How do tumors form?
when cells grow and divide at an abnormal rate
another word for tumor
neoplasm
Neoplasms are classified as _______ or _______.
benign or malignant
Benign tumors:
- local
- often encapsulated
- tend to grow slowly
- seldom kill their hosts if removed before they compress vital organs
Malignant tumors:
- non encapsulated
- spread to other parts of the body
- grow relentlessly
Cancer cells are also called _______.
malignant neoplasms
Define metastasis
spread of a tumor from its site of origin to distant sites
_________ and _______ distinguish cancer cells from the cell of benign neoplasms.
Metastasis and invasiveness
What changes a normal cell into a cancerous one?
radiation, mechanical trauma, certain viral infections, chronic inflammation, many chemicals, and toxins
The factors that change a normal cell into a cancerous one cause ________.
mutations
What are carcinogens?
substances that gives rise to cancer; a cancer forming agent
What are the defenses the body has against carcinogens?
- the liver inactivates many of them
- cells have intrinsic DNA repair mechanisms to help undo mutations
- some immune system cells continuously scan the body cells and eliminate any cancerous cells they find
What are oncogenes?
cancer causing genes
What are proto-oncogenes?
benign forms of oncogenes in normal cells
Oncogenes accelerate growth while the products of __________ inhibit cell growth and division.
tumor supressor genes
What is adenoma?
neoplasm of glandular epithelium
What is carcinoma?
cancer arising in an epithelium; accounts for 90% of human cancers
What is sarcoma?
cancer arising in the mesenchyme-derived tissues, that is, in connective tissues and muscles
What is mesenchyme?
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