why do we fall ill class 9 biology , 14th chapter

WHY DO WE FALL ILL?

What is health ?Health is the level of functional or metabolic effi ciency of a living organism. In humans, it is the general condition of a person's mind and body, usually meaning to be free from illness, injury or pain]] (as in "good health" or "healthy").

Health is a state of physical, mental and social well being.

The conditions necessary for good health are :- i) Good physical and social environment. ii) Good economic conditions.iii) Social equality and harmony. Good physical and social environment includes clean

surroundings, good sanitation, proper garbage disposal and clean drinking water .

Good economic conditions includes job opportunities for all for earning to have nutritious food and to lead a healthy life.

Social equality and harmony are necessary for a healthy and peaceful life.

Healthy Disease free

1. It is a state of physical, mental and social well being.

It is a state of absence from diseases.

2. It refers to the individual, physical and social environment.

It refers only to the individual.

3. The individual has good health. The individual may have good health or poor health.

2) Differences between Healthy and Disease free :-

When a person is affected by a disease either the normal functioning or the appearance of one or more systems of the body changes for the worse.

These changes give rise to signs of the disease called symptoms.

On the basis of the symptoms the physicians look for the signs of a particular disease and conduct tests to confirm the disease.

Maintaining healthAchieving and maintaining health is an ingoing process, shaped by both the evolution of health care knowledge and practices as well as personal strategies and organized interventions for staying healthy known as Lifestyle Management.

The science builds on many sub-fields, including biology, biochemistry, physics, epidemiology, pharmacology, medical sociology. Applied health sciences endeavour to better understand and improve human health through applications in areas such as health education, biomedical engineering, biotechnology and public health.

Role of science in healthHealth science is the branch of science focused on health. There are two main approaches to health science: the study and research of the body and health-related issues to understand how humans (and animals) function, and the application of that knowledge to improve health and to prevent and cure diseases and other physical and mental impairments.

TYPES OF DISEASES.

Acute diseases:Diseases that last for

only very short period of time are called acute

diseases. Acute means brief and severe.

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Other diseases are more long –term, with the symptoms lasting for months or years. Such diseases are called chronic

diseases.

CHRONIC DISEASES:

Tuberculosis [ T.B ]

It is an infectious disease.it includes swelling and tenderness of lymph gland often in the legs which may discharge secretion through skin.

Examples of chronic diseases

Ele

phanti

asi

s .

A lower leg and a scrotum showing

the effect of elephantiasis.

Diseases are of different types. They are :-

are

diseases which last only for a short period of time and does not have

long term effect on health. Eg:- cold, cough, typhoid, cholera etc.

are diseases which lasts for a long time and has long term drastic

effect on health. Eg :- diabetes, tuberculosis,

elephantiasis, arthritis, cancer etc.

Acute diseas

es Chronic disease

Acute diseases will not have time to cause major effects on general health , but a chronic disease will effect drastically.

Principles

of prevention

of diseases.

1) For air borne microbes , we can prevent exposure by providing living conditions that are not over crowded .

1.General ways of prevention of

infectious diseases.

we can prevent exposure by providing safe drinking water.

1)For water borne microbes

, , we can provide clean environments . Such a clean environment, for example , would not allow mosquito breeding.

) For vector borne infections

A vaccine is a biological preparation used as a preventive inoculation to confer immunity against a

disease. The preparation usually employs an innocuous form of the disease-causing agent, which

is in the form of killed or weakened bacteria or viruses. A vaccine may also be composed of the

toxins or surface proteins of the infecting organism.

Another way of prevention is through

VACCINATION.

Examples of vaccines

BCG Vaccine used against

tuberculosis .Sabin vaccine used

against poliomyelitis.

1)Congenital diseases

These diseases are those which are present since birth. They are caused due to genetic abnormality or due to metabolic disorders.

Types of diseases..

2)Acquired diseases

These diseases are those which are developed after birth. They are classified

into two types.

1} Infectious diseases.2} Non-infectious diseases.

