Constructive plate boundaries, also known as divergent plate boundaries, are locations on, Study notes of Earth science

Download Constructive plate boundaries, also known as divergent plate boundaries, are locations on and more Study notes Earth science in PDF only on Docsity! HUMAN HEALTH AND DISEASE INTRODUCTION • Health is a state of complete physical, mental and social well being, and not merely an absence of disease or infirmity (W.H.O - 1948). • Any change from the normal state that causes discomfort or disability or impairs the health is called disease. • Time interval between the entry of pathogen and appearance of symptoms is called the incubation period. During this period, pathogens multiply. • Antibiotics are those substances which are secreted by micro- organism that inhibit the growth or destroy the other micro-organism. This term was given by Walksman (streptomycin-first bacterial antibiotic obtained from bacteria-Streptomycin griseus). E.g., Bacteriostatic - tetracycline, chloramphenicol, Bacteriolytic or Bactericidal-streptomycin, ciprofloxacin, ampicillin. • Antiseptics and disinfectants are agents that inhibit or kill microbes on contact. Conventionally, agents used on living surfaces are called antiseptics while those used for inanimate objects are called disinfectants. In disinfection, it kills only vegetative forms of bacteria. • Sterilization is the process that kills all forms of pathogens, including spores. • The disease agent is a factor (substance or force) which causes a disease by its excess or deficiency or absence. • Types of disease agents are biological, nutrient, chemical, physical, mechanical etc. • Biological agents - It includes viruses, rickettsias, bacteria, fungi, protozoans, helminthes and arthopods. o The biological agents are called pathogens (Gr. Pathos = disease; genes = producing). o Pathogens produce diseases in two ways : tissue damage and toxin secretion. o Tissue damage : The bacteria responsible for tuberculosis, damage cells and cause lesions in the lungs. Blood oozes from the lesions into the air sacs, leading to haemorrhages. The bacteria that cause meningitis attack the protective membranes covering the brain. The virus of rabies destroys brain tissue. The polio virus damages motor nerve cells in the spinal cord. o Toxin secretion : Many microbes produce powerful poisons, called toxins, which cause diseases. o Toxins are of 2 types : endotoxin and exotoxin. o Exotoxins are released as soon as produced. The diseases brought about by exotoxins include tetanus, scarlet fever, diphtheria, and botulism (food poisoning). o Endotoxins are retained in the bacterial cells and released when bacteria die and disintegrate. The diseases caused by endotoxins include typhoid fever, cholera, bubonic plague and dysentery. • Father of Medicine : Hippocrates. He gave a scientific explanation of disease for the first time. • Father of Surgery: Susruta. He used non-poisonous leeches as an anticoagulant during surgery. • Father of Ayurveda : Charaka (Ayu → Life, Veda → Knowledge). He first gave concept of digestive, metabolism and immunity. • Father of Modern Pathology : Rudolf Virchow. • Father of Immunity : Edward Jenner (Smallpox vaccine). • Father of Blood grouping : C. Landsteiner. • Father of Modern Bacteriology : Robert Koch (Anthrax, T.B., Cholera) • Nobel Prize for odorant receptor (olfaction) is given to Richard Axel and Linda B.Buck. TYPES OF DISEASES • The diseases may be broadly classified into two types : congenital and acquired. • Congenital Diseases are anatomical or physiological abnormalities present from birth. They may be caused by – o A single gene mutation (alkaptonuria, phenylketonuria, albinism, sickle-cell anaemia, haemophilia, colour blindness). o Chromosomal aberrations (Down’s syndrome, Klinefelter’s syndrome, Turner’s syndrome) or o Environmental factors (cleft palate, harelip). • Unlike the gene and chromosome-induced congenital defects, environmentally caused abnormalities are not transmitted to the children. • Acquired Diseases develop after birth. They are further of two types : communicable and non-communicable. COMMUNICABLE DISEASES • The diseases which are caused by pathogens (viruses and