Human Health and Disease

Health and its Definition

• Health Definition: A state of complete physical, mental, and social well-being, not just the absence of disease or physical fitness.
• Early Greeks (Hippocrates) and Indian Ayurveda believed in the "good humor" hypothesis (balance of humors).
• Crucial detail: William Harvey disproved the "good humor" hypothesis by discovering blood circulation and demonstrating normal body temperature in persons with "black bile" using a thermometer.
• Health is affected by: Genetic disorders, Infections, and Life style (food, water, rest, exercise, habits).

Common Diseases in Humans

Pathogens: Disease-causing organisms (bacteria, viruses, fungi, protozoans, helminths). Most parasites are pathogens as they harm the host.

Bacterial Diseases

• Typhoid
  • Causative Agent: Salmonella typhi NEET 2020 2023-Manipur
  • High-Yield Details & Symptoms: Enters small intestine via contaminated food/water. Symptoms: Sustained high fever (39°C to 40°C), weakness, stomach pain, intestinal perforation in severe cases. Confirmed by Widal test 2010 2012 NEET 2019. Classic case: Mary Mallon (Typhoid Mary).
• Pneumonia
  • Causative Agent: Streptococcus pneumoniae, Haemophilus influenzae 2012 NEET 2020
  • High-Yield Details & Symptoms: Infects alveoli (air sacs) of lungs; alveoli get filled with fluid, decreasing respiratory efficiency. Symptoms: Fever, chills, cough. In severe cases, lips and fingernails turn bluish. Transmitted by inhaling droplets/aerosols.
• Other Bacterial Diseases: Dysentery, Plague, Diphtheria, Cholera, Tetanus 2012.

Viral Diseases

• Common Cold
  • Causative Agent: Rhino viruses
  • High-Yield Details & Symptoms: Infects the nose and respiratory passage but NOT the lungs. Symptoms: Nasal congestion, discharge, sore throat, cough (lasts 3-7 days). Transmitted via droplets or contaminated objects.
• Chikungunya & Dengue: Transmitted by Aedes aegypti mosquito vectors 2014.

Protozoan Diseases

• Malaria
  • Causative Agent: Plasmodium (P. vivax, P. malariae, P. falciparum) NEET 2020
  • Exception/Crucial detail: Plasmodium falciparum causes malignant and most fatal malaria 2010. Vector: Female Anopheles mosquito.
• Amoebiasis
  • Causative Agent: Entamoeba histolytica
  • High-Yield Details & Symptoms: Amoebic dysentery. Parasite in the large intestine. Symptoms: Constipation, abdominal pain, stools with excess mucus and blood clots. Vector: Houseflies (mechanical carriers).
• Leishmaniasis
  • Causative Agent: Leishmania
  • High-Yield Details: Protozoan disease NEET 2024.
• Babesiosis
  • Causative Agent: Babesia
  • High-Yield Details: A malaria-like parasitic disease transmitted by ticks 2015.

Life Cycle of Plasmodium

• Infectious Stage: The sporozoite is the infectious form that enters the human body through the bite of an infected female Anopheles mosquito 2011 2013 NEET 2019 NEET 2020.
• Asexual Reproduction (Human): Sporozoites travel to the liver, multiply asexually, burst liver cells, and enter Red Blood Cells (RBCs).
• Toxic Release: RBCs rupture, releasing haemozoin, which causes the characteristic chill and high fever recurring every 3-4 days.
• Sexual Stage (Human → Mosquito): Gametocytes develop in human RBCs. Mosquito takes up gametocytes with a blood meal.
• Fertilisation & Storage (Mosquito): Fertilisation and development occur in the mosquito's gut. Mature infectious sporozoites migrate and are stored in the mosquito's salivary glands 2011 NEET 2019.