Prevention methods of

some common diseases.

TYPHOID.

Proper sanitation and

disposal of faecal matter

prevents infection .

TAB vaccination

provides immunity for

3 years .

Typhoral oral vaccine also

prevents typhoid.

DIARRHOEA

Eatables should be covered to

prevent contamination .

Stale food should not be

consumed.

Proper personal hygiene is also very important

Community hygiene is also

important.

Tuberculosis

Isolation and proper rehabilitation of the patient .

Avoidance of over crowding

Provision of good ventilation and better help to reduce the

incidence of the disease.

It is caused by microbes or micro –organisms .These diseases can spread in the community .

Infectious diseases are caused by bacteria, viruses , fungi, and unicellular organisms like protozoans.Some multicellular organisms like worms also cause infectious diseases.

Infectious diseases caused by viruses are such as common cold ,influenza , dengue fever, AIDS etc.

Bacterial diseases of bacteria are typhoid fever , cholera, tuberculosis ,anthrax etc.

Common infectious skin diseases are caused by fungi

Protozoan cause diseases such as malaria ,kala-azar .Worms cause intestinal diseases as well as elephantiasis .

TYPES OF DISEASESINFECTIOUS DISEASES

–These are not spread to other persons. These are of following types:-

i. Deficiency- caused deficiency of nutrients and hormones. E.g. diabetes , scurvy.

ii. Allergic – when body is hypersensitive to foreign elements. E.g. asthma

iii. Cancer- uncontrolled growth of certain tissues.iv. Mental disorder- depression ,anxiety etc.v. Addiction :- alcohol, drugs.vi. Degenerative- malfunctioning of important

organs .E.g. heart diseases.

NON- INFECTIOUS DISEASES

Viral :- influenza , chickenpox , small pox ,common cold, dengue fever and AIDS

INFECTIOUS AGENTS

VIRUS

Fungal :- ringworm etc.

Bacterial :- cholera ,typhoid , tuberculosis and anthrax .

Bacteria

Protozoan

Protozoan :- malaria , kala-azar

Common cold (viral) cause – Rhino virus symptoms – sore throat , cough , headache.

Chicken pox (viral) symptoms – rashes, fever, aches , uneasiness.

Measles (viral) symptoms –red and watery eye, pink rashes, itching or

burning or rashes.

IMPORTANT DISEASES IN HUMAN

Typhoid (bacteria)Cause- salmonella typhi. Symptoms- fever ,headache ,loss of appetite, skin rash

,either constipation or diarrhea.Tuberculosis-(BCG vaccine)

Cause – Mycobacterium tuberculosis. Symptoms – night sweats, fatigue, weight loss.

Malaria(protozoa)Cause –female anopheles mosquitoSymptoms –fever at interal,weakness .

Cancer Cause- abnormal and uncontrolled growth of cellsRisk factors – tobacco, alcohol, high fat diet , smoking.

HypertensionCause- blood pressure levels, stress, tension , salt

intake ,fat intake(large)

Picture of Leishmania ,the protozoan organism that causes kala –azar .The Organisms are oval shaped ,and each has one long whip like structure . One organism(arrow )is dividing ,while a cell of the immune system (lower right ) has gripped on the two whips of the dividing organism and is sending cell processes up to eat up the organism . The immune cell is about ten micrometers in diameter.

Picture of staphylococci ,the bacteria which can cause acne .

Picture of an adult roundworm (Ascaris lumbricoides is the technical name )From the small intestine .The ruler next to it shows

These categories of infectious agents are important factors in deciding what kind of treatment to use .Members of each one of these groups- viruses, bacteria , and so on –have many biological characteristics in common. All viruses , for example ,live inside host cells ,whereas bacteria very rarely do.

