Learning Outcomes:
- Understand the concepts of health and disease.
- Learn the mechanisms of common diseases caused by bacteria, viruses, fungi, and parasites.
- Understand the body’s defense systems, including innate and acquired immunity.
- Recognize the causes, transmission, and prevention of HIV/AIDS and cancer.
- Recognize the consequences of drug and alcohol abuse.
For centuries, health was defined based on the balance of “humors” or bodily fluids, an idea that originated from Greek philosophers such as Hippocrates and was also embraced by Ayurveda. Individuals with an excess of black bile were believed to have a “hot personality” and prone to fever. This theory was later refuted with the advent of modern science, particularly through William Harvey’s discovery of blood circulation and experiments that demonstrated normal body temperature in individuals.
Later, scientific advancements demonstrated that the mind, through the neural and endocrine systems, significantly influences the immune system. Hence, physical, mental, and social factors play a role in health. These include:
Health is more than the absence of disease. It’s a state of complete physical, mental, and social well-being. Healthy individuals contribute to societal productivity and economic prosperity while ensuring longer lifespans and reduced infant and maternal mortality. Key to maintaining health are:
Humans can suffer from various infectious and non-infectious diseases. Infectious diseases, transmitted from one person to another, are often caused by pathogens such as bacteria, viruses, protozoans, and fungi. Non-infectious diseases, such as cancer and those stemming from drug and alcohol abuse, can severely impact health.
Important Note: Maintaining personal and public hygiene is crucial in preventing infectious diseases. Clean drinking water, proper food handling, and avoiding contact with infected individuals are essential.
The body’s ability to protect itself from pathogens is known as immunity. This can be broadly divided into two categories:
Comparison of Innate and Acquired Immunity
Innate Immunity | Acquired Immunity |
---|---|
Non-specific defense | Pathogen-specific defense |
Present from birth | Develops after exposure |
Immediate response | Takes time to develop |
No memory | Memory for future responses |
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the HIV virus, which attacks the immune system, leading to the failure of defense against infections. HIV primarily infects macrophages and helper T-lymphocytes. Over time, the body’s immune system weakens, making the individual susceptible to opportunistic infections. The virus spreads through:
HIV can remain dormant in the body for several years before symptoms such as fever, weight loss, and opportunistic infections become apparent. ELISA is a common diagnostic test for detecting HIV.
Important Note: HIV/AIDS can only be prevented, as there is no definitive cure. Safe practices like using disposable needles and protected sex are essential in preventing the spread.
Cancer is characterized by uncontrolled cell growth, often leading to the formation of tumors. Tumors can be:
Carcinogens, including radiation, chemicals like tobacco smoke, and oncogenic viruses, can trigger the transformation of normal cells into cancerous ones. Early detection through biopsy, CT scans, and MRI helps in effective treatment. Common cancer treatments include:
Important Concept: Some cancers can evade the immune system, and treatments like immunotherapy can help by stimulating the body’s immune response to target cancer cells.
The misuse of drugs and alcohol, especially among youth, is a growing concern. Commonly abused substances include:
Nicotine in tobacco is another addictive substance that increases heart rate and blood pressure, and smoking is linked to various cancers.
Adolescents are particularly vulnerable to drug and alcohol use due to curiosity, peer pressure, and stress. Early intervention, education, and counseling are essential in preventing addiction.
To prevent drug and alcohol abuse:
MCQ: What is the primary mode of HIV transmission?
Answer: Sexual contact with an infected person.