In the previous article we found how the brain processes the signal and induces what we call fear. In this article we’ll have a glimpse of the typical symptoms associated with the brain’s response and why they are necessary.
The fight or flight response is characterized by
a) increased heart rate and blood pressure
b) pupils dilating
c) experiencing a “chill”
d) tensing of muscles resulting in goosebumps
e) shutting down of non-essential systems like digestive and immune system
f) relaxing of smooth muscles
g) trouble focusing on small tasks
Each one of these response is directed by the flood of hormones in the body as ordered by the brain through various channels but before finding out how this is achieved, let us analyse why this kind of a response is necessary in the first place.
In case of danger, any human being has two options (any organism for that matter) – either face the situation and overcome it (fight) or flee the danger (flight). In either case, the body needs to be ready; it needs to take action, and take it fast. Increased heart and blood pressure ensure that enough oxygen is being supplied to all essential part of the body so that quick action can be taken. This would also mean the oxygen intake to the body itself has to be increased. Thus, the smooth muscles relax to let in more oxygen into the lungs. (These are the muscles which do not need any conscious thought for their activation, for example those in lungs, walls of stomach, bladder, walls of blood vessels etc., and are also called involuntary muscles as opposed to the voluntary muscles which are activated only by conscious effort viz. the muscles used for locomotion. The latter are also called skeletal muscle as they are anchored by tendons to the bones.)
Efficiency of circulation is also increased to make sure the requisite organs receive the most amount oxygen. Veins in skin constrict to send more blood to major muscle groups. This is what causes the “chill” as there is less blood in the skin to keep it warm. To allow more energy for emergency functions, non essential systems shut down.
To make sure enough sensory data is being received, pupils dilate to take in as much light as possible.
The level of glucose and adrenaline in the blood rises to energize the muscles. As the muscles tense up, a person experiences goose bumps. The hairs are forced upright as the muscles attached to each hair on the surface tense up.
Since the brain is directed to focus only on the big picture in order to determine where the threat is coming and how best to survive, it finds it difficult to concentrate on smaller tasks.
Thus, every single part of the body is utilized and prepared to combat the danger. And how exactly are all these things coordinated?
There are two systems attached to the fight or flight response – the sympathetic nervous system and the adrenal-cortical system. Let us not worry too much about the complicated names and instead just focus on their functions.
As seen in the previous part whether it is the low road or the high road, they both end at the hypothalamus. Now, hypothalamus activates the two systems mentioned above. Once activated, the sympathetic nervous system uses nerve pathways to initiate reactions in the body. All these reactions have only one goal – to make the body alert. Impulses are sent to glands and smooth muscles and the adrenal medulla is asked to release epinephrine and norephinephrine into the blood stream. These hormones, also called adrenaline and noreadrenaline cause several changes in the body including the increased heart rate and blood pressure.
The adrenal cortical system is activated when the hypothalamus releases corticotrophin-releasing factor (CRF) into the pituitary gland. A hormone called ACTH (adrenocorticotropic hormone) is release which moves through the bloodstream and ultimately reaches the adrenal cortex. This then activates the release of approximately 30 different hormones responsible for the aforementioned symptoms.
Thus, this tsunami of hormones prepares us for the threat.
But then these threats differ for different people. What arouses a deep fear in one person might not ruffle the other in the slightest. Why this disparity? In the next part we’ll analyze the psychology behind fear.
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