Introduction to Pathophysiology

Chapter 1: Introduction to Pathophysiology

Homeostasis

  • Definition: Homeostasis refers to the maintenance of a relatively stable internal environment regardless of external changes.

  • Importance: When homeostasis is maintained, good health is generally maintained.

  • Consequences: When homeostasis is not maintained, disease may develop.

Health and Disease

  • Health: Defined as physical, mental, and social well-being.

  • Disease: A deviation from the normal state of homeostasis.

Health Indicators

  • Normal Values: Normal values occur within a range of values and may vary based on technology used for measurement.

  • Variables Influencing Health:

    • Age

    • Gender

    • Genetics

    • Environment

    • Activity level

Seven Steps to Health

  1. Be a nonsmoker and avoid second-hand smoke.

  2. Consume 5 to 10 servings of vegetables and fruits daily. Choose high-fiber, lower-fat foods and limit alcohol intake.

  3. Engage in regular physical activity.

  4. Protect the skin from the sun.

  5. Follow cancer screening guidelines.

  6. Consult a doctor or dentist if there are any changes in the normal state of health.

  7. Adhere to health and safety guidelines at home and work concerning the use, storage, and disposal of hazardous materials.

Concept and Scope of Pathophysiology

  • Definition: Pathophysiology encompasses functional (physiologic) changes in the body due to disease.

  • Basis: Utilizes knowledge of basic anatomy and physiology.

  • Pathology Relation: Includes aspects of pathology, which describes structural changes in body tissues due to disease.

  • Study Framework: The study is guided by cause-and-effect relationships, defined by signs and symptoms, for specific diseases.

Prevention of Disease

  • Focus: The prevention of disease has become a central focus in health care.

  • Methods of Prevention:

    • Routine vaccination programs

    • Participation in screening programs

    • Community health initiatives

    • Regular routine doctor visits

Stages of Research Process

  1. Stage 1 - Basic Science:

    • Identification of technology to be utilized.

    • Laboratory work which might involve animal or cell/tissue cultures.

  2. Stage 2: Involves a small number of human subjects.

  3. Stage 3 - Clinical Trials:

    • Involves a large number of patients with the disease or at risk of the disease.

    • Utilizes double-blind studies to ensure validity.

Medical History

  • Components of Medical History:

    • Current and prior illnesses

    • Allergies

    • Hospitalizations

    • Treatment history

    • Specific difficulties

    • Any type of therapy or drugs, both prescription and nonprescription, along with herbal items including food supplements.

New Developments and Trends

  • Focus on continuous updates of information and knowledge.

  • Improvements in diagnostic tests.

  • Development of more effective pharmaceutical drugs.

  • Innovations in technology related to health care.

  • Extensive research initiatives aimed at preventing, controlling, or curing various disorders.

New Challenges

  • Zika Virus: First discovered in 1947 in tropical Africa, Southeast Asia, and the Pacific Islands.

  • Recent Findings: In 2015, confirmed cases occurred in Brazil; recognized by the CDC as an international threat. Increased research efforts focus on diagnosis, the spread of the virus, treatment, and prevention strategies.

Basic Terminology

  • Levels of Study in Pathophysiology:

    • Gross level: Organ or system level examination.

    • Microscopic level: Cellular level investigation.

  • Key Terms:

    • Biopsy: Excision of small amounts of living tissue for examination.

    • Autopsy: Examination of the body and organs post-mortem.

Disease Process

  • Diagnosis: Involves the identification of a basic disease, evaluation of signs and symptoms, and laboratory tests.

  • Etiology: Refers to causative factors in a particular disease, including:

    • Congenital defects

    • Inherited or genetic disorders

    • Microorganisms

    • Immunologic dysfunctions

    • Degenerative changes

    • Malignancy

    • Metabolic and nutritional problems

    • Trauma and burns

    • Environmental factors

Causes of Disease

  • Idiopathic: Cause of disease is unknown.

  • Iatrogenic: Disease caused by medical error, treatment, or procedure.

  • Predisposing Factors: Factors like age, gender, inherited factors, and environmental influences that increase susceptibility to disease.

  • Prophylaxis: Measures taken to preserve health and prevent the spread of disease.

  • Prevention: Includes vaccinations, dietary or lifestyle modifications, and avoidance of harmful activities.

Characteristics of Disease

  • Pathogenesis: Refers to the development of the disease.

  • Onset of Disease:

    • Sudden/Acute: Disease that occurs suddenly, with potential high fever and severe pain.

    • Insidious: Gradual onset with vague or mild signs.

  • Acute Disease: Typically short-term, develops quickly.

