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CLASS IX, BIOLOGY, , WHY DO WE FALL ILL?, NOTES, , TOPICS, a), HEALTH, b), DISEASES AND ITS CAUSE, c), DIFFERENCE BETWEEN BEING HEALTHY AND DISEASE FREE, d), TYPES OF DISEASES, e), INFECTIOUS AND NON INFECTIOUS DISEASE, f), ANTIBIOTICS, g), MEANS OF SPREAD, h), AIDS AND ITS CAUSES, i), ORGANSPECIFIC AND TISSUE SPECIFIC MANIFESTATIONS, j), PRINCIPLE OF TREATMENT, k), LIST OF FEW DISESASES, , HEALTH, It is a state of being well enough to function well physically, mentally, and socially., FACTORS THAT DETERMINE BETTER HEALTH:, Public cleanliness :We always stress upon the fact that the environment, surrounding us should be healthy otherwise it may lead to harmful, diseases.Therefore, we can say that public cleanliness is an important factor for, the better health of people in society., Food: Another important factor for proper health is food. Now, we can have food, only if we have the money to buy it and for that, we need to work. Therefore we, can say that good economic conditions of society and employment are needed for, better health., Society :We can stay healthy if we are living a tension free life. Therefore, we can, say that a good social environment is required for better health., WHAT IS A DISEASE?, DISEASE ( DISTURBED EASE) MEANS BEING UNCOMFORTABLE., Disease is any abnormality or disturbance caused in our body. Sometimes internal, dysfunctionality of our body may also lead to diseases.

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HOW CAN WE STAY DISEASE FREE?, We can stay disease-free by maintaining good health that is:, •, By having proper food or a balanced diet, •, By keeping the environment clean, •, By maintaining personal hygiene, , HOW CAN WE IDENTIFY A DISEASE?, a)A disease is associated with symptoms. In other words, our body shows certain, indications with which we can assume that we may be suffering from a disease., b)We know that different parts of our body perform different functions ., c)Any of these functions are disturbed, we can say that something is wrong within, our body or something has changed in it., A symptom is any subjective evidence of disease, while a sign is any objective, evidence of disease. Therefore, a symptom is a phenomenon that is experienced, by the individual affected by the disease, while a sign is a phenomenon that can, be detected by someone other than the individual affected by the disease.

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WHAT IS A SYMPTOM OF DISEASE?, A disease generally has some Symptoms and Signs associated with it., One or more systems of the body will change, give rise to “Symptoms” ( Cough,, loose motions, pus formation, headache, fever, breathlessness, vomiting, fits,, unconsciousness, inflammation , swelling and general effects - a Doctor look for, the basis of symptoms)., Symptoms just indicate that there is a disease. They do not indicate the exact, type of disease., WHAT IS SIGN OF A DISEASE?, The doctors often look for the signs of a disease in order to find out the exact, problem. These signs, unlike the symptoms, are more definite indication of a, disease., , Diseases are basically two types- Acute Disease & Chronic Disease:, (DEPENDING UPON DURATION OF DISEASE )

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Acute Disease: The disease which lasts for only a short period of time is called, Acute Disease .Eg. Common Cold., Chronic Disease: The disease which lasts for long period of time is called Chronic, Disease. Eg: Tuberculosis., , HOW DOES CHRONIC DISEASES AFFECT OUR HEALTH?, Chronic diseases take relatively a long period of time hence they are likely to, affect our general health as well.They may hinder the growth in children or, increase stress in adults.They can make us feel tired all the time.They can also, lead to an increase or decrease in weight. They can also affect our day to day, activities and the ability to learn new things Hence, we cansay that they have, long-term effects on health than acute diseases., WHAT CAUSES DISEASES?, Diseases can be caused by two factors:, Internal factors in our body such as:, 1., Hormonal imbalance, 2., Allergic Reaction, 3., Genetic disorder, 4., Malfunctioning of body organs, External factors such as:, 1., Unhealthy diet, 2., Disease causing germs (bacteria, viruses, fungi), 3., Pollution in the environment, 4., Unhealthy lifestyle

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5., Immediate and Contributory Cause, THE IMMEDIATE AND CONTRIBUTORY CAUSE ARE EXPLAINED AS FOLLOWS:, Immediate cause: The organisms that enter our body and cause the disease are, termed as an, immediate cause. For example, virus, bacteria, protozoa etc., Contributory cause: The secondary factors which led these organisms enter our, body are termed as a contributory cause., Pathogens: Pathogens are external agents that cause diseases in other organisms., The pathogen includes harmful microbes or microorganism such as bacteria, virus,, fungi or protozoa., Vector: Vectors are those organisms that carry a pathogen from the host to a, recipient. Mosquito, rats and mice are some of the common vectors that carry, infectious diseases., Bacteria: Bacteria are microorganisms that are seen in almost all environmental, condition. Not all bacteria are harmful to pathogens. Some bacteria are also, beneficial to human beings. Bacteria are beneficial for, digestion, extracting, antibiotics from them, nitrogen fixation etc., Virus: A virus is a microorganism that is always pathogenic in nature. They do not, have to replicate machinery. Therefore they enter the host cell and replicate and, in the process destroy the host cell. Few of the common diseases spread by the, viruses are cold, influenza, dengue fever AIDS etc., Fungi: Fungi are a group of organisms which are eukaryotic in nature and, saprophytic in nutrition., They could be either unicellular or multicellular organism., Many common skin infections such as ringworm, nail infection, etc are examples, of Fungal diseases., Parasites: A parasite is an organism that lives in another organism, called the, host, and often harms it. It is dependent on its host for survival – it has to be in, the host to live, grow and multiply., THIS CONTENT IS ABSOLUTELY PREPARED FROM HOME .