Disease part 2

Disease

The Nature of Disease

• Historical Background

  • Ancient beliefs attributed diseases to gods' wrath.

  • In the Dark Ages, diseases were thought to be caused by witches or evil vapors.

  • Experiences with plagues revealed the transmissible nature of some diseases, though the transmission method was unknown until the invention of the microscope.

• What Is a Disease?

  • Definition: An abnormal condition hindering normal body function.

  • Types of Disease:

    • Acute: Fast onset after exposure, often reversible, e.g., ammonia exposure.

    • Chronic: Long-lasting effects from low exposure, often irreversible, e.g., effects of harmful chemicals may take years to manifest.

  • Pathology: The study of diseases, associated with specific symptoms and signs.

• Immunology Review:

  • Body has multiple defense lines against diseases.

  • Leukocytes attack pathogens, while antibodies neutralize foreign substances.

Causes of Disease

• Categories of Causes:

  1. Genetic Disorders:

     • Caused by defective genes, can be hereditary. Examples: Hemophilia, muscular dystrophy.

  2. Infections:

     • Caused by microbes (bacteria, viruses, fungi). Example diseases: Colds, measles, STDs.

  3. Poor Nutrition:

     • Caused by imbalanced diets; examples include beriberi (vitamin B deficiency), kwashiorkor (protein deficiency).

  4. Environmental Factors:

     • Caused by pollutants and chemicals, e.g., lead exposure, tobacco smoke.

  5. Tissue Degeneration/Dysfunction:

     • Examples: Alzheimer’s, arthritis, cancer.

Non-communicable Diseases (NCDs)

• Definition: Diseases not spread by germs, leading cause of death. Examples include heart disease and cancer.

• Major Causes:

  1. Genetic Disorders: Results from defective genes affecting organs.

  2. Tissue Degeneration: Organs wearing out (e.g., Alzheimer’s).

  3. Nutritional Disorders: Caused by improper diets (e.g., anorexia).

Communicable Diseases

• Definition: Spread from an infected person to another; contagious diseases.

• Causes: Presence of pathogens like bacteria, fungi, protists, and viruses.

• Examples of Communicable Diseases: Chickenpox, pneumonia, tuberculosis.

Heart Disease

• Overview:

  • Leading cause of death in the U.S., often due to poor diet and lack of exercise.

  • Conditions include arteries narrowing (atherosclerosis) and high blood pressure (hypertension).

• Types of Heart Diseases:

  1. Atherosclerosis: Build-up of plaque leading to reduced blood flow.

  2. Arteriosclerosis: Hardening of the artery walls with age.

  3. Hypertension: Elevated blood pressure damaging heart and vessels.

Sexually Transmitted Diseases (STDs)

• Overview: Infections caused by bacteria and viruses transmitted through sexual contact.

• Common STDs:

  • Gonorrhea: Symptoms include painful urination and discharge; treated with antibiotics.

  • Syphilis: Can affect various organs, with stages causing different symptoms, untreated leads to serious complications.

  • Chlamydia: Often asymptomatic, symptoms can include discharge and bleeding.

  • Herpes: Causes painful blisters on the genitals, no cure available, can be transmitted to infants during birth.