Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.
Definitions [17]
Define homeostasis.
It is to maintain a stable equilibrium of the body in accordance with the pressures and changes of the body environment.
Definition: Health
Define the following.
Pathogen
A pathogen is a biological agent that causes disease to its host. e.g. bacteria, virus, etc.
Definition: Disease
Any deviation from normal state of health is called disease.
Define the following:
Disease
Disease:
The disease can be defined as an impairment or malfunctioning of the normal state of the living organism that disturbs or modifies the performance of vital functions of the body.
Definition: Communicable or infectious diseases
A disease caused by a specific pathogenic organism and capable of being transmitted to another individual by direct or indirect contact is known as communicable (infectious) disease.
Definition: Non-communicable or non-infectious diseases
A disease not caused by pathogenic organisms and not transmitted from one person to another by direct or indirect contact is known as a non-communicable (non-infectious) disease.
or
The diseases which don’t spread from infected person to a healthy person are known as non-communicable or non-infectious diseases.
Definition: Cancer
Cancer is a disease characterised by uncontrolled and abnormal division of body cells due to loss of normal growth regulation.
Definition: Tumour
Tumour is a mass of abnormally proliferating cells formed due to uncontrolled cell division.
Definition: Metastasis
Metastasis is the process by which cancer cells spread from the primary site to distant organs through blood or lymph.
Definition: Benign tumour
Benign tumour is a non-cancerous tumour that remains confined to its original site and does not spread to other parts of the body.
Definition: Malignant tumour
Malignant tumour is a cancerous tumour that grows rapidly, invades surrounding tissues and spreads to distant organs.
Definition: Vaccination
The process of administering a vaccine to stimulate the immune system and provide protection against infectious diseases is called vaccination.
Definition: Vaccine
A preparation containing specific antigens that is administered to induce temporary or permanent immunity against a particular disease is called a vaccine.
Define the following.
Vaccines
Preparation of antigenic proteins of pathogens (weakened or killed) which on inoculation into a healthy person provides temporary/permanent immunity against a particular disease.
Define the following:
Antibiotics
Antibiotics are metabolic products of microorganisms whose very low concentrations are inhibitory or detrimental to other microbes.
Define the following:
Infection
Infection is the entry, development, or multiplication of an infectious agent in the human body or animals.
Key Points
Key Points: Cancer
- Meaning: Cancer is the abnormal, uncontrolled division of cells forming a mass called a neoplasm/tumour. Cancer cells lack contact inhibition and compete with normal cells for nutrients.
- Benign Tumour: Grows slowly, stays restricted to its site of origin (localised), and does not spread. It can still be harmful (e.g., brain tumour). Examples — Adenoma, Fibroid.
- Malignant Tumour: Grows rapidly, invades surrounding tissues, and spreads to other organs via blood or lymph, forming secondary tumours. This spreading process is called metastasis.
- Types of Cancer: Based on tissue affected — Carcinoma, Sarcoma, Lymphoma, Leukaemia, and Adenocarcinoma.
- Causes: Chemicals (e.g., nicotine), radiation (X-rays, gamma rays), viruses (oncogenic), oncogenes, and addictive substances (e.g., tobacco).
- Diagnosis & Treatment: Diagnosed by biopsy. Treated by radiation therapy (X-rays/gamma rays), chemotherapy, immunotherapy, and surgery.
Key Points: Vaccination and Immunization
- Principle: Works on the immune system's memory. A vaccine (weakened/inactivated pathogen or its proteins) stimulates antibody production and generates memory B and T-cells.
- On Re-exposure: Memory cells quickly recognise the pathogen and produce massive antibodies to neutralise it.
- Passive Immunisation: Preformed antibodies/antitoxins are directly injected when quick response is needed (e.g., tetanus, snakebite).
- Types of Vaccines: Protein/sugar from pathogen, dead/inactivated pathogen, toxoid, or attenuated (weakened) pathogen.
- Recombinant DNA Vaccines: Antigenic polypeptides produced in bacteria/yeast for large-scale production (e.g., Hepatitis B vaccine from yeast).
