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What is Epinephrine?

Shashank Nakate
Ephinephrine, also known as adrenaline, is a hormone secreted by the adrenal glands. It is instrumental in generating a response during stressful or emergency situations.
The hormone epinephrine is a fluid released by the adrenal gland. It plays an important role in the body's attempt to respond to emergency situations and acts as a neurotransmitter as well.
A neurotransmitter transfers and regulates the signals between the neurons and other cells of the body. The secretion of this hormone is totally controlled by the central nervous system. The sympathetic nervous system and adrenocorticotropic hormone play an important role in its synthesis.
The fight-or-flight response of the body is initiated by the secretion of epinephrine. It is secreted or triggered in certain situations, mostly in the state of excitement or stress. The excitement leading to the secretion of adrenaline may be both negative or positive in nature.
External factors such as noise pollution or bright lights can also raise its level in the body. The sympathetic nervous system (SNS), a sub division of the autonomic nervous system (ANS), is responsible for the generation of such a response.

Some Facts

• Adrenaline was discovered by Jokichi Takamine of Japan in the year 1900. Interestingly, this same hormone was also discovered by his assistant Keizo Uenaka.

• Its isolation and purification was carried out by them in the next year. The adrenal glands of a cow were used for the process.

• In 1904, Friedrich Stolz produced this hormone artificially. 

Consequences of Epinephrine Secretion

Several changes take place in the body after the release of adrenaline.

➜ The supply of oxygen and glucose to the muscles and brain is increased.

➜ There is a rise in stroke volume and the heart rate increases. Stroke volume is the volume or quantity of blood pumped by a ventricle in a single heartbeat.
➜ It also leads to the dilation of pupils and constriction of arterioles in the skin.

➜ Rise in blood sugar levels is also one of the consequences.

➜ The functioning of the immune system gets suppressed, and the working of the digestive system takes a backseat.

➜ Norepinephrine, a hormone similar to epinephrine, is also released when the stress levels rise.

Feedback Mechanism

The adrenergic receptors function as mediators between the hormone epinephrine and body parts. Adrenaline activates the 'inositol-phospholipid signaling pathway'. The phosphorylation of glycogen and phosphorylase kinase begins with this activation.
Phosphorylase kinase further activates an enzyme called glycogen phosphorylase. This enzyme acts as a catalyst in the process of glycogenolysis, which results in the production of glucose.

Uses of Epinephrine

Now that you know what is epinephrine, let us discuss its uses.

☛ This hormone is used in nasal sprays and different therapies. It can be injected into the muscles, veins, and also in the spinal column.
☛ The term 'adrenaline junkie' is used in America to describe people who enjoy stressful activities. The adrenaline rush gives them a 'high'. Thus, indulging in stressful activities, like adventure sports may turn into an addiction for such people.
Epinephrine is an important hormone required for the smooth functioning of our body. It helps in countering the stress experienced by the body and in turns signals the nervous system to act immediately. Acting quickly in times of emergency is possible only because the hormone helps in generating energy in the form of glucose.
Disclaimer: This is for informative purposes only and should not be used as a replacement for expert medical advice.