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Jinadu: All you need to know about body temperature


As the Coronavirus pandemic lingers, measuring body temperature has become a daily routine in most workplaces and public spheres. But many do not know what constitutes body temperature, or what it is really about. Dr. Olayide A. Jinadu, Medical Director at Charis-Med Hospital, Lagos, explained the need for temperature check and how appropriate body temperature can be maintained.

What is body temperature and what organ of the body regulates body temperature?
The word “temperature” generally means the degree or measure of hotness or coldness of a surface. So, it is safe to say the human body temperature is the degree of hotness or coldness of the human body.  Human beings are warm-blooded organisms, meaning we have the ability to regulate our body temperature within a certain narrow temperature range, unlike cold blooded animals like reptiles (snakes and lizards), which depend solely on their environment to regulate their body temperature. Snakes and lizards come out when it is sunny to bask in the heat, but you never see them out during the cold weather.

Our body temperature needs to be kept within a narrow range, as most, if not all human body processes are temperature dependent. For instance, when the human body temperature is higher than normal, the heart rate increases, enzymes for digestion cannot function optimally, dehydration occurs, the digestive system is prone to haemorrhage (bleeding) and hormones malfunction, among others.

The normal body temperature (core temperature) is 37 degree Celsius. However, our body temperature is maintained within a normal range, which is 36.1 degree Celsius to 37.2 degree Celsius. The hypothalamus is saddled with the responsibility of maintaining the human body temperature within this safe temperature range. The hypothalamus is the body’s thermoregulator situated in the brain, the centre of the brain actually, just above the pituitary gland behind the eyes.

The body temperature is measured using a thermometer. There are various sites for measuring the body temperature namely: the armpit (axillary temperature check), the mouth (oral temperature check) and the anus (rectal temperature check). The rectal route is the most accurate for core body temperature. However, the axillary route is the most convenient, hence the most widely used.

But temperature appears to fluctuate from day to day… 
The body temperature is maintained within a safe range of 36.1 – 37.2 degree Celsius, as stated above. As long as the temperature is within this range, there is no problem. When your environment is hot, the hypothalamus does the following:

The hypothalamus sends signals to the muscles to reduce activity, thereby reducing temperature. The hypothalamus sends signals to the skin to release sweat to encourage heat loss, thereby reducing the body temperature. It sends signals to the erector pili, smooth muscles that anchor hair strands, these muscles relax to make the hair around the body fall, thereby losing heat to the environment, then reducing the body temperature. The hypothalamus sends signals to the blood vessels close to the skin to vasodilate, i.e. to open up, increasing blood supply to the skin, in a bid to lose heat to the environment, thereby reducing the body temperature. The hypothalamus sends signals to the liver to reduce its activity in a bid to reduce the body temperature.

The exact opposite happens during cold, when the hypothalamus does the following:
The hypothalamus sends signals to the muscles to increase activity. This is what we observe as shivering, done in a bid to achieve heat gain to increase the body temperature. The hypothalamus sends signal to the skin, closing the sweat pores, thereby inhibiting sweating, thereby increasing the body’s temperature. The hypothalamus sends signals to the erector pili muscles in the skin to contract, thereby making the hairs around to body to stand erect thereby increasing the body temperature.

The hypothalamus sends signals to the blood vessels close to the skin, causing them to vasoconstrict (narrowing of blood vessels). This process traps heat into the skin, thereby increasing the body temperature. The hypothalamus sends signals to the liver to increase activity, in a bid to generate a lot of heat within the body.

Is it possible to have high body temperature without illness?
High body temperature, also known as fever, is a pointer to an ongoing disease process. Fever is one of the cardinal signs of inflammation. Various things can cause fever: Bacterial infection, viral infection, fungal infection, parasitic infection (example malaria), cancer, drug reaction, blood transfusion reaction and metabolic response to trauma, among others.

Fever can be classified as mild, moderate or severe (hyperpyrexia). Mild fever (37.3 – 38.1 degree Celsius); moderate fever (38.2 – 40 degree Celsius) and hyperpyrexia (40.1 degree Celsius and above). There are actually few conditions where a person can have fever yet no illness. A common example is when an infant is growing new teeth. This is an inflammatory process in the gums and so, has fever as one of the accompanying signs.

Does stress (Lagos traffic for instance) jerk up temperature. Does the external temperature have anything to do with body temperature?
Stress and the external temperature can increase body temperature slightly. However, the hypothalamus keeps it within normal range. Invariably, stress and external temperature would not cause fever, we are warm-blooded organisms, remember! The hypothalamus determines our body temperature, not our immediate environment.

The maintenance of body temperature is the duty of the hypothalamus and not ours. The hypothalamus functions just like your usual pressing iron’s thermostat. The thermostat ensures that the pressing iron temperature does not go beyond or below its set temperature of use. However, during a disease process, when the hypothalamus is overwhelmed, your doctor places you on antipyretics like Acetaminophen (paracetamol) and other medications to rid you of the offending cause of fever.

Aside fever or other ailments, what else can make body temperature rise?
Heat stroke can cause excessive temperature spikes of the human body. This occurs when the body is consistently exposed to high temperature, the kind of which the body is not accustomed to. For instance, when someone who was born in a temperate country and has never been exposed to extreme heat, suddenly visits a tropical country during hot season.

Is there always a link between high body temperature and illness?
Yes, usually. This is because it takes a disease process to occur, for release of pyrogens. This pyrogens reset confuses the hypothalamus, thereby increasing the body’s new core temperature. For example, if the pyrogens reset the body’s new core temperature to 40 degree Celsius, the now confused hypothalamus does everything within its power to call for an increase of the body temperature. Bacteria, fungal, viral and parasitic infections cause a release of pyrogens in the body.

What lifestyle changes should people adopt to stay safe during this pandemic and reduce the risk of abnormal body temperature?
To avoid fever is to avoid all causes of fever, especially at this COVID-19 period. We must ensure that we follow strictly all Nigerian Centre for Disease Control (NCDC) guidelines. Wash hands very frequently and stay indoors. If you must go out, wear a face mask, employ social distancing at all times, prevent mosquito bites by sleeping in insecticide treated nets. Ensure your windows and doors are adequately netted. Stay hydrated, and ensure you eat healthy, by always including fruits and vegetables to your diet. Avoid dangerous activities that might lead to trauma.

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