The Science Behind Adrenaline: Unveiling Its Effects on the Cardiovascular System

Adrenaline, also called Epinephrine, is a hormone and a neurotransmitter. In terms of being a hormone, it is produced and released from the adrenal gland. On the other hand, as a neurotransmitter, adrenaline exists in the central nervous system as a chemical messenger that helps transmit nerve signals (Cleveland Clinic, 2022). As an acute stress response, adrenaline is usually released when facing a perceived stressor or threat, as adrenaline stimulates the nervous system to prepare the body for a quick response (Sheppard, 2021). This article aims to delve deeper into the effects of adrenaline and whether its role in affecting the cardiovascular system. 

General Effects of Adrenaline to the Human Body:

In terms of the release of adrenaline, the body must be in either a great amount of stress or a heightened sense of emotion as adrenaline acts as a stress hormone that shields the body from harm. This release helps with focusing and taking on the situation with high concentration. During the release of adrenaline, the psychological effects span from anxiousness, nervousness, to pure excitement (Brennan, 2021). The physiological effects of an adrenaline rush include heightened senses and strength. A notable detail about the heightened sense is that adrenaline does not bring invincibility, instead, it provides mental concentration that distracts the painful sensation. The heightened senses and strength effect of an adrenaline rush is primarily caused by the blood vessels contracting and directing more blood to major muscle groups like the heart (Brown & Dollery, 1984). Furthermore, adrenaline is commonly used in medication like the Epi Pen. The EpiPen is an auto-injector that contains adrenaline for circumstances such as severe allergic reactions. In the case of a severe allergic reaction, the injection of adrenaline increases arterial blood pressure and coronary perfusion and relaxes the muscles in your airways to make breathing easier (Wong, 2003). Despite the effects of adrenaline might seem alluring, an excess amount of adrenaline for no particular reason can cause symptoms such as a weakened immune system, peptic ulcers, cardiovascular disorders, and DNA damage. Furthermore, damage in the DNA induced by stress can promote tumor growth, miscarriages, and exacerbated anxiety (Callaway, 2013).

Effects of Adrenaline on the Cardiovascular System:

After the release of adrenaline, the cardiovascular system undergoes a complicated process to prepare the body for a fast reaction. During the process, the body shortens the isometric contraction phase, accelerates the speed of contraction, increases the systolic emptying of the left ventricle, increases the amplitude of the pulse pressure, and increases the heart rate (Austin, 2016). Cumulatively, these effects in the cardiovascular system can speed up the circulation of blood in the human body and allow greater strength. Despite the effects of adrenaline might be appealing, excess amounts of adrenaline can cause cardiovascular disorders (Kjellberg et al., 1952). Cardiovascular disorders such as cardiac arrest and heart attack can all be caused by excess adrenaline. Sudden surge of adrenaline can contribute to a plaque rupturing, resulting in a blood clot that could grow large enough to block blood flow and cause a heart attack (Katella, 2024). Furthermore, for people with chronic heart failure, a condition where the heart muscle is permanently damaged, adrenaline can cause further damage through overworking the inefficient heart . 

Conclusion:

Adrenaline, also called Epinephrine, is a hormone and a neurotransmitter released as an acute stress response, when facing a perceived stressor or threat, as adrenaline stimulates the nervous system to prepare the body for a quick response  (Sheppard, 2021). In terms of the general effects of adrenaline on the human body, the psychological effects span from anxiousness, nervousness, to pure excitement (Brennan, 2021). The physiological effects of an adrenaline rush include heightened senses and strength (Brown & Dollery, 1984). These effects are caused by adrenaline affecting the cardiovascular system. During the process, the body shortens the isometric contraction phase, accelerates the speed of contraction, increases the systolic emptying of the left ventricle, increases the amplitude of the pulse pressure, and increases the heart rate(Austin, 2016). With blood vessels contracting and directing more blood to major muscle groups like the heart, adrenaline seems to be appealing. However, an excess amount of adrenaline can cause weakened immune system, peptic ulcers, cardiovascular disorders, and DNA damage. Most importantly, cardiovascular disorders such as cardiac arrest and heart attack can all be caused by excess adrenaline.

References:

1. Austin, P. (2016, December 20). What Are the Negative Effects Of Adrenaline? Promises P.A.T.H. Programs. https://www.promises.com/addiction-blog/what-are-the-negative-effects-of-adrenaline/

2. Brennan, D. (2021, April 27). What to Know About an Adrenaline Rush. WebMD. https://www.webmd.com/a-to-z-guides/what-to-know-adrenaline-rush

3. Brown, M. J., & Dollery, C. T. (1984). Adrenaline and Hypertension. Clinical and Experimental Hypertension. Part A: Theory and Practice, 6(1-2), 539–549. https://doi.org/10.3109/10641968409062582

4. Callaway, C. W. (2013). Epinephrine for cardiac arrest. Current Opinion in Cardiology, 28(1), 36–42. https://doi.org/10.1097/hco.0b013e32835b0979

5. Cleveland Clinic. (2022, March 27). Epinephrine (Adrenaline). Cleveland Clinic. https://my.clevelandclinic.org/health/articles/22611-epinephrine-adrenaline

6. Katella, K. (2024, February 12). Yes, Stress Can Hurt Your Heart: 3 Things to Know. Yale Medicine. https://www.yalemedicine.org/news/stress-affects-your-heart#:~:text=%E2%80%9CFor%20example%2C%20in%20people%20who

7. Kjellberg, S. R., Rudhe, U., & Sjostrand, T. (1952). The Effect of Adrenaline on the Contraction of the Human Heart under Normal Circulatory Conditions. Acta Physiologica Scandinavica, 24(4), 333–349. https://doi.org/10.1111/j.1748-1716.1952.tb00849.x

8. O’Sullivan , J. (2021). How adrenaline can be a heart breaker. Www.bhf.org.uk. https://www.bhf.org.uk/informationsupport/heart-matters-magazine/research/adrenaline#:~:text=We%20know%20that%20the%20body

9. Sheppard, S. (2021, August 26). What Is Adrenaline? Verywell Mind. https://www.verywellmind.com/what-is-adrenaline-5196452

10. Wong, D. L. (2003). Why Is the Adrenal Adrenergic? Endocrine Pathology, 14(1), 25–36. https://doi.org/10.1385/ep:14:1:25