Homeostatic Control Of Body Temperature

The normal body temperature is around 37 degrees Celsius in all humans. But we live in an environment where the outside temperature can change dramatically. From -50 Degrees Celsius in the Arctic to 50 degrees Celsius in Death Valley. This is a huge range that out bodies would not survive in if it wasn`t for out homeostatic response which is a product of millions of years of Evolution.

What happens?

If you are sitting on a beach in a hot country like Dubai where in summer temperatures can reach up to 45 degrees Celsius, our bodies notice this and start to get out core body temperature back to around 37 degrees. This is so important because most metabolic reactions such as respiration are controlled by enzymes. If our temperature gets too high or too low, the rate of activity of most of our enzymes decrease and they will denature if the temperature is too extreme.

If we get too hot....

- Peripheral thermoreceptors on our skin detect this change in temperature and sends electrical signals to our Hypothalamus in our brain. This area of the brain coordinates the response.

- Lots of electrical signals are then sent along many nerves all around the body that result in the following changes.

- Our sweat glands produce more sweat so there is more evaporation of sweat from the surface of our skin. Thus, cooling that area of skin

- Our blood vessels near the surface of our skin vasodilate. Get bigger. More blood flows in those vessels so there is more heat loss due to radiation

- The hairs on our skin lie flat, therefore not creating an insulating layer that traps heat when they are erect.

If we get too cold...

- Peripheral thermoreceptors on our skin detect this change in temperature and sends electrical signals to our Hypothalamus in our brain. This area of the brain coordinates the response.

- Lots of electrical signals are then sent along many nerves all around the body that result in the following changes.

- Our sweat glands produce less sweat so there is less evaporation of sweat from the surface of our skin. Thus, not cooling that area of skin

- Our blood vessels near the surface of our skin vasoconstrict. Get smaller. Less blood flows in those vessels so there is less heat loss due to radiation

- The hairs on our stand up right, therefore creating an insulating layer that traps heat between the surface of the skin and the end of the hair

- Our muscles involuntarily contract and relax. This causes cells in skeletal muscles to respire which creates heat as heat is a product of respiration. This is shivering.

Both of these processes are called Negative Feedback Systems. This is a system where the original state is changed and then our bodies make subsequent changes to go back to the original state. However, our body has its limits. It can only return our body temperature to the optimal temperature, 37 degrees, within a few degrees Celsius. What I mean is if the outdoor temperature isn`t too extreme, then the negative feedback system in place is strong enough to revert the change. If the temperature is too extreme, then the body cannot revert the core body temperature back to 37 degrees and unless secondary changes are made to get the body temperature back to the optimum, you will die from either Hypothermia or Hyperthermia. This just shows how fragile humans are with regards to body temperature and why it is so important that an optimal temperature is always maintained.