WHY DO WE FALL ILL ?

Introduction

Health

Health is a state of well being wherein we can carry out all normal functions physically, mentally and socially.

The Immune System

Immune system

An immune system is the part of the body that provides protection against infection from external agents and toxins.
An immune system is more of a process than an organ.

Skin and Mucous Membranes

Skin and Mucous membranes provide the first layer of defence.
While skin protects the body externally, mucous membrane protects the insides of the body.
Apart from these, white blood cells present in the blood and lymph are the important components of our immune system.

WBC

WBC or White Blood Cells are the most important part of the immune system.
They attack and kill the pathogens.
WBCs are of different types and get their names based on the location as well.

Neutrophils

It is a type of immune cell that has granules with enzymes that are released during infections and allergic reactions.

Macrophages and NK Cells

Macrophages are in-house eliminators, kill the own body cells.
They attack cancer cells through destruction and ingestion.
Natural Killer Cells bind to the enemy cell and they dissolve the membrane so the cell can't function.

Dendritic Cells

Dendritic cells create memory and carry information about the pathogens to the liver, spleen, lymph nodes.

Inflammatory Response

An inflammatory response is seen in the body when it gets injured or infected by a pathogen.
Inflammations help in the localization of the issue and prevent it from spreading.

Diseases

A disease is a discomfort the body experiences physically or mentally.
A disease could be caused due to external or internal factor.

Acute Diseases

Acute diseases are those which lasts for a very short time.
These diseases can be fatal and are usually caused by an external agent.

Chronic Diseases

Chronic diseases are those which lasts for a long time.
They take a lot of time to heal and can be caused by any external or internal factor.

Symptoms and sign

When the body gets diseased, it shows certain symptoms and signs of illness.
These symptoms and signs help in identification and diagnosis of the disease.
A symptom is felt by the affected person while sign can be detected by another person.
A symptom is thus, subjective and a sign is objective.

Causes of Disease

Different types of Causes of Disease

Diseases can be caused due to pathogens such as virus or bacteria.
Some diseases can also be due to internal factors such as genetic mutation.

Infectious Diseases

Diseases that are caused by pathogens and can spread to other individuals in the populations are called infectious diseases.

Non-infectious diseases

Diseases that cannot spread from one individual to another are called as non-infectious diseases.

Usually, these diseases are not caused by a pathogen.

Pathogens

Pathogens are external agents that cause diseases in other organisms.
Usually, a pathogen is a microorganism such as bacteria, virus or protozoa.

Vector

Vectors are those organisms that carry a pathogen from the host to a recipient.
Mosquito, rats and mice are some of the common vectors that carry infectious diseases.

Bacteria

Bacteria are microorganisms that are seen in almost all environmental condition.
Not all bacteria are harmful pathogens.
Some bacteria are also beneficial to human beings.
Examples of bacterial diseases are cholera, typhoid, pneumonia, tuberculosis etc.
Bacteria are beneficial for, digestion, extracting antibiotics from them, nitrogen fixation etc.

Virus

A virus is a microorganism that is always pathogenic in nature.
They do not have a replicating machinery.
Therefore they enter the host cell and replicate and in the process destroy the host cell.
Few of the common diseases spread by the viruses are cold, influenza, dengue fever AIDS etc.

Fungi

Fungi are a group of organisms which are eukaryotic in nature and saprophytic in nutrition.
They could be either unicellular or multicellular organism.
Many common skin infections are caused by fungi.

Parasites

A parasite is an organism that lives in another organism, called the host, and often harms it.
It is dependent on its host for survival - it has to be in the host to live, grow and multiply.

Infections

AIDS

AIDS stands for Acquired Immunodeficiency Syndrome.
It is caused by the Human Immunodeficiency Virus.
AIDS systematically destroys the immune system of the patient, leaving them vulnerable to the easiest of the diseases.

Prevention of Disease

Antibiotics

Antibiotics, also called antibacterials, are a type of antimicrobial drugs used in the treatment and prevention of bacterial infections.

Antibiotics act in the following ways:

Inhibition of Cell Wall Synthesis (most common mechanism)
Inhibition of Protein Synthesis (Translation) (second largest class)
Alteration of Cell Membranes.
Inhibition of Nucleic Acid Synthesis.
Antimetabolite Activity.

Preventive Measures

Preventive measures can be taken to avoid infection of various diseases.
The most common measure is maintenance hygienic condition.

Immunization

Immunization is the process whereby a person is made immune or resistant to an infectious disease.
Vaccines are the common means to immunize people.

Health is a general condition of a preson’s mind and body. According to WHO (World Health Organisation) health is a “state of physical, metal and social well-being of a person”.

To make people aware and conscious of keeping healthy and disease-free we celebrate WORLD HEALTH DAY on 7th April.

• ‘Health’ is a state of being well enough to function well physically, mentally and socially.

• Disease : Any disturbance in the structure or function of any organ or part of body.

• The various causes of diseases are pathogens (virus, bacteria), lack of nutritious diet/balanced diet and lack of public health services.

