Why Do We Fall ill Question Answers: NCERT Class 9 Science

The two conditions essential for good health are :

(i) Person should be physically fit and fine.

(ii) He should have a good and clean environment.

The two conditions essential for being free of diseases are :

(i) Maintaining personal and domestic hygiene.

(ii) Taking a good food (balanced diet)  that contains carbohydrates, fats, proteins, vitamins, fibres, and proper quantity of water.

No. The answers are not the same all the time. This is because the meaning of health varies from person to person. For example, good health for a dancer may be being able to stretch his body into difficult but graceful positions. Good health is the ability of an individual to realise his or her full potential. Individuals can have poor health without having any identifiable disease. Also, health is related to society and community, whereas having a disease is about an individual sick person. Hence, the conditions for good health and for being disease free can be the same or even different.

The three reasons why a person think that he or she is sick and ought to see a doctor are :

a. Cough
b. Fever
c. Headache

Even seeing one of the symptoms, I would go to the doctor. However, if only one of these symptoms is present, we usually do not visit a doctor. This is because such symptoms do not have much effect on our general health and ability to work. However, if a person is experiencing these symptoms for quite some time, then he needs to visit a doctor for proper treatment.

Jaundice can cause long-term effects on our health. It is a chronic disease and it takes a long time to be cured. It does not spread rapidly, but it develops slowly over a period of time.

During sickness the body becomes weak and the digestive system does not work properly. Immunity of the body decreases during disease of infection. So we are normally advised to consume bland and nourishing food when we are sick so that we can get the nutrients and energy quickly to fight off the foreign disease-causing agents.

Infectious diseases can be spread in several ways such as air, water, sexual contact, blood, and vectors.

(i) Through Air: Sneezing or coughing little droplets thrown in the air carry microbes which can cause the spread. For example, tuberculosis, pneumonia, etc. spread through air.

(ii) Sometimes causal micro-organisms get mixed with drinking water and spread water borne diseases. Cholera for example is water borne disease.

(iii) Sexual Contact: Diseases such as syphilis or AIDS are transmitted by sexual contact.

(iv) Certain diseases such as AIDS can spread via blood to blood contact during blood transfusion or pregnancy.

(v) Through vectors : These are intermediaries which carry the infectious agents from the patient to the host. For example mosquitoes spread malaria.

Precautions to reduce incidence of infectious diseases are:

(i) Drinking clean and hygienic water.

(ii) Keeping the toilet neat and clean.

(iii) Stay away from the diseased person.

(iv) Using handkerchief to cover the mouth while sneezing or coughing.

(v) Initiations of the school immunization program for children.

(vi) Preventing over crowded classes.

Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body’s own immune system to protect the person against subsequent infection or disease.

The immunization programme is available at the nearest health centre in our locality.

(i) For infants : DPT, polio, measles and MMR.

(ii) For children : Typhoid, TT, DT, smallpox and TAB.

(iii) For pregnant women : TT and hepatitis-B.

The diseases like jaundice and typhoid are major health problems in our locality.

I fell ill twice in the last one year. The disease I first suffered from was typhoid and secondary the dengue fever.

a. The changes I brought in my habits after suffering from these diseases to protect myself in near future are; I will always drink clean, pure water and also live in a clean environment.

b. Pure drinking water should always be available. The intake of impure water is the main cause of many infectious diseases.

The following precautions must be taken by a doctor/ nurse/ health-worker:

(i) Use of gloves and wearing a mask when in contact with a diseased person.

(ii) Hospital is always kept clean.

(iii) Drinking pure water.

(iv) Eating healthy and nutritious food and avoiding sharing food with patients.

(v) Use of sanitizers and disinfectants whenever required.

Three most common diseases are:

a. Tuberculosis
b. Typhoid
c. Jaundice
d. Viral fever
e. Dysentery

Preventive measures are :

i. Maintaining the neighbourhood clean.
ii. Timely spray of chemicals in the surroundings to kill mosquitoes.
iii. Arrangements of social programmes to educate people about prevention of diseases.

(a) The baby is sick if he / she is crying continuously and also can be noticed by behaviour changes.

(b) The sickness is determined by symptoms and noticing the body temperature of the baby, vomiting, loose motion, paleness in the body, etc.

(c) A person is more likely to fall sick when she is on a four day fast after recovering from malaria and is taking care of someone who is suffering from chicken pox. This is because after malaria her immune system has become weak so for recovery she should take a healthy diet and in this situation, fasting is not acceptable. If she takes care of someone suffering from chickenpox then there is a high probability that she would also gain chickenpox.

(c) When your friend is suffering from measles then you are most likely to fall sick. This is because measles is an infectious disease which spreads through nasal or throat discharge i.e., through air. Thus, if your friend is suffering from measles, stay away from him otherwise you might easily get infected with the disease.

(a) Acute diseases : typhoid, chicken-pox
(b) Chronic diseases : Diabetes, tuberculosis
(c) Infectious diseases : Small-pox,  measles
(d) Non-infectious diseases : Diabetes, goitre, kwashiorkor

Two diseases caused by protozoans are malaria and kala-azar. Causal organism of malaria is Plasmodium vivax and the causal organism of kala-azar is leishmania.

Helicobacter pylori (cause of peptic ulcers)
B. Marshall and R. Warren (2005) discovered this pathogen for the first time.

Antibiotics are the type of medicines which kill or stop the growth of the diseases causing microorganisms are called antibiotics.
Example : tetracycline, penicillin

(a) infectious/communicable
(b) fungi
(c) bacteria
(d) vectors

(a) liver
(b) brain
(c) lungs
(d) skin

Edward Jenner (1796) discovered the vaccine for the first time.
Diseases which can be prevented by using vaccines are smallpox, polio, hepatitis-B, etc.

