When the normal functioning of an organ or a system is hampered, it is said to be diseased. Diseases are caused by following agents.
1. Pathogens : When virus, bacteria, fungi, protozoan, helminthes attack the body they cause diseases.
2. Malnutrition : Deficiency of minerals, vitamins, proteins, fats, etc. in the body causes diseases. These are called deficiency diseases.
3. Chemical Agents : Certain chemical substances such as mercury, lead, cadmium, chromium, cobalt etc. produce many diseases.
4. Mechanical Agents : Injury, fracture and other machanical damages to the body produce injurious effects on the body.
5. Physical Agents : Extreme cold, hot, pressure, radiation etc. give rise to sick effects to the body.
Different Diseases
Communicable Diseases : The diseases caused by virus, bacteria, protozoan, fungi, helminthes etc. are called communicable diseases because they can go from one person to another. Sexually transmitted and blood transfusion diseases are also a kind of communicable diseases.
Non-Communicable diseases : Diseases caused by malnutrition, hypertrophy metabolic disorders etc. are called non-communicable diseases.
Genetic Diseases : These diseases are caused by changes in genes. These are called genetic diseases. Haemophillia, colour blindness etc are genetic diseases.
Some Important Communicable
Diseases
Bacterial diseases :
1. Tuberculosis caused by Mycobacterium tuberculosis
2. Plague caused by Pesteurella pestis
3. Diphtheria produced by Corhnebacterium diphtheriae
4. Typhoid is produced by Salmonella typhosa
5. Cholera is produced by Vibrio cholerae
6. Leprosy : Mycobacterium tetani
7. Tenanus : Clostridium tetani
8. Whooping cough (Pertussis) : Bacillus pertussis
9. Pneumonia comes due to Diplococcus pneumoniae
10. Syphilis (STD) sexually transmitted Treponema pallidium
11. Gonorrhoea (STD) sexual disease by Neisseria gonorrhoeae
Viral diseases
1. Small pox caused by Variola virus
2. Chicken pox : Varicella virus
3. Poliomyelitis : Polio virus
4. Hydrophobia (Rabies) : Rabies virus or Lyssa virus I
5. Rubeola (Measles) : Morbeli virus
6. Jaundice
7. Influenza
8. Trachoma
9. Mumps
Protozoan diseases
1. Malaria : mosquoto bite Plasmodium
2. Sleeping sickness : Trypanosoma
3. Amoebiasis : Entamoeba hystolytica
4. Pyorrhoea : Entamoeba gingivalis
Helminthes diseases
1. Ascariasis : Ascaris lumbricoides (Round worm)
2. Taeniasis : Taenia solium (Tape worm)
3. Filariasis (Elephntiasis) : Wuchereria or Filaria bancrofti
Sexually transmitted diseases (STD)
1. Syphlis : Treponema pallidum
2. Gonorrhoea caused by Neisseria gonorrhoeae
3. Genital herpes : Herpes virus
4. Trichomoniasis : Trichominas vaginalis
Diseases spread through blood transfusion
1. AIDS : Human immuno deficiency virus (HIV)
2. Hepatitis : Hepatitis virus
AIDS
It is a very dangerous disease caused by a virus. The name of the AIDS causing virus is HTLV-III i.e. human T-cell immunodeficiency. Its conventional name is Acquired Immuno Deficiency Syndrome. AIDS has spread to many countries (about 40 countries) of the world.
AIDS virus attacks T-4 cells, entering through blood stream. During incubation period this virus attacks genes. Due to this the immune system collapses. During this many infection appear in the body. WBC becomes less and the body defence mechanism collapses.
Symptoms of AIDS
(i) Weight loss.
(ii) Persistent fever for about a week.
(iii) Fatigue.
(iv) White patches in the mouth.
(v) Dry continuous cough.
(vi) Diarrhoea.
(vii) Blood in the stool.
(viii) Enlarged lymph nodes in neck and armpit.
Hepatitis
Hepatitis is a liver disease. It is a dangerous disease. It can be of following types—
1. Hepatic anoxia : It this disease liver lubules get injured. The scarcity of oxygen is caused in the liver. This may be haemorrhage or heart failure.