living organisms) and readily spread from the infected to the healthy persons are called communicable or infectious diseases. • A German physician, Robert Koch, listed the following four conditions to establish that a specific pathogen causes a particular disease – o The suspected pathogen should be invariably present in the animals suffering from the disease and should not be found in healthy individuals. o The pathogens isolated from the diseased animal should be grown in a pure culture. o When this culture is inoculated into a healthy host, the latter should develop the disease and show its characteristic symptoms. o The pathogen should be recoverable from the experimental host, and it should be the same as the original one. TRANSMISSION OF DISEASES (PATHOGENS) • The diseases (pathogens) are transmitted from the reservoirs of infection to the healthy persons in the following ways : direct and indirect transmission. • Direct transmission : The pathogens of some diseases reach the human body directly without intermediate agents. This can occur as under : o Contact with Infected Persons : Certain diseases produce sores or lesions on the skin. Contact with materials discharged from these sores or lesions brings about infection. Ringworm, athlete’s foot, barber’s itch, chickenpox, smallpox, syphilis and gonorrhoea are spread by direct contact. Kissing also spreads infection. The diseases that are transmitted by direct contact are called contagious diseases. o Droplet Infection : Some diseases are caught by merely being in a confined place (room, theatre, bus) with an infected person. The latter throws out tiny droplets of mucus by coughing, sneezing, spitting or even talking. These droplets may contain pathogens (viruses, bacteria) dislodged from nasal membrane, throat, and lungs. Many of these droplets are inhaled. Diphtheria, scarlet fever, influenza, common cold, measles, mumps, tuberculosis, pneumonia, and whooping cough are spread by droplets. o Contact with Soil : The bacteria responsible for tetanus and blood poisoning enter the human body from the soil through injuries. Hence, skin injuries should not be neglected. o Animal Bites : Virus of rabies, or hydrophobia, is introduced through the wound caused by the bites of rabid animals, most commonly dogs. VIRAL DISEASES Viral diseases are transmitted by contact fomite and droplet method. Types of viral disease are-influenza, small pox, etc. Table : Viral Diseases in Humans s. Disease Pathogen Habitat Main Symptoms Mode of Infection | I. P. No. 1 Influenza Myxovirus Mucous Nasal discharge, By droplets from | 24 to 72 (Flu) Influenzae membrane of — | sneezing, coughing. | nose & throat hours respiratory tact | fever, body ache 2. | Smallpox Variola virus Skin rash changing to | By contact, 12 days (highly contagious pustules, then to scabs} droplets and disease) fomite 3. | Chicken pox Varicella zoster Skin sores that open | By contact 2t05 (DNA virus) & emit fluid weeks 4. Measles Rubeola virus Fever, inflammation | By droplets from 10-14 of nasal mucous nose & throat days membrane, loss of appetite. Red watery eyes, shin rash Ss. Disease Pathogen Habitat Main Symptoms Mode of Infection | 1. P. No. 5. | Rabies Rabies virus Brain & spinal _ | Biting behaviour, Biting or saliva of | 103 (Hydrophobia) cord cells fear of water, rabid dog, months inability to swallow. | monkey, cat ete Severe headache. 6. | Mumps Paramyxo virus | Salivary glands | Painful enlargement | By contact and 12 to 26 (Infectious of parotid glands, droplets from days parotitis) difficulty in opening | throat mouth he Poliomyelitis Polio virus Nerve cells Inflammation of By contaminated Ttol4 (polio) (Highly nervous system, food & water days infectious disease muscle shrinkage, of infants and limb paralysis childrens) 8. | Trachoma Chlamydia Eyelids, Granules on inner By contact Sto 12 audeune conjunctiva & | surface of eyelids, days comea of eye watery eyes 9. | Dengue Arbo virus Mild conjunctivitis, | Biting of female 4-10 (RNA, high fever, backache, | mosquito. Aedes days nausea, vomiting ete. | aegypti 10. | Yellow fever Arbo virus Headache, vomiting, | Infected 4edes 3-6 fever, rupture of aegypti days veins in kidney, spleen, liver ete.  