ICSE Class 8 Biology Chapter 08 Health and Hygiene

Health And Hygiene

Syllabus

1. Diseases may be caused by a deficiency of nutrients. Protein/calorie malnutrition - brief revision of deficiency diseases on account of lack of specific vitamins/minerals.

2. Diseases may arise on account of malfunctioning of organs - e.g. pancreas lack of insulin may lead to diabetes, malfunctioning of kidneys can lead to accumulation of toxic substances in the body.

3. Communicable and non-communicable diseases. Diseases may be caused by infection - viruses, bacteria, protozoa, fungus, insect bite, ingesting infected food and water, pollution/allergies. Examples of each of these. How diseases spread: Droplet infection (Coughs, colds, influenza, tuberculosis); water and food-borne diseases (diarrhoea, typhoid, cholera); vector-borne diseases. (Malaria, dengue, filaria, plague, yellow fever, gastro-enteritis, polio); contact infection (skin diseases, conjunctivitis, lice, chicken pox), bites (snake poisoning, rabies). Note: Detailed treatment of diseases is not required.

4. Fever, allergies.

5. Bites, stings and burns.

6. First Aid measures for cuts, bites, stings and burns. What to do in case of fever.

7. Prevention of disease - routine steps - immunization.

8. Other bad habits that can lead to ill health: lack of personal hygiene and exercise, addictions to fast food, drugs, tobacco.

Quizzes games can be developed by children and tried out amongst themselves or younger students on how to avoid ill-health (E).

Teacher's Note

Understanding health and hygiene helps students recognize the importance of maintaining cleanliness and proper nutrition in their daily lives, from washing hands before eating to choosing healthy foods.

Health

Normally, a person is said to be healthy, if he or she is not suffering from any disease. When a person can work hard, interact well with people, enjoy leisure and can adopt to the changes and stresses of life, then he or she is in good health.

Health is defined as a state of complete physical, mental and social well-being, and not merely an absence of disease or infirmity.

Physical health and mental health are inter-related. A sound mind in a sound body is an old and appropriate saying for good health.

A healthy human being has generally the following features:

- a clear skin,

- bright, clear eyes,

- a body neither too fat nor too thin,

- fresh breath,

- good appetite,

- sound sleep,

- regular activity of bladder and bowels,

- coordinated body movements.

Teacher's Note

Students can observe and discuss how their own energy levels, mood, and focus improve when they get enough sleep, eat nutritious food, and exercise regularly.

Disease is a departure from normal health through structural or functional disorder of the body.

Categories Of Diseases

There are two major categories of diseases:

1. Non-Communicable Or Non-Infectious Diseases

Such diseases are not caused by any germ, therefore these diseases cannot spread from one person to another (i.e., they are non-transmissible). These are caused due to improper functioning of the body organs. Examples: diabetes, heart attack, etc.

2. Communicable Or Infectious Diseases

Such diseases are caused by the germs which are called pathogens. When pathogens reach a healthy person, he or she is infected by a communicable disease. Some examples of communicable diseases are cholera, viral fever, chicken pox, malaria, etc.

Teacher's Note

Students can understand this distinction by recognizing that catching a cold from a friend is communicable, while developing diabetes from family genes is not.

Types Of Non-Communicable Or Non-Infectious Diseases

A simplified classification of non-infectious diseases with some common examples is given below:

1. Metabolic - diabetes mellitus, goitre.

2. Genetic - Haemophilia, thalassemia.

3. Allergies - Hay fever, asthma.

4. Dietary deficiency - Beri-beri, scurvy, goitre.

5. Cancer - Breast cancer, leukemia.

6. Degenerative (ageing) - Arthritis, cataract.

7. Physical and chemical causes - Injury, heat, cold, radiation, poisoning.

8. Mental illness - Depression, schizophrenia.

1. Metabolic Diseases (Also Called Organic Diseases)

These diseases are caused due to the malfunctioning of various body organs. Diabetes is one good example of such diseases. In this disease, pancreas fails to produce sufficient insulin, the hormone which controls the sugar level in the blood. Therefore, sugar starts passing out in urine.

In the case of heart diseases such as, heart attack or coronary thrombosis, blood supply to the heart muscles is obstructed and the cardiac muscles fail to function properly.

You have already learnt in your previous class about malfunctioning of kidneys. You know that nephrons in the kidneys help filter out harmful nitrogenous waste materials from our blood, and throw them out from the body in the form of urine. If, for certain reasons, the kidneys fail to function properly, these toxic wastes get accumulated in the blood and cause a disease known as uraemia.

2. Genetic Diseases Or Congenital Diseases

Such diseases develop at the time of embryonic development due to defects in the genes of the chromosomes inherited from the parents.

Haemophilia. In this disease, the blood clotting takes place very slowly due to the absence of certain special factors in the blood.

Thalassemia is the disease of defective haemoglobin of RBC. A child with such a defect needs blood transfusion very frequently.

3. Allergy

Allergy is an unpredictable reaction to a particular substance. This type of substance is called allergen. Different people are allergic to different substances. A few common allergens are dust, spores, pollen, certain clothes, particular medicines, cosmetics, etc. The common areas of the body parts which are affected by allergies are skin, respiratory and digestive tracts. Asthma, eczema, diarrhoea, vomiting, nausea, etc. are some of the common allergic reactions.

4. Dietary Deficiency Diseases

(i) A diet lacking in nutrients, such as proteins, required for the growth and repair of the body, results in degeneration of muscles and body weight. Some of the examples of protein deficiency diseases are kwashiorkor and marasmus.

(ii) Vitamin deficiency diseases are nightblindness, pellagra, scurvy and beri-beri (Table 1).

(iii) Mineral deficiency diseases. Human body also require different mineral salts. The deficiency of minerals gives rise to disease like anaemia, goitre, rickets, fluorosis, etc. (Table 2).

Teacher's Note

Students can trace the connection between their diet and energy by noting how they feel after eating different foods, and can learn to choose foods rich in vitamins and minerals.

Note: You have already learnt that if a person eats more proteins, carbohydrates or fats than required by his body, i.e., he consumes more calories, the excess energy produced gets stored in the body as fat. This results in gaining more weight and the person become obese. You know that obesity is harmful in many ways.

Teacher's Note

Students can understand that eating balanced meals with fruits, vegetables, and whole grains helps prevent deficiency diseases and maintains healthy growth.

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