How does sunstroke destroy the body minute by minute, leading to death?

During the summer, many tend to spend more time outdoors for longer periods, but hot weather is actually as dangerous as it is exhilarating.

With record high temperatures during this period, experts warn of the dangers of fatal heatstroke, which can begin to develop after just 10 minutes of sitting outdoors, which can cause “complete loss of body functions” and even death.

Here's exactly what happens in the average person's body from the moment they step out into the scorching heat to the worst-case scenario of heatstroke:

Within one minute

As soon as you step outside, exposed skin is exposed to the sun's rays, and you'll likely start sweating immediately, which is the body's way of cooling itself.

When the body senses high temperatures, the hypothalamus, the part of the brain that regulates temperature, tells glands on the skin to secrete sweat.

Sweat, which is mostly water, but contains small amounts of humectant salt, removes heat from the body and cools it when it evaporates on the skin, said Dr. Zachary Schleder, a professor in the department of kinesiology at Indiana University School of Public Health. However, humidity makes it difficult for sweat to cool us, and being outside in very high temperatures results in more fluid loss than the body can keep up with.

Two minutes later

In extreme heat conditions, sweat can evaporate from the skin in less than two minutes, as the body cannot produce enough sweat to cool the body in time.

In an attempt to keep up, the body begins a process called vasodilation, in which blood vessels open and blood flow to the skin increases.

This may prolong the sweating for a few more minutes, after which the sweating usually stops.

5 to 10 minutes

“The heart will start beating faster within five minutes,” says Dr. Christy Ziontz, president and medical director of emergency medicine at Hackensack Meridian Bayshore Medical Center in New Jersey. This is because when blood flow is redirected to the skin, it moves away from other vital organs such as the heart, blood pressure drops, and the heart is forced to pump harder.

“Other places, such as the brain, do not receive blood,” she noted. As blood leaves the brain and travels to the skin, an individual suffering from heatstroke may experience symptoms such as dizziness and confusion and may be at risk of fainting.

The process of drawing blood away from vital organs is called vasoconstriction. “This vasoconstriction is thought to be one of the triggers, which eventually starts a cascade that can turn into heatstroke,” according to Dr. Schleder.

10 to 15 minutes

According to the Centers for Disease Control and Prevention, 10 to 15 minutes is when heat stroke actually begins, unless you take vital steps such as drinking water and electrolytes such as sports drinks, limiting direct exposure to sunlight, and avoiding strenuous activities such as exercise.

But if you find yourself without water or a shaded area, at this stage, blood and oxygen can be drawn away from the intestines, making it more vulnerable, as toxins and bacteria that normally remain in the intestines seep out and enter the bloodstream, which leads to the activation of cells. White blood, according to Dr. Schlader.

When white blood cells attack the contamination, blood clots form, rapidly increasing the risk of multi-organ failure.

After more than 30 minutes

“There is a complete failure of body functions,” Dr. Ziontz explains, and at this point, the body’s internal temperature reaches 41 degrees Celsius (106 Fahrenheit).

Doctors compare this chain of events to sepsis, the body's overreaction to an infection that can lead to complete organ failure.

Doctors noted that it is difficult to determine the order in which organs stop working, but at this stage, seeking emergency care is necessary to reverse the damage.

The patient may suffer from rhabdomyolysis (a disorder that occurs as a result of the severe breakdown of muscle cells, causing the release of their contents into the bloodstream), muscle breakdown and possible death.

According to the Centers for Disease Control, when muscle tissue dies, electrolytes and proteins are released into the bloodstream, causing irregular heartbeats, seizures, and kidney damage.

In addition, heat can cause cell membranes to break down and release potassium into the bloodstream. High levels of potassium can interfere with electrical signals in the heart and even cause cardiac arrest and death, according to doctors.

If a person suffering from heatstroke is about to receive emergency care, doctors immediately begin working to cool him or her down.

Dr. Ziontz estimates that it takes about a day or two of recovery time in the hospital for the patient to fully recover.