Understanding Health and Disease

Health Defined

• Health has been defined as a state of body and mind where there was a balance of ‘humors’ .
• Health achieves complete physical, mental and social well-being.
• Good health requires balanced diet, personal hygiene and regular exercise.

Factors Affecting Health

• Genetic disorders inherited from parents
• Infections
• Lifestyle, including food & water intake, exercise and habits

Common Diseases and Pathogens

• Diseases are broadly classified as infectious or non-infectious.
• Infectious diseases are easily transmitted, some being fatal, like AIDS.
• Cancer is a major cause of death among non-infectious diseases.
• Drug and alcohol abuse can affect health.
• Pathogens include bacteria, viruses, fungi, protozoans, and helminths.
• Most parasites are pathogens, harming the host.
• Pathogens adapt to the host environment by multiplying and interfering with normal body activities in order to cause morphological and functional damage.

Typhoid

• Salmonella typhi is a pathogenic bacterium that causes typhoid fever.
• Pathogens enter the small intestine through contaminated food and water.
• Symptoms include high fever (39° to 40°C), weakness, stomach pain, constipation, headache, and loss of appetite.
• Intestinal perforation and death may occur in severe cases.
• The Widal test confirms typhoid fever.
• Mary Mallon, known as Typhoid Mary, was a typhoid carrier who spread the disease through food.

Pneumonia

• Streptococcus pneumoniae and Haemophilus influenzae cause pneumonia.
• It infects the alveoli of the lungs, filling them with fluid and causing respiration problems.
• Symptoms include fever, chills, cough, and headache.
• Lips and fingernails may turn gray to bluish in severe cases.
• It spreads through inhaled droplets/aerosols or sharing glasses/utensils from infected individuals.
• Dysentery, plague, and diphtheria are other bacterial diseases.

Common Cold

• Rhino viruses cause the common cold.
• It Infects the nose and respiratory passage, but not the lungs.
• Symptoms include nasal congestion, sore throat, hoarseness, cough, headache, and tiredness.
• Symptoms last for 3-7 days.
• It Spreads through droplets from coughs/sneezes or contaminated objects.

Malaria

• Plasmodium is a tiny protozoan that causes malaria.
• P. vivax, P. malariae, and P. falciparum are species that cause can cause different types of malarial.
• Malignant malaria caused by Plasmodium falciparum is the most serious and can be fatal.
• Plasmodium enters the human body as sporozoites through the bite of infected female Anopheles mosquitoes.
• Parasites multiply in liver cells and then attack red blood cells (RBCs), causing their rupture.
• Rupture of RBCs releases haemozoin, a toxic substance causing chill and high fever every three to four days.
• Female Anopheles mosquitoes transmit parasites to humans.
• The parasite requires two hosts (humans and mosquitoes) to complete its life cycle.

Amoebiasis

• Entamoeba histolytica is a protozoan parasite in the large intestine that causes amoebiasis (amoebic dysentery).
• Symptoms include constipation, abdominal pain, cramps, and stools with excess mucous and blood clots.
• Houseflies act as mechanical carriers and transmit the parasite from faeces to food.
• Contaminated drinking water and food are primary infection sources.

Ascariasis

• Ascaris is a common roundworm.
• It leads to internal bleeding, muscular pain, fever, anemia, and blockage of the intestinal passage.
• Eggs are excreted with faeces, contaminating soil, water, and plants.
• Infection occurs through contaminated water, vegetables, and fruits.

Filariasis

• Wuchereria (W. bancrofti and W. malayi) is a filarial worm.
• It causes chronic inflammation of organs, usually the lymphatic vessels of lower limbs.
• This leads to elephantiasis or filariasis.
• Genital organs can also be affected, causing gross deformities.
• The pathogens are transmitted through the bite of female mosquito vectors.

Ringworms

• Microsporum, Trichophyton, and Epidermophyton are fungi genera that cause ringworms.
• Symptoms include dry, scaly lesions on the skin, nails, and scalp, accompanied by intense itching.
• Heat and moisture help fungi grow in skin folds.
• Ringworms are acquired from soil or through towels, clothes, or combs of infected individuals.

