• Question: Hi there! What part of our body controls sweat and what does the process involve?

    Asked by anon-244767 on 29 Apr 2020.
    • Photo: Maria Marti

      Maria Marti answered on 29 Apr 2020:

      Good question! It will all depend on the kind of sweating we are talking about. Usually, we sweat to decrease our body temperature. That happens through sweat glands found across our body and is regulated by a part of the brain called the hypothalamus. However, other times we sweat when we become nervous, and that has nothing to do with temperature. This type of sweating, that some scientists call ’emotional sweating’, mostly happens in sweat glands in our armpits, hands and feet and it is controlled by a different brain region called the limbic system.

    • Photo: Nina Rzechorzek

      Nina Rzechorzek answered on 30 Apr 2020:

      Sweating is ultimately controlled by a small part of the brain called the hypothalamus, but the signalling pathways exclude ‘higher’ (more complex) regions of the brain, so you have no voluntary control over how and when you sweat. The pathways are part of the sympathetic division of the autonomic nervous system or ‘ANS’ (the sympathetic branch of the ANS governs the ‘fight or flight’ response in stressful situations). In a nutshell:
      (1) Hypothalamus senses a temperature increase. The hypothalamus is a small region at the base of the brain – among many other functions, it contains the ‘thermoregulatory centre’ that senses and responds to changes in temperature
      (2) Hypothalamus sends signals (via neurons) to specific regions in the brainstem, thus stimulating sympathetic nerve cells
      (3) Sympathetic nerve cells in the brainstem send signals to other nerve cells in a large region of the spinal cord
      (4) Sympathetic nerve cells in the spinal cord send out processes via peripheral nerves and release a substance called Acetylcholine (Ach) which stimulates the next set of nerve cells
      (5) These last set of nerve cells have fibres that travel all the way to sweat glands in the skin where they release more Ach which stimulates the sweat glands to release sweat
      Sweating is a major route for heat loss in humans, but is less important for the control of body temperature in furry animals like dogs.

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