Why Do We Fall Ill

Chapter-13 Why Do We Fall Ill Anything that prevents proper functioning of cells and tissues will lead to a proper lack of proper activity of the body. When a person experiences such a condition, he is said to be ‘ill’ or ‘in poor health’. What is health?

•A state of ‘being well’ •A state of being well enough to function well physically, mentally and socially. Which are the factors important for staying in good health?

•Physical Environment •Social Environment •Cleanliness (Personal Hygiene and Public Cleanliness) •Good Food •Good economic conditions •Social Equality and harmony (an example of how community issues effect individual health) •To have the opportunity to realise the unique potential in all of us Disease= Dis Ease=Disturbed Ease and there is a specific cause for this discomfort. Disease is any harmful change that interferes with the normal appearance, structure, or function of the body or any of its parts. Conditions essential for being free of a disease

•There should be no discomfort to the individual. •There should be no specific and particular cause for a discomfort Difference between being ‘healthy’ and ‘disease free’

•It is possible to be in poor health without actually suffering from a disease •When we think about health, we think about societies and communities •When we think about disease, we think about individual sufferers To identify a disease, we look for signs and symptoms. Symptoms are

•Unfavorable change in the functioning or appearance of one or more systems of the body. •Signs – things we feel as being “wrong”. •Symptoms give an indication of the disease. Example: Headache, cough, fever, loose motions, pus in the wound etc are symptoms Laboratory tests are done to confirm the presence and type of disease.

Types of Diseases (based on Duration)

Acute Diseases Eg. Common Cold

Chronic Diseases Eg. Elephantiasis

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An Acute disease does not cause major effects on general health

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A Chronic disease will cause major effects on general health(Loss of weight, feeling tired all the time, being short of breath)

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An acute disease may affect a person for a few days or weeks

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A chronic disease may affect a person for years

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An acute disease will not cause drastic long term affects on the health of a person.

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A Chronic disease will cause drastic long term affects on the health of a person.

(Prolonged general poor health)

Causes of Diseases (These are just examples and are not to be generalized for every disease.) Immediate Causes ●

Contributory Causes

Infection by Microorganisms

(Pathogens=Disease causing organisms)

First Level Cause Infection by Microorganisms

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Lack of nourishment

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Economic Status of the Household

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Genetic Factors

Second Level Cause Lack of Good nourishment

Third Level Cause Poverty and lack of public services

Infectious causes

Non infectious Causes

are usually external causes

are usually internal causes

Eg. Infectious agents like microbes

Eg. Some cancers are caused by genetic abnormalities

Microbes can spread in the community and infect others

Cannot infect others

Lead to Infectious Diseases

Lead to Non-Infectious Diseases

Control of the disease depends on

•the type of Disease •the immediate causes •are they infectious or non infectious Infectious diseases are caused by Infectious Agents i.e. the microorganisms.

Name of the Disease

Caused by (Infectious Agents)

Special Biological Characteristics

Common Cold, Influenza, Dengue, AIDS

VIRUSES

Live inside host cells Multiply very quickly

Typhoid fever, Anthrax, Tuberculosis, Cholera

BACTERIA

Live inside host cells Multiply very quickly

Common Skin Infections like Ringworm

FUNGI

Live inside host cells Multiply very quickly

Malaria, Kala-azar

Protozoans

Multiply very quickly

Some intestinal Infections, Elephantiasis

DIFFERENT SPECIES OF WORMS

Multiply slowly

Other Examples: 

Staphylococci, a bacteria causes acne on skin

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Trypanosoma, a protozoan causes Sleeping Sickness.

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Leishmania, a protozoan causes Kala-azar.

Controlling the Infectious Agents: •Closely related groups have similar life processes. •Therefore , drugs that block one of these life processes in one member of the group is likely to be effective against other members of the group.

•However , the same drug may not work against a microbe belonging to a different group. What are Antibiotics?

