Your Body’s Response to Emergency
How does the body prepare for emergencies? The answer lies in the Sympathetic Nervous System (SNS). It is the branch of the Autonomic Nervous System (ANS) that controls the body’s reaction to physical and emotional stressors. The sympathetic branch activates the glands and organs that defend the body against attack. It is called the fight-or-flight response. This is a primitive response designed to protect from danger. When danger is perceived, the sympathetic nervous system responds immediately to prepare a person to stay and fight or take flight. Blood rushes away from nonessential systems such as the digestive and excretory systems and is redirected to the extremities. The heart beats faster to encourage this increased blood flow, sweat is produced to cool the body, pupils dilate in order see better, muscles tense and breathing becomes shallower. Before any of these processes can occur, sensory nerve cells must initiate a response. First, sensory nerve cells pass the perception of a threat to the hypothalamus in the brain. Neurosecretory cells in the hypothalamus will then transmit a signal to the pituitary gland, causing cells there to release a chemical messenger into the bloodstream. The hypothalamus also transmits a nerve signal down the spinal cord. Both the chemical messenger and the nerve impulse will travel to the adrenal gland. These nerve signals activate the release of norepinephrine and epinephrine into the bloodstream. It’s important to note that although known as both a neurotransmitter and a hormone, norepinephrine works alongside epinephrine as a hormone in times of stress.
The release of these two hormones acts as catalyst for all of the body’s reactions. The hormones bind to receptors and trigger a signaling cascade to several different cell types. This results in the production of cortisol and glucose. Cortisol is responsible for the increase in blood pressure, increase in blood sugar...
Citations: Kimball, J.K. (n.d.). Organization of the nervous system. Retrieved May 27, 2010 from http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/PNS.html
Mc Ewan P.h.D, B., & Krahn M.D, D. (n.d.). The Response to stress. Retrieved May 27, 2010 from http://www.thedoctorwillseeyounow.com/content/stress/art1965.html?getPage=1
Genetic Science Learning Center (n.d.) How cells communicate during the fight or flight response. Learn Genetics. Retrieved May 27, 2010 from http://learn.genetics.utah.edu/content/begin/cells/fight_flight/
Norepinephrine. (n.d.). Merriam-Webster 's Medical Dictionary. Retrieved June 01, 2010, from http://dictionary.reference.com/browse/norepinephrine
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