Health and Diseases Science Notes

Health and Diseases Science Notes

Important Points:

→ Health: The state of holistic physical, mental and social well-being is called health.
→ Disease: When physical, physiological and psychological processes in the body are disturbed, then it is said to be the condition of disease. As per the disease, symptoms are varied.
→ Types of diseases: There are different types of diseases. They can be classified generally as follows :

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Classification of diseases:

→ According to duration:
(A) Chronic E.g. Cancer, Arthritis
(B) Acute E.g. Fever that comes up suddenly, cold.

→ According to causes:
(A) Hereditary diseases (Down’s syndrome, Haemophilia, etc.)
(B) Acquired diseases :
(i) Communicable or Infectious diseases: E.g. Cold, dengue.
(ii) Non-communicable or Non- infectious diseases:
E.g. Diabetes, Heart disorders.

Communicable or Infectious Diseases

Agents such as contaminated air, water, food or vectors (insects and other animals) spread certain diseases, which are known as communicable or infectious diseases.

Some important infectious diseases

Hepatitis, Dysentery, Tuberculosis, Cholera, Typhoid

Disease Mode of transmission
Hepatitis Contaminated food and water. Some types of hepatitis such as hepatitis B is transmitted through infected blood
Malaria Bite of female (Anopheles) mosquito
Scabies By contact with scabies- mite
T.B. Contaminated air due to bacteria of tuberculosis
Dengue Bite of female (Aedes) mosquito
Dysentery Contaminated food and water
Ringworm Contact infection due to fungus
Swine Flu Contaminated air with viruses of swine flu (H1N1).

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Communicable or Infectious Diseases

Agents such as contaminated air, water, food or vectors (insects and other animals) spread certain diseases, which are known as communicable or infectious diseases.

Some important infectious diseases

Hepatitis, Dysentery, Tuberculosis, Cholera, Typhoid

Type of the disease Viral Viral and bacterial Bacterial
Name of the disease Hepatitis Diarrhoea and Dysentery Tuberculosis Cholera Typhoid
Causative organism or pathogens Virus of hepatitis A, B, C, D, E Bacteria, virus, Shigella, bacilli, Entamoeba histolytica Mycobacterim tuberculae Vibrio cholerae Salmonella typhi
Mode of infection Contaminated water, sharing of needles, transfusion of infection carrying blood Contaminated food and water Patient’s spittle, through air, continuous contact with patient using the things of patient Contaminated food and water Contaminated food and water
Disease Hepatitis Diarrhoea/ Dysentery Tuberculosis Cholera Typhoid
Symptoms Anorexia (no appetite for food), urine dark colored, general weakness, nausea, vomiting, grey colored stool Watery stool, abdominal pain Chronic cough, bloody spittle, emaciation, difficult breathing Vomiting, severe diarrhoea, cramps in legs Anorexia, headache, rash seen on abdomen, loose motions, high fever reaching to 104°F
Prevention and treatment Drinking boiled water, proper cleaning of hands Consumption of boiled water. Keeping the food covered by proper storage of food. ORS consumption BCG vaccine for protection and prevention of TB.
Isolation of patient, DOT (Daily Observed Treatment) on regular basis.
Following hygienic practices, roadside food should not be consumed, drinking boiled water, preventive vaccination against cholera Drinking clean water, vaccination, proper sewage disposal.

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Some important diseases of present days

→ Spread of diseases by mosquitoes:

  • Malaria → Female Anopheles mosquito
  • Elephantiasis → Female Culex mosquito
  • Dengue → Female of Aedes mosquito
  • Anopheles and Aedes grow in clean water but Culex breeds in dirty, sewage water/gutters.

