Human Health And Disease-Quick Revision

Health

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

Methods of transmission of disease

Methods of transmission of diseases are as follows:
1. Direct transmission – The spread of disease from one host to another host.
2. Indirecttransmission – The spread of disease from host to host by means of a vector. A vector is usually some type of invertebrate animal.

Vaccination

1. Vaccination is the introduction of any kind of dead or weakened germs into the body of a living being to develop immunity (resistance) against the respective disease or diseases.

Immunisation

1. Immunisation is developing resistance to disease-producing germs or their toxins by introducing killed germs or germ substance to induce the production of specific antibodies.

Types of immunity

There are two major types of immunity: innate or natural or nonspecific and acquired or adaptive immunity.
1. Innate immunity is inherited by the organism from the parents and protects it from birth throughout life. For example, humans have innate immunity against distemper, a fatal disease of dogs.
2. The immunity that an individual acquires after the birth is called acquired immunity or adaptive immunity. It is specific and mediated by antibodies or lymphocytes or both which make the antigen harmless.

Active immunity and passive immunity

The difference between active and passive immunity are as follows:

Active immunity	Passive immunity
1. Produced by one’s own body.	1. Received from outside.
2. It is developed by an individual’s own cells in response to an infection or a vaccine.	2. It is developed when ready-made antibodies are inoculated from outside.
3. It provides effective and long lasting protection.	3. The protection is less effective and short lived.
4. It has no side effects.	4. It may cause reactions.
5. Time is required for the effectiveness of the immunity.	5. Immediately effective.

Definition of antigen

1. Antigens are substances which, when introduced into the body, stimulate the production of antibodies.

Definition of antibody

1. Antibodies are immunoglobulins which are produced in the body in response to the antigen or foreign bodies.

Allergy

1. Allergy is the hypersensitiveness of a person to some foreign substance coming in contact with or entering the body.

Autoimmune diseases

1. If the immune system fails to recognize self from non-self and starts destroying the body’s own tissues, this leads to some malfunctions which are called as autoimmune diseases.
2. For example, Addison’s disease, Grave’s disease, Type I diabetes, rheumatoid arthritis, multiple sclerosis, etc.

Symptoms and transmission of AIDS

The symptoms of AIDS are as follows:
1. Some people may experience a flu-like illness within 2-4 weeks after HIV infection.
2. But some people may not feel sick during this stage.

Aids can be transmitted by any one of the following methods.
1. Sexual intercourse
2. Contaminated blood transfusion
3. Mother to child transmission
4. Injected needles

Oncogenes

1. The uncontrolled and abnormal multiplication of cells is known as cancer.
2. Cancer is mainly of two types malignant and benign.
3. Malignant cancer can spread from one organ to the other. So this is known as metastasis. Benign cancer cannot spread.
4. There are specific genes which translate abnormally to produce mutant proteins and may lead to cancer. Such genes are known as oncogenes.

Drug abuse

1. Drug abuse is the use of a drug or other substance affecting mood or behaviour and sold for non-medical purposes or in excessive amounts leading to addiction.
2. Harmful effects of drug abuse are impaired health, tendency to commit crimes like theft, rape or murder.

Alcohol abuse

1. Alcohol addiction refers to a psychological and physical dependency on alcohol.

Prevention and control of drug and alcohol abuse

1. Avoid undue peer pressure
2. Education and counselling
3. Seeking help from parents and peers
4. Looking for danger sign
5. Seeking professional and medical helps

Stages in the Life Cycle of Plasmodium