Health and Diseases Class 8 Science Notes Maharashtra Board

Health and Diseases Class 8 Science Notes Maharashtra State Board

Health is a state of complete physical, mental, and social well-being and not merely the absence of any disease.

What is Disease?
The condition of disturbances in the physiological or psychological processes of the body is called a disease. Each disease has its specific symptoms.
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Types of Diseases:
You must have heard the names of various diseases like diabetes, common cold, asthma, Down’s syndrome, heart disease, etc. The reasons and symptoms of all these diseases are different. To bring coordination in the scientific study of diseases, diseases are classified as follows.
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A. Infectious Diseases:
Diseases spread through contaminated air, water, food, or vectors (insects and other animals) are called infectious diseases.

Name of Disease Pathogen Mode of Infection Symptoms Prevention and Treatment
Tuberculosis Mycobacterium tubercular Spitting by the patient, through the air, prolonged contact with and sharing of materials of patient Chronic cough, bloody spitting, emaciation, difficulty breathing BCG vaccine, isolation of the patient, regular medication like DOT
Hepatitis (Jaundice) Hepatitis virus – A, B, C, D, E Contaminated water, sharing of needles, blood transfusion Anorexia, yellow urine, general weakness, nausea, vomiting, grey stool Drinking boiled water, proper cleaning of hands
Dysentery Bacteria, virus, Shigella, bacilli, Entamoeba histolytica Contaminated food and water Watery stool, pains in the abdomen Drinking of boiled water, proper storage of food, ORS consumption
Cholera Vibrio cholerae (bacterium) Contaminated food and water Vomiting, severe diarrhea, cramps in legs Following hygienic practices, avoiding open place food, drinking boiled water, vaccinating against cholera
Typhoid Salmonella typhi (bacterium) Contaminated food and water Anorexia, headache, rash on abdomen, dysentery, fever up to 104°F. Drinking clean water, vaccination, proper disposal of sewage

Health and Diseases Class 8 Science Notes Maharashtra Board

Some Important Diseases of Present Days
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Mosquitoes lay their eggs in water-logged places and thereby their population increases. Different species of mosquitoes spread different diseases. Dengue is spread by Aedes aegypti. This disease is caused by the DEN-1-4 virus belonging to the type – flavivirus.
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  • Acute fever and headache, vomiting.
  • Pains in the eye socket are a very prominent symptom.
  • Decrease in platelet count that may lead to internal hemorrhage.

Malaria is spread by female Anopheles while elephantiasis by female Culex. Anopheles and Aedes grow in clean water while Culex in dirty, sewage water.

Swine Flu: Reasons for Infection

  • Infection by swine flu occurs in pigs and humans.
  • Viruses of swine flu are spread through secretions of the nose, throat, and saliva.

Symptoms of Swine Flu:

  • Difficulty in breathing.
  • Sore throat, body pains.

Diagnosis of Swine Flu:
For diagnosis of swine flu, liquid from the throat of the patient is sent to the laboratory. Diagnostic facilities are available at the National Institute of Virology (NIV), Pune, and the National Institute of Communicable Diseases (NICD), Delhi. The first case of swine flu was reported in Mexico in 2009. Swine flu is caused by the virus influenza A (H1N1). Persons who come in contact with pigs can contract this disease.

Health and Diseases Class 8 Science Notes Maharashtra Board

AIDS (Acquired Immuno Deficiency Syndrome):
This disease is caused by HIV (Human Immunodeficiency Virus). In this disease, victims suffer from various diseases due to the progressive weakening of natural immunity. Diagnosis of AIDS cannot be confirmed without tests in medical laboratories. ELISA test is used for its proper diagnosis. Symptoms of AIDS are person-specific.
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AIDS does not occur due to touching and sharing the food with HIV HIV-infected persons, or by nursing the HIV patient. Our behavior with HIV-infected persons must be normal. HIV was first reported in an African species of Monkeys. According to the National AIDS Control Program and UNAIDS, 80- 85% of HIV infections in India occur through unsafe sexual contact.

Infections through Animals – Rabies:
This is a viral disease. It occurs due to the bite of the infected dog, rabbit, monkey, cat, etc. The virus enters the brain via neurons. Hydrophobia is one of the important symptoms of this disease. In this case, the victim shows extreme fear of water. Rabies is a fatal disease. However, fatality can be prevented by timely vaccination before the onset of symptoms. Symptoms start to appear within 90-175 days of dog bite.

Symptoms of Rabies:

  • Fever for 2-12 weeks.
  • Exaggerations in behavior.
  • Hydrophobia.

B. Non-infectious Diseases:
Diseases that do not occur through infections and body contact are called non-infectious diseases. Such diseases arise in the human body itself due to certain reasons.

1. Cancer:
Uncontrolled and abnormal cell growth is called cancer. A group or lump of cancerous cells is called a malignant tumor. Cancer can occur in various organs like the lungs, mouth, tongue, stomach, breast, uterus, skin, and tissues like blood.