Preventing Infectious Diseases

• Maintenance of personal and public hygiene is crucial for prevention and control.
• Personal hygiene involves keeping the body clean and consuming clean food and water.
• Public hygiene includes proper waste disposal, disinfection of water sources, and hygiene in public catering.
• Air-borne diseases require avoiding close contact with infected persons and their belongings.
• Vector-borne diseases require controlling or eliminating vectors and their breeding places.
• Avoid water stagnation, clean coolers regularly, use mosquito nets, and introduce larvivorous fishes.
• Use insecticides and wire mesh on doors and windows.

Advancements in Biological Science

• Vaccines and immunization programs have eradicated smallpox.
• Diseases like polio, diphtheria, pneumonia, and tetanus have been controlled through vaccines.
• Biotechnology is developing newer and safer vaccines.
• Discovery of antibiotics and drugs has enabled effective treatment of infectious diseases.

Immunity Explained

• Immunity is the body's ability to defend itself from foreign agents.
• There are two types: innate and acquired immunity.

Innate Immunity

• Innate immunity is a non-specific defense present at birth.
• Consists of four types of barriers:
  • Physical: Skin and mucus coatings trap microbes.
  • Physiological: Acid in the stomach, saliva, and tears prevent microbial growth.
  • Cellular: Leukocytes (WBCs) like neutrophils, monocytes, natural killer cells, and macrophages destroy microbes through phagocytosis.
  • Cytokine: Virus-infected cells secrete interferons to protect non-infected cells.

Acquired Immunity

• Acquired immunity is pathogen-specific and characterized by memory.
• The primary response is of low intensity, while the secondary (anamnestic) response is highly intensified.
• B-lymphocytes produce antibodies to fight pathogens in the blood, while T-cells help B cells to produce antibodies.
• Antibody molecules have two light chains and two heavy chains (H2L2).
• IgA, IgM, IgE, and IgG are different types of antibodies.
• The humoral immune response is antibody-mediated while the cell-mediated immune response (CMI) is T-lymphocyte-mediated.
• Cell-mediated immune response is responsible for graft rejection.

Active vs Passive Immunity

• Active immunity occurs when the body produces antibodies in response to antigens.
• This type of immunity is slow and can be induced by immunization or natural infection.
• Passive immunity involves directly providing ready-made antibodies to protect against foreign agents.
• Colostrum in mother’s milk and antibodies received through the placenta are examples of passive immunity.

Vaccination and Immunisation

• Immunization and vaccination are based on the immune system's memory.
• Vaccines of antigenic proteins or inactivated/weakened pathogens are introduced into the body.
• Antibodies produced neutralize pathogenic agents during actual infection and generate memory cells.
• Preformed antibodies or antitoxins are directly injected in cases like tetanus or snakebites for quick immune response.
• Recombinant DNA technology has enabled large-scale production of vaccines, such as the hepatitis B vaccine from yeast.

Allergies Explained

• Allergies are the exaggerated response of the immune system to certain antigens called allergens.
• Antibodies produced are of the IgE type.
• Common allergens include mites, pollens, and animal dander.
• Symptoms of allergic reactions include sneezing, watery eyes, running nose, and difficulty in breathing.
• Allergies are due to the release of histamine and serotonin from mast cells.
• Anti-histamines, adrenalin and steroids reduce allergy symptoms.
• A protected environment early in life may lead to lowering of immunity and more sensitivity to allergens

Auto Immunity Defined

• Auto immunity is where the body attacks self-cells, resulting in autoimmune diseases like rheumatoid arthritis.

Immune System Components

• The human immune system includes lymphoid organs, tissues, cells, and soluble molecules like antibodies.
• Recognizes foreign antigens, responds, and remembers them
• Plays a role in allergic reactions, auto-immune diseases, and organ transplantation.
• Lymphoid organs are where lymphocytes originate, mature, and proliferate.
• Primary lymphoid organs are bone marrow and thymus, where immature lymphocytes differentiate.
• Secondary lymphoid organs include the spleen, lymph nodes, tonsils, Peyer’s patches, and appendix, where lymphocytes interact with antigens.
• Bone marrow produces all blood cells, including lymphocytes.
• The thymus is a lobed organ near the heart, large at birth but decreases in size with age, it provides micro-environments for T-lymphocyte development.
• The spleen filters blood by trapping blood-borne microorganisms and maintains a large reservoir of erythrocytes.
• Lymph nodes trap microorganisms and antigens, activating lymphocytes to cause immune responses.
• Mucosa-associated lymphoid tissue (MALT) is located within the lining of major tracts and constitutes about 50% of lymphoid tissue in the human body.

