Homeostasis, Allostasis, and Stress: Pathophysiology for Nursing

Homeostasis

Remaining stable while staying the same; all systems in balance; equilibrium; an ideal 'set point' despite alterations within the body.

Allostasis

Overall process of adaptive change necessary to maintain survival and well-being; may involve altering multiple physiologic variables to match the resources of the body to environmental demands; helps the body achieve homeostasis.

Stress

Universal experience; result of both positive and negative experiences; important to understand; response to change.

General Adaptation Syndrome

Observed bodily changes produced by stress; has three stages: alarm, resistance/adaptation, exhaustion.

Alarm stage

Fight-or-flight response as the result of stressful stimulus; involves the hypothalamic-pituitary-adrenal (HPA) axis.

Resistance or adaptation

Activity of the nervous and endocrine systems in returning the body to homeostasis; allostatic state: activity of various systems attempting to restore homeostasis.

Exhaustion

Point where body can no longer return to homeostasis; allostatic overload: 'cost' of body's organs and tissues for an excessive or ineffectively regulated allostatic response; effect of 'wear and tear' on the body.

Catecholamines

Norepinephrine and epinephrine; play an integral role in allostasis; sympathico-adrenal system response mediates the fight-or-flight response.

Adrenocortical Steroids

Cortisol and aldosterone; critical to maintenance of homeostasis; may synergize or antagonize effects of catecholamines.

Sex hormones

Estrogen, testosterone, and dehydroepiandrosterone; affect stress responses, influencing allostasis; may help explain gender responses during stress.

Endorphins and Enkephalins

Endogenous opioids; raise pain threshold; produce sedation and euphoria.

Immune Cytokines

Secreted by macrophages during stress response; enhance immune system response; prolonged stress can suppress immune functioning.

Growth hormone

Can increase during stress to enhance immune function.

Prolactin

Similar to structure of growth hormone; role in immune response.

Oxytocin

Produced during childbirth and lactation; associated with bonding and social attachment; thought to moderate stress response and produce a calming effect.

Coping

Ability to deal with the stressor; influenced by genetics, age, gender, life experiences, dietary status, and social support.

Adaptive coping strategies

Include physical activity, adequate sleep, optimal dietary status, relaxation, distraction, and biofeedback.

Maladaptive coping strategies

Include smoking, substance abuse, and overeating.

Effects of allostatic overload

Affects body organs and systems.