Heatstroke

A heat victim being rehydrated in hospital

The dangers of sunstroke and dehydration occasionally lead to tragedy, even in the less powerful heat of the British summer, and very young children are particularly vulnerable. BBC News Online looks at effects of intense heat on the human body.

Sunstroke, or heatstroke, is an illness caused by prolonged exposure to very hot temperatures or dehydration.

It can also be caused if the body's own temperature regulation mechanisms fail to work properly.

Even a rise of a couple of degrees from the body's normal temperature can have profound effects on the way the metabolism works.

Very often a human exposed to very hot temperatures can suffer first from heat exhaustion, which manifests itself as dizziness, fatigue, a headache, rapid pulse, rapid breathing, and muscle cramps.

The warning signs that this is becoming the potentially fatal sunstroke are hot, flushed skin, no sweating, a high body temperature, confusion, and loss of consciousness.

Body cannot cool itself

Exposure to extreme heat can cause a breakdown in the body's ability to reduce its own temperature through sweating, and body temperature can reach as much as 107F.

If the body is dehydrated and cannot cool the skin through sweat evaporation, this compounds the problem.

This can cause the failure of many of the body's vital systems, such as the heart, lungs, kidney and brain.

The sufferer can fall into shock and unconsciousness.

However, the more rapidly treatment is given, the more likely a full recovery is to be made.

The sufferer should be cooled down as quickly as possible, perhaps by putting them in a cold water bath - and then taken straight to hospital.

If the symptoms of heat exhaustion are present, but the person involved is still sweating, drinks should be given, but not salt pills.