Stress is anything that brings an interruption to your internal equilibrium, as it can be either physiological or physical.

There are many different definitions of stress, but for our purpose, we will be viewing stress as a demand from an external or internal challenge that tests ones ability to cope. When we are faced with this demand, whether it be within our mind or external world, our body goes into a process none other than, The Stress Response.
The Stress Response is a mixture of physical and psychological responses.
The bodies physical response to stress is:

• Faster breathing

• Increased heart rate

• A spike in blood pressure

• Dilated pupils

• Tense muscles
  
  This all occurs as a natural response once we have come in contact with something that our brain has registered as a threat (stressor). Our bodies natural response has been curated to help us survive moments where we believe our life to be in danger, but when over-activated, it can wreak havoc on our body and cause it to become a breeding ground for ailments and diseases.

To understand the Stress Response, it is important that we take time to discuss what happens from the moment a stressor is perceived.

Whether you are being chased by an animal that is trying to kill you or plagued by looming deadlines, the physiological reaction is the same. The amygdala, which is located in front of the hippocampus in the brain, detects the the stressor as a threat and sends a signal to the hypothalamus. The hypothalamus acts as a command center and fires off messages to the nervous system, alerting them to initiate fight or flight.

The sympathetic nervous system is then activated and communicates with the adrenal glands to release adrenaline (epinephrine), into the bloodstream. This starts the cascade of physiological responses. Our hearts would start to work harder, making sure it is able to supply enough blood to all the organs and muscles within the body.
Respiration would increase as our lungs attempted to consume as much oxygen as possible, supplying the brain with enough oxygen it needed to become more sharper and alert. As our heart rate rose, so would blood pressure and sugar levels, as glucose and fats from storage sites around the body are released in response to epinephrine.
This provides the body with the energy needed to carry out the stress response.

The hypothalamic-pituitary-adrenal axis (HPA-axis) is activated once the initial surge starts to idle down. If the perceived stressor is still seen as a threat, the hypothalamus then releases corticotropin-releasing hormone (CRH) to be sent directly to the pituitary gland. Once there, CRH will trigger for the release of adrenocorticotropin-releasing hormone (ACTH), which then travels through the body, all the way down to the adrenal glands.
When it gets to the adrenal glands, the hormone cortisol is released as a response to its arrival. Once cortisol hits the bloodstream, the stress response stays activated and our bodies are in survival mode. Cortisol levels will begin to fall once the perceived threat has passed and our stress response can start to deactivate. This is when the other part of the autonomic nervous system, the parasympathetic nervous system is activated and helps the body fall back into line with homeostasis.

As you can see, there is a lot that happens within the body during the activation of the stress response. When activated during moments of acute stress, this response system is the reason why we are able to respond to life or death situations. It serves to protect us. Yet, we live lives that are filled to the brim with stressors. Due to this, most of us are living with this system being chronically active.

A chronically activated stress response can leave you exposed to high levels of stress hormones and disrupted systems. While activated, systems such as the immune, reproductive, and digestive have their functions halter to use that energy is other areas, such as fueling our muscles and overactive heart and lungs. The Mayo Clinic discussed how long-term activation of the stress response can disrupt nearly all of our body’s processes. This increases ones risk for an array of health problems such as: heart disease, hypertension, stroke, heart attack, digestive issues, brain impairment, weight gain, and much more.

The stress response is a complex mechanism that was naturally curated to help protect us, but as you can see, if left going, can do the opposite of its intended purpose. Thankfully, research within this field continues to deepen and produce emerging studies that are shining a light on all the ways it impacts us and our bodies.