2. Blood Collection in Liver : In this disease the blood is collected in the liver.
3. Portal Obstruction : Due to the liver damage oedema in liver cells is observed. It gives rise to the obstruction in portal vein.
4. Liver failure : Liver failure causes excretory failure, parenchymal failure and obstruction in portal system.
Leprosy : It is a chronic infectious disease caused by a bacteria. In this disease painful nodules are formed. These are beneath the skin. Leprosy is of four types : (a) Indeterminate leprosy,
(b) Lepromatous Leprosy, (c) Tuberculoid Leprosy, (d) Dimorphic Leprosy.
Immune Response
Human body is a powerful machine to fight and resist the disease causing germs. It is achieved by destruction of foreign particles by enzymatic action and development of immune response.
Body defence system is of two types namely :
(a) Non Specific defence mechanism : This gets developed by Skin, Blood and Antibodies.
(b) Specific defence mechanism : This is by developing immunity to a particular disease. Cells which take part in the immune system are ‘B’ cell and ‘T’ cells. Some specific cells also take part in defence mechanism.
Vaccination
Vaccination is a kind of acquired immunity which animal develops during its life time. Today we have about 29 vaccinations which give immunity to 29 diseases. Doses of different vaccination are different. Most of the diseases need only two or three doses.
Vaccination for Polio, tetanus, diptheria, whooping cough, small pox etc. are very common now-a-days.
Auto immunity
This is the immunity which is developed against their own structure.
Allergy
It is the stupidity of the body for certain materials. This may also be described as hypersensitivity for certain substances. The substance which causes allergy is known as allergen. If a man is allergic to a substance, it may cause burning, swelling, granular appearance on the skin, rashes etc.
Allergy may be with dust, cotton fibres, pollen of flowers, house dust, and many other substances. Scientists have found out more than 300 allergens till today. The inflammation is the characterstic of allergic reactions in the body.
Deficiency diseases
The deficiency of essential foods like proteins, iron, vitamins, minerals etc. can cause deficiency diseases.
Kwashiorkar, marasmus : Caused bt protein deficiency
Bery-Bery : Vitamin
Anaemia : Iron
Thyroid : Iodine.
Regenerative diseases
These are non-communicable diseases. They arise due to the malfunction of the different body organs. These mainly occur in old age.
1. Heart diseases : Atherosclerosis, Coronary heart diseases, Rheumatic heart disease, Heart failure etc. are well-known heart diseases.
Hypertension, angina pectoris, myocardial infection etc. are also common heart disease.
2. Diabetes : The level of sugar in the blood becomes higher than the desired one. Insulin is not produced properly by pancreas in the body so glucose level in the blood is not controlled. When glucose becomes higher in the blood, it comes in the urine. Higher levels are controlled by insulin injections. Lower level of glucose can be controlled by brisk walk, exercise, food control etc.
3. Arthritis : It is a disease of joints specially of knees. Joints get inflammated in this disease.
Inherited Diseases
These are the diseases which are inherited from one generation to another generation. Some important genetic disorders are Phenylketoneuria (it is due to recessive genes), Alkaptoneuria (Blood is increased and excreted in urine), and Albinism (recessive mutation of genes). Sickle cell anaemia is also an inherited disease.
Cancer
Unwanted growth of some tissues in the form of tumours is known as cancer. It is a fatal disease. More than 100 kinds of cancers are known to man today. These are of tongue, skin, blood, lungs, abdomen, liver, pancreas, breasts, vagina etc.
The normal cells when get exposed to carcinogen, they undergo certain changes and they are transformed into malignant cells. These are the cancerous cells.
Cancers are mainly of four types—
(i) Carcinoma : epithelial cells
(ii) Sarcoma : bones, connective tissue etc.
(iii) Leukamia : Blood (WBC)
(iv) Lymphoma : lymphocytes.
Cancer can be caused by a virus. This is called oncogenil virus.
Cancer cells are immortal and divide fast and for indefinite period. These cells also affect neighbouring cells. This division does not stop. The disease is very dangerous.
Cancer is treated by X-ray radiations, calcium and phosphorus isotopes. Surgery is the major method of treatment. Chemotherapy is also a way of treating cancers. Radiations are also used to treat cancers.
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