Heatstroke is a condition developed when your body is exposed to an increased temperature for extended periods. It is a widespread phenomenon experienced during summer. This condition is also a consequence of heavy exercise in hot weather. During these conditions, the body also experiences severe dehydration, making it the reason behind various heat stroke symptoms. A heatwave, along with humidity, impacts the heat dissipation mechanism.
What happens with high humidity?
Our body has a natural mechanism to maintain body temperature. Homeostasis is the ability of the human body to maintain equilibrium in response to external stimuli. During the summer, it is common that we sweat more. The primary reason is the accumulation of heat inside our bodies. It exudes the heat in the form of sweat, which evaporates into the air.
During high humidity, the air around us already has high amounts of moisture and is not ready to take anymore. Hence, the sweat eventually accumulates on our body, resulting in heat dissipation failure.
As a result, body heat remains within one, leading to a heat stroke.
Symptoms of a heat stroke
- High body temperature
- Head throbs due to increased heat
- High heart and breath rate: The heart pumps faster to supply oxygen to each organ, in the event of hyperthermia.
- Confusion
- Dizziness and eventually
- Loss of consciousness
People tend to confuse heat stroke, heat exhaustion, heat cramps, heat rash, and sunburn, although all are heat-related illnesses.
Tips to combat heat stroke symptoms
- Stay hydrated: You may feel dehydrated most of the time during hot weather. Drink plenty of water to compensate for the loss. Also, exercise on a calmer time of the day– early morning or evenings.
- Move to a cooler place: Once the symptoms arise, immediately rush to shade. Go back to your home, or drop off at your friends’. An air-conditioned room is the best way to reduce body heat and humidity.
- Choose your clothing accordingly: Avoid wearing excessive clothes that could block the pathway of heat dissipation. Choose light clothing, especially during summer, that keeps your body cool.
- Environmental setting: If you are heat-sensitive, don’t stay in hot exteriors for more extended periods. Your body takes more time to adjust to the heat. Also, look out for medication that can affect your body’s innate ability.
- The temperature in your car: When parked in the sun, the temperature of your vehicle rapidly increases. Never leave your baby in your car, even for a short time.
- Prefer more antioxidants in your meal. They help reduce body heat. Other foods like cucumber, tomato, cantaloupe, oranges, watermelon that have high water content help combat the heat and keeps you hydrated.
Cognitive defects among heat stroke symptoms
An increase in the external temperature can result in mild cognitive impairments, especially attention and memory. It usually takes 1-2 hr before the onset of symptoms after a thermal insult. High-temperature results in dehydration and hence physical stress. Apart from physical stress, it can also result in mental stress. A workspace with no AC usually results in low productivity of the company.
The frequently observed changes in acute cerebral hyperthermia are increased limbic system and dorsolateral prefrontal cortex connections. In contrast, the connections in the temporal, frontal, and occipital lobes reduce. However, performance impairment is different at different temperatures.
Memory impacts
Short term memory variations are prevalent in hyperthermia. For instance, if a subject listens to a repeated identical sound, which is suddenly followed by an alternate sound, the brain responds with mismatch negativity. This response is severely compromised in hyperthermia.
However, hydration can help revert the symptoms. The primary reason behind reduced cognition is hypovolemia, along with physical stress and dehydration. Besides, lack of fluids in the body has its negative impacts.
Apart from cognitive impairments, it can also result in edema. The blood-brain barrier (BBB) is a highly selective membrane– heavy molecules usually cannot pass the barrier to enter the brain. The selectivity of the barrier decreases with increasing temperature. Hyperthermia can result in disruptions of the BBB, eventually resulting in cerebral oedema.
Also, it is easy to slip into a coma with a temperature of more than 40°C. Brain CT scans in these coma patients revealed severe grey-white matter discrimination (GWMD) — also acts as an early indicator of heatstroke.
Denaturation and cell death due to heatstroke
High temperatures can also result in protein denaturation. Any denaturation above a temperature of over 40℃ usually results in irreversible damage. Moreover, these denatured proteins aggregate and interfere with standard cellular functioning and DNA replication, resulting in cell death.
The membranes of neural cells are susceptible to temperature; it is easy to damage neural cells at a temperature of 40-41℃. However, the damage increases with the exposure time. These disruptions can eventually lead to interruptions in cellular signaling. Hyperthermia can also result in neural programmed cell death (PCD). Although protein denaturation is the primary reason behind cell death, caspases can also induce PCD. Caspase inhibitors can help inhibit cell death, even after heat stress.
Excitotoxicity is another mechanism of neural damage. Excitatory neurotransmitters can induce neural cell death. Neurons in hyperthermic conditions are susceptible to calcium influx. The calcium influx reduces ATP production, changing the membrane polarity, eventually inducing caspase-dependent apoptosis.
However, the high levels of Glycine along with Glutamate, in hyperthermia, try to activate the NMDA receptor. The activated NMDA opens a Magnesium channel, which also mediates the efflux of calcium inhibiting the depolarization of membrane potential.
