CLASS 6TH | BIOLOGY | HEALTH AND HYGIENE | REVISION NOTES

Health-
Physical and mental fitness is must for healthy mind of an individual. WHO has defined
health as state of complete physical, mental social well being and not merely the absence of
disease or infirmity.
A disease may occur due to following reasons: viruses, bacteria, fungi.

TYPES OF DISEASES:

▪ CONGENITAL DISEASES:
Diseases which are already present in the body since birth are called congenital
diseases.
Causes- genetic abnormality or when organ in the body is not fully developed.
Eg- colour blindness, haemophilia , thalassaemia.
Colour blindnessColour blindness is due to vision problem. This is because person lacks certain
pigments in eyes therefore it is called colour vision deficiency.
Most common colour blindness is red green colour deficiency.

Haemophilia: In this disease blood loses its ability to clot.

Thalassaemia: In this disease body makes haemoglobin and red blood cells lesser than normal
value.
It ultimately causes amaemia.

Acquired diseases:
Two categories- 1- communicable
2-Non communicable
1- Communicable or infectious diseasesDirectly or indirectly infection is paased from infected person to healty person.
Eg. Viruses ,bacteria.
2- Non communicable or non infectious diseasesDirectly or indirectly the diseases is spread from person to person or by
microorganisms.

COMMUNICABLE DISEASES :This diseases are classified on the basis of oraganisms that cause diseases.
Mode of spread- air, water, food from infectef persons
Diseases caused by bacteria

1- Tuberculosis-
• Causative organism- mycobacterium tuberculosis
• Incubation period: 2-10 weeks It is period between exposure to the
infection and appearance of first symptom
• Symptoms- Cough, sputum with blood, pain in chest, loss of
weight,etc
2- Cholera-
• Causative organism- vibrio cholera
• Incubation period- few hours to 5 days
• Symtoms- acute diaarhoea, vomiting dehydration, extreme thirst and
muscle cramp.
3- Typhoid-
• Causative organism- Salmonella thyphi
• Incubation period- 7-12 days
• Symptoms- high fever in afternoon, acute headache, reddish eruptin
on chest.
4- Leprosy-
• Causative organism- mycobacterium leprae
• Incubation period- several years
• Symptoms- loss of sensation, skin eruptions and deformation of skin
and toes.
5- Tetanus-
• Causative organism- clostridium tetani
• Incubation period- 4-20 days
• Symptoms- painful contraction of muscles, neck amd jaw followed by
paralysis.

Diseases caused by virusesCommon colddroplet infection spreads through moisture.
Incubation period- 1-3 days
Symptoms- running nose, headache , fatigue
InfluenzaDroplet infection
Upper respiratory tract infection
symptoms- fever, cold , chill, body ache
.
Measles Mode of transmission– direct contact through infected saliva and mucous
Symptoms- nasal discharge, redness of eyes and coughing.
ChickenpoxTransmission– contact with skin sores and clothes of patient
Incubation time- 14-16 days.
Symptoms– fever, head ache, small watery sores on skin
PolioAffects liver
Types- Hepatitis A,B,C,D,E,G,H

Causative organism- Human deficiency virus
Spread- sexual contact
Incubation period- 15 months- 5 years
Transmission- can transmit virus from mother to child
Precaution- Avoid sexual contact with infected person

DISEASE CAUSED BY PROTOZOA-
• AMOEBIASIS-
✓ caused by entamoeba histolytica
✓ Transmission- contaminated food and water
✓ Symptoms- diarrhoea, gripping pain, discharge of mucous
✓ Incubation period- one week
• Malaria-
✓ Caused by- Plasmodium
✓ Transmission- bite of female anopheles mosquit0
✓ Symptom- chillness, sever head ache, rising temperature
Diseases caused by worms

AIDS

1. Elephantiasis {Filaria}
   ▪ Causative organism- Wucheria bancrofti
   ▪ Spread-female culex mosquito
   ▪ Symptom- lympnodes in limbs, scotrum in males and breast in females.
2. Ascariasis-
   ▪ Occurs in small intestine
   ▪ Causation- Ascaris lumbricoides Spread- unsafe food and water
3. Taeniasis-
   ▪ Caused by tapeworm
   ▪ Symptom- pain, weight loss, digestive problems.
   TRANSMISSION OF COMMUNICABLE DISEASES
   Airborne diseases or droplet infectionBacteria, spores of fungi and viruses enter our body through inspiration and attack our
   throat, wind pipe and lungs.
   Microbes are present in saliva and blood
   When person sneezes in public places droplets are spread in air and transmitted to healthy
   person
   
