The adrenalin Is considered as the activation hormone and is related to intense situations in which high emotions are experienced.
However, it is much more than that, since it is not a substance that merely gives us sensations of euphoria.
In fact, it is one of the most important hormones in the human body and performs very important functions.
Do you want to know the characteristics of this substance, its operation and the activities that it performs in the organism? We will explain it to you below.
What is adrenaline?
Adrenaline is a hormone in the human body, but in turn, it is also a neurotransmitter.
This means that it is a chemical that performs functions both in the brain (neurotransmitter) and in the rest of the body (hormone).
Chemically, this substance is part of the group of monoamines, neurotransmitters that are discharged into the blood stream and synthesized from the Tyrosine .
Adrenalin is produced in the medulla of the adrenal gland, a structure located just above the kidneys.
Keep in mind that adrenaline is not necessary for the preservation of life, so you can live without it.
In fact, under normal conditions its presence in the blood of the organism is practically insignificant.
However, this does not mean that the functions of these substances are not highly important for the functioning of the body.
In fact, adrenaline is the main hormone that allows us to perform the fight or flight reaction, so without it our behavior would vary significantly.
Thus, adrenaline is considered to be not a vital substance for the maintenance of life, but it is for survival.
Put another way, without adrenaline we would not die but we would have more options to succumb to certain dangers and it would cost us more to survive in the threatening situations.
How is epinephrine secreted?
Adrenaline is stored in the adrenal medulla in the form of granules. Under normal conditions the release of this hormone is practically imperceptible, so it is not poured into the bloodstream and is stored in the adrenal medulla.
In order to be segregated, that is, to leave the adrenal medulla and access the blood, it requires the action of another substance, the Acetylcholine .
Acetylcholine is a neurotransmitter located in the brain that when it enters the bloodstream allows the release of adrenaline.
This release occurs because acetylcholine opens the calcium channels, excites the adrenal gland and allows the adrenaline to exit.
When do we release adrenaline?
As we have seen, under normal conditions the body does not release adrenaline.
In order to do so, it requires the presence of acetylcholine in the blood, but what determines acetylcholine to release the adrenaline?
Well, so that the adrenaline can access the blood and perform its functions, it is required that previously brain Has perceived an excitatory stimulus.
This means that we release only adrenaline when we perceive a situation that requires an extremely fast and effective response.
In fact, if the brain does not perceive such a stimulus, acetylcholine will not release and will not get the adrenaline out.
Thus, adrenaline is a hormone that allows us to perform quick actions known as fight / flight responses.
For example, if you walk down the street quietly, but suddenly you see a dog that is going to attack you imminently, your body will respond automatically with a high release of adrenaline.
This same principle is what happens in"activities to release adrenaline"such as practicing sports risk or climbing attractions such as the roller coaster.
Mechanism of action of adrenaline
When adrenaline is released into the blood it spreads through most tissues in the body.
When you access the different regions of the body, you come across a series of receptors to which it binds.
In fact, in order for the adrenaline to act and perform its functions, it needs to"meet"with this type of receptors.
Otherwise, the adrenaline would be wandering through the bloodstream but would not be able to perform any function and would have no use.
Adrenaline receptors are known as adrenergic receptors and there are different types.
In general, alpha adrenergic receptors can be distinguished from beta adrenergic receptors.
When epinephrine binds to alpha adrenergic receptors (distributed over different body regions), it performs actions such as cutaneous and renal vasoconstriction, contraction of the splenic capsule, myometrium and iris dilator, or bowel relaxation.
On the contrary, when it is coupled to the beta receptors, it performs actions such as vasodilation of skeletal muscle, cardioacceleration, increased contraction force Myocardium Or relaxation of the bronchi and intestines.
What functions does adrenaline work?
Adrenaline is an excitatory hormone that it does is activate the body very high.
In fact, as discussed above, the biological function of this hormone is to prepare the body for the attack / flight response.
If we look at the effects discussed in the mechanism of action of this substance, what makes the adrenaline is to make all the necessary changes in the body to maximize the effectiveness of immediate response.
At a specific level, we can specify the following effects of adrenaline:
1- Dilates the pupils
When adrenaline attaches to the alpha receptors, a contraction of the iris dilator occurs.
This fact becomes a greater dilation of the pupil, so that more light enters the receptors of the eye, the visual capacity increases and we become more aware of what is happening around us.
In emergency and threat situations, this increase in pupillary dilatation is key to being more alert and maximizing the effectiveness of fight / flight response.
2- Dilates blood vessels
We have also seen how when adrenaline attaches to beta receptors, a dilation of the blood vessels occurs automatically.
Specifically, what adrenaline does consists in widening the blood vessels of vital organs and compressing the blood vessels of the outer layer of the skin.
In fact, as we have seen previously, this double action is done through the two types of receptors.
