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Sympathetic Nervous System
Molly Fiser
Michael Banta
Landon Reynolds
Justin Mosteller
What is sympathetic nervous
system?
• The sympathetic nervous system is a division of
the autonomic nervous system responsible for
“fight” or “flight” reactions; primarily concerned
with the elevation of metabolic rate and
increased alertness.
• Ex: adrenaline rush. Being crushed under a 2
ton boulder. Your body will know it is in danger
and adrenaline will be released to give your
body the strength it needs to lift the boulder off
of yourself.
Functions
• Maintain normal digestive
tract contractions and
secretions.
• Maintain the normal tone
of smooth muscle.
• Maintaining blood
pressure.
• “Fight” or “Flight”- The
body’s response to
emergency situations that
induce high stress levels.
• Serves as the defense
mechanism against
stress.
What triggers it?
• Sympathetic neurons communicate with peripheral
sympathetic neurons through the ganglia.
• They join together through chemical synapses.
• During the synapse the preganglionic sumpathetic
neurons realease ACh. The ACh binds to and activates
nicotinic acetylcholine receptors.
• In response to the stimulus, the postganglionic neurons
release norepinephrine.
• This prolonged activation releases adrenaline from the
adrenal medulla.
• Once released the adrenaline and norepinephrine bind
together, which causes the effects seen during the flight
or flight response.
Epi-Pen
• The epi in epi-pen stands for epinephrine also
known more commonly as adrenaline.
• When injecting your self you stimulate your 4
major receptors causing a fight of flight
syndrome.
• This adrenaline rush will suppress your immune
system, causes a higher blood supply, helps
breathing, and stops bladder contraction.
• All these factors help with allergies and allergic
reactions, which may save your life.
Effect on body!
• Dilates pupil in eye.
• Inhibits salivary gland
secretion.
• Relaxes bronchi in lungs.
• Accelerates heart.
• Inhibits activity of stomach and
intestines.
• Stimulates glucose release
from liver; inhibits gallbladder.
• Stimulates adrenal medulla.
• Inhibits emptying of bladder.
• Promotes ejaculation and
vaginal contractions.
Adrenaline
• Adrenaline is a hormone
produced by the adrenal
gland. When it is
produced in the body it
stimulates the heart rate,
dilates blood vessels and
air passages. It’s
naturally produced in high
stress or physically
exhilarating situations.
Receptors
• Alpha receptors– alpha-1: The result is the release of
intracellular calcium ions from reserves in the
endoplasmic reticulum.
– alpha-2: Has an inhibitory effect on the cell.
• Beta receptors– beta-1: Increase in heart rate and force of
contraction in the heart. Increase in metabolic
activity in skeletal.
– beta-2: Create a relaxation of smooth muscle.
Sources
•
McGuigan, Brenden. (2009, December 01). What is Adrenaline?.
Retrieved from http://www.wisegeek.com/what-is-adrenaline.htm
•
Martini, F. H. (1995). Fundamentals of anatomy and physiology.
Englewood Cliffs, New Jersey: Prentice Hall.
•
Campbell, Neil, & Reece, Jane. (2009). Biology. Benjamin Cummings Pub
Co.
•
•
Armbruster, David, Musker, Frank, Irwin, Leslie, Anthony, Catherine,
& Thibodeau, Gary. (1987). Textbook of anatomy & physiology.
Times Mirror Magazine.
Sympathetic nervous system. (2009). Retrieved from
http://www.sciencedaily.com/articles/s/sympathetic_nervous_system.htm