Pathophysiology Unit 2 | Chapter 6 (Porth 5th Edition) Flashcards
(78 cards)
Homeostasis
The maintenance of a stable internal environment despite external changes, crucial for normal physiological functioning.
Constancy of the Internal Environment
A principle of homeostasis where the body regulates variables like temperature, pH, and electrolyte balance within narrow limits.
Control Systems
Biological mechanisms (e.g., nervous and endocrine systems) that monitor and adjust physiological processes to maintain homeostasis.
Negative Feedback
A regulatory mechanism where a system’s output reduces or inhibits the process, maintaining stability (e.g., insulin lowering blood glucose).
Positive Feedback
A mechanism that amplifies a response (e.g., oxytocin during childbirth), often leading to an endpoint.
Stress
A state of threatened or perceived disruption to homeostasis, triggering physiological and psychological responses.
Stress Response
The body’s adaptive reaction to stressors, involving neuroendocrine and immune system activation.
General Adaptation Syndrome (GAS)
Hans Selye’s three-stage model (alarm, resistance, exhaustion) describing the body’s response to prolonged stress.
Alarm Stage
Initial phase of GAS, characterized by fight-or-flight activation via the SAM axis and HPA axis.
Resistance Stage
Second phase of GAS, where the body attempts to adapt and restore homeostasis using sustained cortisol release.
Exhaustion Stage
Final phase of GAS, resulting in resource depletion, immune suppression, and vulnerability to disease.
Neuroendocrine Responses
Stress-induced activation of the HPA axis (cortisol) and SAM axis (adrenaline/noradrenaline).
HPA Axis
Hypothalamic-Pituitary-Adrenal axis: CRH → ACTH → cortisol release, regulating metabolism and immune function during stress.
SAM Axis
Sympathetic-Adrenal-Medullary axis: Activates the sympathetic nervous system, releasing adrenaline and noradrenaline for immediate stress response.
Cortisol
Glucocorticoid hormone released during stress; suppresses inflammation, increases blood glucose, and modulates immune function.
Catecholamines
Adrenaline and noradrenaline; enhance alertness, heart rate, and energy mobilization during acute stress.
Immune Responses to Stress
Stress alters immune function via cortisol (suppression) and cytokines (pro-inflammatory signals).
Psychoneuroimmunology
Study of interactions between psychological processes, the nervous system, and immune function during stress.
Cytokines
Signaling proteins (e.g., IL-6, TNF-α) released during stress; can promote inflammation or immune suppression.
Allostasis
The process of achieving stability through physiological or behavioral change in response to stressors.
Allostatic Load
The cumulative physiological wear and tear from chronic stress, leading to health risks (e.g., hypertension, diabetes).
Coping Mechanisms
Strategies (problem-focused or emotion-focused) to manage stress, such as planning, social support, or avoidance.
Adaptation
Successful adjustment to stress, restoring homeostasis without long-term physiological or psychological harm.
Maladaptation
Ineffective coping leading to chronic stress, dysfunction, or disorders (e.g., anxiety, cardiovascular disease).