Stress Physiology

Everyone is familiar with the term “stress.” In our daily lives, we frequently use the word. Stress is not an event or a state that occurs as a result of a negative scenario, as is commonly understood. It is, in reality, a method through which the body overcomes a difficult or unpleasant environment. When we are in an unfavourable situation (physical or mental), our bodies attempt to preserve homeostasis (internal milieu) and protect ourselves from such events by making ‘changes.’ Stress is a set of processes that our bodies go through in order to cope with difficult conditions. Selye used the term ‘stress’ to represent the effects of anything that seriously threatens homeostasis of the body . The body’s homeostasis is affected by both external and internal causes.

Stress Physiology

Physiological stress is defined as any external or internal circumstance that disrupts a cell’s or organism’s equilibrium. Environmental stress, inherent developmental stress, and ageing are three different facets of it. Changes in the environment provide a challenge to all living creatures throughout their lives. For example, changes in oxygen levels, temperature, and redox state initiate chemical reactions that allow an organism to adapt, live, and reproduce. Organisms face stress related to morphogenesis and changes in interior chemistry throughout normal development, in addition to external stressors.

Physiology of Stress Response

When the body is confronted with a stressor, whether actual event imagined, a reaction is evoked to help the body cope. Individuals’ responses are not all the same. Aside from the stressor’s severity and length, a person’s age, gender, personality, physical and mental health, and previous experiences all impact the stress reaction. General Adaptation Syndrome (GAS) is a profile of how organisms adapt to stress created by Hans Selye. The stress reaction has three stages: 1. Set an alarm 2. Exhaustion or recuperation, and 3. Adaptation. The ‘fight-or-flight’ reaction is triggered during the alarm stage.This is the stage in which we are able to deal with challenging (adverse) events. The body is prepared to either confront or flee the imagined threat. This stage causes the production of stress hormones such as cortisol, noradrenaline, and adrenaline from the adrenal glands, as well as an increase in heart rate, blood sugar level, and blood pressure.

If the body’s compensatory systems have been successful in counteracting the stressor’s effect, the recovery stage begins. The fatigue stage occurs when the body’s resources have been depleted and it is unable to continue regular function. If the tiredness stage lasts for a long time, it can have long-term consequences, putting the person at risk of developing more significant health problems. It has the potential to cause depression, hypertension, and coronary artery disease.

Nervous System Response to Stress

The nervous system has been found to have a critical part in stress response in studies. Neurons not only receive and digest information from their surroundings, but they also actively respond to a variety of challenges in order to help them survive. Changes in the expression of molecules that govern stress resistance and adaptation, such as transcription factors and microRNAs, are among these responses. Furthermore, both internal and extrinsic stressors have a significant influence on neuronal growth and maintenance, with consequences in a variety of illnesses. At the molecular and cellular level, we look at how neurons respond to diverse physiological stresses.

Stress Physiology in Animals

When animals are forced to undertake drastic and/or long-term physiological and behavioural changes to adapt with their environment, they are said to be stressed.

There are three sorts of stress that animals might face: 

• Physical – because of exhaustion or damage.

• Physiological – because of hunger, thirst, or the regulation of body temperature.

• Behavioural – because of the environment, new individuals, or strange settings.

Stressors are things that can create stress, such as noise, strange pen-mates, or dogs. Many animals may be able to withstand a single stressor for a short amount of time, but many stressors over time can cause pain and suffering.

Animals’ capacity to cope with stress will also be determined by:

• the species’s genetic heritage;

• the animal’s previous life experiences

While some tension is unavoidable during transportation, the goal should be to limit it to a minimum.

Mechanism Of Stress

Following a stressful incident, the body responds in various ways to deal with the stressor. This is accomplished by two key changes in the body: 1. a change in the pattern/amount of energy released, and 2. a change in energy distribution. These modifications are brought about by a series of events. All of these occurrences are referred to as stress or the stress response. Stress is a complex process that affects both the neurological and endocrine systems.

The perception of the threat is the initial stage in the stress response (stressor). Whenever a stressor is present, whether the actual event imagined, it has an effect on the brain. The hypothalamus is the part of the brain that detects the stressor. When the hypothalamus detects a threat, it conducts the following tasks:

 1. the autonomic nervous system is activated (ANS)

 2. Releases Corticotropin Releasing Hormone (CRH) and stimulates the Hypothalamic Pituitary Adrenal (HPA) axis. 

3. Arginine vasopressin secretion (Antidiuretic Hormone ADH). The sympathetic (arousal) and parasympathetic (relaxed) nerve systems make up the autonomic nervous system. Circulation, digestion, respiration, temperature regulation, and several essential organs are all regulated by the ANS.

Impact Of Stress on The Body of the Organism

• Effect on Digestive System

Stressed people commonly have disrupted eating patterns, acid reflux, diarrhoea, or constipation. Obesity, which is connected to a slew of other health issues, is linked to stress. Though there is no conclusive evidence that stressful life experiences cause diabetes in children or adults, hormonal changes that occur during acute and chronic stress can influence glucose homeostasis in both healthy and diabetic persons. Acute stress has been shown in several studies to have a deleterious impact on the maintenance of blood glucose concentrations in people with type 1 and type 2 diabetes. 

• Suppression of immune system

In chronic stress, sustained stimulation of the Hypothalamic Pituitary Adrenal (HPA) axis compromises immunological response, leading to a variety of illnesses. Chronic stress makes people more susceptible to viral diseases like the flu and the common cold, as well as other infections, according to studies.

• Some other effects of stress hormones

In addition to the impacts listed above, cortisol affects bone mineral density, which affects the formation of new bones in the body. Stress can stifle the growth of young children. In some situations, stress may be a factor in the development of cancer. In the chronic stress response and depression, sustained activation of the Hypothalamic Pituitary Adrenal (HPA) axis compromises the immune response and may contribute to the formation and progression of various cancers. Stress has been shown in studies to enhance the colonisation of bone by breast cancer cells.

Conclusion

Physical, environmental, physiological, and psychological stresses are all present in our lives. Different forms of stress reactions occur in the body as a result of these stresses, including psychological, physiological, and behavioural responses. When this form of stress lasts for a long time, it leads to a variety of health problems that impact almost all of the body’s systems. Though we cannot completely eliminate stress from our lives, we can manage it by making little changes to our attitude and lifestyle.