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Stress Response

When you are under stress, various organs in your body start responding to the situation in different ways. The nerve impulses from the hypothalamus activate the sympathetic nervous system, including the supra-renal medulla. These nerves start a fight-or-flight response, preparing the body for action. Hormones from the supra-renal medulla prolong the response. Soon after this, the body begins to respond to the stress. This reaction is initiated mainly by hypothalamic-releasing hormones, which trigger the anterior pituitary to release growth hormone and other hormones that prompt the thyroid and supra-renal cortex to secrete their hormones. These mobilise glucose and proteins for repair work and energy.  

Response of various parts when the body is under stress:
Whenever you are stressed out, your brain is the first organ to respond to it, and gradually the response is given by other organs.

  • Brain: blood vessels dilate
  • Hypothalamus: it stimulates the supra-renal medulla and triggers fight-or-flight response. It releases hormones that stimulate anterior pituitary
  • Anterior pituitary – it releases growth hormone, which acts with cortisol to release glucose from liver
  • Eye – the pupil of eye dilates due to stress
  • Thyroid – the thyroid gland releases T3 and T4 to increase use of glucose for energy
  • Lungs – airways and blood vessels dilate in stressful situations
  • Heart – Thumping of heart with increased heartbeats
  • Liver – it functions to convert glycogen into glucose
  • Stomach – digestion activity decreases
  • Supra-renal cortex – releases cortisol, which prompts liver to release glucose, and prompts adipose tissue to release fatty acids
  • Spleen – it contracts when you are under stress
  • Supra-renal medulla – secretes epinephrine and norepinephrine, which supplement the effects of the sympathetic nervous response
  • Kidney – the output of urine decreases when under stress
  • Intestine – the movement of food slows down
  • Bladder – Sphincter muscle tends to constrict
  • Skin – Blood vessels constrict, hair stands – the response is commonly known as getting goose-bumps and sweat pores open
  • Skeletal muscle – Blood vessels dilate



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