CLASS 12TH BIOLOGY CHAPTER- 8 HUMAN HEALTH AND DISEASES NCERT QUICK REVISION NOTES FOR NEET AND CBSE EXAM
CHAPTER 8: HUMAN HEALTH AND DISEASES
Pathogens; parasites causing human diseases (malaria, dengue,chickengunia, filariasis, ascariasis, typhoid, pneumonia, common cold, amoebiasis, ring worm) and their control; Basic concepts of immunology - vaccines; cancer, HIV and AIDS; Adolescence-drug and alcohol abuse.
Interferon: The glycoproteins produced by our body cells in response to a viral infection.
Incubation Period: The time period between infection and first appearance of symptoms.
Metastasis: The property in which the cancer cells spread to different sites through blood and develop secondary tumours.
Oncogenes: Viral genome which causes cancer/Cancer causing genes.
Retrovirus: A virus having RNA as genetic material and forms DNA by reverse transcription and then replicate e.g., Human Immunodeficiency Virus (HIV).
Sporozoites: The infective stage of protozoa Plasmodium which is injected into human blood through saliva of female Anopheles mosquito.
Withdrawal Syndrome: If a drug dependent person stop taking drugs then his body stop functioning normally and he feels severe physical and psychological disturbance called withdrawal syndrome.
Contact Inhibition: It is a property of normal cells in which the cells stop dividing when comes in contact with its surrounding cells.
ABBREVIATIONS
PMNL- Polymorpho-Nuclear Leukocytes
CMI - Cell Mediated Immunity
ELISA - Enzyme Linked Immunosorbent Assay
HLA - Human Leukocyte Antigen
MALT - Mucosal Associated Lymphoid Tissue
SCID - Severe Combined Immuno Deficiency
NACO - National AIDS Control Organisation
MRI - Magnetic Resonance Imaging
¶ Health: The state of complete physical, mental and social well beings
¶ Goods health can be achieved by
(i) Awareness about disease and their effects on different body functions.
(ii) Vaccination.
(iii) Control of vectors.
(iv) Proper disposal of wastes .
(v) Maintenance of hygienic food and resources.
¶ Infectious Diseases
(i) Viral Diseases-e.g., polio, common cold, measles, rabies
(ii) Bacterial diseases-e.g., Typhoid, Pneumonia, Diptheria, Tetanus.
(iii) Fungal diseases e.g., Ring worm & Scabies
(iv) Helminthic diseases-e.g. Ascariasis, Filariasis, Tacniasis
(v) Protozoan diseases e.g. Malaria, Amoebiasis.
Caused by Viruses DEN-1, DEN-2, DEN-3, DEN-4
Vector Female mosquito Aedes aegypti
Caused - by Alpha virus
Vector - mosquitoes (Aedes aegypti and A. albopictus)
Symptoms - rashes on limbs and trunk, arthritis of multiple joints, fever (102-104°F), etc.
Drug - Chloroquine phosphate reduces impact of disease.
Treatment - Rest & increase in fluid intake.
Preventation of Dengue and Chikungunya: Protection against mosquitoes by wearing long sleeves and fullpants, window and doors should have wire gauze screens, use mosquito repellents and there should be no stagnant water nearby.
LIFE CYCLE OF PLASMODIUM
(A) Asexual Phase
¶ When female anopheles mosquito bites human sporozoites (infective stage) are injected into blood stream.
¶ Parasite reaches the liver cells and multiply.
¶ Liver cell burst releasing parasite into the blood.
¶ Parasite then enters into RBCs and multiply.
¶ RBCS ruptured and release hacmozoin that causes symptoms of malaria like chill and high fever.
¶ Finally gametocytes develop in RBCs and are released in blood.
(B) Sexual Phase :
¶ Female Anopheles mosquito takes up gametocytes with blood meal from infected person.
¶ Fertilisation and development takes in mosquito's stomach.
¶ Mature infective stage (sporozoites) escape from intestine.
¶ Sporozoites migrate to the salivary gland.
Immunity: Resistance to infections or antigens.
TWO TYPES OF IMMUNITIES
(i) Innate immunity: inherited by the organism from the parents and present at the time of birth. It consists of four types of barriers :
(a) Physical e.g. skin, mucus coating of epithelium of respiratory, gastrointestinal and urinogenital tracts.
(b) Physiological : e.g. acid of stomach, lysozymes of saliva and tears.
(c) Cellular e.g. PMNL, monocytes, neutrophils and macrophases
(d) Cytokine barriers: e.g. virus infected cells secrete proteins called interferons which protect non-infected cells from further infection
(ii) Acquired Immunity: Acquired by a person after birth by vaccination or contacting the disease.