An antibiotic is a selective poison. It has been chosen so that it will kill the desired bacteria, but not the cells in our body. Each different type of antibiotic affects different bacteria in different ways. For example, an antibiotic might inhibit a bacterium's ability to turn glucose into energy, or its ability to construct its cell wall. When this happens, the bacterium dies instead of reproducing. At the same time, the antibiotic acts only on the bacterium's cell-wall-building mechanism, not on a normal cell's. Antibiotics commonly block biochemical pathways important for bacteria .These inhabit the growth of bacteria or kill them.Antibiotics do not work on viruses because viruses are not alive and viruses do not use biochemical pathways such as bacteria . A bacterium is a living, reproducing life form. A virus is just a piece of DNA (or RNA). A virus injects its DNA into a living cell and has that cell reproduce more of the viral DNA. With a virus there is nothing to "kill," so antibiotics don't work on it.

Means of spread

of Diseases

THREE COMMON

WAYS ,GERMS ARE SPREAD

Germs can spread to the hands by sneezing, coughing, or rubbing the eyes and then can be transferred to other family members or friends. Simply washing your hands can help prevent such illnesses as the common cold or eye infections.

Nose, mouth, or eyes to hands to others:

Hands to food:

Usually germs are transmitted from unclean hands to food by an infected food preparer who didn’t wash his or her hands after using the toilet. The germs are then passed to those who eat the food. Germs are also transmitted from raw foods, such as chicken, to hands while preparing a meal.

Animals to people:

Wash your hands after petting animals or touching any surfaces they come into contact with.

Direct transmission 

refers to the transfer of an infectious agent from an infected host to a new host, without the need for intermediates such as air, food, water or other animals. Direct modes of transmission can occur in many ways:

Touching

Sexual intercourse

Biting

Direct projection of droplets

Across the placenta

Indirect modes of transmission

Indirect transmission is when infectious agents are transmitted to new hosts through intermediates such as air, food, water, objects or substances in the environment, or other animals. Indirect transmission has three subtypes:

Airborne transmission:

The infectious agent may be transmitted in dried secretions from the respiratory tract, which can remain suspended in the air for some time. For example, the infectious agent causing tuberculosis can enter a new host through airborne transmission.

Vehicle-borne transmission: A vehicle is any non-living substance or

object that can be contaminated by an infectious agent, which then transmits it to a new host. Contamination refers to the presence of an infectious agent in or on the vehicle.

Vector-borne transmission:

A vector is an organism, usually an arthropod, which transmits an infectious agent to a new host. Arthropods which act as vectors include houseflies, mosquitoes, lice and ticks.

Organ-specific and tissue-specific

manifestations

Microbes which enter our body are Likely to go to different Sites in our body such as :-

I) MICROBES WHICH ENTERS THROUGH THE NOSE ARE LIKELY TO GO TO THE LUNGS. FOR EXAMPLE -BACTERIA WHICH CAUSE TUBERCULOSIS OF LUNGS.

II) MICROBES WHICH ENTER THROUGH THE MOUTH ARE LIKELY TO STAY IN THE GUT SUCH AS BACTERIA WHICH CAUSES TYPHOID OR LIVER SUCH AS BACTERIA WHICH CAUSES JAUNDICE.

TYPHOID BACTERIA

III) VIRUS WHICH CAUSES AIDS ENTER THE BODY THROUGH SEXUAL ORGANS DURING SEXUAL CONTACT AND SPREADS THROUGH THE LYMPH TO ALL PARTS OF THE BODY AND DAMAGES THE IMMUNE SYSTEM.

IV) VIRUS WHICH CAUSES JAPANESE ENCEPHALITIS (BRAIN FEVER) ENTERS THE BODY THROUGH MOSQUITO BITE AND GOES AND INFECTS THE BRAIN.

Principles ofTreatments

There two ways to treat an infectious disease. One would be

to reduce the effects of the disease and the other to kill the

cause of disease. For the first, we can provide treatments that will

reduce the symptoms .

The symptoms are usually because of inflammation .for example we can take medicines that bring down fever, reduce pain or loose motions .

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Treatment refers to the process of curing a disease or infection to bring back the organism to his normal health . Basic five principles for treating a disease are: 1) To reduce the symptoms of the disease. This is done by medicine, surgery, injection etc. to relieve the patient from pain and suffering.