• Acute diseases occur suddenly and lasts for a short duration while chronic diseases develop slowly and lasts for long period of time.

• The diseases/infections can be prevented by life style (exercise, proper sleep, enough relaxation) modification, taking balanced diet, good personal health and hygiene and also maintaining a clean and healthy surrounding.

• Treatment involves killing of the microbes/pathogens.

Health

• 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.

• Good physical and social environment includes clean surroundings, good sanitation, proper garbage disposal and clean drinking water.

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

Personal and Community Issues Both Matter for Health

Community Health :

• All those activities which people do both individually and in groups for the development of their society, constitute the community health.

• Personal and community health are supplementary to each other.

• We protect ourselves by keeping our body clean.

• For this, we also require a good and healthy environment in our surroundings.

• We can have this only by the means of community health and development.

• So, both personal and community health are inter-related.

Differences between Being Healthy and Disease-free

Being Healthy

1. It is a state of being well enough to function well physically, mentally and socially.

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

Being Disease-free

1. It is a state of absence from diseases.

2. It refers only to the individual.

3. The individual has good health.

3. Te individual may have good health or poor health.

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

• These changes give rise to symptoms and signs of disease.

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

Types of Diseases

(i) Acute Diseases : Acute diseases which last for only very short period of time and affect body suddenly and quickly. E.g., Cold, cough, typhoid etc.

(ii) Chronic Diseases : The diseases which last for a long time, even as much as a life time, are called chronic diseases. E.g., Diabetes, tuberculosis, elephantiasis etc.

Causes of Diseases

Diseases are caused by :

• Pathogens like virus, bacteria, fungi, protozoans or worms.

• Poor health and under nourishment.

• Hereditary and genetic disorder.

• Lack of proper treatment of immunization.

• Environmental pollution (air, water etc.)

Infectious and Non-infectious Diseases

(i) Infectious Diseases : The diseases which spread due to infection by micro-organisms are called infectious diseases. It is communicated from diseased person to healthy person, caused by some biological agents/pathogens like viruses, bacteria, fungi, protozoans, fungi worms.

(ii) Non-infectious Diseases : The disease which does not spread by contact between infected and healthy person through air and water, is called non-infectious disease. E.g., Arthritis, heart disease.

Pictures of Different Micro-organisms

(i) The picture shows SARS viruses coming out of the surface of an infected cell (see the arrows for example).

(ii) 500 nanometer = 0.5 micrometer = 0.001 millimeter.

(i) The picture shows Trypanosoma, a protozoan organism.

(ii) It causes sleeping sickness.

(iii) The saucer-shaped substance lying next to the protozoa, is a red blood cell.

(i) The picture shows Staphylococcus bacteria.

(ii) The Staphylococcus bacteria causes acne.

(iii) The scale is indicated at the line at the top left of the picture. It is 5 micrometers long.

(ii) Its technical name is Ascaris Lumbricoides.

(iii) The ruler next to it shows 4 centimeter to give an idea of the scale

Micro-organisms :

S. No. Infectious Agents Diseases

1. Viruses Common cold, influenza, measles,

chicken pox, AIDS, Hepatitis-B etc.

2. Bacteria Cholera, typhoid, TB, tetanus,

anthrax, food poisoning etc.

3. Fungi Skin infections

4. Protozoan Malaria, kala-azar, amoebic

dysentery, sleeping sickness

5. Worms Intestinal infections, elephantiasis

Antibiotics

• Antibiotics blocks biochemical pathways important for bacteria. Hence, they are effective against them. E.g., Penicillin, tetracycline.

• Many bacteria make a cell wall to protect themselves, the antibiotics (Penicillin) blocks the bacterial process that builds cell wall.

• Antibiotics works only against the bacteria and not against the viruses.

Common method of transmission of diseases

(Diseases spread from affected person to healthy person.

Means of Spread of Infectious Diseases

Infectious diseases spread from an infected person to a healthy person through air, water, food, vectors, physical contact and sexual contact.

• Through air : By sneezing and coughing, the microbes spread into air and enter into the body of a healthy person, like common cold, tuberculosis, pneumonia etc.

• Through water : The microbes enter into our body by drinking/eating polluted and contaminated water/food, like cholera, amoebic dysentery etc.

• Vectors : Some organisms like female anopheles mosquito also work as a vector of disease, like malaria, dengue, yellow fever etc.

• Through sexual contact : Syphilus, AIDS spread by sexual contact with infected person. AIDS virus can also spread through blood transfusion and from the mother to her child during pregnancy and through breast feeding.

AIDS (Acquired Immuno Deficiency Syndrome)

Causes :

AIDS is caused by a retro-virus called HIV (Human Immuno Deficiency Virus).

Method of transmission of AIDS :

The transmission of AIDS from an infected to a healthy person takes place :

• through sexual contact

• blood transfusion

• use of infected needle or blade etc.

• This may also get transmitted from infected mother to her foetus.

Prevention :

• Avoid transfusion of infected blood. This can be done by testing whether the blood is HIV negative or not.