Overview
This lecture introduces core concepts of clinical pathophysiology, focusing on disease mechanisms, cellular injury and adaptation, and the impact of stress on health.
Introduction to Pathophysiology
- Pathophysiology is the study of how normal anatomy and physiology are altered by disease.
- It explains why patients exhibit certain signs, symptoms, and responses to treatments.
- Key components include etiology (cause), pathogenesis (development), clinical manifestations (signs/symptoms), and treatment.
- Understanding normal anatomy and physiology is essential to grasp disease processes.
- Disease presentations can vary widely between individuals.
Etiology and Disease Factors
- Etiology is the cause of a disease; risk factors increase disease likelihood.
- Nosocomial diseases are hospital-acquired; idiopathic diseases have unknown causes.
- Iatrogenic conditions are caused by medical interventions.
- Precipitating factors trigger disease events (e.g., allergen triggers asthma).
Disease Progression & Manifestations
- Pathogenesis describes how a disease develops.
- Acute diseases resolve quickly; chronic diseases persist and may not resolve.
- Sequelae are chronic conditions following acute events (e.g., paralysis after stroke).
- Complications are new problems arising from a disease (e.g., renal failure in diabetes).
- Clinical manifestations are signs (objective) and symptoms (subjective).
- Remission is symptom decrease; exacerbation is symptom worsening.
- Local reactions affect one area; systemic reactions affect the whole body.
Normal vs. Abnormal States
- "Normal" values depend on individual factors like age, gender, culture, and environment.
- Assessment should consider personal baselines before determining abnormality.
Stress and Disease
- Stress can disrupt homeostasis and contribute to disease and unhealthy behaviors.
- The body responds to stress via neuroendocrine and immune systems (allostasis).
- Chronic stress leads to allostatic overload, increasing disease risk.
- General Adaptation Syndrome (GAS) includes alarm (fight or flight), resistance, and exhaustion phases.
- HPA axis hormones (cortisol, catecholamines) play key roles in the stress response.
- Chronic cortisol elevation is linked to various diseases (e.g., obesity, hypertension).
- Coping can be adaptive (positive) or maladaptive (negative).
- Adverse Childhood Experiences (ACEs) increase risk for chronic diseases.
Cellular Injury and Adaptation
- Cell injury may result from infection, nutrition imbalance, hypoxia, genetic factors, trauma, chemicals, or aging.
- Adaptations:
- Atrophy (cell shrinkage)
- Hypertrophy (cell enlargement)
- Hyperplasia (increased cell number)
- Metaplasia (one cell type replaced by another)
- Dysplasia (disordered cell growth, pre-cancerous)
- Hypoxic injury (most common) leads to cellular swelling and dysfunction.
- Reperfusion injury occurs when oxygen returns after hypoxia, creating harmful free radicals.
- Chemical, infectious, immune, and traumatic injuries can all damage cells.
Cell Death, Necrosis, and Aging
- Reversible injury allows cell recovery; irreversible injury leads to cell death.
- Apoptosis is programmed cell death; necrosis is uncontrolled death due to injury.
- Necrosis types: coagulative (kidneys, heart), liquefactive (brain), caseous (lungs), fat, and gangrene (dry, wet, gas).
- Aging involves atrophy, decreased function, and increased risk of frailty and disease.
- Somatic death is the death of the entire person, followed by postmortem changes (algor, livor, rigor mortis).
Key Terms & Definitions
- Etiology — cause of a disease
- Nosocomial — hospital-acquired disease
- Idiopathic — unknown cause
- Iatrogenic — caused by medical treatment
- Pathogenesis — disease development process
- Clinical manifestations — signs and symptoms of disease
- Remission — decrease of disease symptoms
- Exacerbation — worsening of symptoms
- Allostasis — stability through change/adaptation
- General Adaptation Syndrome (GAS) — alarm, resistance, exhaustion stress phases
- HPA axis — hypothalamic-pituitary-adrenal stress hormone system
- Apoptosis — programmed cell death
- Necrosis — uncontrolled cell death
- Atrophy/Hypertrophy/Hyperplasia/Metaplasia/Dysplasia — types of cellular adaptation
Action Items / Next Steps
- Review and understand all key terms presented in this module.
- Prepare for in-class discussions on hormone function and stress responses.
- Read Chapter 10 and assigned materials on stress and cellular injury before next class.