Buzz
Tales of individuals enduring burning, freezing, and immense external pressure are widespread, but what truly occurs within the human body under such extreme circumstances?
10. The Impact of Acceleration
G-forces didn’t significantly impact humans until World War I, when pilots started inexplicably blacking out during flights. Thanks to the efforts of US Air Force officer John Stapp, we gained deeper insights into how g-forces affect the body, a discovery that required immense dedication and sacrifice.
Stapp exposed himself to forces reaching up to 35 g, equivalent to an acceleration of 343 meters per second squared (1,125 ft/s²). This caused his bones to fracture and his dental fillings to dislodge. However, he discovered that the most significant impact was on his blood circulation.
When acceleration occurs along a horizontal axis, the body handles g-forces relatively well since blood flow remains on the same plane. However, vertical g-forces pose a greater challenge. Beyond a certain threshold (typically 4 to 5 g for most individuals), the body struggles to pump blood effectively, causing it to pool in the lower extremities.
Negative g-forces create similar issues, disrupting blood flow and causing excessive blood to accumulate rapidly in one area. This is where g-force suits prove invaluable. Equipped with air bladders, these suits apply pressure to maintain proper blood circulation, preventing pilots from blacking out.
Stapp endured a final test where he accelerated to 1,017 kilometers (632 miles) per hour, came to a stop in one second, and momentarily weighed over 3,500 kilograms (7,700 pounds). He later passed away peacefully at home at the age of 89.
9. Pressure
Decompression sickness, often referred to as 'the bends,' occurs when the body experiences a rapid decrease in external pressure. This prevents blood from effectively dissolving gases such as nitrogen, causing them to form bubbles in the bloodstream. In extreme cases, these bubbles can cluster in blood vessels, obstructing circulation and leading to symptoms like dizziness, disorientation, or even fatality.
The less severe form, DCS I, typically causes joint pain and tissue inflammation. Divers frequently exposed to pressure changes may develop unnoticed cases of the bends, which can result in lasting joint damage. DCS II, the more dangerous form, can be fatal, with symptoms including vertigo, paralysis, and shock.
8. Cold
As the body’s temperature falls to around 30 degrees Celsius (86 °F), all physiological processes begin to slow. Initial signs include fatigue, uncoordinated movements, and delayed responses to external stimuli.
Thermoregulation, the body’s ability to regulate its core temperature, is one of the first systems to fail at approximately 30 degrees. The heart rate and lung function gradually decline, leading to oxygen deprivation. Simultaneously, the renal system collapses, releasing a diluted form of urine into the bloodstream and organs, which can trigger shock or cardiac complications.
The slowed metabolism and reduced strain on bodily systems allow some individuals to survive severe hypothermia and fully recover if they are warmed correctly.
7. Heat
Heatstroke occurs when the body’s core temperature exceeds 40 degrees Celsius (104 °F). Classic heatstroke develops gradually due to prolonged exposure to heat, such as during a summer heatwave. Exertional heatstroke affects individuals engaged in intense physical activity in hot environments, like industrial workers or athletes. Without treatment, only about 20% of victims survive, and many survivors experience some level of brain damage.
Humidity exacerbates the risk of heatstroke by preventing sweat from evaporating, hindering the body’s ability to cool down. When the core temperature reaches 42 degrees Celsius (107 °F) for just 45 minutes, cellular breakdown occurs. Tissues swell, and the digestive lining weakens, allowing toxins to enter the bloodstream. In milder cases, known as heat exhaustion, only the circulatory system is affected. However, full heatstroke also disrupts the nervous system, leading to confusion, seizures, and dizziness.
6. Fire
While hot air and humidity can strain the body, fire takes the impact even further, causing severe damage, death, and eventual disintegration.
Scientists at the University of West Florida are conducting experiments by igniting donated human remains to study the effects of fire on the body. On average, a human body burns for seven hours. The outer skin is the first to go, crisping and crackling before it rapidly burns away. The deeper layers of skin follow, disappearing within approximately five minutes.
Once the outer layers are gone, the fire targets the fat layer. Fat serves as an efficient fuel source, especially when materials like clothing or pyre wood act as a wick. The fat melts, soaks into the wick, and sustains the flames for hours. Additionally, the heat dries out muscles, causing them to contract and resulting in body movements.
The fire usually extinguishes itself once only bones are left, unless they fracture and expose the marrow. Teeth, however, remain intact and do not burn.
The study replicates conditions similar to crime scene fires. In contrast, cremation fires burn at much higher temperatures, accelerating the process. Most cremations occur at 600–800 degrees Celsius (1,110–1,470°F), yet even at these intense heats, reducing the body entirely to ash can take several hours.
Researchers note that the scent of a burning body is strikingly similar to pork ribs on a barbecue.
5. Starvation
While starvation is universally known to be fatal, the details are particularly grim. The stomach physically contracts, making it painful to resume normal eating even if food becomes available. The heart and its muscles also shrink, reducing their capacity and causing a drop in blood pressure. Extended starvation leads to anemia, and in women, menstruation may cease entirely.