2) To remove the cause of disease. Removing the cause will result in avoiding the infection to spread further in the body of the patient. 3) To prevent the spread of the disease from infected individual to the healthy one. 4) To make the patient healthy again by helping him to overcome the effects of the disease like weakness etc. 5) To prevent the reappearance of the disease by vaccinating the person for that disease.

One way is to use medicines that Microbes. The microbes can be Classified into different :-1. viruses2. bacteria3.Fungi4.Protozoa each of these groups of organisms will have some essential biochemical life

Process which is peculiar to that group and not shared with the

other groups. These process may be pathways for the synthesis of new substances or respiration .

These pathways will not be used by us either. For examples ,our cells may make new substances by a mechanism different from that used by bacteria .we have to find the drug that blocks the bacterial synthesis pathway without affecting our own .

This is what is achieved by the antibiotics that we are all familiar with . Similarly, there are drugs that we are drugs that kill protozoa such as the MALERIA PARASITE . There are now effectively anti-viral drugs, for example, the drugs that keep HIV infection under control.

Personal health depends partially on the active, passive, and assisted cues people observe and adopt about their own health. These include personal actions for preventing or minimizing the effects of a disease, usually a chronic condition, through integrative care. They also include personal hygiene practices to prevent

Self- care strategies

The information gleaned from personal observations of daily living – such as about sleep patterns, exercise behaviour, nutritional intake, and environmental features – may be used to inform personal decisions and actions.

infection and illness, such as bathing and washing hands with soap; brushing and flossing teeth;, storing preparing and handling food safely; and many others.

Q1: Which one of the following is an infectious disease?

(a) diphtheria(b) diabetes(c) hypertension(d) cancer

Q2: Elephantiasis disease can have

(a) short-term affect on our health(b) no effect on our health(c) long term affect on our health(d) sometimes bad effect on our health

MCQs

 (

1: (a) diphtheria2: (c) long term affect on our health

Q3: Ascaris worm lives in which part of human body?

(a) kidneys(b) liver(c) small intestine(d) large intestine

Q4: Microbes which enter the body through nose most likely affect

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

Q5: Which of the following is a viral infection?

(a) Diphtheria(b) Influenza(c) Cholera

(d) Typhoid

3: (c) small intestine4: (d) lungs5: (b) Influenza

Q6: HIV virus when active in body mainly attacks on

(a) lungs(b) liver(c) immunity(d) nerves

Q7: An Organism which carries pathogens is termed as

(a) host(b) vector(c) parasite(d) predator 

Q8: Diseases which are always present in certain location are called?

(a) epidemic diseases(b) endemic diseases(c) acute diseases(d) chronic diseases 6: (c) immunity

7: (b) vector8: (a) epidemic diseases

Q9: DPT vaccines are administered to develop immunity against

(a) Tetanus(b) Diphtheria(c) Pertusiss(d) All of these

Q10: Anti-viral drugs are difficult to make because, viruses

(a) live outside the host cells(b) live inside the host cells(c) live in consumed food particles(d) live in blood stream

Q11: BCG vaccine is used to develop immunity against

(a) jaundice(b) polio(c) influenza(d) tuberculosis

9: (d) All of these10: (a) live outside the host cells11: (d) tuberculosis

Q12: Which of the following is a communicable disease?(a) Rickets(b) Scurvy(c) Marasmus(d) Cholera

Q13: The causative organism for malaria is a:(a) bacteria(b) protozoa(c) virus(d) fungi

Q14: Vaccination helps in controlling diseases because (a) it develops resistance against the pathogen attack(b) it kills the pathogens causing disease(c) it blocks the food supplied to pathogens(d) it does not allow pathogens to multiply in hosts

12: (d) Cholera13: (b) protozoa14: (a) it develops resistance against the pathogen attack

Q15: ORS is given in

(a) diarrhea(b) measles(c) typhoid(d) tetanus

Q16: Which of the following is an example of nutritional deficiency disease?

