Unit 3 - Section 1 - Commentary - Temperature Flashcards
Signs of heat exhaustion
Mildest form of heat stress:
- Faintness
- Nausea
- Vomiting
- Headache
- Restlessness
Replacement of lost water and sale, with rest, will cure heat exhaustion
Define ambient environment
- Refers to features, properties, or characteristics of the immediate physical environment that surrounds us in any particular setting
- Include temperature, light, and sound
Heat Stroke
Most serious form of heat stress
- Confusion
- Staggering
- Headache
- Delirium
- Coma
- Eventually, death
The sweating mechanism has broken down (the absence of sweat distinguishes it from heat exhaustion) and immediate cooling, such as immersion in ice water, is necessary for survival
Hypothermia
- Lowering of the body core temperature
- As core body temperature approaches 32C, shivering is replace by muscular rigidity, confusion, and eventually, loss of consciousness.
- If warmth is not restored, coma and death from heart attack follow below a core temperature of about 25C
List the factors that influence the impact of personal thermal stress
Factors that influence the impact of
What is ambient air temperature?
The air temperature of the immediate surroundings
What influences our perception of ambient temperature?
- Air temperature
- Humidity
- Air velocity
- In general, high humidity makes temperatures seem hotter than they actually are
- Air movement increases comfort through the cooling effect of evaporation
Body reactions to cold temperatures
- Loss of manual dexterity and tactile sensitivity
- Increase in reaction time
- Takes longer to complete tasks
What is acclimatization?
Increased physiological tolerance after continued exposure to high or low thermal environments.
How does acclimatization influence a person’s response to temperature?
- Some thermal acclimatization may emerge from a genetically inherited ability to tolerate thermal extremes
- We can acclimatize to one or more environmental factors as with changing seasons, or exhibit diminished central nervous system reactivity to a particular stimulus
- Acclimatization takes a couple of days and is supplemented by behavioural adjustment such as changing clothes and changes in diet
What happens with prolonged exposure to high ambient temperatures?
- Acclimatization achieved in 4 - 7 days
- Primary consequence of acclimatization to heat is increased sweating efficiency, the classic pattern is one of reduced discomfort, reduced heart rate, reduced body temperature, and higher volume of sweat with reduced concentration of salt
- Daily exposure of an hour or so is adequate to achieve acclimatization
- The better physical condition one is in, the faster the acclimatization is achieved
Value of black skin
- Pigment provides some protection from sunburn and from overexposure to ultraviolet light
- Pigment increases skin temperature by increasing the absorption of heat, which promotes sweating
- Acclimatized Europeans showed the same response to heat as native Africans, including initial sweating at the same temperature, equivalent rates of sweating, and similar low salt content in the sweat
What influence does high and low body temperature have on heat tolerance?
- Lower body temperatures = more tolerant of heat
- High body temperatures associated with low maximum oxygen intake
What is a modal comfort envelope (MCE)?
A range of ambient conditions that will provide comfort for most people
What are the physical and personal factors that influence personal thermal comfort?
- Air temperature
- Radiant temperature - heat sources in the environment - computers, stove, machinery, etc.
- Air velocity - speed of the air moving over a person
- Humidity - if water is heated and it evaporates to the surrounding environment, the resulting amount of water in the air will provide humidity
- Clothing insulation - synthetic versus natural fabrics? Wicking fabrics?
- Metabolic heat - the heat we produce inside our bodies as we carry out physical exercise