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Heat, our body and what we can do (1)

This is a part of 3-part series and will be published as single blog post in our web site. The first part explains what’s thermoregulation of the body’s heat since the body operated within limited window of temperature range.

Part 2 will cover what are health implications of heat moments outside temperatures rise above 35 degrees.

And, part 3 will cover what we must do, what we must try to do and solutions over time.

The human body is comfortable at a 35-degree temperature in the outside atmosphere.

Body’s internal system is operational at appx. 37 degrees plus minus 2 degrees. Beyond that it goes into emergency firefighting mode as instinct to protect it.

This whole process is called thermoregulation of body. The thermoregulation system includes the hypothalamus, sweat glands, circulatory system, and skin.

Hypothalamus –part of brain based on cues it receives takes a call and accordingly acts. The easiest response to understand is when body heats it starts sweating and when it gets cold ---shivering.

Thermoregulation is how mammals (including all humans –irrespective of differentiations we create artificially) maintain a steady body temperature. Unlike reptiles, which have a body temperature that changes with their environment, mammals need to keep a consistent body temperature all of the time. In humans, the healthy range is within a degree or two of 98.6°F (37°C).

How does thermoregulation work in humans?

The human body uses of thermoregulation:

·        efferent responses

·        afferent sensing

·        central control

Efferent responses are the behaviours that humans engage in to regulate their own body temperature. Examples of efferent responses include putting on a coat before going outside on cold days and moving into the shade on hot days.

Afferent sensing involves a system of temperature receptors around the body to identify whether the core temperature is too hot or cold. The receptors relay the information to the hypothalamus, which is part of the brain.

The hypothalamus acts as the central control, using the information it receives from afferent sensing to produce hormones that alter body temperature. These hormones send signals to various parts of the body so that it can respond to heat in following way.


dilated blood vessels, known as vasodilation

decrease in metabolism

vasodilation is when blood arteries widen to carry more blood while reducing blood pressure.

Blood’s two primary roles are carrying oxygen and nutrition across body and thermoregulation of body temperature.


Whole body heat balance is a function of metabolic heat production and the various forms of heat losses.

What is metabolism?

Metabolism refers to the chemical (metabolic) processes that take place in body converts foods and drinks into energy.

What does your metabolism do?

Metabolism never stops, even when your body is at rest. It constantly provides energy for basic body functions, such as:

  • Breathing.

  • Circulating blood.

  • Digesting food.

  • Growing and repairing cells.

  • Managing hormone levels.

  • Regulating body temperature.

So, reduction in metabolism means it reduces the internal generation of heat and sluggish in need to have food/water and feeling of bloating in the stomach.


Sweating and evaporation as a cooling agent:

The two main ways that we are able to control our rising body temperature is by pumping a lot of blood flow to the skin — which is a system unique to humans — and by sweating over most of the body surface area and evaporating that sweat.

But that process can go awry when there's extreme heat, particularly when it is coupled with high humidity. Those factors in tandem disrupt the evaporation of sweat so it does not have any cooling impact on the body, while also making you more dehydrated. (Scientists call the concept the wet-bulb temperature, the point where water stops evaporating from a wet thermometer bulb. At 35 C, humans can no longer cool themselves.)

So, since sweating is mostly water, salts all sweating is water loss in body and hence the fear of dehydration, water loss which creates cascading effect.

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