AIDS Overview

• AIDS stands for Acquired Immuno Deficiency Syndrome and is not a congenital disease.
• It was first reported in 1981.
• It is caused by the Human Immuno deficiency Virus (HIV), a retrovirus with an RNA genome.
• Transmission occurs through sexual contact, contaminated blood transfusions, sharing infected needles, and from infected mothers to their children via the placenta.
  • This puts individuals with multiple sexual partners, intravenous drug users, those requiring repeated blood transfusions, and children born to infected mothers at high risk.
• HIV/AIDS is not spread by touch but through body fluids.
• There is a time-lag between infection and the appearance of AIDS symptoms, usually 5-10 years.

How HIV Works

• The virus enters macrophages, where its RNA genome replicates to form viral DNA with the help of reverse transcriptase.
• Viral DNA gets incorporated into the host cell’s DNA and directs infected cells to produce virus particles.
• Macrophages act like a HIV factory. Simultaneously, HIV enters helper T-lymphocytes (TH), replicates, and produces progeny viruses.
• Progeny viruses attack other helper T-lymphocytes, progressively decreasing their numbers.
• The person suffers from fever, diarrhoea, and weight loss.
• Due to decreased helper T lymphocytes, the person starts getting infections from bacteria (Mycobacterium), viruses, fungi, and parasites (Toxoplasma).
• The patient becomes immuno-deficient.
• Enzyme-linked immunosorbent assay (ELISA) is a widely used diagnostic test for AIDS.
• Treatment with anti-retroviral drugs is only partially effective in prolonging life but cannot prevent death.

AIDS Prevention

• Prevention is the best option given that AIDS has no cure.
• HIV spreads due to conscious behaviour patterns.
• “Don’t die of ignorance” because the only excuse is ignorance.
• The National AIDS Control Organisation (NACO) and other non-governmental organizations (NGOs) educate people about AIDS.
• WHO has started programmes to prevent the spread of HIV infection.

AIDS Prevention Techniques

• Making blood (from blood banks) safe from HIV
• Ensuring use of only disposable needles and syringes
• Free distribution of condoms
• Controlling drug abuse
• Advocating safe sex
• Promoting regular check-ups for HIV in susceptible populations
• HIV/AIDS-infected people need help and sympathy.
• Societal and medical fraternity action is necessary to prevent the spread of the disease.

Cancer Overview

• Cancer is a dreaded disease and a major cause of death.
• Over a million Indians suffer from cancer annually.
• Research focuses on cancer development, treatment, and control.
• Cell growth and differentiation are highly controlled and regulated in a normal body.
• Cancer cells lose regulatory mechanisms and the property of contact inhibition.
• Cancerous cells divide and form masses called tumors.
• Tumors are of two types:
  • Benign tumors
    • Remain confined to their original location and do not spread
    • Cause little damage
  • Malignant tumors
    • A mass of proliferating cells called neoplastic or tumor cells
    • Grow rapidly
    • Invade and damage surrounding normal tissues
    • Starve normal cells by competing for vital nutrients
    • Cells sloughed from tumors reach distant sites and start new tumors, also known as metastasis

Cancer Causes

• Transformation into cancerous neoplastic cells can be induced by physical, chemical, or biological agents, also known as carcinogens.
• Ionizing radiations
  • X-rays and gamma rays
• Non-ionizing radiations
  • UV cause DNA damage
  • Chemical carcinogens tobacco smoke have been identified as a major cause of lung cancer
• Oncogenic viruses have genes called viral oncogenes.
• Cellular oncogenes or proto oncogenes (c-onc) in normal cells can lead to oncogenic transformation when activated.

