When the brain perceives danger, the amygdala triggers the hypothalamus to activate the autonomic nervous system. Signals from the autonomic nervous system stimulate the adrenal gland to start pumping epinephrine into the bloodstream. People often refer to this surge of epinephrine as an adrenaline rush or the fight or flight response. Epinephrine affects the heart, lungs, muscles, and blood vessels. Its release into the bloodstream brings about several physiological changes, such as:.
The adrenal medulla produces norepinephrine in response to low blood pressure and stress. Norepinephrine promotes vasoconstriction, which is a narrowing of the blood vessels, and this increases blood pressure. A rare condition called genetic dopamine beta-hydroxylase deficiency prevents the body from converting dopamine into norepinephrine. According to a article , genetic dopamine beta-hydroxylase deficiency results from a mutation in the norepinephrine transporter gene gc.
The authors concluded that this condition might decrease sympathetic nerve activity and increase the risk of damage to the heart and blood vessels. Low levels of epinephrine and norepinephrine can result in physical and mental symptoms, such as:. In addition, norepinephrine plays a role in focus and promotes periods of sustained attention.
Low levels of norepinephrine may contribute to the development of attention deficit hyperactivity disorder ADHD. Certain medical conditions, such as tumors, chronic stress, and obesity , can affect the adrenal glands and cause excess production of epinephrine and norepinephrine. Symptoms of high levels of epinephrine or norepinephrine can include :.
An epinephrine overdose can occur in people who use epinephrine injections to treat certain medical conditions. An overdose of injected epinephrine can lead to dangerously high blood pressure, stroke , or even death. Synthetic forms of epinephrine and norepinephrine have several medical uses, which we discuss below:.
Doctors prescribe epinephrine to treat severe medical conditions that affect the heart and airways, such as anaphylaxis. Epinephrine counters anaphylactic shock by narrowing the blood vessels, relaxing the muscles, and opening up the airways.
It is common for people at risk of anaphylaxis to carry an epinephrine autoinjector with them at all times. Doctors also use epinephrine to treat severe asthma attacks, cardiac arrest, and serious infections. Aubrey Bailey is a Doctor of Physical Therapy with an additional degree in psychology and board certification in hand therapy. Bailey is also an Anatomy and Physiology professor. Gideon Hoyle. Gideon Hoyle is a writer living outside of Houston.
Previously, he produced brochures and a wide variety of other materials for a nonprofit educational foundation. He now specializes in topics related to health, exercise and nutrition, publishing for various websites. Adrenaline triggers body changes related to your "fight-or-flight" response. Video of the Day. Tip Adrenaline is a hormone that prepares your body for a "fight-or-flight" response, which includes boosting your heart rate to pump more oxygen to your muscles.
Basics of Adrenaline. Epinephrine and Heart Rate. Excessive Adrenalin Production. Klabunde Circulating catecholamines, epinephrine and norepinephrine , originate from two sources. Epinephrine is released by the adrenal medulla upon activation of preganglionic sympathetic nerves innervating this tissue.
This activation occurs during times of stress e. Normally, most of the norepinephrine released by sympathetic nerves is taken back up by the nerves a small fraction is also taken up by extra-neuronal tissues where it is metabolized.
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