Human Health and Diseases

• Health and Disease Basics

  • Health: State of complete physical, mental, and social well-being
  • Factors Affecting Health: Genetic disorders, Infections, Lifestyle
  • Disease Types:
    • Infectious (Communicable): Easily transmitted (e.g., AIDS, Flu)
    • Non-infectious: Not transmitted (e.g., Cancer)

• Common Human Diseases

  • Bacterial Diseases
    • Typhoid: Salmonella typhi | Confirmed by Widal test | Symptoms: High fever, intestinal perforation
    • Pneumonia: Streptococcus pneumoniae | Affects alveoli | Symptoms: Chills, fever, gray/blue lips
  • Viral Diseases
    • Common Cold: Rhino virus | Affects nose and respiratory passage (not lungs)
  • Protozoan Diseases
    • Malaria: Plasmodium (P. falciparum is most fatal) | Vector: Female Anopheles mosquito | Infective stage: Sporozoite | Toxic substance: Haemozoin
    • Amoebiasis (Amoebic Dysentery): Entamoeba histolytica | Carrier: Housefly | Symptoms: Stool with excess mucus and blood clots
  • Helminthic Diseases
    • Ascariasis: Ascaris (Intestinal parasite) | Transmission: Contaminated water/vegetables
    • Elephantiasis (Filariasis): Wuchereria bancrofti / W. malayi | Vector: Female Culex mosquito | Inflammation of lymphatic vessels
  • Fungal Diseases
    • Ringworm: Microsporum, Trichophyton, Epidermophyton | Symptoms: Dry, scaly skin lesions

• Immunity

  • Innate Immunity (Non-specific, present from birth)
    • Physical Barriers: Skin, Mucus coating
    • Physiological Barriers: Acid in stomach, Saliva, Tears
    • Cellular Barriers: PMNL-neutrophils, Monocytes, Natural Killer (NK) cells
    • Cytokine Barriers: Interferons (secreted by virus-infected cells)
  • Acquired Immunity (Pathogen-specific, memory-based)
    • Humoral Immune Response: B-lymphocytes produce Antibodies (IgA, IgM, IgE, IgG)
    • Cell-Mediated Immunity (CMI): T-lymphocytes | Responsible for Graft Rejection
  • Active vs Passive Immunity
    • Active Immunity: Slow, body produces antibodies (e.g., Natural infection, Vaccination)
    • Passive Immunity: Readymade antibodies injected (e.g., Colostrum containing IgA, Tetanus antitoxin)
  • Vaccination & Immunisation
    • Based on property of Memory of immune system
    • Produced via Recombinant DNA Technology (e.g., Hepatitis B vaccine from yeast)
  • Allergies & Autoimmunity
    • Allergy: Exaggerated response to allergens | IgE antibodies | Release of Histamine and Serotonin
    • Autoimmune Disease: Body attacks self-cells | Example: Rheumatoid Arthritis
  • Immune System Organs
    • Primary Lymphoid Organs: Bone marrow, Thymus (Maturation of lymphocytes)
    • Secondary Lymphoid Organs: Spleen, Lymph nodes, Tonsils, Peyer's patches, MALT (Mucosal Associated Lymphoid Tissue - 50% of lymphoid tissue)

• AIDS (Acquired Immuno Deficiency Syndrome)

  • Causative Agent: HIV (Human Immunodeficiency Virus) - Retrovirus (RNA genome)
  • Target Cells: Macrophage (HIV factory) and Helper T-cells ($T_H$)
  • Transmission: Unsafe sex, Contaminated blood, Shared needles, Infected mother to fetus
  • Diagnostic Test: ELISA (Enzyme-Linked Immunosorbent Assay)
  • Prevention: NACO (National AIDS Control Organisation), WHO guidelines, Safe blood transfusion

• Cancer

  • Characteristics: Loss of Contact Inhibition, Uncontrolled cell division
  • Tumors
    • Benign: Remains confined to original site
    • Malignant: Mass of proliferating cells (Neoplastic) | Shows Metastasis (sloughing and spreading to distant organs)
  • Causes (Carcinogens)
    • Physical: Ionizing radiation (X-rays, Gamma rays), Non-ionizing radiation (UV)
    • Chemical: Tobacco smoke (lung cancer)
    • Biological: Oncogenic Viruses containing viral oncogenes
  • Detection: Biopsy, Histopathological studies, MRI, CT Scan, Radiography
  • Treatment: Surgery, Radiotherapy, Chemotherapy, Immunotherapy ($\alpha$-interferon)

• Drugs and Alcohol Abuse

  • Commonly Abused Drugs
    • Opioids: Heroin (Smack) | Binds to CNS & GI tract receptors | Depressant, slows body functions | Extracted from Papaver somniferum
    • Cannabinoids: Marijuana, Hashish, Charas, Ganja | Interacts with cannabinoid receptors in brain | Affects cardiovascular system | Source: Cannabis sativa
    • Cocaine (Erythroxylum coca): Stimulant | Interferes with Dopamine transport | Causes euphoria and hallucinations
    • Hallucinogens: Obtained from Atropa belladonna, Datura, LSD
  • Tobacco & Alcohol
    • Tobacco: Contains Nicotine | Stimulates adrenal gland to release Adrenaline | Increases blood pressure
    • Alcohol: Chronic use leads to Liver Cirrhosis and CNS damage
  • Addiction and Dependence
    • Dependence: Manifested by Withdrawal Syndrome (Anxiety, shakiness, nausea, sweating)
    • Effects of Abuse: Drop in academic performance, violent behavior, reckless driving, HIV/Hepatitis transmission (via intravenous injection)
  • Prevention and Control
    • Avoid undue peer pressure
    • Education and counseling
    • Seeking help from parents and peers
    • Professional and medical assistance