Download CANCER = UNCONTROLLED CELL DIVISION

CANCER = UNCONTROLLED CELL DIVISION
Cancer cells do not respond normally to the body’s control.
Many different forms of cancer affecting different tissues of the body.
In cancer, cells divide by mitosis repeatedly without control or regulation. An
irregular mass of cells called tumour is formed. Sometimes tumour cells break away
and carried to other parts of the body forming a secondary tumour. Unchecked
cancerous cells ultimately take over the body leading to malfunction and death.
Cancers are thought to start when changes occur in the genes that control cell
division. Mutated gene that causes cancer is an oncogene, a change in any gene
called mutation.
Mutations are not unusual events, and most mutated cells are either crippled in
some way that results in their early death or destroyed by the immune’s system.
It is thought that a single mutation cannot be responsible for cancer but several
independent accidents must occur in all cells. A factor which brings any mutation is
called mutagen. Any agent that cause cancer is called carcinogenic. Some factors
which can increase mutation rates are :
o
Ionizing radiation
o
Chemicals
o
Virus infection
o
Hereditary predisposition
Benign or malignant?
A small group of tumour cells is called a primary growth. 2 types: benign and malignant.
If the abnormal cells remain at the original site, the lump is called benign tumour.
Most benign tumour do not cause serious problems and can be completely removed
by surgery.
Malignant tumour becomes invasive enough to impair the functions of one or more
organs. Individual with malignant tumour is said to have cancer.
Malignant tumour interfere with the normal functioning of the area where they have
started to grow. They may block the intestines, lungs or blood vessels to other parts
of the body to form secondary growths. There, they may proliferate and form new
tumour. This spread of cancer cells to locations distant from their original site is
called metastasis. It is the most dangerous characteristics if cancer, since it can be
very hard to find secondary cancers and remove them.