Helminthic & Fungal Diseases

• Ascariasis
  • Causative Agent: Ascaris lumbricoides (Roundworm)
  • High-Yield Details & Symptoms: Intestinal parasite. Symptoms: Internal bleeding, muscular pain, fever, anemia, blockage of intestinal passage. Transmitted via contaminated soil, water, plants.
• Filariasis (Elephantiasis)
  • Causative Agent: Wuchereria bancrofti, W. malayi (Filarial worm) NEET 2020 2024
  • High-Yield Details & Symptoms: Causes slowly developing chronic inflammation of organs, usually the lymphatic vessels of lower limbs and genital organs. Vector: Female mosquito.
• Ringworm
  • Causative Agent: Microsporum, Trichophyton, Epidermophyton NEET 2024 2023-Manipur
  • High-Yield Details & Symptoms: Appearance of dry, scaly lesions on skin, nails, and scalp accompanied by intense itching. Thrives in heat and moisture (e.g., skin folds, groin).

Immunity

Immunity: The overall ability of the host to fight disease-causing organisms conferred by the immune system.

Innate Immunity

Non-specific defense present at the time of birth. Consists of four barriers:

• Physical Barriers: Skin (main barrier), mucus coating of respiratory, gastrointestinal, and urogenital tracts.
• Physiological Barriers: Acid in stomach, saliva in mouth, tears from eyes.
• Cellular Barriers: Polymorphonuclear leukocytes (PMNL-neutrophils), monocytes, natural killer (NK) lymphocytes in blood, and macrophages in tissues.
• Cytokine Barriers: Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection 2010 2012.

Acquired Immunity

Pathogen specific, characterized by memory.

• Primary Response: First encounter with a pathogen, produces a low-intensity response.
• Secondary (Anamnestic) Response: Subsequent encounters yield a highly intensified response due to memory B and T cells.
• B-lymphocytes: Produce an army of proteins (antibodies) into the blood to fight pathogens (Humoral immune response).
• T-lymphocytes: Do not secrete antibodies but help B cells produce them. Mediate Cell-Mediated Immunity (CMI) 2013.

Antibody Structure and Types

• Each antibody molecule has four peptide chains: two light (L) and two heavy (H), represented as H₂L₂.
• Types: IgA, IgM, IgE, IgG.

Cell-Mediated Immunity (CMI)

Mediated by T-lymphocytes. The CMI is responsible for distinguishing "self" from "non-self" and is responsible for graft rejection (transplanted organs) 2012 2015 NEET 2019. Immunosuppressants are required for life after transplant.

Active vs. Passive Immunity

Immunity Type	Mechanism	High-Yield Examples (PYQs)
Active Immunity	Host produces antibodies upon exposure to antigens (living/dead microbes). Slow process.	Natural infection (Natural Active Immunity), Vaccination (Artificial Active Immunity).
Passive Immunity	Ready-made antibodies are directly injected to protect the body against foreign agents.	1. Yellowish fluid Colostrum secreted by mother during early lactation has abundant IgA antibodies 2013 NEET 2019. 2. IgG crosses the placenta (Natural Passive Immunity. 3. Anti-tetanus injection (Artificial Passive Immunity)2015. 4. Anti-snake venom (Artificial Passive Immunity).

Vaccination and Immunisation

• Based on the property of 'memory' of the immune system. Generates memory B and T cells.
• If a person is infected with deadly microbes requiring quick response (e.g., Tetanus, Snakebite), preformed antibodies or antitoxin (preparation containing antibodies to the toxin) are injected. This is Artificial Passive Immunisation.
• Recombinant DNA technology: Allowed production of antigenic polypeptides in bacteria/yeast. Example: Hepatitis B vaccine produced from yeast.

Allergies

• The exaggerated response of the immune system to certain antigens (allergens) present in the environment.
• B-Cells produces antibodies of IgE type 2013.
• Symptoms: Sneezing, watery eyes, running nose, difficulty breathing (e.g., Asthma).
• Mechanism: Due to the release of chemicals like histamine and serotonin from mast cells NEET 2019.
• Drugs like anti-histamine, adrenalin, and steroids quickly reduce symptoms.

Autoimmunity

Memory-based acquired immunity sometimes loses the ability to distinguish "self" from "non-self". The body attacks self-cells, resulting in auto-immune disease.

• Classic Example: Rheumatoid arthritis NEET 2018.

Immune System in the Body

Consists of lymphoid organs, tissues, cells, and soluble molecules like antibodies.