Cancer Detection

• Early detection of cancers is essential for successful treatment.
• Cancer detection is based on biopsy and histopathological studies of the tissue, blood, and bone marrow.
• Biopsy involves examining stained tissue sections under a microscope.
• Radiography (X-rays), CT (computed tomography), and MRI (magnetic resonance imaging) are useful for detecting cancers of internal organs.
  • Computed tomography uses X-rays to generate a three-dimensional image
  • MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.
• Antibodies against cancer
  • specific antigens are also used for detection.
• Molecular biology techniques can detect genes for inherited susceptibility to certain cancers.
  • Identification of genes or carcinogens may be very helpful in prevention of cancers.

Cancer Treatment

• Common approaches include surgery, radiation therapy, and immunotherapy. Radiotherapy
  • Tumor cells are lethally irradiated, taking proper care of the normal tissues
• Chemotherapy
  • Uses chemotherapeutic drugs to kill cancerous cells
  • May cause side effects like hair loss and anemia
  • Most cancers are treated by combination of surgery, radiotherapy and chemotherapy.

Immunotherapy

• Tumor cells avoid immune system detection and destruction, where patients are given biological response modifiers such as α-interferon, which activates the immune system

Drugs and Alcohol Overview

• Drug and alcohol use has been on the rise, especially among the youth.
• Drugs commonly abused include opioids, cannabinoids, and coca alkaloids, which are mostly obtained from flowering plants

Opioids

• Opioids
  • Bind to specific opioid receptors in the central nervous system and gastrointestinal tract.
  • Heroin
    • Commonly called smack.
    • Is chemically diacetylmorphine
    • Is obtained by acetylation of morphine that is extracted from the latex of poppy plant Papaver somniferum.
    • It is taken by snorting or injection.
    • It is a depressant and slows down body functions

Cannabinoids

• Cannabinoids
  • Are a group of chemicals that interact with cannabinoid receptors in the brain.
  • Natural cannabinoids
    • Obtained from the inflorescences of the plant Cannabis sativa (Figure 7.10). The flower tops, leaves and the resin of cannabis plant are used in various combinations to produce marijuana, hashish, charas and ganja.
    • Are taken by inhalation and oral ingestion
    • known for their effects on cardiovascular system of the body.

Coca Alkaloid/Cocaine

• Coca Alkaloid/Cocaine
  • Is obtained from coca plant Erythroxylum coca, native to South America.
• Interferes with the transport of the neuro-transmitter dopamine
• Cocaine, commonly called coke or crack
  • It is usually snorted
  • Has a stimulating action on central nervous system, producing euphoria and increased energy.
  • Excessive dosage of cocaine causes hallucinations
• Other plants with hallucinogenic properties
  • Atropa belladona and Datura These days cannabinoids are also being abused by some sportspersons.
• Drugs that are normally used as medicines to help patients cope with mental illnesses
  • Barbiturates
  • Amphetamines
  • Benzodiazepines These are often abused.
• Morphine - Is an effective sedative and painkiller, and is useful in patients who have undergone surgery. Plants, fruits and seeds having hallucinogenic properties have been used in folk-medicine, religious ceremonies and rituals all over the globe.
• When they are taken for a purpose other than medicinal use or in amounts/frequency that impairs one’s physical, physiological or psychological functions, it constitutes drug abuse.

Tobacco and Smoking

• Smoking paves the way to hard drugs. Tobacco
  • Has been used by human beings for more than 400 years.
  • Is smoked, chewed or used as a snuff.
• Tobacco contains a large number of chemical substances with nicotine, an alkaloid.
• Nicotine Stimulates adrenal gland to release adrenaline and nor-adrenaline, which raise blood pressure and increase heart rate.

Smoking risks

• Increased incidence of cancers of lung, urinary bladder and throat
• Bronchitis
• Emphysema
• Coronary heart disease
• Gastric ulcer
• Those who chew have increased risk of cancer of the oral cavity.
• Smoking increases carbon monoxide (CO) content in blood and reduces the concentration of haembound oxygen which causes oxygen deficiency in the body.

