CHPT 6

Mechanisms of Disease

Chapter Overview

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Learning Objectives - Lesson 6.1: Mechanisms of Disease and Pathogenic Organisms

• Disease Study: Understanding terminology and patterns of disease.

• Disease Mechanisms: Describe basic mechanisms of disease and associated risk factors.

• Pathogenic Organisms: Describe six categories of pathogens and their disease-causing mechanisms.

Studying Disease

Disease Terminology

• Health: Encompasses physical, mental, and social well-being, not just absence of disease.

• Disease: Abnormality in body function threatening health.

• Etiology: Study of factors causing diseases.

Additional Terminology

• Idiopathic: Disease with unknown cause.

• Signs and Symptoms: Indicators associated with a disease; signs are objective, symptoms are subjective.

• Pathogenesis: Development pattern of a disease.

Patterns of Disease

Key Definitions

• Epidemiology: Study of disease occurrence, distribution, and transmission.

• Endemic Diseases: Native to specific local regions.

• Epidemics: Widespread diseases affecting many people simultaneously.

• Pandemics: Large-scale epidemics, potentially global.

• Disease Mitigation: Can be achieved through preventive measures and therapy.

Pathophysiology

Mechanisms of Disease

• Pathophysiology: Study of the physiology underlying diseases.

• Genetic Mechanisms: Involves genetic influences on disease.

• Infectious Mechanisms: Caused by pathogens and particles.

• Neoplastic Mechanisms: Related to tumors and cancer.

• Traumatic Mechanisms: Arising from physical and chemical agents.

Additional Mechanisms

• Metabolic Mechanisms: Include endocrine imbalances and malnutrition.

• Inflammatory Mechanisms: Involve autoimmunity, inflammation, and degeneration.

Risk Factors

• Genetics: Hereditary factors influencing disease.

• Age: Age-related susceptibility to diseases.

• Lifestyle: Effects of personal habits on health.

• Stress: Impacts biological and mental health.

• Environment: Surroundings that affect health outcomes.

• Preexisting Conditions: Existing health issues that elevate risk.

Pathogenic Organisms

Viruses

• Definition: Microscopic intracellular parasites composed of nucleic acid and protein.

• Function: Invade host cells, utilizing host organelles and materials.

• Classification: Based on shape, nucleic acid type, and reproduction methods.

Prions

• Description: Pathogenic proteins that alter normal proteins, leading to disease.

• Diseases Caused: Include BSE (mad cow disease) and vCJD.

Bacteria

• Characteristics: Tiny cells, lack nuclei, secrete toxins, or parasitize.

• Classification: Based on oxygen requirement (aerobic vs. anaerobic) and staining properties (Gram-positive vs. Gram-negative).

• Shapes: Bacilli (rod-shaped), cocci (round), and curved/spiral forms.

Fungi

• Overview: Simple organisms, similar to plants without chlorophyll.

• Types: Yeasts (single-celled) and molds (multicellular).

• Challenges: Mycotic infections often resist treatment.

Protozoa

• Nature: Large single-celled organisms with organized nuclei.

• Effects: Can infest and damage human cells.

• Major Groups: Include amebas, flagellates, ciliates, and sporozoa.

Pathogenic Animals

• Description: Larger multicellular organisms that parasitize or harm human tissues.

• Key Groups: Nematodes (roundworms), platyhelminths (flatworms), and arthropods (vectors like ticks and mosquitoes).

Learning Objectives - Lesson 6.2: Pathogen Prevention and Control

• Pathogen Transmission: Understand how diseases spread and effective control measures.

• Tumors and Cancer: Differentiate between benign and malignant tumors; describe cancer pathogenesis.

• Inflammatory Response: Outline events and role in disease.

Prevention and Control

Mechanisms of Transmission

• Person-to-Person: Can be mitigated through education and aseptic techniques.

• Environmental Contact: Avoidance and sanitation practices are key prevention strategies.

• Opportunistic Invasion: Prevented by maintaining skin integrity and effective wound care.

• Vector Transmission: Managed by controlling vector populations and reducing contact.

Prevention and Treatment Strategies

• Vaccination: Enhances immunity against pathogens.

• Drug Therapy: Includes antibiotics to combat bacteria and antiviral agents against viruses.

• Antibiotic Resistance: Important to consider in treatment decisions.

Tumors and Cancer

Definitions

• Neoplasms: Abnormal cell growths.

  • Benign: Remain localized.

  • Malignant: Invasive and can spread (metastasis).

Classification of Tumors

• Benign Epithelial Tumors: Include papillomas, adenomas, and nevi.

• Benign Connective Tissue Tumors: Include lipomas, osteomas, and chondromas.

• Malignant Tumors: Carcinomas (melanomas, adenocarcinomas) and sarcomas (lymphomas, myelomas).

Causes of Cancer

• Nature and Influence: Complex interactions of genetic factors, carcinogens, age, environment, and viruses.

Pathogenesis of Cancer

• Detection: Methods include self-examination, imaging, biopsies, and blood tests.

Inflammation

Inflammatory Response

• Purpose: Reduces tissue injuries, maintains homeostasis.

• Signs: Redness, heat, swelling, pain.

• Mediators: Histamine, prostaglandins, kinins assist in modulating blood flow and immune response.

Inflammation Effects

• Local vs. Systemic: Can be targeted or widespread body response.

• Chronic Inflammation: Can lead to tissue damage and diseases.

Questions?

• Feedback and Clarifications: Open for discussion regarding the material.