Antibiotics (Greek anti, “against”; bios, “life”) are chemical compounds used to kill or inhibit the growth of infectious organisms. •Commonly block biochemical pathways important for the growth of bacteria. •Example- An antibiotic – Penicillin blocks the bacterial processes that build cell wall. If human beings take Penicillin, it will not effect humans as human cells do not have cell walls.

•therefore antibiotics will control a number of bacterial infections. •Antibiotics do not work against viral infections as viruses do not have the same biochemical processes as bacteria.

•That is why an antibiotic does not control viral infections like common cold. Spread of Infectious Diseases/How they can be communicated? Since the infectious agents(microbes can move from an affected person to a healthy person, therefore these diseases are also called Communicable Diseases.

Medium for spread of the disease

Air

Process of spread of the disease

Names of Diseases that can be spread this way

When an infected person sneezes or coughs, little droplets are thrown out by him.

Common Cold, Pneumonia, Tuberculosis.

When the excreta from someone suffering from an infectious disease of digestive system, such as Cholera gets mixed with drinking water, and this water is used by a healthy person.

Cholera

Sexual Act

Sexually transmitted Disease

AIDS, Syphilis

(Sexually Transmitted Diseases)

Not spread by casual physical contact like handshakes, hugs etc.

Animals

These animals are called VECTORS or INTERMEDIARIES

(Airborne Diseases) Water (Waterborne Diseases)

(Eg. Mosquitoes and dogs)

Malaria, Rabies

Carry infecting agent from a sick person to a potential host.

How does the AIDS virus spread from a healthy person to a diseased person? 1.Sexual Contact, 2. Blood to Blood contact with infected people, 3. Infected mother to her baby during pregnancy, 4. Infected mother to her baby through breast feeding.

Why do the female mosquitoes of a species, suck blood from warm blooded animals like human beings? Because the female mosquitoes need highly nutritious food in the form of blood, in order to lay mature eggs.

Manifestation of the Disease(In what ways does the disease affects a person) How does the microbe enter the body

Organ/ tissue likely to be targeted by the microorganism

Symptoms of the Disease

Through air via nose

Lungs

Sneezing , coughing

Tuberculosis

Through Mouth

Gut Lining or Liver

Diarrhea etc.

Typhoid,Jaundice

By Mosquitoes

Liver, Red Blood Cells Shivering, fever, Jaundice Malaria

By Mosquitoes

Brain

Headache, fever, vomiting, fits, unconsciousness The above table shows some specific effects.

Examples of Diseases

Japanese Encephalitis

There are COMMON EFFECTS too. The body’s immune system is activated in response to an infection. An active immune system will send to the affected tissue to kill the pathogens. This causes inflammation.

Local effects of inflammation=swelling and pain General Effects of inflammation=fever

Limitations to Principles of treatment for infectious diseases: 1) The body functions may be damaged due to the disease and the patient may never recover completely. 2) Treatment takes time and may cast a lot of money. 3) the infection may spread to other people.

THAT IS WHY PREVENTION OF DISEASES IS BETTER THAN THEIR CURE Principles of Prevention Two types of methods: a) General Methods

b) Methods Specific to a disease General Methods of prevention: Prevent exposure and availability of proper and sufficient food to build a strong immune system. How to prevent exposure: Type of Disease/Microbe

Air Borne

How to prevent exposure By providing living conditions that are not overcrowded.

Water Borne

By providing safe drinking water, treating water to kill microbial contamination

Vector Borne

Clean environment that does not allows mosquitoes to breedPublic Hygiene

Specific Methods of prevention-are disease specific Immunization ie Vaccination by which we can fool the immune system into developing antibodies against a disease. By this method the body builds up ‘strength’ to fight against a disease. Questions: 1) Why is it difficult to make antiviral medicines? 2) What is HIV-AIDS? How does this disease spread from one person to another? List the symptoms of this disease. What are its general effects? How does a person suffering from AIDS die? 3) How was small pox eradicated? 4) Why are children living in many parts of India usually immune to Hepatitis –A? 5) Name five disease against which vaccines are available. 6) Comment on the following statement: ‘ Having a disease means preventing subsequent attacks of the same” [email protected] http://biology-secondarylevel.blogspot.com