Systems responsible for body’s physical response to stressors

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This blog post will explore the systems that are responsible for the body’s physical response to stressors. 

We have also discussed what are some of the physical systems that are affected by stress.

What are the systems that are responsible for the body’s physical response to stress?

The systems that are responsible for the body’s physical response to stress are:

  • the autonomous nervous system
  • the endocrine system.

A stress inducing situation can trigger the release of stress hormone cortisol which inturn can impact various systems within the human body that lead to various physical, behavioural reactions. 

An individual’s response to stressors affects various systems within the human body including:

  • Musculoskeletal system
  • Respiratory system
  • Cardiovascular system
  • Endocrine System
  • Gastrointestinal System

Autonomic Nervous system

The autonomic nervous system has a direct role in how the body reacts to stress. The autonomic nervous system is divided into the sympathetic nervous system (SNS), and the parasympathetic nervous system (PNS). 

It is these two systems that activate and regulate the flight-or-fight response of the body towards stress.

When the body is under stress, the SNS contributes to what is known as the “fight or flight” response. The body shifts its energy resources toward fighting off a life threat, or fleeing from an enemy.

The most notable system that is affected when an individual is under stress, other than the nervous system,  is the endocrine system, involving the HPA axis triggered by the brain. 

The HPA axis or the Hypothalamic-pituitary-adrenal axis is the primary player in the way stress affects the body and usually it is this axis that plays a major role in the body’s response to stress.

When this axis is triggered there is a specific hormone that is produced in excess called Cortisol. 

This hormone influences the levels of glucose and fatty acids in the liver, thus increasing energy for flight or fight thus helping an individual cope with the demands of the stressful situation.

Glucocorticoids such as cortisol also regulates the immune system thus helping the individual cope with various threats to immunity and health. However, when there are elevated levels of cortisol due to chronic stress, this can increase immune system response which can lead to various physical and mental conditions. 

When someone is under stress or perceives a threat, the amygdala of the brain that processes the threat sends a signal to the hypothalamus which inturn communicates with the rest of the body via the nervous system to either prepare to fight or flight. 

The hypothalamus activates the sympathetic nervous system which then sends a signal to the adrenal glands which then pumps the hormone epinephrine (also known as adrenaline) into the bloodstream as a response to the signal. 

This particular hormone is what leads to a number of physical changes and responses in the body under stress. This hormone is what causes the heart to beat faster thus, pushing blood to the muscles, heart, and other vital organs. 

The person will also start to breathe more rapidly to take in as much oxygen as possible with each breath so as to increase alertness. The hormone also triggers the release of glucose and fats so as to supply energy to parts of the body that can aid in the flight or fight response. 

When an individual is under stress, it is the sympathetic nervous system that signals the adrenal glands to release hormones called adrenalin (epinephrine) and cortisol. 

And it is this hormone that influences other bodily systems to react to stress such as causing the heart to beat faster, respiration rate to increase, blood vessels to dilate, digestive process to change to deal with the emergency.

Once the moment of stress is over, the body returns to the natural state that is not stressed and this return to a normal state of functioning is facilitated by the Parasympathetic Nervous system. 

All of these changes happen so quickly that people aren’t aware of them due to which one’s reactions in stressful situations at times tend to be automatic and quick. 

What are the various systems within the body that are affected by stressors?

The various physical systems that are also affected by stressors as a result of the nervous system and the HPA axis being triggered include:

Musculoskeletal system

In stressful situations, muscle tension is also a response to stress as a way for the body to cope with injury and pain as well as sustain movement to run or fight the stressor. 

This particular strain and stress on the muscle is also a result of the activation of the HPA axis which leads to the musculoskeletal system being triggered leading to tension within the body to endure stress.

While this is supposed to be an adaptive response, prolonged muscle and skeletal strain due to chronic stress can lead to a constant state of vigilance that keeps the muscles taut leading to aches and pains. 

For example, migraines, tension headaches, aches around shoulders, neck, arms etc can all be part of the body’s physical reaction to chronic stress. 

Respiratory system

Another system that is responsible for the physical response to stressors include the respiratory system that supplies oxygen to the body. 

In stressful situations, the body shows symptoms related to rapid breathing and shortness of breath due to lung and airway constriction. 