Consumption of tobacco, gutkha, smoking, alcoholism, lack of fiber content (fruits and leafy vegetables) in food, and excessive consumption of junk food (pizza, burger, etc) are some of the many possible reasons. Heredity may also be a reason.


  • Chronic cough, hoarse voice, difficulty in swallowing.
  • Incurable scar and inflammation.
  • Lumps in the breast.
  • Unexplained weight loss.

Modern Diagnostics and Treatment of Cancer:
Various techniques like CT scans, MRI scans, mammography, and biopsy are used in the diagnosis of cancer. In the case of treatment, along with conventional methods like chemotherapy, radiation therapy, and surgery, modern techniques like robotic and laparoscopic surgery are also followed. A controlled diet helps to prevent some types of cancers. Physical exercise along with modern treatment is more beneficial to cure cancer. Avoid addictions like tobacco chewing, smoking, etc.
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2. Diabetes:
The hormone – insulin produced in the pancreas controls the level of sugar glucose in the blood. If insulin is secreted in low quantity, glucose levels cannot be controlled; this disorder is called as diabetes.

Health and Diseases Class 8 Science Notes Maharashtra Board

Symptoms that cannot be ignored- Frequent urination at night, increased obesity or weight loss

Reasons for Diabetes:

  • Heredity
  • Obesity
  • Lack of physical exercise
  • Mental stress

Preventive Measures:
Following the proper diet, medicines, and exercise under the supervision of a doctor helps to keep diabetes under control.

India has the largest number of diabetes patients in the world. At present, approximately 7 crore diabetes patients are present in the country. Each disease has a specific scientific reason. Diseases do not occur due to divine curse or hating by anyone. Diseases can be cured by proper medical treatment and not by chanting mantras or performing magic tricks.

3. Heart Diseases:
The efficiency of the heart decreases due to decreased blood supply and thereby oxygen and nutrient supply to the heart muscles. Due to this, the heart has to perform more work which leads to stress. This may cause a heart attack. If someone has a heart attack, immediate consultation with a doctor and treatment is necessary.
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One should not ignore these symptoms – Severe chest pains, pains in the shoulder, neck, and arms, cramps in the hand, uneasiness, and tremors.

Reasons for Heart Attack:
Smoking, alcoholism, diabetes, hypertension, obesity, lack of physical exercise, heredity, mental stress, anger, and anxiety.

First Aid for Heart Disease
First, call 108 for an ambulance. Check the consciousness of the patient by shaking the shoulders. Keep the patient lying on the back in a horizontal position on a hard surface and perform compression-only life support (C.O.L.S). In this, press the center of the thorax at least 30 times at the rate of 100 to 120 strokes per minute.

Health and Diseases Class 8 Science Notes Maharashtra Board

Misuse of Medicines:
Sometimes, some people take medicines without a prescription from a doctor. Overdose of medicines may affect our bodies. Ex. Overdose of painkillers may damage the nervous system, excretory system, and liver. Overdose of antibiotics may lead to nausea, stomach ache, dysentery, rash, white patches on the tongue, etc.

Generic Medicines:
Generic medicines are also known as general medicines. These are manufactured and distributed without any patent. These medicines are at par in quality with branded medicines. The production cost of these medicines is very low due to fewer expenses on research as their formula is readily available.
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Lifestyle and Diseases:
Lifestyle includes the daily routine and the type of food. Nowadays, habits like staying in bed till late morning and going to bed late at night, frequent changes in meal timings, lack of physical exercise, consumption of junk food, etc. have increased. Due to this, such people are getting sick frequently. If the frequency of becoming sick is to be lowered, people should follow the right lifestyle. It must include sufficient sleep, the right food, yoga asanas, pranayam, and physical exercise. Physical exercise should also be as per one’s capacity. Pranayam and yogasanas should be performed under expert supervision. See the videos of pranayam and yogasanas.

Vaccination is important to prevent infectious diseases. Collect the vaccination schedule chart from a nearby clinic and study it.

Health and Diseases Class 8 Science Notes Maharashtra Board

The government of India declared the Pradhan Mantri Jan Aushadhi Yojana on 1st July 2015. In this scheme, best quality medicines are made available at affordable prices to the citizens. ‘Jan Aushadhi Stores’ are launched for this purpose. Indian companies export generic medicines on a large scale. However, those medicines are sold under the brand name at high prices in India. In America, 80% of medicines used are generic. Due to this, hundreds of billions of money are saved there. Let us celebrate Health Awareness Days

  • 7th April – World Health Day
  • 14th June – World Blood Donation Day
  • 29th September – World Heart Day
  • 14th November – World Diabetes Day

Blood Donation:
One unit of blood donated by a person can fulfill the needs of three persons at a time, for example – RBCs, WBCs, and platelets. One can save the life of twelve persons by donating the blood for four times a year.
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Good Maharashtra State Board Class 8 Science Notes Health and Diseases can simplify complex concepts and make studying more efficient.

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