Patho (temperature)

Q: What are the three main processes of thermoregulation?

A: Heat production, heat conservation, and heat loss .

Q: What factors affect body temperature variation?

A: Location (core vs extremities), activity level, environment, circadian rhythm, and gender .

Q: Which part of the brain is the body’s thermostat?

Hypothalamus

Q: What are peripheral thermoreceptors, and where are they located?

A: Sensors in the skin, liver, and skeletal muscle that detect external temperature .

Q: What are central thermoreceptors, and where are they located?

A: Sensors in the hypothalamus, spinal cord, and viscera that monitor internal/core temperature .

Q: What produces heat in the body?

A: Chemical reactions of metabolism, skeletal muscle tone/contraction, and chemical thermogenesis (like hormone-triggered activity in brown fat, especially in infants) .

Q: How does the body conserve heat?

A: Vasoconstriction (narrowing blood vessels), shivering (involuntary muscle contractions), and voluntary actions like putting on warm clothes .

Q: How does the body lose heat?

Radiation (infrared waves to environment)

Conduction (direct transfer to cooler surface)

Convection (moving air/water carries heat away)

Vasodilation (blood vessels widen to release heat)

Evaporation (sweat turns into vapor, taking heat with it)

Decreased muscle tone & increased respiration

Voluntary behaviors (like shade, lighter clothes)

Body lose heat: radiation

infrared waves to environement

body lose heat: conduction

direct transfer to cooler surface

body lose heat: Convection

moving air/water carries heat away

body lose heat: Vasodilation

Blood vessels widen to release heat

Body lose heat:Evaporation  

sweat turns into vapor, taking heat w/ it

Body lose heat: decreased muscle tone & ?

increased respiration

Body lose heat: Voluntary behaviors

like shade, lighter clothes

Q: Why does rubbing your arms or sitting in a breeze cool you?

A: It activates conduction (direct transfer) or convection (moving air/water taking heat away).

Q: Why are elderly people more vulnerable to heat and cold?

• Slow circulation & skin changes

• Less heat-producing activity

• Lower shivering & sweating response

• Lower metabolic rate

• Reduced vasoconstriction

• Less awareness of hot/colD

Q: What causes fever?

A: Resetting of the hypothalamic thermostat to a higher level, triggered by exogenous pyrogens (bacterial toxins) or endogenous pyrogens (cytokines from immune cells like IL-1, IL-6, TNF) .

Q: What is “fever of unknown origin”?

A: A fever lasting more than 3 weeks with no clear diagnosis .

Q: Benefits of fever?

• Kills many microorganisms

• Lowers iron, zinc, copper (starves pathogens)

• Promotes lysosomal breakdown of infected cells

• Increases WBC activity (lymphocytes, phagocytes)

• Boosts antiviral interferon productio

Q: How is hyperthermia different from fever?

A: Fever = hypothalamus resets thermostat;

hyperthermia = uncontrolled rise in body temp without hypothalamic reset .

Q: What damage can hyperthermia cause?

A: Nerve injury, coagulation of proteins, death .

Q: What is therapeutic hyperthermia?

A: Controlled heating (local, regional, or whole-body) to kill microorganisms or tumor cells .

Q: Types of accidental hyperthermia?: Heat cramps

muscle cramsp from sodium loss due to sweating

Q: Types of accidental hyperthermia?: Heat exhaustion

Dehydration, vasodilation, sweating → dizziness/fainting

Q: Types of accidental hyperthermia?: Heat stroke

Temp >40C (104F), life-threatening; body cannot lose heat

Q: Types of accidental hyperthermia?: Malignant hyperthermia

Genetic reaction to anesthesia causing muscle contractions and lactic acid buildup

Q: What temperature defines hypothermia?

A: Core body temperature <35°C (95°F) .

Q: What happens in hypothermia?

A: Nervous & respiratory system depression, vasoconstriction, clotting changes, ischemia, and in severe cases → ice crystals form inside cells, causing rupture & death .

Q: What is tissue hypothermia?

A: Cold damages tissue by slowing metabolism, thickening blood, promoting clotting, and restricting circulation .

Q: What is therapeutic hypothermia used for?

A: To slow metabolism and protect tissue during surgery, cardiac arrest, or limb reimplantation .

Q: What causes accidental hypothermia?

A: Cold water immersion, prolonged cold exposure, or poor thermoregulation .

Q: What is central fever, and how does it differ from infectious fever?

A: Fever from CNS trauma (like head injury or increased intracranial pressure). It does NOT cause sweating and is resistant to antipyretic (fever-reducing) drugs .

Q: What traumas can alter body temperature regulation?

A: Accidental injuries, hemorrhagic shock (blood loss), major surgery, and thermal burns .