Stress affects all systems of the body including the nervous, endocrine, musculoskeletal, cardiovascular and gastrointestinal systems.
Our bodies are well equipped to handle stress in small doses, but when that stress becomes long-term or chronic, it can have serious effects on your body
The nervous system has several divisions: the central division involving the brain and spinal cord and the peripheral division consisting of the autonomic and somatic nervous systems.
The autonomic nervous system has a direct role in physical response to stress and is divided into the sympathetic nervous system (SNS), and the parasympathetic nervous system (PNS). When the body is stressed, 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 SNS signals the adrenal glands to release hormones called adrenalin (epinephrine) and cortisol. These hormones, together with direct actions of autonomic nerves, cause the heart to beat faster, respiration rate to increase, blood vessels in the arms and legs to dilate, digestive process to change and glucose levels (sugar energy) in the bloodstream to increase to deal with the emergency.
The SNS response is fairly sudden in order to prepare the body to respond to an emergency situation or acute stress—short term stressors. Once the crisis is over, the body needs to quickly return to the pre-emergency, unstressed state. This recovery is facilitated by the PNS, which generally has opposing effects to the SNS. (Homeostasis) Both the SNS and the PNS have powerful interactions with the immune system, which can also modulate stress reactions. The central nervous system is particularly important in triggering stress responses, as it regulates the autonomic nervous system and plays a central role in interpreting contexts as potentially threatening.
Chronic stress, experiencing stressors over a prolonged period of time can result in a long-term drain on the body. As the autonomic nervous system continues to trigger physical reactions, it causes a wear-and-tear on the body. It’s not so much what chronic stress does to the nervous system, but how continuous activation of the sympathetic nervous system can severely damage other bodily systems and cause many types of chronic health conditions over time. (Sympathetic Dominance) PNS over-activity can also contribute to stress reactions, for example, by promoting bronchoconstriction (e.g., in asthma) orexaggerated vasodilation and compromised blood circulation.
When someone perceives a situation to be challenging, threatening, or uncontrollable, the brain initiates a cascade of events involving the hypothalamic-pituitary-adrenal (HPA) axis, which is the primary driver of the endocrine stress response. This ultimately results in an increase in the production of steroid hormones called glucocorticoids, which include cortisol, often referred to as the “stress hormone”.
During times of stress, the hypothalamus, a collection of nuclei that connects the brain and the endocrine system, signals the pituitary gland to produce a hormone, which in turn signals the adrenal glands, located above the kidneys, to increase cortisol production.
Cortisol increases the level of energy fuel available by mobilizing glucose and fatty acids from the liver. Cortisol is normally produced in varying levels throughout the day, typically increasing in concentration upon awakening and slowly declining throughout the day, providing a daily cycle of energy.
Musculoskeletal system (Migraines and Magnification of Pain) When the body is stressed, muscles tense up. Muscle tension is almost a reflex reaction to stress—the body’s way of guarding against injury and pain.
With sudden onset stress, the muscles tense up all at once, and then release their tension when the stress passes. Chronic stress causes the muscles in the body to be in a more or less constant state of guardedness. When muscles are taut and tense for long periods of time, this may trigger other reactions of the body and even promote stress-related disorders and the magnification of pain.
For example, both tension headaches and migraine headaches are associated with chronic muscle tension in the area of the shoulders, neck and head.
The heart and blood vessels comprise the two elements of the cardiovascular system that work together in providing nourishment and oxygen to the organs of the body. The activity of these two elements is also coordinated in the body’s response to stress. Acute stress—stress that is momentary or short-term such as meeting deadlines, being stuck in traffic or suddenly slamming on the brakes to avoid an accident—causes an increase in heart rate and stronger contractions of the heart muscle, with the stress hormones—adrenaline, noradrenaline, and cortisol—acting as messengers for these effects.
n addition, the blood vessels that direct blood to the large muscles and the heart dilate, thereby increasing the amount of blood pumped to these parts of the body and elevating blood pressure. This is also known as the fight or flight response. Once the acute stress episode has passed, the body returns to its normal state.
Chronic stress, or a constant stress experienced over a prolonged period of time can contribute to long-term problems for heart and blood vessels. The consistent and ongoing increase in heart rate, and the elevated levels of stress hormones and of blood pressure, can take a toll on the body. This long-term ongoing stress can increase the risk for hypertension, heart attack and/or stroke.
Repeated acute stress and persistent chronic stress may also contribute to inflammation in the circulatory system, particularly in the coronary arteries, and this is one pathway that is thought to tie stress to heart attack. It also appears that how a person responds to stress can affect cholesterol levels.
The gut has hundreds of millions of neurons which can function fairly independently and are in constant communication with the brain—explaining the ability to feel “butterflies” in the stomach. Stress can affect this brain-gut communication, and may trigger pain, bloating, and other gut discomfort to be felt more easily. The gut is also inhabited by millions of bacteria which can influence its health and the brain’s health, which can impact the ability to think and affect emotions.
Commonly known as UTI, frequent urinary tract infections can be induced by stress. Feeling highly stressed is not the direct cause, but it leads to high levels of cortisol, which reduce the effect of the immune system. Early life stress can change the development of the nervous system as well as how the body reacts to stress. These changes can increase the risk for later gut diseases.
Stress or exhaustion can also increase the severity of regularly occurring heartburn pain.
Stress may make pain, bloating, nausea, and other stomach discomfort felt more easily. The latter are actually caused by a bacterial infection. When stressed, ulcers may be more bothersome.
Stress can also make pain, bloating, or discomfort felt more easily in the bowels. It can affect how quickly food moves through the body, which can cause either diarrhea or constipation. Furthermore, stress can cause painful muscle spasms in the bowel.
The intestines have a tight barrier to protect the body from (most) food related bacteria. Stress can make the intestinal barrier weaker and allow gut bacteria to enter the body.
Stress especially affects people with chronic bowel disorders, such as inflammatory bowel disease or irritable bowel syndrome. This may be due to the gut nerves being more sensitive, changes in gut microbiota, changes in how quickly food moves through the gut, and/or changes in gut immune responses.
The AMA has stated that 75 -90% of all primary care office visits are in response to stress and anxiety. Successful primary care practices of the future are going to have to create treatments programs that deal with the stress and anxiety of their patients. Medical technology devices are now available to help them determine the stress level of their patients and whether they are suffering from sympathetic dominance and/or an impaired immune system.