While alpha receptors perform vasoconstriction on the skin, beta receptors perform vasodilation in the innermost regions of the body.
This allows you to overprotect the most important organs of the body and lower blood pressure in the areas of the skin, because in the face of a threatening situation they could break down and cause bleeding.
3- Mobilizes glycogen
Another of the main functions of adrenaline is to mobilize the Glycogen .
Glycogen is the energy we have stored in muscles and other regions of the body.
In this way, adrenaline converts glycogen into glucose ready to be burned to increase the energy level of the body.
In emergency situations, the most important thing is to have more energy, so that adrenaline stimulates the reserves so that the body can have all of its stored energy.
4- Increases the heart rate
When we have to carry out fast, intense and effective actions, we need the blood to circulate at great speed through the body.
In this way, adrenaline attaches to beta receptors to increase heart rate, pump more blood, better nourish oxygen muscles and make them work harder.
5- Inhibits the intestinal functioning
The intestines expend large amounts of energy to perform the necessary digestion and nutrition processes.
However, in emergency situations this action is not essential, so the adrenaline inhibits it to not waste energy and reserve it all for the attack or flight reaction.
Through this action the adrenaline gets all the energy is concentrated in the muscles that are the organs that will have to act, and do not deposit in other regions.
6- Increase of the respiratory system
Finally, in emergency situations we also need higher amounts of oxygen.
In fact, the more oxygen enters the body, the better the blood will perform and the more muscle the muscles will have.
For this reason, adrenaline increases the respiratory system and motivates ventilation to be more abundant and faster.
Medical Adrenaline Applications
As we have seen, adrenaline produces a bodily activation in order to assure a more effective response.
Thus, although there are people who experience greater or lesser pleasure in the effects of adrenaline, the biological goal of this hormone is not to provide pleasure.
In addition, adrenaline has been used to treat a number of conditions, including cardiorespiratory arrest, anaphylaxis and superficial bleeding.
The adrenaline in medical use is known both through the name of adrenaline itself, and through the name of epinephrine. Both nomenclatures refer to the same chemical, adrenaline.
1- Heart failure
Adrenaline is used as a medicine to treat cardiac arrest and other conditions such as Arrhythmias .
The usefulness of this substance is that as we have seen, when adrenaline enters the bloodstream, the heart rate increases when coupled to beta receptors.
Thus, when suffering from diseases caused by decreased or absent cardiac output, adrenaline can increase and regularize the good functioning of the heart.
2- Anaphylaxis
The anaphylaxis Is a generalized immune reaction of the body that causes the body to enter into anaphylactic shock and puts the individual's life at immediate risk.
As adrenaline has dilatation effects in the area, it has today been erected as the drug of choice to treat this disease.
It is also used for the treatment of septicemia (overwhelming and potentially deadly systemic response to infection) and for the treatment of protein allergies.
3 - Laryngitis
The laryngitis Is a respiratory disease that is usually triggered by acute viral infection of the upper respiratory tract.
Adrenaline allows to improve and increase respiratory systems so this substance has been used for many years as a treatment for laryngitis.
4- Local anesthesia
Adrenaline is added to a number of local injectable anesthetics, such as bupivacaine and lidocaine.
The reason adrenaline is used in anesthetic processes relies on its vasoconstricting power.
When the adrenaline reaches the blood the blood vessels become narrower, a fact that allows to delay the absorption of the anesthetic and, therefore, prolong its action on the body.
Adrenaline and stress
The adrenaline, next to the Cortisol Is the main stress hormone.
As we have seen throughout the article, the effects of adrenaline on the body are only triggered.
Thus, when this substance is in the blood, the body acquires a state of activation much greater than normal.
One of the main factors that explain stress is therefore the presence of adrenaline in the body.
When we are stressed, adrenaline is not released only when we are in an emergency situation, but it is released in higher amounts than usual steadily.
This fact makes the body of the stressed person more active than normal permanently, and the anxiety relative to moments of threat is prolonged in situations that should be more tranquil.
Thus, stress causes a greater release of adrenaline, which is responsible for causing much of the symptomatology of this disease.
References
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- Emery, F. E. and W. J. Atwell. Hypertrophy of the adrenal glands following administration of pituitary extract. Anat. Rec, Vol. 58, No. 1, Dec, 1933.
- Reiss, M., J. Balint and V. Aronson. Compensatory hypertrophy of adrenals and the standardization of the adrenal cortex hormone on rats. Endokrinol., Vol. 18, p. 26, 1936.
- Rogoff, J. M., and G.N. Stewart. The influence of adrenal extracts on the survival period of adrenalectomized dogs. Science, Vol. 66, p. 327, 1927.
- Hartman, F.A., and G. W. Thorn. The effect of cortin in asthenia. Proc. Soc. Exper. Biol. And Med., Vol. 29, p. 49, 1931.