Glossary: Human Health & Diseases | Biology for Grade 12 PDF Download

Common Diseases in Humans

• Pathogens: Disease causing organisms are called pathogens.
• Amoebiasis: Entamoeba histolytica is a protozoan parasite in the large intestine of human which causes amoebiasis (amoebic dysentery).
• Elephantiasis: Wuchereria (W. bancrofti and W. malayi), the filarial worms cause a slowly developing chronic inflammation of the organs in which they live for many years, usually the lymphatic vessels of the lower limbs and the disease is called elephantiasis or filariasis.

Immunity

• Immunity: Overall ability of the host to fight the disease-causing organisms, conferred by the immune system is called immunity.
• Primary Response: Our body when it encounters a pathogen for the first time produces a response called primary response.
• Active Immunity: When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called active immunity.
• Passive Immunity: When ready-made antibodies are directly given to protect the body against foreign agents, it is called passive immunity.
• Allergy: The exaggerated response of the immune system to certain antigens present in the environment is called allergy.
• Auto Immune Disease: due to genetic and other unknown reasons, the body attacks self-cells. This results in damage to the body and is called auto-immune disease.

AIDS

• Retrovirus: AIDS is caused by the Human Immuno deficiency Virus (HIV), a member of a group of viruses called retrovirus, which have an envelope enclosing the RNA genome.

Cancer

• Contact Inhibition: Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth.
• Tumor: Cancerous cells just continue to divide giving rise to masses of cells called tumors.
• Benign tumors: Benign tumors normally remain confined to their original location and do not spread to other parts of the body and cause little damage.
• Malignant tumors: The malignant tumors, on the other hand are a mass of proliferating cells called neoplastic or tumor cells.
• Carcinogens: Transformation of normal cells into cancerous neoplastic cells may be induced by physical, chemical or biological agents. These agents are called carcinogens.

Drugs and Alcohol Abuse

• Cannabinoids: Cannabinoids are a group of chemicals, which interact with cannabinoid receptors present principally in the brain. 
• Opioids: Opioids are the drugs, which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract.
• Heroin: Heroin, commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound.
• Cocaine: Coca alkaloid or cocaine is obtained from coca plant Erythroxylum coca. It interferes with the transport of the neuro-transmitter dopamine.

Abbreviations

• MALT:  Mucosa Associated Lymphoid Tissue
• AIDS: Acquired Immuno Deficiency Syndrome
• ELISA: Enzyme linked immuno-sorbent assay