Organ Type	Function	Examples & Key Details
Primary Lymphoid Organs	Where immature lymphocytes differentiate into antigen-sensitive lymphocytes.	Bone Marrow: Main organ where all blood cells (including B & T lymphocytes) are produced. Thymus: Lobed organ near the heart. Crucial detail: Large at birth but keeps reducing in size with age; very small by puberty, leading to weaker immune responses in older individuals 2013.
Secondary Lymphoid Organs	Provide sites for interaction of lymphocytes with antigen, where they proliferate to become effector cells.	Spleen: Bean-shaped, contains lymphocytes and phagocytes. Acts as a blood filter trapping blood-borne microorganisms. It has a large reservoir of erythrocytes (RBCs) 2012. Lymph Nodes: Trap microorganisms/antigens present in lymph/tissue fluid. Others: Tonsils, Peyer's patches of small intestine, Appendix.
MALT	Mucosa-Associated Lymphoid Tissue	Located within the lining of major tracts (respiratory, digestive, urogenital). Constitutes ~50% of the lymphoid tissue in the human body NEET 2017.

AIDS (Acquired Immuno Deficiency Syndrome)

• First reported in 1981. It is a syndrome (group of symptoms), not a congenital disease.
• Caused by HIV (Human Immunodeficiency Virus), a retrovirus with an RNA genome enclosed in an envelope NEET 2018.
• Transmission: 1. Sexual contact. 2. Transfusion of contaminated blood. 3. Sharing infected needles (IV drug abusers). 4. Infected mother to child through placenta.
• Exception: HIV does NOT spread by mere touch or physical contact; it spreads only through body fluids. Time lag from infection to symptoms varies (usually 5-10 years).
• Mechanism of Action:
  • Virus enters the body and targets Macrophages (act as an HIV factory) where RNA replicates to form viral DNA via Reverse Transcriptase.
  • Viral DNA incorporates into host DNA and directs infected cells to produce virus particles.
  • HIV simultaneously enters Helper T-lymphocytes (T_H) NEET 2018, replicates, and produces progeny viruses.
  • Progeny viruses lyse the cell, attack other T_H cells, causing a progressive decrease in Helper T-lymphocyte count.
  • The person suffers from recurrent infections (e.g., Mycobacterium, viruses, fungi like Toxoplasma) due to severe immunodeficiency.
• Diagnosis: ELISA (Enzyme-Linked Immuno-Sorbent Assay).
• Treatment: Anti-retroviral drugs are only partially effective; they can prolong life but cannot prevent death.

Cancer

• Contact Inhibition: Normal cells show this property where contact with other cells inhibits their uncontrolled growth. Cancer cells appear to have lost this property 2013.
• Tumors: Masses of cells resulting from uncontrolled division.
  • Benign Tumors: Remain confined to original location, do not spread, cause little damage.
  • Malignant Tumors: Mass of proliferating cells (neoplastic cells) that grow rapidly, invading and damaging surrounding normal tissue. They exhibit Metastasis (cells sloughed off reach distant sites via blood and start new tumors)—the most feared property of malignant tumors 2011 2015.
• Causes of Cancer (Carcinogens):
  • Physical: X-rays, gamma rays (ionising); UV rays (non-ionising) cause DNA damage.
  • Chemical: Tobacco smoke (lung cancer).
  • Biological: Oncogenic viruses (have viral oncogenes). Normal cells have cellular oncogenes (c-onc) or proto-oncogenes which, when activated, cause oncogenic transformation.
• Detection & Diagnosis:
  • Biopsy and histopathological studies.
  • Radiography (X-rays), CT (uses X-rays for 3D internal images), MRI (uses strong magnetic fields and non-ionising radiations to detect pathological/physiological changes).
  • Antibodies against cancer-specific antigens. Techniques in molecular biology to detect susceptible genes.
• Treatment: Surgery, radiation therapy (lethal irradiation of tumor), and chemotherapy (side effects: hair loss, anemia).
• Immunotherapy: Tumor cells avoid immune detection. Patients are given biological response modifiers like α-interferons which activate their immune system and help destroy the tumor.

