Ever found you get more work done two days before an exam, than you’ve done in a month? Or wondered about that feeling you get when you’ve lost your keys, wallet or phone? Our body is able to rapidly respond to changes in temperature, pollution, diet and particularly environmental stresses. The increased heart rate, sweating, breathing rate and muscle tension is known as the ‘fight or flight response’. It is all caused by the activity of the sympathetic nervous system (SNS). The sympathetic nervous system is part of the autonomic nervous system, which includes nerves outside the brain and spinal cord. The autonomic system is responsible for managing and regulating bodily functions under subconscious control.
When you are put in stressful situations, such as final exams or losing something important, your body automatically reverts to our fight or flight response. By releasing chemicals such as adrenaline and noradrenaline, your body hopes to be able to deal with the problems at hand. Of course, this stems from human history where ancestral lineages have run from, or fought with, various threats from nature. Adrenaline is an endocrine hormone that is released by the adrenal gland and travels in the bloodstream. Noradrenaline is a neurotransmitter that transmits signals between neurons and target cells. Both these chemicals act on neural receptors which are responsible for most of the bodily changes under these conditions.
There are three main changes to consider during a ‘fight of flight’ response: increased heart rate, pupil dilation and dilated bronchi.
Increasing heart rate is to get as much oxygen containing blood around your body as possible- especially to muscles. This means if you need to run you’ll have the oxygen that the tissues need ready! Usually, under stressful situations muscle use is greater, so we will need as much oxygen as possible. Sympathetic fibres and adrenaline activate receptors on the pacemaker cells in the heart. Speeding up contractions, and increasing blood flow.
Pupil dilation occurs under stressful situations too although it is less often noticed. This is caused by sympathetic fibres to maximise the amount of light entering the eye, allowing for greatest possible vision to spot those important keys!
Bronchi dilate to increase oxygen flow into your lungs. Noradrenaline and adrenaline will act on receptors on the smooth muscle in the bronchi. Dilatation of airways will allow more air into the body and thus facilitate respiration.
The fight or flight response is part of our body’s built in reaction to be able to prepare yourself for a fight or to flee from a potential attack, increasing the probability of your survival. So in terms of evolution it is a response to protect us from predators. These responses are designed to occur quickly and without hesitation! Which is why they will occur in any stressful situation you encounter. That’s why you should always go with your gut!
Article by Nasira Ahmed