(a) Chronic, long term effect
(b) Acute
(c) Health
(d) infectious/communicable
(e) fungi

Infectious diseases: AIDS, tuberculosis, cholera, pneumonia.
Non-infectious diseases: High blood pressure, heart disease, cancer.

Bacteria and Fungi

Kala-azar : Phlebotomine sandflies
Malaria :  Anopheles mosquito
Dengue :  Aedes mosquito

(a) A balanced diet is the first and foremost condition necessary for good health. It provides all the nutrients (carbohydrates, fats, vitamins, minerals, proteins) in appropriate amounts required by the body in the correct proportion. When our body lacks a balanced diet results in occurrence of diseases or nutritional disorders. So, a balanced diet is necessary for maintaining a healthy body.

(b) Our health depends on the cleanliness of our surroundings. If the area in which we live or work has uncleaned garbage, pools of stagnant water or open drains. We might get infected and diseased.

(c) If the area in which we live or work has uncleaned garbage, pools of stagnant water or open drains. We might get infected and diseased. So, our surrounding area should be clean of stagnant water.

(d) Human beings live in societies and different localities like villages or cities, which determines the social and physical environment and therefore both are to be kept in harmony to -maintain every individual’s health. We need good food for a healthy body and for this we have to earn more. For the treatment of diseases, one has to be in good economic condition so as to avail proper vaccination, good sanitary conditions, medicines, health advice, etc.

A disease is a particular abnormal condition that negatively affects the structure or function of part or all of an organism, and that is not due to any external injury. Diseases are often construed as medical conditions that are associated with specific symptoms and signs.

Human diseases can be classified in different ways:

(i) Acute and chronic diseases.
(ii) Infectious and non-infectious diseases.

1. (i) Acute and chronic diseases

   • Acute diseases: Diseases that last for only very short periods of time, are called acute disease. Examples—common cold, typhoid, diarrhoea, etc.

   • Chronic diseases: Diseases that last for a long time even as much as a lifetime are called chronic diseases. Examples— elephantiasis, diabetes, arthritis, etc.

2. Infectious and non-infectious diseases

   • Infectious (or communicable) diseases: Diseases which are caused by microorganisms are known infectious diseases. These diseases can spread from one person to another by vectors or by other means such as air, food and water. Examples—tuberculosis, chicken-pox, dengue, etc.

   • Non-infectious (or noncommunicable) diseases: Diseases that are not caused by infectious agents. Their causes are like microbes that can spread in the community. Instead , these are mostly internal, non-infectious causes. Examples—Epilepsy, allergy, goitre, Marasmus, etc.

Any subjective change in the body or its functions that indicates disease or phase of disease, as reported by the patient is called the symptoms of disease.

Examples
(i) Lesions on the skin are the symptoms of chickenpox.
(ii) Cough is the symptom of lung infection.

The immune system is made up of special organs, cells and chemicals that fight infection (microbes). The main parts of the immune system are; whte blood cells, antibodies, the spleen, the thymus, and the bone marrow. These are the parts of our immune system that actively fight infection.

There are many diseases that cannot be cured. No medicines are there yet to treat them like AIDS or Cancer. So it is better not to get the disease rather than to cure it.

For preventing the occurrence of disease following precautions should be taken :

1. Keep yourself as clean as possible.
2. Take a bath daily.
3. Eat balanced food to prevent nutrient deficiency.
4. Always wash your hands before and after every meal.
5.  Awareness on sexually transmitted disease should be given to every person as possible to avoid these diseases.
6.  Medical checkup at regular intervals.
7.  Well-isolated sewer system should be provided.

Some children fall ill more frequently than others living in the same locality are listed below ;

• Lack of balanced diet leading to malnutrition
• Weak immunity 
• Living in congested , unhygienic conditions 
• Lack of clean drinking water and hygienic food 
• Missing vaccinations

Antibiotics are medicines that cannot kill viruses like common cold, the flu. Antibiotics fight bacteria, which are completely different from viruses in their structures and functions. Infections caused by bacteria that need antibiotics include strep throat, whooping cough, urinary tract infections and life threatening illnesses like sepsis. It’s important not to take antibiotics unless you need it, because they can have serious side effects and lead to antibiotics resistance where the bacteria can no longer be stopped by antibiotics.

Our body possesses many white blood cells which are part of our immunity and they help in fighting diseases. Every disease has a particular incubation period. If within that time, W.B.C fights off the microbe, the disease does not develop.

Sometimes, there exist some diseases that damage our body internally but don’t show any changes which are noticeable e.g diabetes.

Four factors necessary for being healthy are:

1. Clean water and a hygienic surrounding can keep us away from water and air borne diseases.
2. We should keep our body clean to be healthy.
3. Hygienic and nutritious food helps to boost the immune system hence a balanced diet is essential for being healthy.
4. Vaccination against severe disease is very essential to be healthy.

AIDS has acquired immune deficiency syndrome. It is called a syndrome because it is a group or one can say a collection of symptoms. It is so because due to AIDS many other diseases like pneumonia and typhoid can occur as our immune system becomes so weak that it is vulnerable to any pathogen. So there is no particular symptom of this disease as in fact the first signs of the disease may occur after many years pro to the disease. That’s the main reason why AIDS is considered a syndrome. Unlike any other disease you can't tell any particular symptom related to this disease but as our immune system becomes too weak so many other diseases get to us and there symptoms occur. AIDS is fatal due to this reason only because of the weakening of the immune system and attack of the other pathogens.