Drugs and Alcohol Abuse

• Opioids: Drugs that bind to specific opioid receptors in the Central Nervous System (CNS) and gastrointestinal tract.
  • Morphine: Extracted from the latex of the poppy plant (Papaver somniferum) NEET 2019 2014. Highly effective sedative and painkiller, useful for post-surgery patients 2011.
  • Heroin (Smack): Chemically it is diacetylmorphine NEET 2019. A white, odorless, bitter crystalline compound formed by the acetylation of morphine. Taken by snorting or injection. It is a depressant and slows down body functions.
• Cannabinoids: Interact with receptors in the brain. Extracted from the inflorescence of Cannabis sativa. Includes marijuana, hashish, charas, and ganja. Known for effects on the cardiovascular system.
• Coca Alkaloid (Cocaine): Extracted from Erythroxylum coca (native to South America).
  • Mechanism: Interferes with the transport of the neurotransmitter dopamine 2014.
  • Has a potent stimulating action on CNS, producing euphoria and increased energy. Excessive dosage causes hallucinations.
• Hallucinogens: Plants with hallucinogenic properties include Atropa belladonna and Datura. LSD (Lysergic acid diethylamide) is also a powerful hallucinogen.
• Medical Drug Abuse: Drugs like barbiturates, amphetamines, and benzodiazepines, normally used to cope with mental illnesses (depression, insomnia), are often abused.
• Tobacco: Smoked, chewed, or used as snuff. Contains Nicotine (an alkaloid) which stimulates the adrenal gland to release adrenaline and nor-adrenaline, raising blood pressure and heart rate. Smoking increases carbon monoxide (CO) in blood and reduces the concentration of haem-bound oxygen.
• Dependence & Withdrawal: The tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome (anxiety, shakiness, nausea, sweating) if regular dose of drugs/alcohol is abruptly discontinued. Receptor tolerance increases with repeated use, requiring higher doses.

Introduction to Health

• Health Definition: A state of complete physical, mental, and social well-being, not merely the absence of disease or physical fitness.
• The ancient "good humor" hypothesis (advocated by early Greeks like Hippocrates and Indian Ayurveda) posited that health was a balance of humors (e.g., 'black bile' causing hot personality/fevers).
• Crucial detail: The "good humor" hypothesis was disproved by William Harvey, who discovered blood circulation and demonstrated normal body temperature in persons with black bile using a thermometer.
• Health is affected by: Genetic disorders, Infections, and Life style (food, water, rest, exercise, habits).
• Diseases are grouped into Infectious (transmitted easily, e.g., AIDS) and Non-infectious (not transmitted, e.g., Cancer).

Common Diseases in Humans

Bacterial Diseases

• Typhoid: Caused by Salmonella typhi 1998 2020 2023 2024. Enters the small intestine via contaminated food/water. Symptoms: Sustained high fever (39°C - 40°C), stomach pain, intestinal perforation in severe cases. Confirmed by the Widal test 2010 2012 2019. Mary Mallon (Typhoid Mary) was a classic carrier.
• Pneumonia: Caused by Streptococcus pneumoniae and Haemophilus influenzae 2012 2020 2024. Infects the alveoli (air sacs) of lungs, filling them with fluid. Symptoms: Fever, chills, cough. In severe cases, lips and fingernails turn grayish to bluish. Transmitted by droplet/aerosol infection.
• Dysentery (Shigellosis): Caused by Shigella. Transmitted via faecal-oral route. Characterized by blood and mucus in stool 2009.
• Plague (Black Death): Caused by Yersinia pestis 1995. Transmitted by the rat flea (Xenopsylla cheopis). Symptoms include enlarged axillary lymph nodes.
• Diphtheria: Caused by Corynebacterium diphtheriae 1997. Affects throat, causes suffocation. Investigated by Schick test.
• Tetanus & Botulism: Clostridium tetani causes Tetanus (Lockjaw) 2001 2012. Clostridium botulinum causes Botulism, which directly affects the central nervous system 1998.

Viral Diseases

• Common Cold: Caused by Rhino viruses. Crucial detail: Infects the nose and respiratory passage but NOT the lungs 2009 2012. Cannot be cured by antibiotics because it is a viral disease 2011.
• Dengue and Chikungunya: Viral diseases transmitted by the vector Aedes aegypti mosquito 2015.