Prevention

• Advertisements present on the packaging which warns against smoking
• Addicts require counselling and medical help to get rid of the habit.

Drugs and Adolescence

• Adolescence is a bridge linking childhood and adulthood and is accompanied by biological and behavioural changes.
• Curiosity, adventure, excitement, and experimentation motivate youngsters towards drug and alcohol use.
• Stress from academics or examinations, is also a cause.
• Perception that it is ‘cool’ or progressive to smoke, use drugs or alcohol, is a major cause to start these habits.
• Television, movies, newspapers, and internet also promote this perception.
• Unstable or unsupportive family structures and peer pressure are also associated with drug and alcohol abuse.

Addiction and Dependence

• Drugs are frequently used repeatedly because of the effects, such as euphoria and a temporary feeling of well-being Addiction
  • A psychological attachment to certain effects with drugs and alcohol.
• Tolerance level of the receptors in the body increases with repeated use, where receptors respond only to higher doses of drugs or alcohol leading to greater intake and addiction Dependence:
  • the body's tendency to manifest withdrawal syndrome if regular dose of drugs/alcohol is stopped.
  • Characterized by anxiety, shakiness, nausea and sweating, which may be relieved when use is resumed again

Drug Effects

• The immediate effects of drugs and alcohol abuse -Reckless behavior -Vandalism -violence.
• Excessive doses of drugs lead to -coma, death -Respiratory failure -Heart failure -Cerebral hemorrhage. The most common warning signs of drug and alcohol abuse among youth
  • Drop in academic performance,
  • Unexplained absence from school/college,
  • Lack of interest in personal hygiene, withdrawal,
  • Isolation
  • Depression
  • Fatigue
  • Aggressive and rebellious behaviour
• There is some far-reaching implications of drug/alcohol abuse
  • An abuser turns to stealing, mental and financial distress to his/her entire family and friends.

Health Risks Associated with Drug Use

Those who take drugs intravenously are much more likely to acquire serious infections like AIDS and Hepatitis B, which are transferred by sharing needles and syringes, are chronic and can be transmitted through sexual contact or infected blood.

• The use of alcohol during adolescence can lead to heavy drinking in adulthood and damage the nervous system and liver (cirrhosis).
• The use of drugs and alcohol during pregnancy is known to adversely affect the foetus.
• Sportspersons use narcotic analgesics, anabolic steroids, diuretics and certain hormones in sports to increase muscle strength and bulk and to promote aggressiveness and as a result increase athletic performance Anabolic steroids: Females
  • Masculinisation, increased aggressiveness, mood swings, depression, abnormal menstrual cycles, excessive hair growth on the face and body, enlargement of clitoris, deepening of voice. Males
  • Acne, increased aggressiveness, mood swings, depression, reduction of size of the testicles, decreased sperm production, potential for kidney and liver dysfunction, breast enlargement, premature baldness, enlargement of the prostate gland. These effects may be permanent with prolonged use. Adolescent male/female -Severe facial and body acne, and premature closure of the growth centres of the long bones may result in stunted growth.

Drug and alcohol control techniques

• Prevention is better than cure
• Parenting that combines with high levels of nurturance and consistent discipline, has been associated with lowered risk of substance abuse. Avoid undue peer pressure
  • Respect the choice and personality of a child without pushing beyond his/her threshold limits Education and counselling
  • Educate to face problems and stresses to accept frustrations to accept failures Channelise
  • Channelize energy into healthy activities such as sports, reading, music, yoga and extracurricular activities Seeking help
  • Seek guidance to sort out problems Look for signs and symptoms
  • Look for danger signs that were discussed above Medical assistance
  • A lot of help is available in the form of psychologists, psychiatrists, and de-addiction and rehabilitation programmes

Summary of chapter

Health - Health is a state of complete physical, mental, social and psychological well-being Prevention and cure for diseases diseases like typhoid, cholera, pneumonia, fungal infections of skin, malaria, vector-borne diseases Our immune system: - The one that keeps us in check from pathogens, is the best way of preventing these diseases (skin, mucous membranes, antimicrobial substances in our tears, saliva) If those fail: - Our Specific immunity is rapid and more intense, due to Immune System memory.