What are Cells?
Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy and carry out specialised functions.
What is a cell made of? A cell is made up of three parts: the cell membrane, the nucleus and the cytoplasm.
What is a cell membrane? This is also called the plasma membrane. This is found in all cells and separates the interior of the cell from the outside environment. The cell membrane regulates the transport of materials entering and exiting the cell.
What is the nucleus? This is the control hub of the cell. Inside the nucleus are 23 pairs of chromosomes made up of genes. Genes are coded messages that tell cells how to behave. They control how our bodies grow and develop. We have about 25,000 genes with information we inherit from our parents.
What is cytoplasm? This is a gel-like fluid inside the cell. All the functions for cell expansion, growth and replication are carried out in the cytoplasm of a cell.
The organs and tissues of our body are all made up of cells. Cancer is a disease of these cells and is caused by an uncontrolled growth of abnormal cells, causing them to multiply, which may happen in any part of the body. The abnormal cells grow more rapidly than normal cells and eventually form a cancerous lump called a tumour. The cancerous lump then competes with normal cells for nutrients and blood supply. Eventually the cancerous cells may spread into the bloodstream or grow into surrounding structures, making it more difficult or even impossible to cure. The earlier the cancer is detected the better chance there is of halting its spread, a cure and living longer.
How does Cancer grow?
Primary Tumour – This is the name for where a cancer starts.
Secondary Tumour or Metastasis – when cancer spreads to other parts of the body.
Benign tumours (lumps) – benign means it is not cancerous. These cells usually grow very slowly and don’t spread to other parts of the body and can have a covering made up of normal cells. They only cause a problem if they grow very large, become uncomfortable or painful, are visible and unpleasant to look at, press on other body organs, take up space inside the skull or release hormones that affect how the body works.
Malignant tumours – These lumps are made up of cancerous cells and grow faster than benign tumours, spreading into surrounding tissues and causing damage. They may spread to other parts of the body in the bloodstream to form secondary tumours. This is called metastasis.
How does cancer get bigger?
Carcinoma in situ (CIS) – This is when cancer cells start by staying inside the tissue they developed in and is also known as superficial cancer growth.
Invasive cancer – All body tissues have a layer (membrane) that keeps the cells of that tissue inside. Cancer cells can break through this membrane. The cancer is then called an invasive cancer if it breaks through this membrane.
Tumour – this is when the cancer cells grow and divide to create more cells eventually forming a tumour, which may contain millions of cancer cells.
As the tumour gets bigger, its centre gets further and further away from the blood vessels in the area where it is growing. Cancer cells can’t live without oxygen and nutrients, so they send out signals which encourage new blood vessels to grow into the tumour. Without a blood supply, a tumour can’t grow much bigger than a pin head. Once a cancer can stimulate blood vessel growth, it can grow bigger. It stimulates hundreds of new small blood vessels to grow and to bring in nutrients and oxygen.
How does cancer affect our body systems?
Cancer and its treatments can cause significant changes in the body. Some cancers may block channels in the body and stop some body systems from working properly, as well as causing changes in the body by pressing on surrounding body tissues and organs.