Thermoregulation Flashcards by Madeline Wing

fever in a cyclical pattern (on and off for days to weeks)

Pel-Ebstein fever

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disease that has Pel-Ebstein fever

Hodgkin lymphoma

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in patients with typhoid, do they experience tachycardia or bradycardia

bradycardia

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intermittent fever example (gaps between temperatures, but it does reach normal temp.)

Sepsis

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2 specific types of non-infectious fevers

vascular (ischemia, hemorrhage)
aseptic inflammation (not involved w. infection)

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what is the normal mid morning ORAL temperature

36.5-37.5 C
(97.7-99.5 F)

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2 things that having optimum body temperature facilitates:

integrity of membrane lipids
enzyme activity

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what balances heat production and heat dissipation

hypothalamus

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the hypothalamic neurons will read the change in temperature in the body and do what

increase or decrease neuronal firing to increase or decrease heat production/cooling

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2 things that will first sense change in temperature before sending information to hypothalamus

blood and skin

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core body temperature sensor

blood

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cold receptor on the skin

CMR1

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heat receptor on the skin

TRPVR1

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what happens after hypothalamus receives message about a change in body temperature

sends signals to organs

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skin arterioles receive message from hypothalamus and can either _____ or ______

constrict: to conserve heat (traps it)
dilate: to lose heat

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sweat glands receive message from hypothalamus and can do what

release sweat: lose heat

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the liver receives message from hypothalamus and activates what

non-shivering thermogenesis

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brown fat receives message from the hypothalamus and activates what

non-shivering thermogenesis

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muscles receive message from hypothalamus and activates what

shivering thermogenesis

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what happens when the set point is raised

need to heat the body to match the set point

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what happens when the set point is lowered

need to cool the body to match the set point

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first step to raise temperature to set point: (we get a fever)

prevent heat loss (vasoconstriction), skin cools to ambient temp., cold receptors activated, pt. feels cold and wraps in blanket

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second step to raise temperature to set point:(we get a fever)

shivering (generate heat from muscle)

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third step to raise temperature to set point: (we get a fever)

non-shivering (generate heat from liver)

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what happens when body temp. matches the raised set point

hypothalamus maintains fever (balancing act)

first step to lower temperature to set point: (when the fever quits)

1. increase heat loss (skin vasodilation), skin heats up to core fever temp, heat receptors activated, pt. feels hot

second step to lower temperature to set point: (when the fever quits)

2. lose heat by evaporation of sweat

what happens once body temp. matches the lowered set point

hypothalamus maintains normal body temp. (balancing act)

what does shivering do

traps heat

what does sweating do

releases heat

a fever of >41.5 C (>106.7F); increased temperature set point

hyperpyrexia (fever)

overheated body exceeding heat loss capacity; normal temperature set point

hyperthermia (no fever)

when skin temperature is >30C, what happens

preoptic warm-sensitive neuron is fired from hypothalamus and leads to heat loss

when skin temperature is <24C, what happens

preoptic cold-sensitive neuron is fired from hypothalamus and leads to heat retention and generation

what kind of cytokines produce fever

pyrogenic

pyrogenic cytokines (4 main ones)

IL-1, IL-6, and TNF-alpha, INF-gamma

what induces the synthesis of PGE2

pyrogenic cytokines

an increase in PGE2 in the periphery leads to what

muscle and joint pain w/ fever

myalgia

muscle pain

arthralgia

joint pain

an increase in PGE2 in the hypothalamus leads to what

fever

humoral control of increased set point: 4 steps

1. macrophages in blood vessel produces IL-1 (pyrogenic cytokine) 2. IL-1 induces PGE2 to be made and binds to EP3 on astrocyte 3. EP3 decreases production of cAMP leading to decreased firing of preoptic warm-sensitive neuron 4. decreased firing leads to increased set point

these molecules are against raising the temperature

antipyretics

what 2 things have very tight junctions

brain (think blood-brain barrier) and retina

what organ has fenestrated capillaries that deals with lots of exchange

kidney

what 2 things have sinusoidal capillaries (whole cells can pass through)

liver, bone marrow

what causes polarity of cells

tight junctions

sensory organ in the hypothalamus that is circumventricular (allows cytokines to pass through)

OVLT

this hypothalamic nucleus contains warm-sensitive neurons and allows access to pyrogens (deals with non-shivering)

preoptic nucleus

this hypothalamic nucleus receives information from pyrogens (deals with shivering)

posterior nucleus

this specific anastomoses in the skin causes vasoconstriction and vasodilation

glomus bodies

this happens when acetylcholine binds to M3 on sweat gland

sweating

this happens when norepinephrine binds to alpha1 in vascular smooth muscle

vasoconstriction

this happens when norepinephrine binds to beta2 in vascular smooth muscle

vasodilation

what neuron causes the main big muscle to contract

alpha

what neuron takes over when alpha neuron caused big muscle to contract

gamma

gamma neuron causes what to contract

muscle spindle

4 steps to host defense response to inflammation and infection:

1. macrophages produce pyrogenic cytokines (IL-1, IL-6, TNF-alpha) 2. immune response: activation of neutrophils, macrophages, and lymphocytes 3. acute phase response: liver produces fibrinogen, CRP (helps w/ phagocytosis) 4. fever

used to treat fever by blocking activation of PGE2

NSAIDs (acetaminophen)

what drug is contraindicated in thyrotoxic storm by leading to increase of free T4

aspirin

leads to increase in Na/K ATPase and increase expression of uncouplers (UCPS) of protein gradient

increase in T3

an increase in T3 ultimately leads to what loss

energy lost as heat

does not involve increase in the set point; NSAIDs don't work to treat this

hyperthermia

released/absorbed heat produces this if heat dissipation mechanisms are overwhelmed

hyperthermia

activity of ATPases and UCPs increase what process

thermogenesis

2 main CAUSES of hyperthermia

heat stroke (decreased sweating) malignant hyperthermia (RyR mutation)

what do you not treat hyperthermia with

aspirin (exacerbate bleeding) or acetaminophen (metabolizing by deranged liver)

stages of hyperthermia (3)

heat stress heat exhaustion heat stroke

3 main signs of heat stroke

CVS collapse CNS abnormalities temp. >40C

receptor mutation leading to malignant hyperthermia

ryanodine

what drug is used to inhibit mutated RyR (ryanodine receptor) to alleviate burden of SERCA and stop hyperthermia from happening

Dantrolene

Thermoregulation Flashcards

(71 cards)