   WATER BORNE AND FOOD BORNE DISEASES
   • Water is polluted in so many ways.
   • Dumping of sewage water in water bodies is cause of disease.
   • Uncleansed food contains bacteria and eggs of parasite; if not washed properly than
   diseases like diarrhoea and vomiting occur.
   • Botulism is serious food poisoning due to special bacterium.
   INSECT BORNE OR VECTOR BORNE
   o Organisms which carry disease containing pathogens to a healthy person without
   getting affected.
   o Contact diseases: spreads from one person to anothe directly or indirectly.
   o Unsanitary toilet habits should be avoided.
   Eg; conjunctivitis, chicken pox, common cold, etc.
   WAYS TO PREVENT COMMUNICABLE DISEASES
   o We should be very much careful regarding our personal cleanliness by taking a
   regular bath with good soap and shampoo.
   o Cove your nose and mouth with a tissue or handkerchief while coughing or sneezing.
   Do not forget to throw the tissue.
   o We should avoid using bathrooms and lavatories of railway station and cinema hall.
   o We should dustbins.
   o Food items exposed to flies should not be used.
   NON COMMUNICABLE DISEASES
   Nutritional deficiency diseases
   When all nutrients are done in right amount and ratio according to need its called balanced
   diet.
   A.PROTEIN ENERGY MALNUTRITION
   Deficiency of protein, fats and carbohydrates is called protein energy malnutrition.
   Eg- Kwashiorkor and marasmus
   Kwashiorkor- results due to diet poor in protein.
   Symptoms- protruding belly, mental retardation, bulging eyes, etc.
   
   Marasmus- Deficiency of proteins and carbohydrates.
   Child may suffer mental retardation.
   No change in skin colour and ribs look prominent and becomes thin.
   B. VITAMIN DEFICIENCY DISEASES
   Vitamins are vital though they are required in small quantities.
   1- Night blindness is caused by vitamin A
   2- Rickets are caused by vitamin D
   3- Haemolysis and sterility are caused by vitamin E.
   C. MINERAL DEFICIENCY DISEASES
   Metals and non-metals and their salts are called minerals.
   They do not supply energy to body.
   1- Muscle cramps is caused by deficiency of sodium
   2- Weakness of muscles or paralysis is caused by potassium
   3- Rickets is caused by deficiency of calcium
   DISEASES DUE TO MALFUNCTIONING OF ORGANISMS:
   • Diabetes mellitusIt is a hereditary disease
   When insulin secreted by pancreas is not in enough amounts than it can neither use the
   sugar nor store in liver in form of glycogen.
   Than sugar level becomes high. This is called diabetes mellitus.
   • Heart diseasesCoronary artery diseases and atherosclerosis are common.
   The blood vessels that supply blood to heart muscles are called coronary arteries. And
   arteries become hard its called atherosclerosis.
   The blood supply is reduced due to which heart muscles don’t get proper supply its called
   coronary artery disease.
   • Arthritis :It is joint disease.
   Found as two types – rheumatoid arthritis and osteoarthritis.
   
   • CANCER :It is characteristic by uncontrolled cell division.
   Malignancy refers to growing mass of cancerous cells. Renal disease or malfunctioning of
   kidney Due to some reason if kidney is malfunctioning and waste material accumulating in
   body is called uraemia. Due to head ache and extreme fatigue patient may go into coma.
   • ALLERGY :Unusual hypersensitivity of body tissues.
   Substances causing it are called allergens.
   • Asthma: Respiratory passage become swollen and constricted.
   Symptoms include coughing at night and shortness of breath, etc.
   BITES AND STINGS
   It needs immediate medical attention and is dangerous.
   Bite of snake may be dangerous and that of mosquito may be serious sometimes in case of
   carrier.
   BURNS AND FIRST AID
   First degree of burns is superficial burned
   Second degree of burns is called serious burns.
   Third degree of burn is called severe burns.
   CUTS AND THEIR FIRST AID
   If the cut is not deep is called superficial cut.
   If the cut is deep a cloth or pad should be kept on cut
   Bruises are injuries under the skin.
   Ways to prevent communicable diseases
   ❖ Diet and exercise play an important role
   ❖ Regular health screening and doctor check-up
   ❖ One should avoid fast food
   
   CLEANLINESS, HYGIENE, EXERCISE
   • Always eat clean and healthy food.
   • Always wash hands after and before meal
   • Never split in public places
   • Always cover your mouth and nose while sneezing.
   • Always take a balanced and healthy diet.
   BAD HABITS LEAD TO ILL HEALTH
   • Tobacco addiction- chewing of tobacco may lead to cancer of mouth
   • Drug addiction- symptoms like nausea, vomiting and pain in stomach may occur’
   • Addiction of fast food- they have dangerous effect on health
   • Alcohol consumption- it retards mental health and driving under influence of alcohol
   may cause accident
   • Unhealthy lifestyle- absence of physical activity and workout than unhealthy lifestyle
   increase the risk of heart ailments, blood pressure, and obesity and also makes us
   feel stressed