When the body exhausts its sugar reserves, it begins to metabolize fat. While this might seem beneficial, the rapid breakdown of stored fat releases compounds called ketones, along with energy. The accumulation of ketones results in nausea, fatigue, and notably, bad breath.
Temporary starvation can permanently weaken bones. More surprisingly, it also has lasting effects on the brain. Without essential nutrients like potassium and phosphorus, brain function deteriorates. You may lose gray matter—some of which is irreplaceable, leading to permanent cognitive impairment even after resuming a normal diet.
Children and teenagers experiencing starvation may face chronic health problems in adulthood, such as a woman’s inability to carry a pregnancy to full term. One of the more unusual effects is the growth of a fine, soft layer of hair called lanugo, which helps the body maintain its temperature during prolonged starvation.
4. Height
Even if heights don’t frighten you, you’ve probably felt a dizzy, nauseating sensation when peering down from a tall building. This is vertigo, and it’s more than just a mental reaction.
Maintaining balance is complex. On the ground, we rely on stable, stationary objects to orient ourselves. However, when standing atop a 30-story building, this system fails. The closest stationary object (aside from the floor under your feet) is too distant for your body to use as a reference point, leaving it unable to confirm its own stability.
The slight sway of tall buildings introduces another challenge. At great heights, everything moves subtly, and our bodies sense this movement even if we’re not consciously aware of it. The higher we go, the more pronounced the sway becomes, making it increasingly difficult to maintain balance. If the sway becomes too intense, it can disrupt our sense of equilibrium.
Individuals who struggle with judging distances often experience more severe acrophobia. A study by California State University examined how people estimated the heights of buildings. Those who overestimated a building’s height exhibited stronger reactions when standing at the top. The findings indicate a direct connection between perception and fear.
3. Loneliness
Loneliness is a common human experience. Even in a crowded room, we can feel profoundly isolated if we fail to connect with others. However, chronic loneliness can have tangible physical effects on the body.
Psychologists at the University of Chicago have found that individuals who report feelings of loneliness exhibit significantly weakened immune systems. This occurs because lonely individuals perceive the world as hostile and threatening, causing their immune systems to prioritize combating bacterial infections. As a result, they produce fewer antiviral antibodies, making them more vulnerable to viral diseases.
Lonely individuals are also at greater risk of high blood pressure, as hardened arteries have been associated with chronic loneliness. Additionally, they often experience sleep difficulties. Elevated stress levels further increase their susceptibility to heart disease and strokes.
2. Radiation
Radioactive decay emits energy into the surrounding environment, which interacts with the body’s cells, either destroying them or causing mutations. These mutations can lead to cancer, and certain radioactive materials target specific organs. For instance, radioactive iodine concentrates in the thyroid gland, increasing the risk of thyroid cancer, particularly in children.
A substantial amount of radiation exposure is required to noticeably raise a person’s cancer risk. On average, individuals are exposed to between 0.24 and 0.3 rem of radiation annually. To increase cancer risk by 0.5 percent, exposure to approximately 10 rem is necessary.
At much higher levels, such as 200 rem, radiation sickness occurs. This condition triggers immediate symptoms like vomiting, a decrease in red blood cells, and bone marrow damage. The harm to bone marrow poses a longer-term issue, as it is responsible for producing platelets, which are crucial for blood clotting.
1. Chemicals
Hydrogen sulfide is a highly toxic substance, commonly recognized as the smell of rotten eggs. In large quantities, it may have contributed to the extinction of dinosaurs and much of prehistoric life. However, all living organisms produce it in tiny amounts, where it helps regulate internal processes. Recently, it has been discovered to induce a state of suspended animation in mice.
When administered in the correct dosage, hydrogen sulfide reduces the body’s metabolic rate and lowers the core temperature far below the hypothermia threshold. This causes nearly all bodily functions, including circulation and breathing, to slow down significantly.
In animal studies, hydrogen sulfide has been shown to suppress normal bodily functions, potentially serving as a critical tool in minimizing damage caused by burns or illnesses until proper medical treatment can be administered.
+Water
While dehydration risks are widely known, the dangers of excessive water consumption are less frequently discussed.
Water intoxication leads to numerous issues, with hyponatremia being the most severe. When the kidneys fail to eliminate excess water, it enters the bloodstream, diluting the blood and causing a sharp decline in electrolyte levels. This lack of salt in the body results in symptoms like headaches, fatigue, nausea, and confusion.
Once the bloodstream reaches its limit, water floods into cells, causing them to swell. This becomes fatal in areas with limited space for expansion, such as the brain and spinal cord. This can lead to brain swelling, coma, seizures, and even death.
Excessive water consumption can also introduce another issue: pollutants. Regularly consuming more water than the recommended safe amount (which is less than the commonly cited eight glasses a day) allows pollutants to accumulate to levels the body cannot handle.
