The Physiology and Effects of Stress

As an IB student, I am undoubtedly subjected to a large amount of stress, ranging from academic to social pressures. Not only do I have to worry about college applications and final examinations as a senior, but I also have to consider balancing out my sports and extracurricular activities, my social life and sleep. My parents and even doctor have told me repeatedly that I need to watch out for my stress level because too much stress can cause negative repercussions. However, this made me wonder, how exactly does stress work in our bodies, and to what extent is it harmful for us? Thus, this post will first examine the physiology of stress, and then lead to an evaluation between its pros and cons.

To begin, the science behind stress is coincidentally linked to our current IB chemistry study on the topic of equilibrium. In Chemistry, stress is defined as something that interferes with a system’s equilibrium, such as a change in temperature, number of moles or volume. (Brucat, 2008) Similarly, this equilibrium state can also exists in our body. In fact, homeostasis within our bodies is defined as, “an elusive state of metabolic equilibrium between the stimulating and the tranquilizing chemical forces.” (The Franklin Institute, 2004) Ultimately, stress disturbs this homeostasis. The automatic nervous system (ANS), which controls all the involuntary activities and functions of our body, such as digestion and blood pressure, consists of two branches. The first branch, the sympathetic nervous system (SNS) is the fight-or-flight response that becomes automatically activated when our brain perceives danger or stress. The other branch, the parasympathetic nervous system (PNS), is responsible for restoring the body back to homeostasis after the threat is over. To best explain the physiology of stress, I shall use an example.

Imagine you are strolling casually in a forest when you suddenly notice a menacing lion gazing at you. Immediately, your hypothalamus in the brain sends a blazing “DANGER!” message through the nervous system to the other body systems. The hypothalamus also signals the endocrine system to start secreting hormones, mainly adrenalin and cortisol, into the bloodstream so that the every cell in your body gets ready for the fight-or-flight response. While the systems necessary for increasing power and speed are emphasized, the other systems, such as the digestive and immune system, are inhibited to allow for the extra work of the vital systems. (Olpin) Under our medicine and drugs unit in IB Chemistry, we studied the adrenaline hormone and its effects on our body, such as increased heart rate, blood flow to the brain and muscles, and mental awareness. (Ford & Brown, 2007) Thus, I will focus on the other primary stress hormone, cortisol, which is secreted by the adrenal cortex.

Cortisol affects the entire body and contributes to the physiological changes that occur when the ANS or fight-or-flight is activated. One of these effects is the metabolic process of gluconeogenesis, which makes “glucose from oxaloacetate” (Randall, 2011, p.1). Cortisol also prompts glucose synthesis in the liver. Altogether, it is responsible for regulating the bloodstream’s glucose level, which is essential when you demand a lot of energy trying to fight or run away from the angry lion, because cortisol ensures a continual supply of glucose. As aforementioned, other unneeded systems, like the immune system, are suppressed to divert more oxygen and blood to the systems that require them. Cortisol helps put this into effect by suppressing the immune system. It prevents the multiplication of T-cells and the secretion of histamine (a lack of histamine inhibits inflammations). (Randall, 2011)

Functional groups: Carboxylic acid, alcohol (2), carbonyl
Functional groups: Carboxylic acid, alcohol (2), carbonyl

(Structure of Cortisol, 2010)

Although stress seems to be widely accepted as something that is bad, our fight-or-flight response is evolutionary beneficial for our survival.  In situations of acute stress, an immediate and temporary disruption of our homeostasis is necessary for us to react more powerfully and rapidly to life-threatening situations, like an angry lion chasing us. Without the increased flow of adrenaline and other hormones in your bloodstream, an adequate supply of oxygen, glucose and fatty acids can’t be pumped fast enough to your muscles and brain during the emergency. Therefore, stress and our body’s response to it is not necessarily deleterious. (Olpin)

However, the problem is our stress reaction is only advantageous for the ephemeral demands. It is not everyday that we get attacked by an animal or experience a life-threatening emergency like an earthquake. The emotional and social stresses that we do face on a daily basis cause the stress response to be activated for a much longer time, as our brain does not perceive the challenge to be over. This persistent activation of the SNS is termed “chronic stress”, which has been found to bring harm to our health. Since our body is kept in the fight-or-flight response and not reverted back to homeostasis, the physiological activities that occur during the response are also prolonged. (Olpin) It is not difficult to realize why our body starts to deteriorate when you remember that cortisol suppresses our immune system, which makes us susceptible to diseases. Furthermore, as “the hippocampus, the region of the brain where memories are processed and stored, contains many cortisol receptors,” (Randall, 2011, p.1) exorbitant levels of cortisol can lead to atrophy of the hippocampus, causing memory loss and the brain’s inability to form new memories. These health claims came from credible sources made for educational purposes, such as the Dartmouth Undergraduate Journal of Science, so I have confidence in their reliability.


Therefore, stress works in our body by disrupting our internal equilibrium. In the short run, this response characterized by an activation of our SNS proves valuable, as it helps us react fast enough to urgent situations and stimulates our brains during challenges. However, in the long run, chronic stress prevents our body from functioning normally at homeostasis, leading to the breakdown of our organ systems. This understanding of stress, especially chronic stress, is definitely significant for me, students and adults all over the world, because current troubles may cause long-term, irreversible consequences on our body. Thus, when making decisions in commitments and decisions, one should consider the amount of stress that might be involved as to not overwhelm oneself. In addition, with the finding that an increase in the stress hormone cortisol for an extended amount of time is adverse to the body, another significant application of this knowledge would be to reduce other activities that also raise cortisol levels. (Randall, 2011) In my research, I found that sleep deprivation, caffeine, alcohol, too little exercise and too much eating could all elevate cortisol levels (Gahr, 2008). Hence, people already under chronic stress are even more at risk when they react to it by pulling all-nighters and gulping down cups and cups of coffee. In conclusion, the physiology of stress and the effects of chronic stress on health tremendously emphasize the importance of stress management. In order to best benefit from our body’s stress response, we must alter our lifestyle and behavior accordingly.


Brucat, P. (2008, April 27). Advancement, stress, and chemical equilibrium. Retrieved from

Ford, M., & Brown, C. (2007). Chemistry developed specifically for the ib diploma. (pp. 639-641). International Baccalaureate Organization.

The Franklin Institute. (2004). The human brain. Retrieved from

Gahr, T. (2008, October 28). The science behind stress. The Cornell Daily Sun. Retrieved from

Olpin, M. (n.d.). Retrieved from

Randall, M. (2011). The physiology of stress: Cortisol and the hypothalamic-pituitary-adrenal axis.Dartmouth Undergraduate Journal of Science, Retrieved from


Olpin, M. Chronic Stress. N.d. Graphic. Weber State UniversityWeb. 3 Sep 2013. <>.

Structure of Cortisol. 2010. Graphic. Dartmouth Undergraduate Journal of ScienceWeb. 3 Sep 2013. <

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