PROTOZOAN DISEASE These are caused by protists. They include malaria, amoebiasis, giardiasis, kala azar, Ciliary dysentery, trypanosomiasis etc. (a) Malaria • Laveran (1880) discovered malarial parasite in blood of malaria patient. • Pfeiffer (1892) proposed that malaria is spread by blood sucking insect. • Discovery of Plasmodium and its transmission by Anopheles (female) was confirmed by Ronald Ross (1897). o P. ovale : It also causes benign tertian malaria, which recurs every 48 hours. This species is found only in West Africa and South America. o P. malariae : It causes quartan malaria, which recurs every fourth day, i.e., after 72 hours. This species is found in both tropical and temperate regions, but it is not very common. o P. falciparum : It alone is capable of causing three types of malaria, viz., quartan malaria, which attacks almost daily, malignant tertian malaria, which occurs every 48 hours, but is very severe and often fatal; and irregular malaria. This species is found only in the tropical region. • Malaria result in anaemia, toxaemia and splenomegaly (enlarged spleen). • Antimalarial drugs are quinine, chloroquine etc. Dalaprim drug kills the parasitic stages present in both liver cells and RBC's of blood. (b) Amoebiasis • It is caused by intestinal endoparasitic protozoan Entamoeba histolytica of man. • Infection is transmitted by contamination. • It is characterized by abdominal pain alternating diarrhoea and constipation etc. • Entamoeba secretes cytolysin that erodes the mucous membrane of the intestine. (c) Giardiasis • Also called backpeper's disease, it is caused by Giardia intestinalis. • It inhabits upper part of small intestine (duodenum and jejunum) • Infection is transmitted by contamination of cysts with food and drinks. • It is characterized by mild diarrhoea. (d) Kala azar • Kala azar or leishmaniasis is caused by Leishmania donovani and spread by sandfly (Phlebotomus) • It is characterized by fever and enlargement of visceral organs. • It is also known as dum-dum fever. • Leishmania braziliensis causes espundia and oriental sore is caused by L.tropica. (e) Ciliary dysentery (Balantidiasis) • It is caused by Balantidium coli. It inhabits the human large intestine (colon). • Infection occurs by ingesting cysts with food and drinks. • Balantidium coli causes ulcers in the colon and invades mucous membrane by secreting an enzyme hyalurodinase. Thus, generally results in diarrhoea. • Tetracycline or lodoquinol are effective treatment. (f) Trypanosomiasis • It is caused by different species of Trypanosoma. • It is characterized by high fever, swelling of the neck and armpit, weakness, anaemia, lethargy, unconsciousness etc. • T. gambiense causes Gambian fever of West African sleeping sickness, which is spread by both sexes of tse-tse fly (Glossina palpalis). • Rhodesian or East African sleeping sickness, caused by T. rhodesiense is spread by G. morsitans. Chagas disease or South American sleeping sickness is caused by T. cruzi and spread by Panstrongilus sp. It is more common in children and young adults. Table : Sexually Transmitted Diseases (STD) in Human HELMINTHIC DISEASES • It is transmitted by infected larva via contaminated food and vegetables. • Symptoms include chronic blood loss, depletion of body's iron stores leading to anaemia, inflammation of skin etc. (f) Schistosomiasis (Bilharzia) • It is caused by Schistosoma haematobium. • It is transmitted by snail. • It is found in urinary bladder, blood vessels and causes itching, rashes, aches, fever etc. FUNGAL DISEASES These are caused by fungi, the non green heterotrophic organisms. They include ringworm and athlete's foot. (a) Ringworm • Ringworm is caused by different genera of fungi - Microsporum, Trichophyton and Epidermophyton. • It is an infection of skin, hair and nails. • Its symptoms includes red scaly patch or bump. • Ringworm is contagious and is easily spread from one person to another, so avoid touching an infected area on another person. (b) Athletes foot • It is caused by a fungus called Tinea pedis. • It is a very common skin condition that affect the sole of the foot and the skin between the toes. • Common symptoms include various degrees of