Protozoan Diseases

• Malaria: Caused by Plasmodium (P. vivax, P. malariae, P. falciparum). P. falciparum causes malignant and fatal malaria 1991.
  • Vector: Female Anopheles mosquito.
  • Infectious Stage: Enters the human body as a Sporozoite 1990 2011 2020. Sporozoites are stored in the salivary glands of the mosquito 2011.
  • Mechanism: Parasite multiplies asexually in the liver, then attacks RBCs (Schizont stage occurs in human cells 1993). Rupture of RBCs releases a toxic substance called haemozoin, causing recurring chills and high fever every 3-4 days 2010.
  • Sexual Stage: Gametocytes develop in human RBCs 1990. The motile zygote forms in the gut of the female Anopheles mosquito 2012.
• Amoebiasis (Amoebic dysentery): Caused by Entamoeba histolytica, a parasite of the large intestine. It feeds upon erythrocytes, mucosa, and submucosa of the colon 2015. Houseflies act as mechanical carriers.
• African Sleeping Sickness: Caused by Trypanosoma gambiense, transmitted by the bite of the Tse-tse fly (Glossina palpalis) 1989 1991 1993 2004.
• Kala-azar: Caused by Leishmania donovani, spread by the Sandfly 1990 1993.

Helminthic & Fungal Diseases

• Ascariasis: Caused by Ascaris (roundworm). Symptoms: internal bleeding, muscular pain, fever, anaemia, and blockage of the intestinal passage 2013. Acquired via contaminated water/food.
• Elephantiasis (Filariasis): Caused by Wuchereria (W. bancrofti, W. malayi) 2020 2024. Causes slowly developing chronic inflammation of organs, usually the lymphatic vessels of the lower limbs and genital organs 2017 2018. Vector is the female Culex mosquito.
• Ringworm: Caused by fungi Microsporum, Trichophyton, and Epidermophyton 2010 2011 2023 2024. Symptoms: Dry, scaly lesions with intense itching. Thrives in heat and moisture.

Immunity

Immunity is the overall ability of the host to fight disease-causing organisms.

Innate Immunity

Non-specific defense present at birth. Comprises four barriers:

• Physical Barriers: Skin (main barrier) and mucus coating of respiratory, gastrointestinal, and urogenital tracts.
• Physiological Barriers: Acid in stomach, saliva, and tears containing lysozyme, which destroys bacteria 2007.
• Cellular Barriers: Phagocytic cells like PMNL-neutrophils, monocytes, macrophages, and non-phagocytic Natural Killer (NK) cells.
• Cytokine Barriers: Virus-infected cells secrete proteins called Interferons, which protect adjacent non-infected cells from further viral infection 1994 1996 2000 2024.

Acquired Immunity

Pathogen-specific and characterized by memory.

• Primary Immune Response (PIR): First encounter with a pathogen produces a slow, low-intensity response.
• Secondary (Anamnestic) Response (SIR): Subsequent encounter with the same pathogen elicits a rapid, highly intensified response due to immunological memory.
• B-lymphocytes: Produce an army of proteins called antibodies into the blood to fight pathogens (Humoral Immune Response) 2000 2024.
• T-lymphocytes: Do not secrete antibodies but help B-cells produce them. Responsible for Cell-Mediated Immunity (CMI) 2013.

Antibodies & Cell-Mediated Immunity

• Antibody Structure: Complex glycoproteins 2006 consisting of four polypeptide chains (two light, two heavy: H₂L₂), linked by interchain and intrachain disulfide bonds.
• IgA: Secretory antibody (dimer) found in saliva, tears, and Colostrum. Imparts natural passive immunity to infants 1999 2015 2019 2020.
• IgG: Most abundant. Can cross the placenta, providing natural passive immunity to the foetus 2003.
• IgE: Involved in allergic reactions 2000 2001.
• IgM: Largest (pentamer), oldest, and first formed antibody.
• Cell-Mediated Immunity (CMI) & Grafting: The immune system differentiates "self" from "non-self". The CMI response is responsible for graft (transplant) rejection 2010 2015 2017 2019 2022. Requires lifetime use of immunosuppressants.

Active vs. Passive Immunity

Immunity Type	Mechanism	Examples
Active Immunity	Host's immune system produces antibodies against antigens (living/dead microbes or proteins). Slow response 1999 2020.	Vaccination, natural infection.
Passive Immunity	Ready-made antibodies are directly administered for quick response 2010 2020.	Anti-Tetanus Serum, Anti-venom 2016, Colostrum, Placental IgG.