→ Currently important diseases: Dengue, Swine flu, AIDS

Name of the disease Dengue Swine flu AIDS
Transmission 1. Aedes aegypti. Mosquito spreads infectious disease called dengue.
2. The sickness spreads by DEN-1, 2 virus belonging to the type-flavivirus.
1. The infection of swine flu is transmitted through pigs or infected humans.
2. The virus influenza A (H1N1) causes the infection of swine flu.
3. Spread of the disease is through sweat, secretions of nose, throat and saliva.
HIV (Human Immunodeficiency Virus)
Symptoms 1. Acute and severe fever.
2. Severe headache
3. Vomiting
4. Pain in the eye sockets.
5. Decrease in the count of blood platelets.
6. Internal haemor­rhages in the body.
1. Palpitations.
2. Difficulty in breathing.
3. Sore throat.
4. Body pains
Symptoms are specific to every person. There is progressive weakening of natural immunity which makes a person susceptible to variety of infections. The unsafe sexual contact and the contaminated blood and blood products cause transmission of HIV.
Diagnosis Blood test, Serological tests in the laboratories. Scrappings from pa­tient’s throat are sent to the laboratory. The testing helps to see the occurrence of virus. ELISA test.
Additional information The stagnant water in man-made containers can cause profuse breeding of Aedes aegypti. Diagnosis can be done
at National Institute of
Virology (NIV), Pune
and National Institute of          Communicable Diseases (NICD), Delhi.
In 2009 the first case of swine flu was reported in Mexico.
AIDS is not transmitted through touching or sharing the food with HIV infected person. It cannot be caused by nursing the HIV patient.

We can have normal behaviour with HIV infected person. For the first time HIV was reported in an African species of Monkeys. National AIDS Control Program and UNAIDS work in the research field of AIDS.

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Infections through Animals: (Zoonotic infections)


Rabies Causative organism Symptoms Treatment
It’s a fatal disease.
It is called zoonotic disease as it spreads through the animals to humans.
Virus. Infected dog, rabbit, monkey or cat can transmit the virus through its bite. Symptoms are seen within 90 – 175 days of animal bite. Virus enters the brain via neurons. Fever for 2-12 weeks.
Exaggerations in behaviour. Hydrophobia
Vaccination can be preventive if taken immediately after the bite.

Non-infectious diseases: (Cancer, Diabetes, Heart Diseases)

Non-infectious or Non-communicable diseases : The diseases that are not spread through contact or through infections are called non-infectious or non-communicable diseases. Certain degenerative processes or some metabolic errors can cause such diseases.

→ Cancer

Cancer is the uncontrolled and abnormal growth of the cells. When there is loss of control on the cell division, then the cells keep on dividing and growing. This makes formation of lump of cancerous cells. Commonly it is known as tumour. Sometimes the tumour is said to be maligant. In such case person is said to be cancer patient. Any tissue or organ of the body can develop cancer. E.g. lungs, mouth, tongue, breast and uterus and cervix in females. Even the blood or skin can get cancer.

→ Causes

  • Consumption of carcinogenic substances (substances that cause cancer) such as tobacco, gutkha.
  • Cigarette smoking, consuming alcohol (alcoholism).
  • Eating junk food such as pizza, burger, etc. and not taking enough fibre content in the form of fruits and leafy vegetables in food.
  • Due to cancer genes, i.e. due to hereditary reasons.

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→  Symptoms

  • Weight loss without any apparent reasons.
  • Chronic cough that does not get cured,
  • Hoarse voice and difficulty in swallowing.
  • Incurable scar that does not get healed. Inflammation that persists for long time.
  • Lump in breast.

→  Modern diagnostics

Following techniques are used for the diagnosis of cancer:

  • Tissue diagnostics
  • CT scan
  • MRI scan
  • Mammography
  • Biopsy

→  Treatment of cancer

  • Chemotherapy
  • Radiation therapy
  • Surgery
  • Robotic surgery
  • Laparoscopic surgery

→ Preventive and control measures of Cancer

  • Control over diet
  • Physical exercise
  • Never to consume tobacco, smoking or alcoholism
  • Avoiding addictions.

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→ In normal persons, there is secretion of insulin hormone from the pancreas. This hormone maintains the blood sugar level. In case of diabetic individuals, the secretion of insulin is either in deficiency or it is not secreted at all.

→ The role of insulin is to keep control over the blood glucose level by changing the metabolism accordingly. But in case of diabetic patients, the sugar in the blood is never maintained in its normal amount.

