Homeostasis and Adaptive Responses to Stressors

Vocabulary flashcards covering key terms related to homeostasis, stress physiology, neurohormonal mediators, and coping mechanisms.

Homeostasis

A stable, balanced state in which all body systems remain at an ideal set point despite internal or external changes.

Allostasis

The dynamic process of achieving stability through physiological or behavioral change to meet environmental and lifestyle challenges.

Stress

A physical, chemical, or emotional factor that creates tension and threatens homeostasis, whether perceived or real.

General Adaptation Syndrome (GAS)

Hans Selye’s three-stage response to stress: alarm, resistance/adaptation, and exhaustion.

Alarm Stage

The first GAS stage; the fight-or-flight response initiated via the hypothalamic-pituitary-adrenal (HPA) axis.

Resistance (Adaptation) Stage

The second GAS stage; nervous and endocrine activity attempt to restore homeostasis—an allostatic state.

Exhaustion Stage

The final GAS stage in which the body can no longer maintain homeostasis, leading to allostatic overload.

Allostatic Overload

The wear-and-tear cost of chronic or excessive allostatic responses, resulting in illness or dysfunction.

Stressor

Any internal or external agent or condition that endangers homeostasis; varies in type, scope, intensity, and duration.

Risk Factor

A condition or situation that increases the likelihood of encountering a stressor but is not itself a stressor.

Catecholamines

Stress mediators (e.g., norepinephrine, epinephrine) released by the sympathico-adrenal system to drive the fight-or-flight response.

Norepinephrine

A catecholamine that constricts blood vessels, raises blood pressure, reduces gastric secretions, and improves night/far vision.

Epinephrine

A catecholamine that increases heart rate, cardiac output, bronchodilation, and blood glucose via glycogenolysis.

Adrenocortical Steroids

Hormones (e.g., cortisol, aldosterone) essential for stress adaptation that may enhance or counter catecholamine effects.

Cortisol

The primary glucocorticoid; influences protein metabolism, stimulates appetite, and exerts anti-inflammatory effects.

Aldosterone

The primary mineralocorticoid; promotes sodium and water reabsorption, thereby increasing blood pressure.

Endorphins

Endogenous opioids that raise the pain threshold and produce sedation and euphoria during stress.

Enkephalins

Short-acting endogenous opioids functioning similarly to endorphins in pain modulation and stress relief.

Immune Cytokines

Macrophage-secreted proteins (e.g., interleukin-1) that enhance immunity during stress but may be suppressed by chronic stress.

Sex Hormones

Estrogen, testosterone, and DHEA; modulate stress responses and contribute to gender differences in allostasis.

Growth Hormone

A hormone that can rise during stress to bolster immune function.

Prolactin

A hormone structurally similar to growth hormone with a contributory role in immune responses under stress.

Oxytocin

A peptide produced during childbirth and lactation; fosters bonding, social attachment, and a calming stress-modulating effect.

Adaptation

A biopsychosocial process of adjusting to new or altered internal or external circumstances.

Coping

Behavioral strategies, often culturally based, used to manage stressors and facilitate adaptation.

Distress

The perceived inability to cope effectively with a stressor.

Habituation

An adaptation method whereby repeated exposure to a stressor reduces the stress response.

Desensitization

Gradual exposure techniques (e.g., biofeedback, visualization, meditation) that diminish stress reactions.

Allostatic State

The active state of physiologic adjustment of multiple systems striving to restore or maintain homeostasis.

Wear and Tear

The cumulative physiological cost on organs and tissues from prolonged or excessive allostatic activity.