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60 Cards in this Set

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Homeothermic temperature regulation is achieved through...
precise balancing of heat production, heat conservation and heat loss.
Normal temperature ranges are (F & C)
97.2-99.9 F

36.2-37.7 C
Daily normal variations in temperature (each 24 hr cycle)is known as...
Circadian rhythm
How is temperature regulated?
-Hormonally by the hypothalamus
-Peripheral thermoreceptors in the skin
-central thermoreceptors
-spinal cord, abdominal and other organs provide the hypothalamus with info about skin and core temp.
Name the series of hormones involved in the heat producing mechanism of the hypothalamus.
-Hypothalamus-TSH-RH
-Anterior pituitary-TSH
-Thyroid gland-thyroxin (T4)
-T4-adrenal medulla
-Adrenal medulla releases epi
-Epinepherine causes vasoconstriction, stumilates gycolysis and increased metabolic rates
-RESULTS: HEAT PRODUCTION
(that's alot, but I knew you could do it!!)
The hypothalamus triggers heat conservation 2 ways, How?
1. Stimulates the sympathetic nervous system which results in increasing skeletal muscle tone, shivering and vasoconstriction

2. Relays infor to the cortex to provoke cold awareness and cause voluntary responses (put on a sweater)
Mechanisms of heat production are...
-metabolism
-skeletal muscle tone and contraction
-chemical thermogenesis
-then distrobuted through the circulatory system
Chemical reactions of metabolism are responsible for...
Maintenance of core temp
How do skeletal muscles produce heat? (2 ways)
1. gradual increase in muscle tone
2. rapid muscle oscillations (shivering)
Results in the release of epi and produces rapid transient increase in heat production by raising the metabolic rate.
nonshivering thermogenesis
Does chemical thermogenesis through epi produce a brief or prolonged increase in basal metabolism?
Brief
Thyroxine also increased basal metabolism is this function rapid or slow?
causes a slow and prolonged increase in basel metabolism.
What is the function of the brown adipose of newborns?
maintains body temperature
Why is brown adipose important in helping the newborn to maintain their body temp?
Because newborns lose more heat throug conduction and convection than they are capable of generating.
9 mechanisms of heat loss
List as many as you can (smile)
1. radiation
2. conduction
3. convection
4. vasodilation
5. decreased muscle tone
6. evaporation
7. increased respiration
8. voluntary measures
9. adaptation to warmer climates
Body loses heat to the air is an example of....
Radiation
heat loss by direct molecule to molecule tranfer from one surface to another is considered....
Conduction
transfers heat through currents of gases or liquids is considered...
Convection
heat loss through vasodilation is regulated by...
The hypothalamus
What mechanism catagory does perspiration fall under?
evaporation
What are 2 mechanisms of heat conservation?
1. Involuntary vasoconstriction: keeping blood away from periphery
2. Voluntary mechanisms to bundle up, keep moving and "curl up in a ball"
What are 2 reasons why infants exhibit poor heat conservation.
1. Greater body surface area for heat loss.
2. Thin layer of subcutaneous fat.
What are some reasons elderly people have difficulty regulating body heat.
-poor response to the environmental temp
-slowed circulation
-changes in structure and function of skin
-decreased shivering response
-slowed metabolic rate
-decreased vasoconstriction
-diminished or absent sweating
-desynchronization of circadian rhythm
-decreased perception of heat and cold
In thermoregulation what does "set point" refer to?
The level in which the hypothalamus and brain stem adjust heat production, conservation and loss to maitain body core temp
What happens to the "set point" during a fever?
The thermoregulation centers adjust to function at "new set point"
What are some benefits of fever?
-kills microorganisms
-interfers with bacteria/viral replications
-causes lysosomal breakdown and phagocytosis. ( to name a few)
When should one treat a fever?
if fever is high and produces serious side effects such as nerve damage or convulsions.
Will children exhibit higher or lower temps compared to adults for minor infections?
Higher
At what temp is there a danger of febrile seizures in children?
39 C or 102.2F
