Health and Disease Class 9 Chapter 13

Health and Disease

• Health is defined as the ability to function well physically, mentally, and socially.
• Disease refers to disturbances in the structure or function of any organ, often caused by pathogens, poor nutrition, or an unbalanced diet.

Difference between Healthy and Disease-Free

• Being healthy encompasses physical, mental, and social well-being.
• Being disease-free indicates the absence of diseases and does not guarantee overall health.

Types of Diseases

• Acute diseases: Last for short periods; examples include influenza and the common cold.
• Chronic diseases: Persist for long durations, sometimes for a lifetime; examples include tuberculosis and cancer.

Acute vs. Chronic Diseases

• Acute diseases have short-term effects and generally recover completely.
• Chronic diseases have long-term effects and may not recover completely, e.g., diabetes or tuberculosis.

Causes of Diseases

• Immediate causes: Pathogens such as viruses, bacteria, and protozoa directly induce disease.
• Contributory causes: Factors that facilitate the entry of pathogens, like dirty water and contaminated food.

Infectious vs. Non-Infectious Causes

• Infectious diseases: Caused by microbes, can spread from person to person.
• Non-infectious diseases: Internal diseases that do not spread, such as cancer.

Infectious Diseases

• Communicable diseases spread easily from one individual to another.
• Antibiotics target bacterial diseases by blocking essential processes, like cell wall formation, in bacteria.

Means of Spread of Infectious Diseases

• Airborne transmission: Common cold, pneumonia, tuberculosis.
• Food and water: Cholera, typhoid, hepatitis.
• Sexual contact: AIDS, syphilis.
• Vectors: Animals and mosquitoes transfer infectious agents between hosts.

Inflammation

• An immune response involving recruitment of cells to affected tissues, resulting in swelling, pain, and fever.

Principles of Treatment

• General method: Reducing disease effects through medicine and vaccinations.
• Specific method: Killing disease causes through hygiene, purified water, and balanced diets.

Immunisation

• Prior exposure to diseases like smallpox grants immunity and prevents future infections due to the immune system's memory of the pathogen.