Adrenalin

Adrenaline (also known as epinephrine) is a naturally produced hormone in the human body. It is created in the adrenal medulla, part of the adrenal gland. It is commonly referred to as the "fight or flight" hormone, as it stimulates higher alertness in the body and prepares it for the physical activity involved in fighting or fleeing from a particular situation. This hormone is also synthetically produced and used in the medical field to treat severe allergic reactions and occasionally aid in CPR.

Natural and Synthetic Production
Adrenaline is a hormone produced by the adrenal glands, a part of the endocrine system. The adrenal glands, located near the kidneys consist of two major parts: the outer cortex, which secretes hormones to regulate metabolism, blood pressure, immune response, etc., and the inner section, called the adrenal medulla, which secretes the hormones adrenaline and noradrenaline (or epinephrine and norepinephrine). When the adrenal medulla is stimulated by nerve impulses, chromaffin cells within the gland release adrenaline, allowing it to enter the bloodstream and initiate its responses. The body constantly produces epinephrine in small quantities, but when the adrenal medulla receives more frequent nerve impulses from the brain, which may be responding to danger, stress, or excitement, it will increase its hormone production.

As well as being naturally produced in the human body, adrenaline is produced in animals. Adrenaline medications for humans used to be produced with the adrenal glands of animals, but now, with more efficient methods of production, epinephrine is synthetically produced.

Effects
Adrenaline is considered a "fight or flight" hormone, and it yields many effects on different organs in the body with one common purpose: to provide energy for muscles to respond in a reaction to a potential threat. These effects prepare the body to either fight by facing the potential danger or escape the danger through flight. Some of these basic fight or flight reactions include increased heartrate and blood pressure, enlargement of the air passages in the lungs, dilation of the pupils, and increasing blood glucose levels.

Epinephrine significantly affects the liver cells, as it is necessary, along with the hormone glucagon for the breakdown of the polysaccharide glycogen into glucose molecules. Adrenaline aids in this process by attaching to a receptor outside of the liver, therefore causing a structural change that allows a G-protein to bind. The G-protein allows adenylate cyclase and ATP to bind to the structure, where the adenylate cyclase breaks down ATP into a messenger molecule known as cyclic AMP. The cyclic AMP activates the protein kinase, which in turn activates phosphorylase, which breaks down the glycogen into glucose for the rest of the body to use.

In the skin, adrenaline binds to receptors that begin a chain of stimulations that ultimately results in the hairs on the surface of the skin raising through muscular contraction, which allows for increased ability to react to external stimuli.

In the lungs, adrenaline causes the smooth muscles to relax, allowing increased breathing.

Epinephrine affects the heart by binding to receptors on the cardiac muscle cells, stimulating increased heart rate and higher blood pressure, therefore increasing the blood supply to the rest of the body.

Medicinal Uses
Adrenaline has multiple uses in various emergency situations. Most commonly, it is used as a treatment to severe allergic reactions. Several companies sell adrenaline injections to treat allergic reactions. These injections operate by intramuscularly or subcutaneously injecting the adrenaline solution into the thigh. Epinephrine injections are commonly used in severe reactions to foods (such as milk, nuts, etc.), medications, insect stings or bites, latex, etc. The solution combats serious allergic reactions by relaxing the muscles in the airways, which sometimes contract during a reaction, leaving one incapable of breathing, and through tightening the blood vessels. Although adrenaline injections often help with these reactions, it is not a replacement for medical attention. Right after taking an epinephrine injection, one should get emergency medical equipment. People who may be prone to severe allergic reactions should carry an epinephrine injection with them at all times. Severe allergic reactions may result in the following symptoms: closing of the airways, wheezing or sneezing, hives, itchiness, swelling, increased heartrate, weak pulse, anxiety or confusion, stomach pain, losing control of urine or bowel movements, faintness, or loss of consciousness.

As many people have seen in movies, adrenaline is also used in cardiopulmonary resuscitation (CPR). In fact, it is the most common drug in pediatric CPR, used to treat hypotension, bradycardia, asystole, or pulseless arrest. Typically, adrenaline will be administered to a vein that will deliver the solution to the heart. If no venous options are available, the drug may also be administered through the endotracheal tube into the lungs. If no other route is available, adrenaline manufacturers state that it can be injected directly into the heart. The use of adrenaline in cardiac arrest results in an increased aortic diastolic pressure that improves coronary and cerebral blood flow. Adrenaline also strengthens cardiac contractions. Adrenaline may yield negative side effects when used in CPR. Some of these effects include excessively high heart rate, hypertension, and excessive narrowing of the blood vessels.

Epinephrine dosages for allergic reactions and cardiac arrest are very different. Typically, epinephrine for allergic reactions is mixed in a ratio of 1:1000, while injections for cardiac arrest are much smaller, at a ratio of 1:10,000. Adrenaline injections for cardiac arrest used to be much higher than they currently are, but after research indicating no benefit from a higher dose and a lower rate of survival after twenty-four hours, the amount of adrenaline was decreased. During cardiopulmonary resuscitation, if adrenaline does not work the first time, it may be repeated every three to five minutes.

Video
This video describes the effects of epinephrine in the human body, and provides a specific example of how the hormone saved lives.

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