itching and burning. NON COMMUNICABLE (NON-INFECTIOUS) DISEASES • These diseases remain confined to the person who develops them and do not spread to others. • The main non-communicable diseases are diabetes, inflammatory diseases of joints such as arthritis, gout, cardiovascular diseases and cancer. (a) Diabetes Mellitus • Diabetes is characterized by chronic hyperglycemia which is excessive concentration of glucose in the blood. • Diabetes is primarily a result of relative or complete lack of insulin secretion by the β cells of islets of Langerhans in pancreas. • Diabetes is established by blood and urine sugar levels. (b) Arthritis • Arthritis is any inflammatory condition of the joints characterized by pain and swelling. • Types of arthritis are : rheumatoid arthritis, osteoarthritis and gout. • There is no cure for arthritis, drugs are available which relieve pain. • Rheumatoid arthritis o It is characterized by inflammation of the synovial membrane. o A kind of rheumatoid arthritis that occurs in younger people is Still’s disease. o It usually starts in the small joints in the hand and progress to other body joints. • Osteoarthritis o It is a common disease among the elderly persons resulting from erosion of articular cartilage. o In osteoarthritis, the secretion of lubricating synovial fluid between the bones at the joint stops. The joints become inflammed, its movement becomes painful and its function is diminished. o It is common in old person, mainly affecting weight bearing joints. • Gout o Gout results from accumulation of uric acid crystals in the synovial joints. o Gout is a disease associated with an inborn error of uric acid metabolism that increases production or interferes with excretion of uric acid. • The immune system consisting of several organs as well as WBC in blood and lymph has the job of fighting off invading pathogens and preventing growth and spread of cancers. • Lymphoid organs are those organs where origin and maturation and proliferation of lymphocyte occurs. • The primary lymphoid organs are bone marrow and thymus. • Bone marrow manufactures billions of WBC needed by the body everyday. Some newly produced WBC remain in the bone marrow to mature and specialize while others travel to the thymus to mature. • Secondary lymphoid organs includes lymph node, adenoids tonsils, spleen, peyer's patches (within intestine) and the appendix. • Lymph nodes filter pathogens from the lymph and exposes them to WBC. • Spleen filters pathogens from blood. It is stocked with WBC that respond to the trapped pathogen. • Lymphoid tissue located within the lining of the major tracts (respiratory, digestive and urogenital tracts) is called mucosal associated lymphoid tissue (MALT). It constitutes about 50% of the lymphoid tissue in human body. • Immunology is the science of development of immunity against particular pathogen. • The foundations of science of immunology were discovered by workers-Edward Jenner (1796), Louis Pasteur (1879) and Von Behring (1841). • Some terms related to immune system are – o Immunity: Resistance of the body against a pathogen or disease. o Antigen or Agglutinogen : Proteinous substance which stimulates the production of antibodies. o Antibody : It is a complex glycoprotein secreted by B-lymphocytes in response to an antigen. It is also called agglutinin. o Antiserum: Serum of any animal which contains the antibody for a specific antigen. o Venom (poison) : Toxic substances secreted by snake and some insect. o Toxoid: A bacterial exotoxin which is detoxicated by special procedures to allow its safe use in immunization against the disease. • Immunity was defined by Sir Mac Farlane Burnet. • Immunity developed in 3 ways-by vaccination, antitoxin and through disease. • Immunity are of two types- o Congenital immunity or innate immunity or Non-specific immunity. o Acquired immunity or Adaptive or specific immunity INNATE OR NON SPECIFIC IMMUNITY • Innate immunity, present from birth, are specific (acts on many organism) and does not become more efficient on subsequent exposure to the same organism. • The non-specific defence mechanisms is further of two types- external defence (first line of defence) and internal defence (second line of defence) • First line of defence comprise physical and chemical barriers to the entry of pathogens into the blood. • Physical barrier includes skin and mucous membrane and chemical barriers includes chemicals secreted by skin and mucous membrane like skin secretion and bacteria, nasal secretion, cerumen (ear wax), saliva, tear, vaginal bacteria. memory is absent here and the readymade antibodies are given in immunosuppressive individual. Natural : Resistance passively transferred from mother to baby. Mother milk gives passive immunity to the newborn child by colostrum (first mother milk). Artificial: Resistance passively transferred to a recipient by administration of antibodies. E.g. : Human immunological administration. Anti - Tetanus serum (ATS) Anti - rabies serum (ARS) Anti - diptheria serum (ADS) Table : Difference between Active and Passive immunity TYPES OF ACTIVE IMMUNE SYSTEM CELL MEDIATED IMMUNE SYSTEM (CMIS) OR CELLULAR IMMUNITY This immune system is based on T-cells (60-70%) with antigen specific receptors on their surfaces. Table : Cells of Immune System ANTIBODY MEDIATED IMMUNE SYSTEM (A.M.I.S.) OR HUMORAL IMMUNITY • Antibody or immunoglobulin are complex glycoprotein molecule made up of 4 polypeptide chains-two light and two heavy chains. • These two chain held together by disulphide bond in shape of Y molecule. Two tips of this molecule bind with antigen (large and complex foreign molecules mainly proteins that activate the specific immunity) like lock and key fashion and make antigen-antibody complex. Fig. : Structure of an antibody molecule • Precipitation : Antibodies combine with the antigens to form precipitates that are early ingested by the phagocytes. They are known as precipitins. • Complement activation : Antibody antigen complexes activate complement proteins which may opsonise antigen, lyse cell wall of bacteria causing their disintegration, attract phagocytes to the area of infection. Table : Type of antibodies o Second generation vaccines : Antigenic polypeptides of pathogens are produced with recombinant DNA technology in transgenic organisms. These are made by multiplication of surface antigen by genetic engineering. They have no side effects. E.g., Hepatitis B vaccine produced from transgenic yeast. o Third generation vaccine : These are highly potent, synthetic in nature & prepared by genes. They are also called DNA vaccine. • Passive immunisation may be induced by administration of an antibody containing preparation, transfer of maternal antibodies across the placenta and by transfer of lymphocytes to induce passive cellular immunity. • Passive immunisation may be natural or artificial. • Natural passive immunisation includes the passage of maternal IgG across the mammalian placenta. In humans, IgA is transmitted to the babys' gut via colostrum and milk. • Artificial passive immunisation is affected when immunodeficient patients are given doses of antibodies from a donor. Table : Some Important Vaccines NOTES • Edward Jenner (1796) noticed that milkmaids did not suffer from smallpox but they had scabs of cowpox. He transported the material from the sore of milkmaid who was suffering from cowpox to the young body of 8 year old. After sometime, he injected live smallpox material into that boy. But symptoms of diseases did not appear. He tried this procedure on other person and got success. He gave the term vaccination for this process. • Louis Pasteur: He discovered the process of inactivating the pathogen & prepared vaccines for anthrax, cholera, rabies. • Von Behring : He discovered the process of passive immunization and prepared the antidiphtherial serum by injecting diphtheria antigen into sheep. Von Behring is known as 'Father of passive immunization'. CANCER • Cancer is an abnormal and uncontrolled division of cells, known as cancer cells, that invade and destroy the surrounding tissues. • Generally cancer is defined as uncontrolled proliferation of cells without any differentiation. • Cancer cells are different from normal cells in some aspects. They do not remain confined to one part of the body. • Neoplasm (called tumor) is a new abnormal tissue which is capable of continued growth. • Tumors may be