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Adrenaline, also known as epinephrine, is a hormone and neurotransmitter that plays a crucial role in the body's fight or flight response to stress, danger, or physical exertion. Produced by the adrenal glands, adrenaline stimulates various physiological processes, including increasing heart rate and blood pressure, expanding airways, and mobilizing glucose for energy. This article provides an overview of adrenaline's biosynthesis, functions, medical uses, and potential side effects.

Adrenaline molecule ball

Biosynthesis[edit | edit source]

Adrenaline is synthesized in the adrenal medulla, which is the inner part of the adrenal glands located above the kidneys. The biosynthesis of adrenaline involves a series of enzymatic reactions starting with the amino acid tyrosine. Tyrosine is first converted to dihydroxyphenylalanine (DOPA) by the enzyme tyrosine hydroxylase. DOPA is then converted to dopamine, which is further converted to norepinephrine by the enzyme dopamine β-hydroxylase. Finally, norepinephrine is converted to adrenaline by the enzyme phenylethanolamine N-methyltransferase.

Functions[edit | edit source]

Adrenaline serves as both a hormone and a neurotransmitter, mediating various physiological processes, including:

  • Increased heart rate and blood pressure: Adrenaline stimulates the heart to pump faster and more forcefully, increasing blood flow to the muscles and organs.
  • Bronchodilation: Adrenaline relaxes the smooth muscles in the airways, allowing for increased airflow and improved oxygenation.
  • Mobilization of glucose: Adrenaline stimulates the breakdown of glycogen in the liver and muscles, releasing glucose for energy production.
  • Redistribution of blood flow: Adrenaline constricts blood vessels in the skin and digestive system, redirecting blood flow to the muscles and brain.

Medical uses[edit | edit source]

Adrenaline has several medical applications, including:

  • Anaphylaxis treatment: Adrenaline is the first-line treatment for anaphylaxis, a severe allergic reaction that can be life-threatening. An intramuscular injection of adrenaline can rapidly reverse symptoms such as airway swelling, low blood pressure, and shock.
  • Cardiac arrest: Adrenaline is used during cardiopulmonary resuscitation (CPR) to stimulate the heart and increase blood flow to vital organs.
  • Local anesthesia: Adrenaline is sometimes added to local anesthetics to constrict blood vessels, reducing bleeding and prolonging the anesthetic effect.

Side effects[edit | edit source]

While adrenaline can be a life-saving medication, it may also cause side effects, particularly when administered in high doses or in individuals with certain medical conditions. Common side effects include:

  • Rapid or irregular heartbeat
  • High blood pressure
  • Anxiety or nervousness
  • Tremors
  • Headache

See also[edit | edit source]

External links[edit | edit source]

Adrenaline Resources
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Contributors: Prab R. Tumpati, MD