(a) Hypertension(b) Rickets(c) Diabetes(d) Gastroenteritis

15: (a) diarrhea16: (b) Rickets

ANSWER SHORTLY

2-Marks Questions

1.Define antibiotic?Ans: Antibiotic are the chemical substances produced by living organisms such as

bacteria, fungi,etc which can kill or stop the growth

of some pathogenic microorganism such as

fungi , bacteria

2.What are vaccines?Ans: A vaccine is an antigen

that is injected. It causes the development of active immunity in the patient. It stimulates the production of antibodies . There are vaccines against tetanus,

polio, diphtheria etc.

3. What is dehydration?Ans: Dehydration is the loss of water from body tissues which makes the patient dangerously ill in a short time. In case of dehydration the patient

becomes irritable, sudden weight loss, fever

, or fits.

4.How food poisoning is caused?

Ans: Food poisoning by bacteria salmonella is

called salmonellosis. The infection of bacteria is contracted from sick farm animals through their milk , meat or

eggs.

6.List some basic principle of prevention of infectious diseases?Ans: 1) Availability of proper and sufficient

food.2) Have regular check

up’s .3)Try to be in clean

environment.

7. What do you mean by immunity?

Ans: The ability of an organism to resist a

particular infection is called immunity.

8.Give a classification of diseases caused by

protozoa, viruses & bacteria.Ans: Diseases caused by

protozoa- Malaria.Diseases caused by viruses-

Influenza,jaundice,Rabies,Polio

Diseases caused by bacteria -T.B, Cholera, typhoid ,

diarhoea..

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a) Define disease? b)What are the two major categories of human diseases.

Give two examples of each ?Ans a)-Any functional or physical change from the natural state

that cause discomfort or disability is called a disease.Ans b) The major categories of human diseases are :

Communicable (infectious) diseases e.g.- Malaria ,jaundice. Non –communicable (non-infectious)diseases. e.g.– Cancer, diabetes.

What are the causes of non-infectious diseases?Ans- These are not spread to other persons and are not caused by

any infection are called non –infectious. Causes are-i. Genetic abnormabilities: Haemophilia, some type of

cancers .etc.ii. Internal causes : Such as high blood pressure can be caused

by excessive weight and lack of exercise.

QUESTIONS AND ANSWERS(3MARKS)

What is infectious disease and their causes?Ans-These are spread to other person and are caused by microbes are called infectious disease. They are caused by – i) bacteria ii) viruses iii)Fungi iv)protozoan

List the causes of diseases .i. Infection ii. Poor health iii. Lack of proper and sufficient food iv. Lack of public services v. Genetic differences .

List four diseases caused by viruses?Ans- diseases caused by viruses are –• Common cold • Influenza • Dengue fever • AIDS

What are the difference between communicable and non- communicable diseases?

COMMUNICABLE(INFECTIOUS ) DISEASES

NON-COMMUNICABLE (NON-INFECTIOUS )DISEASES

They are infectious diseases .They are transferred from a patient to the healthy person .

They are not infectious diseases and cannot be transferred from a patient to a healthy person.

They are caused by a pathogen (disease causing bacteria).

They are not caused by pathogen.

They are spread through some agency such as air , food , contact ,insects, etc.

They do not spread through any agency.

These are not caused by nutritional deficiency. These are due to infection.

They are caused by nutritional deficiency degeneration of organs or malfunctioning of a vital organ, not caused by infection.

Explain why antibiotics are more effective in curing bacterial diseases than viral diseases.

Ans-Antibiotics are effective in curing bacterial and fungal infections (e.g.-tuberculosis)but they are ineffective in viral diseases (e.g.-common cold ).Antibiotics affect on life process of bacteria and inhibit their growth .On the other hand virus is just apiece of DNA (RNA ),not well defined life form .Viruses can reproduce inside host cells .They do not use biochemical pathways as used by other microbes (bacteria ,fungi , parasites).That's why antibiotic are ineffective in viral infections.

