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Heart racing in your chest, and your breathing is getting quicker and quicker. Do these symptoms sound familiar? They are some physiological symptoms of stress; another example is altered PH levels in the body. The physiology of stress is when the homeostatic condition of the body changes as a result of encountering stressors. Researchers have identified several parts of the body that are activated when we are stressed, and these are responsible for the physiological causes of stress.
Homeostasis is the optimal condition that the body needs to be in, to work effectively.
What happens to our bodies when we are stressed?
The stress response is considered an innate response in animals (including humans). If the body is exposed to stress for too long, then the physiological effects of stress can damage the body. However, there are short-term evolutionary advantages to stressful encounters, such as helping us perceive and react to potentially harmful stimuli and situations. Therefore, it is essentially a survival mechanism.
When stressed, many changes occur in the body; the General Adaptation Syndrome describes the stages of stress that we experience and how these affect the physiology of our body.
The GAS model was proposed by Selye (1936) to describe what happens to the body when we experience stressors and how the body adapts to stressful situations.
Stressors are negative stimuli, events or threats that cause a physiological ‘stress’ response in the body. Some stressors are divorce, moving house, injury, losing a job, deadlines, work.
The model states that there are three stages that we experience when we encounter a stressor, these are:
The alarm phase - the body kicks into “fight-or-flight mode” after encountering a stressor; this leads to a physiological response such as increased heart rate, quickened breathing.
The phase of resistance - the parasympathetic branch is activated to try and calm the body and counteract the symptoms triggered by the alarm phase. The body does this by releasing the hormones adrenaline and cortisol. During this stage, a lot of the body’s energy is depleted.
The phase of exhaustion - the body has used up all its energy resources, and it couldn’t counteract the stress symptoms. Continual exposure to this stage leads to cardiovascular and immunity problems.
Images to show the “fight or flight” response to stress (Image created in Canva using pictures from Pixabay)
The hormones that are released when we are stressed are adrenaline and cortisol. These hormones are released to stop the adverse effects of stress damaging our bodies.
Adrenaline is released when we are stressed. This hormone affects the sympathetic nervous system and triggers the fight-and-flight response. An increase in adrenaline leads to an increased heart rate. Adrenaline prepares the body by:
Too much and too frequent exposure to high levels of adrenaline causes the heart to work harder, leading to cardiovascular problems.
Cortisol is a hormone that helps regulate blood sugar levels, metabolism and reduces inflammation. Cortisol is also released when we encounter stressors. The hormone ‘turns off’ systems that are not needed in the body. The body is then better prepared to deal with stressors and can stop cells and hormones involved in inflammatory responses from being released. The body needs to have a balanced amount of cortisol to function correctly.
If we experience high cortisol levels too frequently, it can lead to health issues, such as immunosuppression. Chronic stress causes cells to become resistant to cortisol. Cortisol becomes less effective at stopping cells/hormones from causing inflammatory responses, compromising the functioning of the immune system.
Too little cortisol can cause tiredness, muscle weaknesses, weight loss and low blood pressure.
Two different pathways are activated when we experience stressful situations the Hypothalamic Pituitary Adrenal (HPA) system and the Sympathomedullary Pathway (SAM).
The purpose of the HPA system is to try and maintain homeostasis when we experience stress. The body needs to stay in optimal conditions, e.g., a specific temperature or pH to work properly; this is homeostasis. When we encounter stressful situations, the hypothalamus is activated, activating the pituitary gland. The pituitary gland releases a hormone, ACTH (adrenocorticotropic hormone), which is transported to the adrenal glands and responsible for the production of cortisol.
Corticosteroids are produced in the adrenal cortex, and are also a synthetic version of cortisol, mimicking the effects of cortisol in the body.
Cortisol turns off the systems, such as inflammatory reactions caused by the activation of the SAM pathway. People with high blood pressure are more likely to get inflammatory diseases.
During stressful situations, the hypothalamus also activates the adrenal medulla, which works as a part of the Autonomic Nervous System. The adrenal medulla causes the release of adrenaline that is responsible for the “fight-or-flight” mode that we enter when we are stressed. The activation of this region leads to increased activity in the sympathetic nervous system and decreased activity in the parasympathetic nervous system; this is known as the SAM pathway.
Adrenaline (made in the adrenal medulla, and is a hormone) and noradrenaline (made in the sympathetic nervous system, and is a neurotransmitter) can act as hormones and neurotransmitters, but they favour one over the other respectively. Both help the body prepare for fight-or-flight.
When you experience stressful situations you may have noticed an increase in your heart and breathing rate, this is the physiological symptoms of stress.
Increase in heart rate and breathing rate. The body's PH levels also change.
When we are exposed to physiological symptoms of stress for too long then it can cause inflammation. Inflammation has been linked to many mental health illnesses.
This is also known as the General Adaptation Syndrome (GAS) model which explains the three stages of stress (the alarm phase, the phase of adaptation and the phase of exhaustion) and the effects these have on the body.
These have been linked to inflammation and cardiovascular problems.
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