Learning Objectives
By the end of this section, you will be able to:
- Define homeostasis as it relates to stress.
- Identify fundamental concepts of stress.
- Identify and explain fundamental concepts of adaptation.
The human body has a remarkable ability to adapt. It is dynamic and ever-changing as it responds to internal and external stimuli and triggers in the environment. These stimuli may be the malfunction of a body system or organ, or an external factor such as a job loss or death of a family member.
Many body systems work together to maintain stability. When one malfunctions, stress is created on other systems. As a nurse, it is important to understand the relationships between these systems.
Fundamental Concepts of Homeostasis
The process of adjusting to the environment as conditions change, either suddenly or over time, is called adaptation. Through these adjustments, the body attempts to keep all its systems in a state of balance, or homeostasis, that is conducive to life (Venes, 2017). To maintain homeostasis, the body relies on biological, chemical, and fluid processes that occur autonomically in response to change (Venes, 2017). When the body cannot maintain homeostasis, it experiences illness or disease, and, eventually, death. Even when injury, illness, or disease is present, the body still attempts to find balance. It uses all its systems to regain that balance until it either overcomes the injury or illness or perishes.
An example of homeostasis is the body’s attempt to regulate its temperature within the normal range so all cells, tissues, and systems can optimally perform their normal functions. The body is like a thermostat set to maintain an ideal temperature in a house. When the temperature rises, the air conditioner turns on to cool off the house; if the house cools below the established set point, the heater turns on until the air is sufficiently warm. Similarly, if the body overheats, it may generate perspiration to cool down; if its temperature drops too low, the body may begin shivering to generate sufficient heat.
Body Systems and their Effects on Homeostasis
Although body systems may seem like segmented pieces of the whole body, they are completely interdependent and respond to each other in a holistic manner through the process of adaptation. For example, the respiratory and renal systems interact to keep the blood pH in the normal range of 7.35 to 7.45. Carbon dioxide, which affects the acid level in the blood, is controlled by the respiratory system, whereas bicarbonate, which controls alkalinity, is controlled by the kidneys. The lungs may breathe faster or slower to exhale or retain carbon dioxide, and the kidneys may excrete or hold onto bicarbonate in respnse; the perfect interplay of these systems helps maintain homeostasis, allowing optimal functioning of the blood as it courses through the body.
Each body system performs its own inherent functions but, at the same time, affects other systems. The brain is known as the master controller for the entire body, but there are many backup systems throughout the body to help. For example, the medulla oblongata in the brainstem helps control vital signs such as breathing, pulse, temperature, and respiratory rate; the carotid arteries and the kidneys contain chemoreceptors (which measure chemicals) and baroreceptors (which measure pressure) to help regulate blood pressure. Table 8.1 briefly summarizes the main functions of different body parts and systems in maintaining homeostasis.
| Body System | Function |
|---|---|
| Brain | Responds to emotions, sensory input, and internal and environmental triggers |
| Integumentary | Controls body temperature, absorbs vitamin D, stores hormones, and protects the body from external damage |
| Respiratory | Controls respiratory rate and the exchange of oxygen and carbon dioxide |
| Cardiovascular | Controls blood pressure and volume, and transports essential nutrients, gases, electrolytes, and hormones to the various cells within the body |
| Gastrointestinal | Transports, digests, absorbs, and excretes nutrients |
| Musculoskeletal | Enables body movement and creates blood elements |
| Renal | Filters, reabsorbs, and excretes fluids and electrolytes |
| Reproductive | Creates and maintains sex hormones and physical sex characteristics |
| Endocrine | Responds to changes in body chemistry through positive and negative feedback by increasing or decreasing hormones |
| Hematopoietic | Stimulates red blood cells, white blood cells, and platelets in the blood |
| Immune | Responds to antigens and activates the body’s immune response |
Although there are medical specialists who focus on just one body system, such as cardiologists for the heart or endocrinologists for hormones, nurses practice with a holistic approach to client health. In your practice, you will need to understand the processes that each system uses to maintain homeostasis. Therefore, each system and its main disorders will be explored in greater detail in later chapters of this textbook.