benign and malignant. • Benign tumor is a large localized mass of abnormal tissue enclosed in connective tissue which does not invade adjacent tissue. • Malignant tumor is not encapsulated and is capable of invading adjacent tissues and distant sites. • They penetrate and infiltrate into the adjoining tissues and dislocate their functions. Some of the cancer cells get detached from the main site of origin and travel by blood and lymph to sites distant from the original tumour and form fresh colonies, called metastasis or secondary growth. SYMPTOMS OF CANCER • Thickening or lump in the breast or any other part of the body. • Changes in bowel or bladder habits. • Indigestion or difficulty in swallowing. • Unexplained changes in weight. o Sexual contact (most common mode of transmission) (Probability < 1 %) o Blood contact (100%), o By mother to child by placenta (33%), by mother milk • HIV is not transmitted through ordinary contact (hugging, dancing, talking, touching etc.) with someone who has HIV or AIDS; sweat, tears or saliva etc. • The major cell affected by HIV is the helper-T-lymphocyte. • The HIV virus multiplies and slowly begins to destroy the CD4 lymphocyte (T cells or helper T-cells) • AIDS was first recognised in Hatai (USA) in 1981 among a group of young homosexuals who were addicts of heroin and other narcotics. Fig. : Replication of retrovirus • AIDS includes 3 phases- o Asymptomatic phase - Initially within 2-12 weeks, there is no antibody production so infectivity of patients or activeness of virus is maximum in this period. This period is called the window period (No specific symptoms appear in this phase so ELISA test is negative in window period.) Low grade fever, body aches, sore throat. o AIDS related complex (A.R.C.) - 3 to 6 weeks It is characterized by - ▪ Diarrhoea ▪ Weight loss (> 1 0%) ▪ Cough ▪ Generalised lymphadenopathy ▪ Fever. o Full blown AIDS – In this, patient becomes fully immune deficient and T-Iymphocytes or CD4 count is less than 200 × 106 / litre. INVESTIGATION • Screening test is Enzyme Linked Immuno Sorbent Assay (E.L.I.S.A.) . • Confirmatory tests : Western blot test : Detects antibodies (proteins) in patient's serum. • ELISA is a technique which can detect and even quantitate extremely small amount of a protein, antibodies or antigens with the help of enzymes. The commonly used enzymes are peroxidases and alkaline phosphatase. • Western blot test is the culturing of blood and testing plasma for virus. • Viral load test measures the amount of virus in the blood which will help in determining the probable progression of the disease. TREATMENT • The main harmful effects of smoking are respiratory diseases and cardiovascular disease. • One of the common cancer attributed to cigarette smoking is lung cancer. • The withdrawal symptoms include irritability, anxiety, craving, sleep problems, headache and lethargy. It may continue for 4-6 weeks and craving may continue for many months. • Some of the important measures for the prevention and control of alcohol and drug abuse among adolescents are as follows- o Drug education and counselling program. o Looking for danger signs. o Avoid undue peer pressure. o Seeking help from parents and peers. o Seeking professional and medical help. o Enforcing stronger laws and penalties. Table : Categories of Psychotropic Drugs, their Effects and Clinical uses. Type of drug Examples Effects Clinical Uses Sedativesand —— Barbitumtes, Renzodiazepines | Depress brain activity and produce feeling — Hypnotic, antianxiety tranquilizers (e.g. Valium) of calmness, relaxation, drowsiness and (depressanr) deep sleep (high doses) Opiate Opium. morphine. heroin, Suppress brain function. relieve intense Analgesic narcotics pethidine. methadone pain (physical and mental), produce temporary euphoria Stimulants Caffeine (very mild), Stimulate the nervous system: make a ‘Weight control amphetamines (including person more wakeful. increase alermess Neurotic dexamphetamine), cocaine and | and activity, produce exeitement. (Depressive) disorder its derivative, Novacaine Ha llucinogens LSD, mescaline. psilocybin. Alter thought. feelings and perceptions: None charas, hashish, marijuana (bhang) hallucinations.