CH 1 - Introduction to Pathophysiology

Pathophysiology

• Study of the functional changes produced by injury, disorder, or disease.
• Integrates knowledge from related sciences:
  • Pathology (structural changes)
  • Anatomy & Physiology (normal structure/function)
  • Biology (cellular & molecular basis)
  • Microbiology (microorganisms)
  • Chemistry (biochemical reactions)

Disease

• Defined as functional impairment of cells, tissues, organs, or systems.
• Broadly encompasses:
  • Injuries (e.g., burns, fractures)
  • Disorders (e.g., genetic metabolic errors)
  • Illnesses (subjective experience of being unwell)
  • Syndromes (recognizable clusters of findings, e.g., Down syndrome)

Pathogenesis

• Describes the origination & development of disease.
• Captures the timeline from the initial trigger to the first clinical presentation.
• Considers risk factors:
  • Modifiable: lifestyle, diet, environmental exposures
  • Non-modifiable: age, genetics, ethnicity

Etiology

• Specifies the precise cause of a disease.
• Categories:
  • Pathogen: disease-causing microorganism (e.g., Mycobacterium tuberculosis)
  • Multifactorial: >1 contributing cause (e.g., hypertension)
  • Idiopathic: cause unknown
  • Nosocomial: acquired in a healthcare setting (e.g., MRSA post-surgery)
  • Iatrogenic: unintentionally induced by medical therapy (e.g., chemotherapy-induced anemia)

Clinical Manifestations

• Collective term for presenting signs & symptoms.
• Terminology distinctions:
  • Signs: objective, measurable (fever, rash)
  • Symptoms: subjective, reported by patient (pain, fatigue)
• Patterns & distribution:
  • Local vs. Systemic (e.g., cellulitis vs. sepsis)
  • Acute, Subacute, Chronic (based on duration)
  • Remission (↓ severity) vs. Exacerbation (↑ severity)
  • Asymptomatic: disease present, no noticeable manifestations

Diagnosis, Prognosis, & Treatment

• Diagnosis: the disease label, assigned using diagnostic criteria (objective & subjective data, lab tests, imaging).
• Prognosis: predicted course & outcome.
  • Morbidity: disease impact on quality of life/function
  • Mortality: likelihood of death
• Treatment: interventions aimed at cure, symptom relief, or palliative goals; guided by evidence & patient values.

Concept Map (Mechanisms to Care)

• Etiology → Pathogenesis → Clinical Manifestations (Signs/Symptoms) → Diagnosis → Treatment
• Feedback loops exist: treatment modifies pathogenesis & manifestations.

Individual Health Perspective

• Considers the whole person—body, mind, spirit.
• Health–Illness Continuum:
  • Health: perceived wholeness, optimal functioning
  • Illness: state of suffering/distress
• Homeostasis: physiologic equilibrium the body strives to maintain.

Population Health & Epidemiology

• Epidemiology studies disease patterns in groups.
• Core metrics:
  • Incidence (new cases): \text{Incidence} = \frac{\text{New cases during period}}{\text{Population at risk}} \times 10^n
  • Prevalence (existing cases): \text{Prevalence} = \frac{\text{All existing cases}}{\text{Total population}} \times 10^n
• Global classifications:
  • Endemic: routinely found in a region (e.g., malaria in parts of Africa)
  • Epidemic: sudden ↑ above expected levels
  • Pandemic: worldwide spread (e.g., COVID-19)
• Oversight & data collection by the World Health Organization (WHO).

Prevention Levels

• Primary Prevention: stop disease before it occurs (vaccination, smoking cessation).
• Secondary Prevention: early detection & prompt treatment (mammography, BP screening).
• Tertiary Prevention: rehabilitation to limit complications/progression (stroke rehab, diabetic foot care).

Evidence-Based Practice (EBP)

• Care aligned with current, cumulative research + expert clinical judgment + patient preferences.
• Key characteristics:
  • Synthesizes multiple studies—not single reports.
  • Applies across the spectrum of human variation.
  • Requires ongoing critical appraisal & lifelong learning.

Human Diversity Factors Influencing Pathogenesis

• Gender: hormonal & chromosomal influences (e.g., autoimmune prevalence in females)
• Age: developmental stage affects susceptibility & response.
• Race / Ethnicity: genetic predispositions, cultural practices.
• Locale: urban vs. rural exposures, environmental toxins.
• Socioeconomic Status: access to care, nutrition, stress levels.

Functional Concepts of Altered Health

• Concept: broad idea applicable to multiple diseases (e.g., inflammation, oxidative stress).
• Grouping of concepts forms a conceptual approach—facilitates applying general mechanisms to specific disorders, aiding comprehension & memory.