Advanced Physiology and Pathophysiology Concepts
NURS 6160: Advanced Physiology and Pathophysiology Across the Lifespan
Unit 1 Overview
Concepts of Health and Disease: Understanding the transition from normal physiological function to disease states.
Stress and Adaptation: The body's mechanisms for maintaining stability amidst internal and external changes.
Required Reading: Chapters 1 and 7 (Norris, 2024).
Objectives: Chapter 1 - Concepts of Health and Disease
Pathophysiology: The study of disordered physiological processes associated with disease or injury. It serves as a bridge between the basic sciences (biology, chemistry, anatomy) and clinical practice.
Defining Health:
WHO Definition: A state of complete physical, mental, and social well-being, not merely the absence of disease.
Healthy People 2030 Determinants: Focuses on "Social Determinants of Health" (SDOH) classified into five domains:
Economic Stability: Poverty, employment, food security.
Education Access and Quality: High school graduation, higher education.
Healthcare Access and Quality: Health literacy, insurance coverage.
Neighborhood and Built Environment: Housing quality, transportation, environmental safety.
Social and Community Context: Social cohesion, civic participation, incarceration.
Aspects of the Disease Process:
Etiology: Cause(s) of the disease. Can be biological (bacteria), physical (trauma), chemical (toxins), or genetic.
Idiopathic: Unknown cause.
Iatrogenic: Resulting from medical treatment or error.
Nosocomial: Acquired in a hospital setting.
Pathogenesis: The step-by-step evolution of a disease process from the initial stimulus to the ultimate expression of the disease.
Morphologic Changes: Gross anatomic and microscopic changes that are characteristic of a disease.
Clinical Manifestations: The functional consequences of these changes.
Symptoms: Subjective complaints by the patient (e.g., pain, dizziness).
Signs: Objective, observable findings (e.g., fever of 102^{\circ}F, elevated blood pressure).
Syndrome: A compilation of signs and symptoms characteristic of a specific disease state.
Diagnosis: The process of identifying the nature and cause of a health problem. It requires clinical history, physical exams, and diagnostic tests.
Reliability and Validity: Reliability refers to the consistency of a result; validity refers to whether the tool measures what it is intended to measure.
Sensitivity (S_n): The ability of a test to correctly identify those with the disease (true positive rate).
Specificity (S_p): The ability of a test to correctly identify those without the disease (true negative rate).
Classification of Disease:
Congenital: Present at birth.
Acquired: Developed after birth (e.g., infections, nutrition, trauma).
Clinical Course:
Acute: Relatively severe but self-limiting.
Subacute: Between acute and chronic; not as severe as acute and not as prolonged as chronic.
Chronic: Continuous or episodic, but taking place over a long period.
Preclinical: Disease is not clinically evident but is destined to progress.
Subclinical: Not clinically apparent and not destined to become apparent (e.g., tuberculosis that stays dormant).
Epidemiology and Prevention:
Incidence: The number of new cases occurring in a population during a specified period.
Prevalence: A measure of existing disease in a population at a given point in time.
Morbidity vs. Mortality: Morbidity focuses on the functional effects and quality of life; mortality provides data on the causes of death.
Prevention Levels:
Primary: Removing risk factors (e.g., immunizations, seat belts).
Secondary: Early detection while still asymptomatic (e.g., Pap smears, BP screening).
Tertiary: Clinical interventions to prevent further deterioration or reduce complications (e.g., cardiac rehab after an MI).
Objectives: Chapter 7 - Stress and Adaptation
Homeostasis and Allostasis:
Homeostasis: The purposeful maintenance of a stable internal environment by coordinated physiological processes.
Allostasis: The process of achieving stability through physiological or behavioral change; it differs from homeostasis by focusing on the adaptive nature of changes rather than just a fixed set point.
Negative Feedback: Corrects a deficit in the system (e.g., blood glucose regulation). If glucose is high, insulin is released to lower it.
Positive Feedback: Displaces a system away from its normal set point; often unstable (e.g., oxytocin during labor).
Stress and the General Adaptation Syndrome (GAS):
Definition: Stress is a state manifested by a specific syndrome of the body developed in response to any stimuli that made an intense systemic demand on it.
Three Stages of GAS:
Alarm: The "fight or flight" response. Activation of the Sympathetic Nervous System (SNS) and the HPA axis.
Resistance: The body selects the most effective channel of defense. Cortisol levels drop as they are no longer needed at the high alarm level.
Exhaustion: Resources are depleted, and systemic damage (wear and tear) occurs.
Neuroendocrine Response to Stress:
HPA Axis Activation: The Hypothalamus releases Corticotropin-releasing Factor (CRF), stimulating the Anterior Pituitary to release Adrenocorticotropic Hormone (ACTH), which then signals the Adrenal Cortex to release Cortisol.
Cortisol: The "stress hormone" that increases blood glucose, supresses the immune response, and enhances the effects of catecholamines (epinephrine/norepinephrine).
Sympathetic Nervous System (SNS): Rapid release of norepinephrine and epinephrine from the adrenal medulla, increasing heart rate and respiratory rate.
PTSD (Post-Traumatic Stress Disorder):
Risk Factors: Previous trauma, lack of social support, high-stress occupations.
Symptom Clusters:
Intrusion: Flashbacks, vivid nightmares.
Avoidance: Emotional numbing, avoiding places or people related to the trauma.
Hyperarousal: Irritability, exaggerated startle response, difficulty concentrating.
Diagnosis: Symptoms must be present for more than 1 month and cause significant distress or functional impairment.