Vaccination and Immunisation

• Based on the property of 'memory' of the immune system. Vaccines contain weakened/inactivated pathogens or antigenic proteins.
• Polio drops administered into the body contain attenuated pathogens 2016.
• Recombinant DNA technology produced Hepatitis B vaccine from transgenic yeast.

Allergies & Autoimmunity

• Allergy: Exaggerated immune response to environmental antigens. Mediated by IgE antibodies. Due to the release of chemicals like histamine and serotonin from Mast cells 2000 2001 2004.
  • Asthma is characterized by spasm of bronchial smooth muscles. Increased asthmatic attacks in certain seasons are due to inhalation of seasonal pollen 2007. Treated with antihistamines, adrenalin, and steroids.
• Autoimmunity: Body loses the ability to distinguish self from non-self and attacks its own cells.
  • Examples: Rheumatoid arthritis (attacks synovial membrane) 2018 2022, Myasthenia gravis (attacks Ach receptors), Pernicious anaemia (attacks Oxyntic cells), Type 1 Diabetes, Multiple Sclerosis (attacks myelin sheath).

Lymphoid Organs

• Primary Lymphoid Organs: Bone marrow (where all blood cells and lymphocytes are produced) and Thymus (provides micro-environment for T-lymphocyte maturation) 2024.
  • Crucial detail: The thymus is large at birth but keeps reducing in size with age. Damage to the thymus in a child leads to loss of cell-mediated immunity 2005.
• Secondary Lymphoid Organs: Spleen, Lymph nodes, Tonsils, Peyer's patches. Sites for lymphocyte interaction with antigens. The spleen is a large reservoir of erythrocytes 2012.
• MALT (Mucosa-Associated Lymphoid Tissue): Constitutes about 50% of the lymphoid tissue in the human body 2017.

AIDS (Acquired Immuno Deficiency Syndrome)

• Pathogen and Mechanism: Caused by HIV (Human Immunodeficiency Virus), a retrovirus with an envelope enclosing a single-stranded RNA (ssRNA) genome and the enzyme Reverse Transcriptase 1998 2016.
• Transmission: Sexual contact, contaminated blood transfusion, sharing infected needles, transplacental route.
• Infection Mechanism:
  • Virus enters Macrophages (which act as an HIV factory). Viral RNA synthesizes viral DNA via reverse transcriptase.
  • Viral DNA incorporates into host genome, directing the production of new virus particles.
  • HIV simultaneously attacks Helper T-lymphocytes (T_H / T₄ cells) 2005 2015 2016, replicating and destroying them.
  • This causes a progressive and massive decrease in the number of Helper T-lymphocytes, leading to severe immunodeficiency.
• Symptoms & Opportunistic Infections: Progresses from AIDS Related Complex (ARC - fever, diarrhea, weight loss) to full-blown AIDS. Patients suffer from opportunistic infections like Mycobacterium, Toxoplasma, Pneumocystis, and Kaposi sarcoma.
• Diagnosis & Treatment: Screened by ELISA; Confirmed by Western Blot. Treated with Anti-Retroviral Therapy (e.g., HAART, Reverse Transcriptase inhibitors), which only prolongs life but cannot prevent death.

Cancer

• Characteristics and Tumors: Normal cells show contact inhibition (contact with other cells inhibits uncontrolled growth). Cancer cells lose this property, dividing uncontrollably to form masses called tumors 2012.
  • Benign Tumors: Remain confined to their original location.
  • Malignant Tumors: Proliferating cells (neoplastic cells) that invade and damage surrounding tissues. Cells sloughed from such tumors reach distant sites via blood and start new tumors—a feared property called Metastasis 1994 2003.
• Tumor Classifications: Carcinoma (Epithelial tissue, e.g., skin/lung) 2003, Sarcoma (Connective tissue/fibroblasts) 1994, Leukaemia (Blood cancer) 1995.
• Causes, Detection, and Treatment:
  • Carcinogens: Physical (X-rays, UV rays), Chemical (tobacco smoke), Biological (oncogenic viruses). Normal cells possess proto-oncogenes (c-onc) that can transform into cancer-causing oncogenes (v-onc) 2016.
  • Detection: Biopsy, Histopathology, Blood tests, MRI (safest technique using strong magnetic fields 2010), CT scan, and antibodies.
  • Treatment: Surgery, Radiotherapy (cancer cells easily destroyed by radiation due to rapid cell division 2002), and Chemotherapy (side effects: hair loss, anemia).
  • Immunotherapy: Tumors avoid immune detection. Patients are given biological response modifiers like α-interferon to activate the immune system and destroy tumors.