This response to stress is to enable more oxygen flow into the blood so as to facilitate more efficient ways of dealing with the stress- either to fight the stressor or fight it. 

The rapid breathing allows for more oxygen and hence better blood flow into the brain, the body, muscles, etc so that the body is able to cope with the stressor- the body’s reaction to stress such as rapid breathing and shortness of breath is also part of the body’s reaction to stressors. 

Cardiovascular system

Acute stress can cause an increase in heart rate and stronger contractions of the heart muscle due to the release of the hormones adrenaline, noradrenaline, and cortisol. 

This can lead to the blood vessels to dilate so as to increase blood flow into muscles and the brain. This can lead to more alertness thus making people more aware of sensations and the world around them. 

While thai is an adaptive response to help people cope with the stressor, chronic stress can contribute to long-term problems for the cardiovascular system. 

Long-term ongoing stress can increase the risk for hypertension, heart attack, or stroke as well as inflammation in the circulatory system and can also affect cholesterol levels. 

Gastrointestinal system

Stress can affect this brain-gut communication and bring about changes in gut bacteria which in turn can influence the health of the individual. 

Stress or exhaustion can also increase the severity of heartburn pain and can make swallowing foods difficult or increase burping, gassiness, and bloating.

Vomiting may occur if the stress is severe as well as cause an increase or decrease in appetite. 

Stress can also affect metabolism and how quickly food moves through the body and can affect digestion and what nutrients the intestines absorb. 

What are some ways you can cope with stress?

According to the Centres for Disease control and prevention, some of the ways one can cope with psychological and physical stress include:

  • Taking breaks from strenuous work and labour. 
  • Take breaks from watching, reading, or listening to news stories that are negative as well as limiting time spent on social media. 
  • Eating healthy and nutrition dense diets
  • Exercise that is not too strenuous. 
  • Maintaining healthy sleep hygiene. 
  • Taking breaks when needed. 
  • Engaging in relaxing activities and exercises such as deep breathing and meditation.
  • Avoid excessive alcohol, tobacco, and substance use.
  • Making time to unwind by relaxing and also doing nothing. 
  • Engaging in activities that are relaxing, makes you happy, and what one enjoys, 
  • Talk to others about the stress such as Talking with a professional to help you manage and cope with the stress.
  • Seeking out support from people you trust about your concerns 
  • Connect with your community and spirituality that can help you cope with the stress and instil hope and optimism. 
  • Seek out ways to remove or minimise your stressor. 


This blog post has explored the systems that are responsible for the body’s physical response to stressors. We have also briefly discussed the various systems that are affected by stress.

FAQ related to Systems responsible for body’s physical response to stressors

What 2 body systems are affected by stressors?

Two body systems that are affected by stressors include your respiratory and cardiovascular systems. 

During the stress response, your brain activates the flight or fight response which can influence the functioning of your respiratory system and lead you to breathe faster in an effort to quickly distribute oxygen-rich blood to your body to respond to the stressor.

It can also influence your heart rate so as to pump more blood into muscles and the brain to help you react more efficiently.

What are the 3 stages of responses to stressors?

Three stages of response to stressors include:

Alarm where the individual’s first response is a reaction in terms of physical reaction or even psychological manifestation of stress such as inability to process, shock, panic etc.

Resistance is the next stage as to how one processes and reacts to stressors where an individual might try to resist the stressor either by denial or by actively trying to do things to minimise or reduce the stressor.

Exhaustion is the final stage when the individual is unable to resist the stressor in effective ways, they might physically and mentally collapse out of exhaustion. 

What is the stress response system?

The stress response, or “fight or flight” response is the result of the reaction system of the body that has been designed to help you survive in the face of threats and stress and includes physical and thought responses to the stressor. 

Which system is responsible for fight-or-flight response?

The autonomic nervous system is what is responsible for one’s reaction to stress particularly the flight or fight response. It is the sympathetic nervous system and the parasympathetic nervous system of the nervous system that triggers the response to help people cope with the stress,


American Psychological Association (2018) Stress effects on the body. 1st november 2018. Retrieved on 27th December 2021.

Harvard Health. (2020) Understanding the stress response. 6th July 2020. Retrieved on 27th December 2021.

Centres for Disease Control and Prevention. Coping With Stress. Retrieved on 27th December 2021. 

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