→ Symptoms

  • Increased thirst
  • Increased and frequent urination.
  • More urge of urination at night.
  • Uncontrolled weight gain or weight loss.
  • Feeling of fatigue.

→ Causes

  • Heredity
  • Obesity
  • Lack of physical work or exercise
  • Mental stress, anxiety

→ Preventive measures/Control

  • Proper diet
  • Control over consumption of carbohydrates and fats.
  • Taking proper medicines and treatment as per doctor’s advice.
  • Physical exercise and regular walking.

→ Diagnosis

  • To test the blood sugar level.
  • HbA1C tests.

→ Treatment

  • Injections of insulin or tablets that will stimulate the secretion of insulin.
  • Complete control over diet.

→ On the international level, India has largest number of diabetic patients of about 7 crores.

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Heart Diseases:

→ When the efficiency of the heart is reduced due to some causes, the heart does not perform its regular work. This causes heart disease. Continuous supply of blood is needed for the heart muscles. This blood provides oxygen and nutrients to the heart. When this supply is hindered the heart gets stressed. This can cause heart attack. In such condition, immediate treatment and doctor’s advice is a must. This can save the life of a patient.

→ Symptoms

  • Chest pain which is severe.
  • Shoulder, neck and left arm pains.
  • Cramp in the hand.
  • Excessive perspiration.
  • Uneasiness and tremors.
  • Urge to defecate or urinate.

→ Causes

  • Smoking, alcoholism.
  • Diabetes.
  • Hypertension.
  • Obesity, Lack of physical work.
  • No exercise, sedentary habits.
  • Heredity.
  • Mental stress, anger, anxiety.

→ First Aid for Heart Disease

  • Immediately seeking help from 108 for calling ambulance.
  • Checking whether the patient is conscious.
  • Giving first aid of C.O.L.S. type i.e. Compression Only Life Support.
  • In this the patient is made to lie on a hard surface in horizontal position and the pressure is given on his or her thorax to keep the heart working. The pressure and stroking is continued till the doctor arrives.

→ Diagnosis

  • ECG is taken to check the activity of the heart.
  • Complete check-up by the cardiologist.
  • Few specific blood tests.

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  • Angioplasty
  • By-Pass surgery
  • Open heart surgery
  • Heart transplant
  • Installation of stents
  • Installation of pacemaker

Every disease is caused by a specific reason. They are not caused due to j divine curse or hatred. People who are unaware about the scientific and medical knowledge resort to blind faith. Disease can be cured only through the proper medical treatment and care.

Misuse of Medicines

→ Pain killers when taken in overdose cause damage to nervous system, excretory system, liver, etc.
→ Overuse and unnecessary use of antibiotics can case nausea, abdominal pain, loose motion, rashes on the body and white patches on tongue.
→ Taking medicines without doctor’s prescription and overuse of medicines will certainly cause harmful side-effects on the body.

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Genetic medicines

→ Generic medicines or general medicines are manufactured and distributed without any patent. These medicines are comparatively much cheaper than the branded medicines. However, they are equal in their quality with branded medicines.
→ Generic medicines are exported on a large scale by Indian companies. But in India, the same medicines are sold as branded medicines by increasing their price. In America 80% medicines used are generic and hence they save billion of dollars.
→ Under Pradhan Mantri Jan Aushadhi Yojana best quality medicines are made available at affordable prices to the common people. These medicines are available in ‘Jan Aushadhi Stores’. This scheme was started by the Government of India on 1st July 2015.

Lifestyle and diseases:

  • Lifestyle is type of diet, the routine and the pattern of thinking too.
  • Right kind of lifestyle includes sufficient sleep, right food, yoga, pranayama and sufficient physical exercise.
  • By wrong kind of lifestyle, there is increased frequency of ill health and episodes of diseases.

→ Vaccination

For prevention of the infectious diseases, preventive vaccination can be given. This saves the health of a person. By vaccinations, babies can be protected against many diseases.

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→ Important days

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

→ Blood donation and eye donation are said to be supreme gifts any one can give. If blood donation is done 4 times in one year, 12 patients can be saved. By eye donation, some blind person may regain the sight.

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