Learning Objectives
By the end of this section, you will be able to:
- Understand the brain’s physiological adaptation and response to stress
- Differentiate the sympathetic versus parasympathetic nervous system response
- Explain the theory of adaptation
- Discuss the nurse’s role in identifying indicators of stress in a patient
The physiological response to stress includes each body system’s attempt to adapt to stressors. Activation of the sympathetic nervous system is the hallmark response to stress. Involvement of all body systems when the sympathetic nervous system is activated is the goal of adapting to the stressor. The nurse plays an important role in identifying factors that contribute to stress, the patient’s response to stress, and intervening to help restore balance to the patient.
Physiological Adaptation and Response
The body’s key adaptation response to stress is activation of the sympathetic nervous system, known as the fight-flight-freeze system. It activates all body systems to be prepared to fight or flee against the stressor. The classic scenario is a threat of attack, so the body is primed for defense. Muscles are tensed, pupils are dilated to see wide and clearly, lungs are open to suck in all oxygen possible, and blood is shunted away from the gut so it can be sent to the brain and muscles. In completing a physical examination of a patient in stress, many hallmark clinical manifestations will reveal activation of the sympathetic nervous system. This stress response is useful for acute and immediate stress but is not meant for chronic stress. The wear and tear of the body in constant stress exhausts the body and may end in collapse.
Patients who are chronically stressed with work or life’s demands may find their other body systems become depleted as hormones and chemicals being exchanged in the hypothalamus and pituitary initiate the stress response throughout the body (Welt, 2023). For example, the body of a person with untreated sleep apnea is chronically stressed due to the lack of adequate oxygen during sleep. As a result, the patient is always in fight-or-flight mode, even when at rest. Some conditions that could easily be managed can be exacerbated by chronic stress as the body diminishes its resources and ability to adapt. Many times, this is the condition in which nurses see patients: their body’s ability to adapt has decreased.
Interpretation by the Brain
The human mind responds to signals and messages that are sent through various hormones and chemicals, all trying to maintain or restore balance in the brain. The complex process responds to perceived stress or threats with a sympathetic fight, flight, or freeze behavior—even if the threat is actually quite irrational. This is why a person may know, logically, that it is extremely unlikely that the elevator they are riding in will crash, yet they still experience full-blown panic attacks at the mere suggestion of taking the elevator in their building. In those moments, they will feel the rush of rising blood pressure, their heart will race, they will feel as though they cannot catch their breath—they may hyperventilate. This response looks and feels as though the body is getting ready to defend itself or flee from some major attack. And the brain interprets that stress as a threat and responds as it should, even if the treat is not much of an actual threat at all in reality.
Cognitive behavior therapy and other psychotherapies focus on controlling the brain’s interpretation of stressful events by controlling thoughts. Nurses can help decrease a patient’s sympathetic response by role modeling breathing techniques and reorienting the patient to reality.
Sympathetic Nervous System Response
The sympathetic nervous system is part of the autonomic, or involuntary, system that affects organs, in opposition to the parasympathetic nervous system (Figure 8.4). Whereas the parasympathetic system is known as the “rest and digest” or “feed and breed” response, the sympathetic system is primed for fight-flight-freeze activities for the body under stress. The common phrase “fight or flight” was altered in 2015, with “freeze” added as a possible response after studying the impacts of traumatic and adverse events on sexual assault victims, plane or car crash victims, soldiers who had been in battle, and people attacked by animals. (Kozlowska et al., 2015). They could neither fight nor flee and literally became immobile (frozen) with fear.
The sympathetic nervous system activates body organs to prepare for a response to an assault. Pupils dilate, muscles become tense and engorged with needed oxygen rich blood, glucose levels are elevated by the adrenal glands and liver for energy, lungs and airways dilate, and blood from the gastrointestinal system is shunted to more vital organs. The result is elevated blood pressure to support activity to fight the stressor. If the sympathetic nervous system remains activated for a long time, it results in constipation, chronic hyperglycemia, decreased immune response, and overall body fatigue. People with chronic stress, therefore, may develop chronic disease such as hypertension, hyperglycemia, poor nutritional absorption, and ulcers (Sheng et al., 2021).
Recognize that medications and substances can trigger a sympathomimetic response, such as caffeine consumption and cocaine. Excessive use of these substances can create stress on the heart. Some medications are used purposefully to stimulate the sympathetic response (also called adrenergic response), such as medications used for a nonstress test or epinephrine used to treat a cardiac arrest.
Hypothalamic-Pituitary Axis Response
A complex system that helps the brain respond to stress is the hypothalamic-pituitary axis (HPA). Through a neuroendocrine mechanism, messages from hormones in the blood (the endocrine component) and the nervous system (the neurological component) pass through the hypothalamus and pituitary gland in the brain. These messages are mediated by the brain to regulate metabolism, the immune response, body temperature, body fluids balance, and the autonomic nervous system. Known as the control center for hormones, the hypothalamus receives messages from the body’s organs and then sends signals to the pituitary. The pituitary, which is further divided into anterior and posterior compartments, emits the appropriate hormones to the body to respond to internal and external environmental signals (Welt, 2023).
One key hormone that is activated by the HPA is glucocorticoid-releasing factor, which, in turn, stimulates the adrenal cortex to release cortisol and other glucocorticoids. A main function of cortisol, also known as the stress hormone, is to elevate the blood glucose level; glucose is needed to supply muscles for the flight-fight-freeze response of stress. Short-term elevation of the cortisol level allows the body to have the energy it needs; however, long-term release of cortisol can create chronic hyperglycemia and its associated complications.
