Thermoregulation Flashcards
core temperature regulated by…
hypothalamus/preoptic area
3 processes that regulate temperature
shivering - increase temp
sweating - decreases temp
vasoconstriction - increase temp/conserve heat
3 main parts for body temperature regulation
- sensors
- hypothalamus
- effector system
where are the most sensors for temp regulation located in the body?
skin
-more for cold than warmth
Factors for affecting heat production
- BMR
- Muscle activity
- thyroxine output
- fever
- epinephrine, norepinephrine, stress response
BMR
minimal amount of energy to sustain vital processes; changes throughout the day
muscle activity
increases BMR; muscles burn energy at rest
thyroxine output
hormone release by thyroid; metabolism
fever
raises BMR, therefore…heat
4 heat transfer processes
- radiation
- conduction
- convection
- evaporation
radiation
NO physical contact
heat transfer through electromagnetic waves
Ex: sunlight, warming hands by fire
conduction
transfer heat through direct touch
PHYSICAL CONTACT
convection
heat transfer in gas or liquid
Ex: hot air balloon
evaportation
liquid changes to a gas;
Ex: sweat evaporating on skin, boiling kettle of water
febrile response phases
chill and flush
chill phase
body warms itself to raise core temp to new set point.
-warms itself by peripheral vasoconstriction, shivering, warmth-seeking behaviors
“brain sets thermostat to high temp to inhibit growth - now the body does the work to get it there.”
flush phase
body cools itself
-cools itself by peripheral vasodilation, sweating, cool-seeking behavior
“brain sets thermostat to lower temp to return to homeostasis - now the body has to do the work to lower temp”
benefits of fever
- protective mechanism
- enhances neutrophils & t-lymphocytes
- slows growth of bacteria and viruses
- may slow growth of certain tumors
- may act synergistically with penicillin
- early exposure to fevers caused by infections may protect children from asthma, allergies, and cancer in adulthood
neutrophils
WBC that fights bacteria
t-lymphoctyes
WBC that fights viruses
hyperthermia
- body temp increases uncontrollably
- brain damage and death can occur
- delirium, convulsions, coma
- heat stroke/heat exhaustion
- may be due to neurological impairment/brain injury
malignant hyperthermia
rare response to anesthesia, can be deadly or inherited
-can be screened for genetic risk
hypothermia
excessive loss of heat
-inadequate heat protection, impaired hypothalamic thermoregulation, vasoconstriction and tissue ischemia
vasoconstriction for extended period of time….
ischemia or gangrene
fever is controlled by…
hypothalamus
fever and death/brain damage…
fever very rarely causes brain damage or death. however it can adversely affect critically ill patients
antipyretics
used to prevent or reduce fever.
Types of antipyretics
- acetaminophen
- ibuprofen
- naproxen
- aspirin
acetaminophen
tylenol, tempra
- acts on hypothalamus by peripheral dilation
- liver damage with overdose
- can be given q4-6 hrs
- use with caution in liver disease
ibuprofen
advil, motrin
- NSAIDs
- inhibits prostaglandin
- q6-8 hrs OVER 6 mths of age
- use with caution with kidney disease
naproxen
- NSAID
- over the age of 12
aspirin
- ASA
- inhibits prostaglandin
- NEVER to a child (linked to Reye Syndrome)
newborn and thermoregulation
- less SubQ fat
- blood vessels closer to surface
- brown adipose fat
- premies have less brown adipose fat
brown adipose fat
non-shivering thermogenesis
children and thermoregulation
handle high temps well if healthy
elderly
- less SubQ fat
- less active
- sensitive to extremes in environment temp
- thermoregulation not as efficient
Types of Temperature Assessments
- mouth/oral
- rectum
- axillary
- tympanic membrane (ear)
- temporal artery
mouth/oral temp assessment
PRO:
-accessible, convenient
CON:
- can break
- inaccurate if ingested cold/hot liquid or smoked
- could injure mouth after oral surgery
rectum temp assessment
PRO:
-reliable measurement
CON:
- inconvenient, unpleasant
- difficult if patient can’t turn on side
- stool may interfere
- may be contraindicated in clients with cardiac problems
axillary temp assessment
PRO:
-safe and noninvasive
CON:
must be left in place for a long time
tympanic membrane
(ear) PRO: -readily accessible -reflects core temp -very fast -less scary for kids
CON:
- can be uncomfortable
- involves risk of injuring membrane
- repeated measurements can vary
- R/L can differ
- presence of cerumen can affect reading
temporal artery
PRO:
- safe and noninvasive
- very fast
- less scary for children
CON:
- requires electronic equipment that may be expensive or unavailable
- variation in technique is needed if client has perspiration on forehead
Culture & fever
- ethnic differences in parental management of fever
- fever phobia in many cultures, ethnic groups
hispanics and fever…
more likely to believe fever can cause brain damage and death
African Americans and fever…
more likely to over treat with ibuprofen and more concerned about febrile seizures
