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Stress and the Body Systems

Updated: Jun 21, 2023

A brief introduction to the human body

The human body is in a state of balance when it readily regulates the different body systems through physiological processes for its optimal survival. This is also called homeostasis, where the body can return itself to its normal equilibrium state after responding to physiological and psychological stimuli. A simple example is when the body produces sweat in response to a rise in body temperature. When this balance is lost, the internal body systems become affected and may cause diseases and even lead to death.

What is Stress?

According to the American Psychological Association, stress is a normal reaction to everyday pressures, but can become unhealthy when it upsets your day-to-day functioning.

Living in a fast-paced world and having a tendency to control most things can cause stress for some individuals when events deviate from their plans. Stress is any physiological or psychological stimuli that impacts homeostasis. Stress can also be described as a challenge, and it is oftentimes an offspring of fear. It may manifest as anger or anxiety, and it may lead to issues like fatigue. Anything that causes stress is called a stressor. Stress in itself is not harmful; it is our levels of exposure to stressors and our response to the stressors that determine if the situation is stressful or not.

Many types of stressors exist in our environment and people face different levels of exposure to them, but people are subjective, and their responses may vary even to the same things. Exposure to stressors may be further classified as constant (prolonged or chronic) or short-term (acute). When exposed to a stressful situation (whether actual or perceived), the body elicits the “fight or flight” response where it decides to either fight or escape the threat. Stress response or the “fight or flight” response is an adaptive reaction of the body to prepare itself for external or internal stressors and this process is crucial for the survival of the body. In stressful conditions, the body narrows its focus on the problem/stressor. After responding to the stimuli, the body systems work together to reinstate the body back to its homeostatic state. However, in the presence of severe stress and/or long-term exposure to stressors, the stress response may become maladaptive and detrimental. It is comparable to driving with the parking brake on-- your car can get wrecked or damaged in some parts, especially if you drive at a high speed or for a long duration.

Stress on the human body

The effect of stress on the body systems include:

  • The nervous system perceives the stressor, then activates the HPA (hypothalamus-pituitary-adrenal) axis and the sympathetic nervous system (SNS). The SNS then sends information to the endocrine system to release hormones (like adrenaline and cortisol) that help the body respond adequately to the stressor.

  • The endocrine system activates the body’s stress response by producing more steroid hormones like cortisol. These hormones trigger other systems such as increasing muscle contraction to intensify alertness, increase heart rate and glucose supply.

  • The musculoskeletal system defensively contracts and creates muscle tension to protect the body from injury and pain. The pupils dilate to enhance visibility and alertness.

  • The cardiovascular system responds by raising the heart rate to increase blood flow and blood pressure.

  • The respiratory system reacts to muscle constriction of the airways and causes faster breathing. It collaborates with the cardiovascular system by increasing the supply of oxygen to the cells of the body and removing carbon dioxide waste.

  • The gastrointestinal system slows down digestion to conserve energy and controls the nutrients absorbed by the intestines.

  • The reproductive system reduces sex hormones and affects sexual behavior.

These are some of the responses to acute stress and once the stressful situation is over, the parasympathetic nervous system returns the body to its normal homeostatic state.

However, in the presence of chronic stress or under constant exposure to stressors, the nervous system will continually trigger the endocrine system to produce more stress hormones (cortisol and adrenaline). High levels of stress hormones in the body causes the stress response system to be overactive.

Hyperreactivity disrupts the body’s regulatory mechanism- the body initiates a homeostatic response to counteract the elevated levels of stress hormones (resistance stage). However, if the stressors persist, the body undergoes this response repeatedly until it reaches a state of exhaustion that weakens the immune system causing psychological and physiological anomalies. For instance, continuous muscle contraction and tension can lead to chronic pain in the back, joints, and neck. Chronic stress negatively impacts the immune system by suppressing the body’s immune-inflammatory response (ability to effectively fight pathogens and heal wounds) which may result in disorders such as autoimmune diseases and increased susceptibility to infections.

Take Action

Self-awareness is paying attention to yourself, being aware of your thought process, your emotions, and actions. Living intentionally, focusing on the present moment, and being grateful for each moment. Being conscious of your stressors, what causes them, and why they affect you is a crucial first step to recovery. Practices such as yoga and breathing meditation may be helpful in alleviating stress levels.

Relax and take care of yourself. We sometimes forget to be human beings as we are occupied with doing things. We may need to take a break from social media or TV to create some space to just be.

Laughter is a natural, non-pharmacological method to reduce stress. Laughing may relax muscle tension, reduce blood pressure, boost your immunity, decrease levels of stress hormones, increase the production of endorphins, and consequently enhance your overall well-being. Enjoying precious moments with good friends and family members, watching/attending a good comedy show, and having a good sense of humor are a few ways to introduce laughter into your life.

Engage in productive hobbies that improve your mood and reduce stress. Examples include doing physical exercises (running, jogging, swimming, etc.), playing sports, painting, writing, reading, dancing, gardening, flying kites, hiking, volunteering, playing chess, and music.

Practice healthy habits. Smoking, excessive drinking, stimulant use, and eating disorders are some of the coping mechanisms that some individuals use to deal with stress. These unhealthy habits may result in temporary relief, but the risks outweigh the benefits and are eventually damaging to one’s health. Eat healthy diets, avoid processed foods and sugars, avoid excessive intake of alcohol, and improve the quality of your sleep.

Make meaningful connections. Have a good support system, bond with pets, or join a community that benefits you. This may relieve stress and improve your health.

Seek professional help, talk to your healthcare provider, and know that you are not alone.

Be intentional, and take care of yourself - you are a precious being!


1. APA Dictionary of Psychology

2. Physiology, Stress Reaction. Chu B, Marwaha K, Sanvictores T, et al. [Updated 2022 Sep 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:

3. Laughter therapy: A humor-induced hormonal intervention to reduce stress and anxiety. Akimbekov NS, Razzaque MS. Curr Res Physiol. 2021;4:135-138. doi: 10.1016/j.crphys.2021.04.002. Epub 2021 Apr 30. PMID: 34642668; PMCID: PMC8496883

4. Eckhart Tolle quote.

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