D. Janavi, Chennai
Our body responds to stress, worry, anxiety, fear and excitement by activating the “fight or flight” system. At chemical level, our body releases a series of hormones that makes us hyper-alert, focused, and energised, and this chemical cascade causes increased heart rate, respiratory rate, and perspiration.
From an evolutionary standpoint, this is a system we needed in place for survival.
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When a danger is encountered, our brain just sends signals to our entire body warning us that we need to leave the life-threatening situation. The hormones then create adrenaline that will keep us awake and alive while we are fighting or fleeing. Our cells too contribute by keeping everything working and pumping and so that adrenaline can pump through our blood. While the adrenaline is pumping through our blood, so are the fat and sugar. That fat and sugar make our bronchi open wider causing heart beat and breathing rate to accelerate. That is why our heart beats faster when we get frightened.
Normally, heart-rate control is a balance between the two circuits of the Autonomic Nervous System – the Parasympathetic Nervous System and the Sympathetic Nervous System. The Sympathetic Nervous System (SNS) is often referred to as our “fight or flight” system. The Parasympathetic Nervous System (PSNS) is its counterpart, and can be termed as the “rest and digest” system. Together, the PSNS and SNS work in all areas of the body to help us act, react, recover and survive.
Rashmi Jasin, Greater Noida, UP
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This week’s questions
Why are there numerous thin copper strands inside an electric wire instead of a single copper strand that is as thick as the numerous copper strands?
S. Udayaprakash, Karur, Tamil Nadu
Why is the shape of cells in a honeycomb always hexagonal?
C.R. Srinivasa, Bengaluru