Adrenaline, also termed Epinephrine, is a key hormone in the human system that is involved in the “fight or flight” response to make the body ready to act quickly in challenging or sudden situations that trigger undue amounts of stress, fear. This hormone is synthesised primarily by the adrenal glands - situated on top of the kidneys and hence otherwise referred to as suprarenal glands, with minor amounts being produced by neurons in the central nervous system.

During a tense situation or a sudden terrifying instance, the nerves leading up to the suprarenal glands are stimulated, which in turn triggers the medulla i.e. the central part of the adrenal glands, to produce adrenaline. Subsequently, adrenaline is released into the blood, which helps to either combat the problem head-on or run away and escape the frightening scenario, thereby being aptly dubbed as the “fight or flight hormone”. This entire sequence of events occurs rather quickly, within just 2 – 3 minutes, following which the nerve impulses to the adrenal glands are decreased and the synthesis and release of adrenaline cease once the stressful situation comes to an end. Yet another hormone that is synthesised in response to stress is cortisol, which assists in dealing with undue physical strain and emotional trauma, by means of anti-inflammatory effects in the body.

Also Read: Cortisol: Structure, Crucial Functions, Adverse Effects
Adrenaline

Adrenaline And Its Structure:

The major credit for the discovery of adrenaline undeniably goes to the renowned physiologist from Poland, Napoleon Cybulski, who first identified the compound in the year 1895, though several other scientists have followed up on this work and conducted research on the structure, isolation, functions of the hormone. In 1897, the famous American biochemist widely regarded as the “father of modern pharmacology” John Jacob Abel, revealed a substance known as epinephrine produced by the adrenal glands, which eventually was concluded to be the same as adrenaline. Two well-known Japanese chemists, Jokichi Takamine and Keizo Uenaka worked separately and also identified adrenaline in 1900, with Takamine carrying out studies to successfully isolate and purify adrenaline extracts from sheep and oxen in 1901. In the year 1904, the German chemist Friedrich Stolz and the scientist from England Henry Drysdale Dakin worked independently and synthesised adrenaline in the laboratory environment, which further helped in incorporating it for the treatment of certain medical conditions of the heart such as cardiac arrests, besides in remedying allergies and performing eye surgeries. Hermann Pauly, a recognised German chemist, was the first scientist to determine the structure of adrenaline in 1903.

The adrenaline hormone is derived from tyrosine – an amino acid in the body. Adrenaline is categorised as a catecholamine along with two other hormones – noradrenaline and dopamine. It is composed of a catechol unit, which is a molecule made up of carbon, hydrogen and hydroxyl groups, alongside a methyl group affixed to the nitrogen molecule. The molecular formula of adrenaline is C9H13NO3  and it has a molar mass of 183. 206 g/mol (grams per mole – mole being the standard unit of atomic mass/molar mass).

Functions Of Adrenaline:

Adrenaline is primarily responsible for mediating the fight or flight response and induces associated bodily phenomena in times of stress, including:

  • Elevates heart rate
  • Increases blood pressure
  • Widens the pupils of the eyes
  • Vastly promotes lung power
  • Augments energy metabolism and stimulates glucose supply to the brain
  • Triggers excess sweating in the forehead and palms from nervousness, enthusiasm
  • Enhances strength, stamina in high-pressure, scary and unforeseen circumstances

Moreover, adrenaline is also produced in massive amounts while engaging in adventure activities such as bungee jumping, sky diving, mountain climbing, thrilling pursuits such as watching a horror movie and even while recollecting traumatic or exciting events from the past, which is termed as an adrenaline rush.

Also Read: Adrenaline Rush: Causes, Symptoms And Treatment

Adverse Effects Of Imbalance If Adrenaline Levels:

Low Levels:

A deficiency in adrenaline happens very rarely and in most cases, does not instigate any severe health consequences as a result of epinephrine hormone imbalance in the body. Only people with genetic disorders that hamper or reduce the synthesis of catecholamine enzymes responsible for producing adrenaline face the risk of adrenaline insufficiency. This leads to a weakening of the fight or flight response, but these gene-related ailments are seldom reported.

High Levels:

The production of considerable concentrations of adrenaline and its subsequent passage into the bloodstream is ideal in dangerous or traumatic situations, but not when the body is undergoing only slight stress. Surplus adrenaline in the system invariably gives rise to anxiety, restlessness, insomnia, dizziness, hazy vision, mood swings, irritability and could even lead to heart problems. Furthermore, tumours in the adrenal glands also prompt overproduction of the hormone, with weight loss, palpitations, heavy rapid breathing, irregular fast-paced heartbeats and high blood pressure.