis: we have the resolution of the fever, so the set point goes down, now our core knows that we are too hot and we get vasodilation and sweating (“fever breaks”)

What are the 3 major medications that she went over for fever?

corticosteroids (decrease the pyrogenic cytokines at the beginning)

antipyretics

dantrolene (inhibits shivering and heat production)