Pathophysiology

Page 1: Introduction to Pathophysiology

Pathophysiology Overview

  • Definition: Pathophysiology is the study of the body’s response to altered function or disease.

  • Origin of the term: From pathology (disease study) and physiology (body function).

  • Importance: It delineates changes at the organ and cellular levels due to diseases, impacting overall body function.

Health Definitions

  • WHO Definition: Health as a complete state of physical, mental and social well-being, not just absence of disease.

  • U.S. Department of Health and Human Services (Healthy People 2020) emphasizes:

    1. Elimination of preventable diseases, disabilities, and deaths.

    2. Achieving health equity.

    3. Promoting health universally.

    4. Encouraging healthy behaviors.

Disease Definition

  • Definition: An illness that leads to abnormal physiological function.

  • Can be congenital (present at birth) or acquired (developed over time).

  • Disease Process Steps:

    1. Etiology

    2. Pathogenesis

    3. Morphologic changes

    4. Clinical manifestations

    5. Diagnosis

    6. Clinical course

Etiology

  • Etiologic factors lead to diseases:

    • Physical forces: trauma, burns, radiation

    • Chemical agents: poisons, alcohol

    • Biologic agents: bacteria, viruses

    • Genetic predisposition

    • Nutritional imbalances

  • Most are idiopathic or nonspecific, affecting various organs and systems (e.g., sickle cell anemia, cystic fibrosis).

Page 2: Risk Factors & Disease Development

Risk Factors

  • Defined: Predisposing factors for disease categorized into:

    • Congenital: present from birth

    • Acquired: post-birth, from external factors (injury, infections, diet).

  • Diseases often stem from heredity and environmental interactions.

Pathogenesis

  • Definition: The development of disease at cellular and tissue levels.

  • Morphologic alterations are foundational in disease characterization.

  • Histology: Study of tissue at a cellular level; essential for diagnosing diseases through microscopic examination.

Clinical Manifestations

  • Ways diseases present:

    • Signs: Objective observations (fever, swelling).

    • Symptoms: Subjective perceptions (pain, fatigue).

  • Syndromes: Combinations of signs and symptoms.

  • Complications: Problems arising from diseases/treatments. Sequelae: aftermath of disease effects.

Page 3: Diagnosis & Diagnostic Testing

Diagnosis Process

  • Involves identifying the cause through:

    • Patient history collection

    • Physical Examination (PE) for signs

    • Diagnostic testing: labs, imaging (X-ray, MRI)

  • Factors Considered: Age, gender, race, lifestyle, genetic background.

Laboratory Tests

  • Normal values: Based on population studies.

  • Reliability, validity, and specificity/sensitivity are crucial for test interpretation.

  • False positives/negatives can cause undue stress or missed treatments.

  • Predictive values help assess the likelihood of disease presence based on test results.

Page 4: Clinical Course and Epidemiology

Clinical Course

  • Categories:

    1. Acute: Severe but self-limiting.

    2. Chronic: Long-term, with exacerbations/remissions.

    3. Subacute: Intermediate severity and duration.

  • Epidemiology: Study of disease distribution in populations. Factors include age, race, lifestyle, and location.

Disease Frequency

  • Prevalence: Existing cases in a population.

  • Incidence: New cases in a risk population over time.

  • Morbidity: Impact of illness on life quality; Mortality: Cause of death analysis.

Natural History and Prognosis

  • Natural history: Disease progression without treatment.

  • Prognosis: Expected outcomes based on health factors and disease nature.

Page 5: Disease Prevention

Prevention Types

  • Primary Prevention: Elimination of risk factors (e.g., vaccinations).

  • Secondary Prevention: Early detection and treatment (screenings).

  • Tertiary Prevention: Mitigating complications and managing existing diseases (medications post-heart attack).

Evidence-Based Practice

  • Involves reliance on scientific evidence for patient care decisions.

  • Clinical practice guidelines assist practitioners in healthcare delivery.

Study Types

  • Types include:

  1. Cross-sectional studies

  2. Case-control studies

  3. Cohort studies

Page 6: Cells and Disease

Importance of Cellular Understanding

  • Cells are basic life units; understanding them is vital for disease processes.

Cell Components

  • Eukaryotic cells consist of:

    1. Nucleus

    2. Cytoplasm

    3. Plasma membrane

Functions of the Nucleus

  • Command center for genetic material (DNA/RNA) and protein synthesis regulation.

  • Chromatin structure suggests its role in neoplasm progression.

Page 7: Cytoplasmic Organelles and Functions

Organelles

  • Ribosomes: Protein synthesis.

  • Endoplasmic reticulum (ER): Transport and synthesis of proteins/lipids.

    • Rough ER: Produces enzymes;

    • Smooth ER: Lipid synthesis and detoxification.

  • Golgi apparatus: Modifies and packages proteins from ER.

  • Lysosomes: Digestive capacity; critical for cell metabolism.

  • Peroxisomes: Control free radicals; break down harmful substances.

Page 8: Mitochondria and Cytoskeleton

Mitochondria

  • Powerhouse of the cell; energy conversion via cellular respiration.

  • Plays role in apoptosis regulation.

Cytoskeleton

  • A network of structures for cell shape and movement.

  • Microtubules: Maintain form, assist transport, and form cilia/flagella.

Page 9: Plasma Membrane Structure and Function

Membrane Composition

  • Semipermeable barrier regulating material movement; contains lipids and proteins.

Transport Mechanisms

  • Passive transport (diffusion, osmosis, facilitated diffusion) vs active transport (requires energy).

  • Endocytosis and exocytosis for molecule uptake and secretion.

Page 10: Membrane Potentials

Ion Movement

  • Importance in nerve impulses and muscle contractions.

  • Membrane potentials reflect ion differences across the cell membrane.

Page 11: Tissue Types

Epithelial Tissue

  • Covers surfaces; avascular, relies on underlying connective tissue.

Connective Tissue

  • Provides support; differentiated into loose, dense, specialized types.

Muscle Tissue

  • Enables movement; includes skeletal, cardiac, and smooth types.

Nervous Tissue

  • Communication and control; consists of neurons and glial cells.

Page 12: Cellular Adaptation, Injury, and Death

Adaptation Types

  • Atrophy, hypertrophy, hyperplasia, metaplasia, and dysplasia indicate cellular responses to stress.

  • Prolonged stress can result in pathological changes.

Page 13: Types of Cell Injury

Common Injuries

  • Physical, biological, chemical, radiation-induced, and nutritional injuries.

Reactive Oxygen Species (ROS)

  • Cause oxidative stress leading to cellular damage.

Page 14: Hypoxia and Cell Function

Hypoxic Injury

  • Low oxygen supply leading to decreased ATP production and cell death.

Page 15: Apoptosis vs. Necrosis

Cell Death Types

  • Apoptosis: Programmed and controlled cell death; vital for cellular turnover.

  • Necrosis: Uncontrolled cell death due to injury; triggers inflammatory response.