Fight or flight: The sympathetic nervous system
The sympathetic nervous system makes up part
of the autonomic nervous system, also known as the involuntary nervous system.
Without conscious direction, the autonomic nervous system regulates
important bodily functions such as
1.
heart rate,
2.
blood pressure,
3.
pupil dilation,
4.
body temperature,
5.
sweating and
6.
digestion,
Research suggests that distinct types of nerve
cells, called neurons, control these different physical reactions by directing
the action of skeletal muscle, cardiac muscle and gland secretion. The
system allows animals to make quick internal adjustments and react without
having to think about it.
The sympathetic nervous system directs the
body's rapid involuntary response to dangerous or stressful situations. A flash
flood of hormones boosts the body's alertness and heart rate, sending extra
blood to the muscles. Breathing quickens, delivering fresh oxygen to the brain,
and an infusion of glucose is shot into the bloodstream for a quick
energy boost. This response occurs so quickly that people often don't realize its
taken place, according to Harvard Medical School. For instance, a person
may jump from the path of a falling tree before they fully register that it's
toppling toward them.
The sympathetic nervous system doesn't distress
the body once the tree is felled or the danger has passed. Another component of
the autonomic nervous system, the parasympathetic nervous system, works to calm
the body down. To counter the fight-or-flight response, this system encourages
the body to "rest and digest." Blood pressure, breathing rate and
hormone flow return to normal levels as the body settles into homeostasis,
or equilibrium, once more.
The sympathetic and
parasympathetic nervous systems work together to maintain this baseline and
normal body function.
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