At what temp is the a danger of seizures in a adult?
41 C or 105.8 F (Do people really live to see this?)
At what temp does death occur?
43C or 109.4 F
What can hyperthermia cause?
nerve damage, coagulation of cell proteins, convulsions and death
What are 4 forms of accidential hyperthermia?
heat cramps, heat exhaustion, heat stroke and malignant hyperthermia
Is hyperthermia caused by pyrogens?
No, and there is no resetting of the set point.
What happens during heat exhaustion?
Person collapse as a result of prolonged high core or environmental temp.
-hypothalamus responds with vasodialtion and profuse sweating
-dehydrates, hypotension, decreased CO, tachycardia.
A potentially lethal result of a breakdown in control of an overstressed thermoregulatory center.
Heat Stroke
How does the thermoregulatory center respond to cool the brain for temps >104.9.
The brain shunts maximal blood flow through the veins of the head, face and forehead to produce sweat and induce evaporation to promote cooling.
A potentially lethal complication of a rare inheritied muscle disorder precipitated by the administration of volatile anesthetics and neruomuscular agents.
Malignant hyperthermia
Malignant hyperthermia is caused by...(pathophysiology)
Either increased calcium release or decreased calcium untake with mucsle contraction allowing calcium levels to rise, producing sustained uncoordinated muscle contractions.
Why does the temp increase during malignant hyperthermia?
Increased muscle work, oxygen consumption, and lactic acid production resulting in acidosis and increased temp.
How fast does the temp rise in malignant hyperthermia?
1 C (1.8F) every 5 minutes.
What are some of the sympathetic responses to malignant hyperthermia?
tachycardia, cardiac dysrhythmias, hypotension, decreased cardiac output, and eventually cardiac arrest.
What other CNS changes can occur during malignant hyperthermia?
flat line EEG (BIS monitor),fixed pupils, absent reflexes, unconsciousness.
What is the treatment for malignant hyperthermia?
-DC agents
-give dantrolene sodium (skeletal muscle relaxant that inhibits calcium release during muscle contraction)
-Pronestyl for cardiac dysrhymias
-NaHCO3
-cooling blankets and iced saline lavage.
This condition can cause vasoconstriction, increased blood viscosity, coaguation and ischemic tissue damage.
Hypothermia
Temperatures < ? are considered to be hypothermic?
below 35 C (95F)
How does the body respond to acute hypothermia?
-peripheral vasoconstriction
-shunts blood to the core
-intermittent reperfusion of extremities (lewis phenomenon)
-intermittent reperfusion continues until core temperatures drop.
-hypothalamic center stimulates shivering until core temp drops to about 30C-32C (86-89F)
Passive rewarming includes...
-provision of warm, dry clothes
-warm drinks
-isometric exercises
Active rewarming includes...
-warm baths
-warm blankets
-heating pads
-warm oral fliuds
At what temperature is active warming employed?
Core temp at or below 30C (86F).
How can core rewarming be accomplished?
-warm IV fluids
-warm gastric lavage
-warm peritoneal lavage
-inhalation of warm gas
-exchange of transfusions (extreme casee)
-warming blood in a pump oxygenator circuit
-mediastinal lavage
What are the benefits of therapeutic hypothermia?
-preserve ischemic tissue
-slowed metabolism
-preserve ATP
What are 4 rewarming complications that can occur with accidental hypthermia?
-Acidosis
-rewarming shock
-deep-ended hpothermia
-dysrhythmia
A sustained temperature that is highly resistant to antipyretics and caused by CNS damage is known as?
Central fever
Hemorrhagic shock is associated with decreased core temperatures?
True or False
True
Hypothermia can be caused by major surgery?
True or False
True
What are some unintentional causes for induce hypothermia during surgery?
-exposure of body cavities
-irrigation of body cavities with room temp solutions
-room air temp IV infusions
-some drugs impair thermoregulatory mechanism
-unwarmed inhaled anesthetics
How can unintentional surgical induce hypothermia be avoided?
-use warmed irrigants and IV solutions
What causes the loss of the skin barrier to fluid evaporation & loss of control of the microcirculation in the skin that results in hypothermia.
Thermal burns
Core temperatures are thought to be inversely related to the severity of an injury.
True or False
True