Middle School Life Science: Diseases and the Body's Defenses - Noninfectious Diseases — Flashcards

Noncommunicable diseases (NCDs), also known as chronic diseases, tend to be of long duration and are the result of a combination of genetic, physiological, environmental and behavioural factors.

Cancer is a disease in which cells divide out of control. The rapidly dividing cells may form a mass of abnormal tissue called a tumor. As a tumor increases in size, it may harm normal tissues around it. Sometimes cancer cells break away from a tumor. If they enter the bloodstream, they are carried throughout the body. Then the cells may start growing in other tissues. This is usually how cancer spreads from one part of the body to another. Once cancer spreads, it is very hard to stop.    
Most cancers are caused by mutations. Mutations are random errors in genes. Mutations that lead to cancer usually occur in genes that control the cell cycle. Because of the mutations, abnormal cells are allowed to divide. Some mutations that lead to cancer may be inherited. However, most of the mutations are caused by environmental factors, such as certain chemicals and some types of radiation.    
Many cases of cancer can be cured if the cancer is diagnosed and treated in an early stage. Therefore, it's important to know the warning signs of cancer so it can be diagnosed as early as possible. Having warning signs doesn't mean that you have cancer, but you should check with a doctor to be sure. Warning signs of cancer include:    
- a change in bowel or bladder habits.    
- a sore that doesn't heal.    
- unusual bleeding or discharge.    
- a lump in the breast or elsewhere.    
- persistent indigestion.    
- difficulty swallowing.    
- obvious changes in a wart or mole.    
- persistent cough or hoarseness.