Lecture 2: Skin and Temperature Regulation Flashcards
State the normal core body temperature
37 degrees +/- 0.5
State some factors which can vary the body temperature
External body temp
Activity
Circadian rhythm
Menstrual cycle
State the mechanisms that maintain the core temperature
- Radiation
- Evaporation (resp and sweating)
- Convection
- Conduction
How are temperature changes detected
Warm receptors
Cold receptors
Location of thermoreceptors
Peripheral thermoreceptors:
Skin, scrotum
Central thermoreceptors:
Spinal cord, abdominal organs, hypothalamus
Where is the thermoregulatory centre locatored
Hypothalamus
Describe the physiological response to cold stress
Heat generation:
General metabolism
Voluntary muscular activity
Shivering thermogenesis
Nonshivering thermogenesis: brown adipose tissue in infants
Reducing heat loss:
Vasomotor response control- sympathetic arteriolar constriction
Behavioural responses- putting on warm clothes, moving to warmer environments
Describe the pathophysiology of frostbite
Vascular:
- Reduced blood flow
- Increased blood viscosity
- Promotion of thrombosis
Cellular:
- Ice crystals form in the extracellular space
- Increases the extracellular osmolality
- Causes movement of water from the intracellular space
- Cell death
Describe the physiological response to heat stress
Decreased physical activity Decreased food intake Vasodilation Sweating Behavioural responses
Explain the difference between heat exhaustion and heat stroke
Heat exhaustion:
37.5-40 degrees
Increased vasodilation causes a drop in central blood volume
Disturbance in salt/fluid balance due to excessive sweating
Symptoms: weak pulse, hypotension, clammy nausea, headache, confusion, profuse sweating, fainting and collapse
Heat stroke:
Body temp raised above 40
Control mechanisms fail
Symptoms: dry hot & circulatory collapse
What is a fever
Part of bodies mechanism for fighting infection
Caused by endogenous pyrogens (IL-1, IL-6)
They change the set point in the hypothalamus via the production of prostaglandins by cyclo-oygenase