Sympathetic-Adrenal-Medullary Response
In response to chemical and hormonal signals from the HPA, the adrenal glands, which sit on top of each kidney, create, and excrete chemicals known as catecholamines that respond to the sympathetic nervous system. Commonly known as adrenaline, the adrenal medulla makes epinephrine and norepinephrine, which activate sympathetic nervous system responses, including tachycardia and vasoconstriction, to elevate blood pressure. Additionally, corticosteroids are released from the adrenal cortex on the outer layer of the adrenal glands, which increases blood glucose levels, contributing to the needed energy demands of a sympathetic response. The body is well designed with feedback loops to send signals from organs to the brain and back to respond as needed to regulate homeostasis.
Autonomic Nervous System/Immune Response
Thankfully, the autonomic nervous system does not require conscious activation of any of its functions; it responds automatically. However, some functions can be affected by conscious thought. For example, some people learn to lower their own blood pressure and heart rate by meditating and or using calm breathing techniques. Another system affected by the autonomic system is the immune system, which helps fight antigens and pathogens. An antigen is something that generates an antibody response—hence, the term “anti-gen.”
In addition to elevating glucose levels, cortisol decreases the function of lymphocytes, one of the types of white blood cells that directly fight pathogens. Therefore, long-term stress can decrease the effectiveness of the immune system and put someone at risk for infection because the body may not be able to fight off infections.
Read the Electronic Health Record
Uncontrolled Diabetes and Stress
You, the nurse, are reviewing morning laboratory text results of a patient who has been hospitalized for uncontrolled diabetes and is now in diabetic ketoacidosis.
| Laboratory Test | Normal Range | Patient’s Laboratory Test Values |
|---|---|---|
| Fasting glucose, mg/dL | 70–100 | 254 |
| White blood cells, mL | 5,000–10,000 | 15,000 |
| Red blood cells, million/μL | 3.8–5.8 | 5.2 |
| Sodium, mg/dL | 135–145 | 156 |
| Urine ketones | Negative | Present |
Theory of Adaptation
Hans Seyle, the founder of Stress Theory, introduced the concept of adaptation in his work on stress. As a physician, he noticed that patients who experienced mental or physical stress and were able to adapt to the stressor in a positive way were able to recover, whereas those who could not adapt and adjust to a stressor deteriorated.
Medical treatments are used to intervene and help the body adapt, but individual qualities and abilities of each patient influence the success or failure of treatment. For example, a patient who has substance use disorder with alcohol may not have the liver capacity to rebound from a gallbladder attack, because the liver cannot respond correctly under the additional stressor.
General Adaptation Syndrome
The General Adaptation Syndrome is a process comprising three distinct physiological stages the body passes through when experiencing stress. As shown in Figure 8.5, the first stage is alarm, followed by resistance, and, finally, exhaustion. First described in a medical journal in 1936, Dr. Seyle identified that when a toxin is introduced into the body, predicted sympathetic nervous system physical responses were seen in laboratory rats and, later, in clinical patients.
The first alarm stage is characterized by the classic sympathetic nervous system responses to ready the body for fight or flight. Dr. Seyle also noticed the increase in corticosteroid levels during the alarm phase, with a resulting decrease in ability to fight the infection. Interestingly, an enlargement of the adrenal glands was also noticed that was due to the increased released of adrenal hormones during the alarm stage. If the stressor continues, yet the body can resist and adapt, these symptoms decline, but if the stressor continues and the body is unable to adapt, the body becomes exhausted. Prolonged exposure to the stressor or toxin can result in exhaustion or death if the body cannot adapt.
Local Adaptation Syndrome
Systemic stress has been discussed; it results in an overall sympathetic response of the body. In contrast, local adaptation syndrome is when the body responds only locally to an external stressor such as a wound, which may result in only a local response of the nearby tissues and circulation. The inflammatory response is the first physical response to injury or a pathogen. Blood vessels begin to dilate in an attempt to increase the flow of red and white blood cells and platelets to the area. Ideally, white blood cells will attack the pathogen, red blood cells will deliver needed oxygen to damaged tissue, and the platelets begin their clotting cascade to close off any wound. Depending on the size of the wound, tissues can then move through the healing process. Although the local area may go through the similar alarm, resistance, and exhaustion stages, these occur on a much smaller scale and do not affect blood sugar levels, overall white blood cell decline, or other sympathetic responses.
The concept of local adaptation is important for nurses to understand specifically for wound and tissue healing. Nurses can help tissues heal by improving the patient’s nutrition with adequate fluids and protein and also intervening with cold packs, pressure, and elevation to local sites of injury that naturally respond to the stressful injury with tissue swelling from the initial inflammatory response.
Indicators of Stress
One major tool nurses use during a patient assessment is vital signs. Also, a full head-to-toe physical assessment is required for a nurse to properly provide care for a patient, especially during a stressful event. As outlined previously, each body system can reveal physical signs of stress. For example, hair loss may be due to alopecia or aging but can also be seen in someone who is pulling their hair due to stress. Short, irregular nails can also indicate nervous nail biting. The astute nurse needs to pay attention to signs the body gives regarding stress. The following are physical signs of stress:
- acne
- blurred eyesight or sore eyes
- chest pains
- constipation or diarrhea
- difficulty breathing
- fatigue
- headaches
- high blood pressure
- indigestion or heartburn.
- menstrual cycle changes
- muscle aches
- panic attacks
- picking at nails, skin, or hair
- poor concentration
- sleep problems
- sweating
- teeth grinding
- weight loss or gain