  • Chronic Disease: Develops gradually, characterized by milder symptoms that may be interspersed with acute episodes.

Characteristics of Disease (continued)

  • Subclinical State: Pathologic changes occur, but no obvious symptoms manifest.

  • Latent State: No symptoms or clinical signs are evident.

  • Incubation Period: Specific to infectious diseases where symptoms have yet to manifest.

  • Prodromal Period: Early development phase of the disease where signs are nonspecific or absent.

  • Manifestations: Clinical evidence characterized by signs and symptoms, can be local (at the site of the problem) or systemic (general indicators of illness).

Characteristics of Disease (continued)

  • Signs: Objective indicators of disease.

  • Symptoms: Subjective feelings reported by the patient.

  • Lesions: Specific local changes in tissues.

  • Syndrome: A collection of signs and symptoms that occur together.

  • Diagnostic Tests: Various laboratory tests selected based on presentation and medical history.

Characteristics of Disease (continued)

  • Remissions and Exacerbations: These mark the course or progress of a disease.

    • Remission: A period in which manifestations subside.

    • Exacerbation: A worsened severity of symptoms.

  • Precipitating Factor: A condition that triggers an acute episode of a disease.

  • Complications: New secondary or additional problems arising from an existing condition.

Characteristics of Disease (continued)

  • Therapy: Measures implemented to promote recovery or slow progress of disease.

  • Sequelae: Potential unwanted outcomes from a disease or treatment.

  • Convalescence or Rehabilitation: This period marks recovery and the return to a healthy state.

Disease Prognosis

  • Morbidity: Rates of disease within a specific group.

  • Mortality: The relative number of deaths resulting from a particular disease.

  • Autopsy: Postmortem examinations to determine cause of death.

  • Epidemiology: The study of tracking patterns and occurrences of disease, major data collection centers include WHO and CDC.

Disease Prognosis (continued)

  • Occurrence of Disease:

    • Incidence: The number of new cases within a specific population over a given time period.

    • Prevalence: Total number of new, old, or existing cases within a given population and time period.

  • Epidemics: A situation where a higher than expected number of cases of an infectious disease occurs within a specific area.

  • Pandemic: A global outbreak involving a higher number of infectious diseases across multiple regions.

Disease Prognosis (continued)

  • Communicable Diseases: Infectious diseases capable of spreading from one person to another.

  • Notifiable or Reportable Diseases: Certain diseases that must be reported by physicians to relevant authorities, the specifics of required reporting may vary.

Cellular Adaptations

  • Atrophy: A decrease in the size of cells, leading to reduced tissue mass.

  • Hypertrophy: An increase in cell size, resulting in an enlarged tissue mass.

  • Hyperplasia: An increase in the number of cells, leading to an enlarged tissue mass.

Abnormal Cell Growth Patterns

  • Metaplasia: A process in which a mature cell type is replaced by a different mature cell type.

  • Dysplasia: A condition where cells vary in size and shape within a tissue.

  • Anaplasia: Refers to undifferentiated cells that have variable nuclear and cellular structures.

  • Neoplasia: A term for “new growth,” commonly referred to as a tumor.

Cell Damage

  • Apoptosis: Programmed cell death, a normal physiological process in the body.

  • Ischemia: Refers to a deficit of oxygen supply to cells.

  • Hypoxia: A condition marked by reduced oxygen levels in tissues.

  • Nutritional Deficits: Shortages affecting cellular functions.

  • Pyroptosis: Cell death associated with lysis, causing nearby inflammation.

Cell Damage (continued)

  • Physical Damage: Results from excessive heat, cold, mechanical stress, or radiation exposure.

  • Chemical toxins: May be of exogenous origin (from the environment) or endogenous (from within the body).

  • Microorganisms: Such as bacteria and viruses that can induce damage.

  • Abnormal Metabolites: Genetic disorders or inborn errors of metabolism leading to cell damage.

  • Altered Metabolism: Imbalances related to fluids or electrolytes may also contribute to cell injury.

Necrosis

  • Necrosis: Occurs when dying cells cause further damage through cellular disintegration. Types include:

    • Liquefaction Necrosis: Dead cells liquefy due to the release of cell enzymes.

    • Coagulative Necrosis: Cell proteins undergo alteration or denaturation, leading to coagulation.

    • Fat Necrosis: Breakdown of fatty tissue into fatty acids.

    • Caseous Necrosis: A form of coagulative necrosis, forming thick, yellowish, "cheesy" substances.

Necrosis (continued)

  • Infarction: Refers to an area of dead cells resulting from oxygen deprivation.

  • Gangrene: An area of necrotic tissue invaded by bacteria.