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托福阅读材料：夏日中暑heatstroke急救的相关知识(上)
What is heatstroke?
Heat exhaustion is a collection of symptoms brought on as the body struggles to control its temperature. Left untreated, heat exhaustion can progress to a more severe form known as heatstroke.
The body normally uses several mechanisms to cool itself down, including directing more blood to the skin and by sweating. Everyone sweats. Most people lose more than a litre of sweat a day. In hot weather or during exercise, when the muscles generate large amounts of heat, they sweat even more heavily - losing large amounts of water and salts. If the body loses too much liquid or salt, the symptoms of heat exhaustion develop.
If someone with heat exhaustion continues to be exposed to high temperatures, the more serious and life-threatening condition of heatstroke may develop.
In this situation, the body becomes dangerously dehydrated. Its cooling mechanisms malfunction and are no longer able to assist the body in losing enough heat, so the body temperature starts to rise.
Symptoms
The symptoms of heat exhaustion include:
* Excess sweating
* Nausea and vomiting
* Feeling light-headed/faint
* Tiredness
* Headache
* Muscle cramps
With heatstroke, the temperature of the body rises and the following symptoms may occur:
* Confusion
* Disorientation
* Rapid and shallow breathing
* Fits (seizures)
Causes and risk factors
Anyone can develop heat exhaustion and heatstroke, although some people are more at risk than others. These include:
* Small babies, children and older people, who have less efficient body cooling systems.
* People suffering from diarrhoea, who are more likely to become dehydrated.
* People from cooler climates who travel to hotter climates, as it may take a while for their bodies to get used to the heat. Being in areas of high humidity also increases a person's risk, as this reduces the efficiency of sweating and decreases the amount of heat lost from the body.
* People with certain medical conditions that reduce the efficiency of the body's cooling mechanisms. For example diabetes, obesity and chronic heart failure.
* Those who drink excessive amounts of alcohol, which dehydrates the body.