Define antibiotic? Explain how it is able to control bacterial infections but not viral infections?

Ans-Antibiotics (anti means against , biotic –living) are types of medications that destroy or slow the growth of bacteria. They are often termed as antibacterial .They work against the life processes of bacteria .Many bacteria ,for example ,make a cell-wall to protect themselves .The antibiotic penicillin blocks the bacterial processes that build the cell wall. Thus bacteria fail to build their cell –wall, stop multiplying and die out .Human cells don’t make a cell-wall anyway, so penicillin cannot have such effect on us.

Give causes and remedy of i) Hepatitis ii)AIDS iii)MalariaAns - Causes Remedy i) Hepatitis is caused by virus - Hepatitis A and B vaccination (preventive measure) - Avoid eating stale food .

ii) AIDS is caused by HIV. - Avoid any type of infection - Now anti – viral drugs that keep HIV infection under control are available .

iii) Malaria is caused by -Avoid breeding of mosquito in stagnant

Plasmodium(Protozoan microbe) water ditches ,ponds,etc. Spread by bite of female - Consult doctor for treatment .Anopheles mosquito. -Use mosquito repellents.

What Is Cancer? What Causes Cancer?ANS-Cancer is a class of diseases characterized by out-of-control cell growth. There are over 100 different types of cancer, and each is classified by the type of cell that is initially affected.Cancer harms the body when damaged cells divide uncontrollably to form lumps or masses of tissue called tumors (except in the case of leukemia where cancer prohibits normal blood function by abnormal cell division in the blood stream). Tumors can grow and interfere with the digestive, nervous, and circulatory systems, and they can release hormones that alter body function. Tumors that stay in one spot and demonstrate limited growth are generally considered to be benign. More dangerous, or malignant, tumors form when two things occur:1.a cancerous cell manages to move throughout the body using the blood or lymph systems, destroying healthy tissue in a process called invasion 2.that cell manages to divide and grow, making new blood vessels to feed itself in a process called angiogenesis. When a tumor successfully spreads to other parts of the body and grows, invading and destroying other healthy tissues, it is said to have metastasized. This process itself is called metastasis, and the result is a serious condition that is very difficult to treat.

Long type questionQ -1 What is AIDS to be a ‘Syndrome’ and not a disease ?Ans-AIDS causing virus (HIV)enters the body of a person generally blood transfusion and spreads to lymph nodes . It damages our immune system and, thus, body no longer is able to fight off many minor infections. Instead, even a small cold infection can become pneumonia or minor gut infection may lead to severe diarrhoea with blood loss.

The effect of minor diseases become to severe that they kill

the patients suffering from AIDS . In other words, there are no

specific disease symptoms for AIDS and the patients develops

complex diseases and symptoms. Therefore, AIDS is termed as

‘syndrome’ and not a disease.

Q-2 what precautions will you take to justify “prevention is better than cure”Ans- the precautions are :-• Sanitation• Sterilization• Eradication of vectors• Proper and suffi cient food • Education• Isolation• Immunization against diseases

Q-3 write the about infectious disease?Ans-INFECTIOUS DISEASES1.These occur due to external ( extrinsic) factors .2. These are caused by the attack of pathogens (viruses, bacteria, fungi, protozoans, worms)3. These can spread from infected person to healthy person (s).4.Infection is transmitted through direct contact or through medium (air, water ,food , insects ,etc. )

Q-4 What do you mean by vaccination? Who first conceived the idea of vaccination?Ans- vaccination is a technique in which a preparation of antigenic protein of pathogen or weakened or dead pathogens are injected into a person to develop immunity in him with infection.Edward Jenner first conceived the idea of vaccination.

Q-5 What do you mean by disease symptoms ? Explain giving two examples?Ans- symptoms of the disease are the manifestation or evidences of the presence of disease (s). These indicate that there is some abnormality in the body.EXAMPLES :- (i) Cough and breathlessness are symptoms of lung infection .(ii) Yellowness of sclera (white portion ) of eye and skin are symptoms of jaundice.

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