Drugs and Alcohol Abuse

Commonly Abused Drugs

• Opioids: Bind to specific opioid receptors in the CNS and GI tract.
  • Morphine: Extracted from the latex of the poppy plant (Papaver somniferum) 2018. Highly effective sedative and painkiller, useful for post-surgery patients 2001 2012.
  • Heroin (Smack): Synthesized by the acetylation of morphine 2019. A white, odorless, bitter crystalline compound. It is a depressant and slows down body functions.
• Cannabinoids: Interact with brain receptors. Derived from Cannabis sativa. Includes marijuana, hashish, charas, and ganja. Known for effects on the cardiovascular system 2012.
• Coca Alkaloid (Cocaine): From Erythroxylum coca. Interferes with the transport of the neurotransmitter dopamine 2012. Potent CNS stimulant causing euphoria and hallucinations.
• Hallucinogens: Plants like Atropa belladonna and Datura have hallucinogenic properties. LSD (Lysergic acid diethylamide) is a powerful hallucinogen 2001.
• Tobacco: Contains nicotine, which acts as a stimulant by mimicking acetylcholine's effect and stimulating the adrenal gland 1995. Increases CO in blood.

Effects of Drug/Alcohol Abuse and Dependence

• Immediate adverse effects: Manifest as reckless behaviour, vandalism, and violence. Excessive doses (especially when drugs are mixed with alcohol) lead to coma or death due to respiratory failure, heart failure, or cerebral haemorrhage.
• Chronic effects: Chronic alcohol/drug abuse severely damages the nervous system and causes liver cirrhosis 2012.
• Intravenous (IV) risks: Drug abusers injecting directly into veins using shared needles are at extremely high risk of acquiring chronic, fatal infections like AIDS and Hepatitis B 2010.
• Dependence: The body’s tendency to manifest a characteristic and unpleasant withdrawal syndrome (anxiety, shakiness, nausea, sweating) if the regular dose is abruptly discontinued. Dependence often drives the abuser to ignore social norms to obtain funds (e.g., stealing), causing immense mental and financial distress to family.

Misuse by Sportspersons

Certain sportspersons misuse narcotic analgesics, anabolic steroids, diuretics, and certain hormones to increase muscle strength, bulk, and aggressiveness, enhancing performance.

• Crucial Detail: In adolescent males/females, steroid abuse causes severe acne and premature closure of the growth centres of long bones, resulting in stunted growth.

Target Group	Side-Effects of Anabolic Steroids
Males	Severe acne, increased aggressiveness, mood swings, depression, reduction in the size of the testicles, decreased sperm production, liver/kidney dysfunction, breast enlargement, premature baldness, and enlarged prostate.
Females	Masculinisation (male-like features), increased aggressiveness, mood swings, depression, abnormal menstrual cycles, excessive facial/body hair, enlargement of the clitoris, and deepening of the voice.

Prevention and Control

• Core principle: "Prevention is better than cure." Adolescence is a highly vulnerable phase requiring careful guidance.
• Avoid undue peer pressure: A child should not be pushed unreasonably beyond their natural limits in academics or sports.
• Education and counselling: Teaching youth to handle stress, accept failures as a part of life, and channel energy into sports, reading, or yoga.
• Seeking help from parents and peers: Immediate help should be sought to sort out feelings of guilt and anxiety with proper guidance.
• Looking for danger signs: Identifying dropping grades, isolation, or aggressive behavior early to initiate remedial steps.
• Seeking professional and medical help: Utilizing psychologists, psychiatrists, and specialized de-addiction and rehabilitation programmes to help individuals overcome addiction completely.