The Heat Flashcards
What are the basic physics of heat control?
Heat loss through evaporation of sweat
Heat exchange through convection with air/water
Heat exchange through conduction
Heat exchange through radiation
What happens when temperature rises above body temp
38 C Sweat rate increases Dehydration 40C Weakness, dizziness, sickness 41C Heat exhaustion 42C Heat stroke - damage to internal proteins Above 42 Death
Methods to measure core and peripheral temperature
Internal methods: Oesophageal/rectal thermistor Ingestible thermistor Aural thermistor (ear) External methods: Skin thermistor Infrared
What are some non environmental contributors to heat gains
Time of day - coldest in the night, caused by hormones eg. Cortisol
Different environments
Body heat production
Effects of humidity - amplifies effect of temperature
Central regulation of temperature
Increase in body temperature Detected by central and peripheral thermoreceptors Hypothalamus Increase sweat secretion Vasodilation Decrease in metabolic rate
What is heat exhaustion
Results from the bodys thermoregulatory mechanisms eg. Sweating
What is heat stroke
Results from failure to thermoregulate
Mechanisms stop
Symptoms of heat illness
Muscle cramps - mitochondria impaired Thirst Pale and cool skin - so much sweat Chills and goose bumps - upregulation of heat loss mechs Cessation of sweating
What is cardiovascular drift
Heart rate responds to exercise changes because of changes in temperature
During exercise in hot conditions body is conflicted to cool down muscle or skin
Real world applications of heat thermoregulation
Jobs with heat eg. Firefighters
Infant car deaths
Military training
Sports - acclimatisation
What are some short term strategies to compensate for changes in temperature?
Hand cooling
Remove heat stimulus
Changes with acclimatisation in heat
⬆️aldosterone secretion, increase NaCl reabsorption ⬆️ aldosterone sensitivity ⬇️hematocrit ⬆️ capillary perfusion ⬆️earlier onset of sweating ⬇️ core temp ⬆️capacity for work ⬆️comfort ⬇️reliance on carbs
What is thermal distribution like in hot environments
Right to the edge
Increase convective heat loss and sweating