Fundamental Concepts of Stress
We define stress as any disruption to the body’s normal state. It can be physical, biological, emotional, or psychological. Stress exists from the moment a person is born, as the baby feels the stress of leaving the comfort and warmth of their mother’s womb and entering a cold, unfamiliar world. Because stress is universal, it is considered a normal physiological process as the body adjusts to change and attempts to restore homeostasis. Some stress actually triggers the body to breathe, since the atmospheric air pressure around us is not the same as the pressure in our lungs. The difference in air pressure puts stress on the body, causing the diaphragm to contract. This, in turn, makes our chest expand, and we inhale through our nose, mouth, trachea, bronchioles, and alveoli.
As this example shows, stress can have positive effects. A positive stress is when a stressful event produces healthful outcomes such as breathing, which provides us the oxygen our bodies need to live. The stress of exercise is also positive, resulting in increased muscle strength and cardiovascular health. However, most people probably associate stress mainly with negative effects. A negative stress, also called distress, is when a stressful event produces unhealthful outcomes, such as illness or disease (Lazarus & Folkman, 1984).
Stressors
A stressor is an event or stimulus that activates an individual’s stress response (Centre for Studies on Human Stress, n.d.). Even though all people experience stress, the experience itself is highly individualized and varies from one person to another. Several factors affect a person’s response to a stressor, including their physical and emotional states. A person's intellectual understanding of a stressor also matters. Under most circumstances, a person may be able to handle an exposure to a seasonal virus. Their body quickly fights off the infection, and they experience few, if any, symptoms of illness. However, suppose they encounter the same virus during a physically or emotionally challenging time. A person may struggle to fight off a virus if there are additional stressors taxing the immune system. For example, if the person lost a job or is not getting adequate sleep or nutrition, the body may be weaker against a physical stressor such as a virus. This example explains why someone who is already sick generally should not be given a vaccine: their body is in a weakened state and may struggle to adapt to additional stressors.
In a recent poll, 73 percent of respondents identified financial concerns as their primary stressor (White, 2023). Some other common stressors people experience include environmental stressors (e.g., living environment; politics); lifestyle stressors (e.g., work; relationships; recreational choices); major life event stressors (e.g., childbirth; marriage; death; new job); organizational stressors (e.g., daily routines or lack thereof); physiological stressors (e.g., pregnancy, illness).
Fundamental Concepts of Adaptation
A crucial part of adaptation is the ability to cope with stressors to decrease negative stress. A person’s coping ability depends on multiple variables, including their mental and physical abilities (Segerstrom & Miller, 2017).
Behavioral approaches to coping with stress are called adaptive behaviors. There are two opposite approaches: positive adaptive behaviors and maladaptive behaviors. Both may reduce stress, but maladaptive coping creates additional negative outcomes. An example is dealing with emotional stress by overusing alcohol, which may result in social distress, financial problems, and alcoholism leading to physical illness. Other maladaptive behaviors include pulling out one’s hair and cutting oneself; again, these behaviors may relieve stress in the short term but they cause physical harm to the stressed individual and are often signs of underlying psychological problems.
Nurses are in a position to assess adaptation to stress in their patients and educate them on positive adaptive behaviors. For example, a nurse might teach a patient with chronic obstructive pulmonary disease to use pursed-lip breathing to release more carbon dioxide trapped in the lungs.
Stress Adaptation Model
The Stress Adaptation Model is based on the work of Dr. Hans Seyle, who declared that stress affects overall health. According to Seyle, stress and health are biochemically linked, and chronic stress creates physiological illness when the endocrine system is exhausted. He recognized similar responses by all people when they perceived stress, thus he named it the General Adaptation Syndrome (Selye, 1965). He recognized that when an event is new, unpredictable, a threat to self, or creates a sense of lack of control for the person, the individual will experience stress. The response by any individual experiencing stress passes through three stages: (1) the alarm reaction, (2) resistance, and (3) exhaustion if the stressor continues unresolved. Each of these will be explored in more detail, because nurses must be able to assess physical and emotional responses to stress in their patients.