¶ The antigenic preparations of proteins of pathogens or a solution of inactivated or weakened pathogens are introduced in the body.
¶ The antigenic properties are recognised.
¶ Cascade of reactions forms antibodies.
¶ History of reactions is stored as memory.
¶ Subsequent exposures result in intensified response.
Allergy: Exaggerated response of immune system to certain antigens present in the environment.
Allergens: Substances to which immune system shows exaggerated response. e.g. mites in dust, pollens, animal dander, perfume, wool, nail polish and drugs. Symptoms of Allergy: Sneezing, watery eyes, rashes, running nose and difficulty in breathing.
Auto Immunity: When the immune system of body starts destroying "self" cells and molecules, called auto immune diseases e.g. Rheumatoid arthritis. multiple sclerosis and insulin-dependent diabetes. Immune system in the body plays an important role in organ transplantation, allergic reactions and auto immune diseases.
Lymphoid Organs: Organs where lymphocytes are formed proliferate and mature are called lymphoid organs.
Bone Marrow: It is a primarylymphoid organ. Lymphocytes maturing here are called B-lymphocytes.
Thymus: Lymphocyte which matures in thymus are called T-lymphocyte.
Secondary Lymphoid Organs: Spleen, lymph nodes, tonsils, Peyer's patches of small intestine are secondary lymphoid organs.
MALT: (Mucosal associated lymphoid tissue) is a lymphoid organ present in the lining of respiratory tract, digestive tract and urinogenital tract.
AIDS-(ACQUIRED IMMUNO DEFICIENCY SYNDROME)
¶ caused by HIV (Human Immuno deficiency Virus) which belongs to retrovirus category of viruses.
MODES OF TRANSMISSION
¶ By sexual contact with infected person
¶ By transfusion of contaminated blood and blood products
¶ By Sharing the infected needles
¶ From infected mother to child through placenta
PERSONS WHO ARE AT HIGH RISK OF GETTING INFECTION INCLUDE
¶ Individuals who have multiple sex partners.
¶ Drug addicts taking drugs intravenously, individuals who require repeated blood transfusions
¶ Children born to HIV infected mother.
PREVENTION OF AIDS
¶ Using disposal syringes and needles, screening the blood of HIV, controlling drug abuse, free distribution of condoms and advocating safe sex.
¶ Main test for AIDS is ELISA (Enzyme Linked Immuno Sorbent Assay)
CANCER
¶ Cells loose the property of contact inhibition.
¶ Carcinogens induce the transformation of normal cells into cancerous cells e.g. UV rays, X-rays, gamma-rays, aniline dyes and tumour viruses, cadmium oxide, mustard gas, Ni & Cr compounds etc.
¶ Two types of tumors
(a) Benign-confined to the area of formation and do not spread to other parts.
(b) Malignant show metastasis i.e. cells of these tumors can be carried by blood stream or lymph to other parts of body and form secondary tumors in neighbouring organs.
¶ Treatment: through, surgery, radiotherapy, chemotherapy, immunotherapy.
¶ Detection: and diagnosis By radiography (X-rays), CT Scan, MRI, Biopsy.
DRUGS
Adolescents are vulnerable for drug abuse
1. Need for adventure, experimentation
2. First use of drugs for curiosity but later uses to escape facing problems. (like academic stress)
Sports person use drugs to enhance performance to fluid up muscles and for aggressiveness, e.g. dopamine.
ADVERSE EFFECTS:
In males: Acne, mood swing, depression, premature boldness, reduced male hormones.
In females: Masculinisation, aggressiveness, hirusitism (excessive hair growth) disturbed ovulation, stunted growth.
Withdrawl Symptoms: Dependence or addiction is a state of compulsion to take drug in absence of which body shows withdrawl symptoms such as insomnia, craving, tremors, cramps, twitching and convulsions.
HARMFUL EFFECTS OF DRUGS AND ALCOHOL ABUSE
¶ Change in behaviour i.e. vendelism, violence
¶ Damage to liver and kidney
¶ Disturbed respiratory system
¶ Affects cardiovascular system
¶ Sexual dysfunctions
¶ Nausea, vomiting
¶ Influence body coordinations
¶ Economic loss to family
PREVENTING ALCOHOL/DRUG ABUSE
¶ Avoid peer pressure
¶ Education and counselling
¶ Help from parents and peers
¶ Identify danger signals
¶ Seeking medical help
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