oncology Flashcards
cell division
Not all cells divide at the same rate
Do not divide: Neurons, skeletal muscle cells
Divide slowly: Liver cells (once every 1-2 years)
Divide rapidly: GI epithelial cells lining GI tract (divide two or more times per day)
Cell Proliferation
The process by which cells divide and reproduce.
Cells of body can be divided into three groups: Undifferentiated Stem Cells, Parent (“progenitor” cells), Well-differentiated Cells
Undifferentiated Stem Cells
triggered to enter cell cycle & produce parent (progenitor) cells
Parent (“progenitor” cells)
Continue dividing and reproducing, Examples: blood cells, skin cells, liver cells
Well-differentiated Cells
Do not normally divide and reproduce
Examples: neurons and cells of skeletal & cardiac.
What affects cell proliferation?
Speeds up in response to: Tissue injury, Tissue loss
In some cases, reproduction is normally repressed but it can also be triggered under certain circumstances: repair of liver damage.
the cell cycle
The cell cycle is a sequence of growth stages that a cell moves through for mitosis and regeneration.
In order for cells to undergo mitosis, the cell must go through stages G0, G1, S, G2, and M.
cell cycle phases
G0-cell at rest
G1- cell enter cycle, prepare for DNA replication, Proto-oncogenes, genes that control cell replication, are activated.
S- Synthesis of structures, move to opposite poles in preparation for division into two separate cells. 46 chromosomes reorganize as two separate sets of 23 chromosome.
G2- Cells prepare to divide
M- divison complete, 2 daughter cells created.
Differentiation
the extent that neoplastic cells resemble normal cells both structurally and functionally.
anaplasia
lack of differentiation
indicates total cellular disorganization, abnormal cell appearance, & cell dysfunction.
what are tumor markers?
biologic substances, markers that shed off
What type of substances are tumor markers?
hormones, enzymes, antigen, genes
Where can tumor markers be found?
blood, urine, cerebral spinal fluid, tumor plasma membrane
What are tumor markers useful for?
screening or diagnostic purposes
can help follow clinical course
Are tumor markers diagnostic of cancer?
not always
carcinogenesis involve 3 things, what are they?
genes
carcinogens
promoters
4 phases of carcinogenesis
initiation
promotion
progression
metastasis
Tumor Suppressor Genes
inactivated
Normally function to restrain cell growth.
Can also become defective and lose the ability to inhibit cell growth and division, thus allowing cancer formation.
Proto-oncogenes
genes that stimulate and regulate a cell’s movement through the cell cycle, resulting in cellular growth and proliferation.
oncogenes
proto-oncogenes become oncogenes that stimulate constant, unrelenting cellular proliferation and cell cycling.
Carcinogens
Substances that cause development of cancer
Can alter cell DNA
Damage = cumulative!
classifications of carcinogens
Known
Probable
Possible
promoters
Agents that promote development of cancer
ex. Diet, Alcoholic beverages, Tobacco, Hormones.
viral- induced cancer
Certain malignancies are associated with cancer-inducing viruses.
MOA - always involve the activation of growth-promoting pathways or inhibition of tumor suppressors in infected cells.
primary tumor
is where the tumor begins
secondary tumor
where it metastasizes too
cancer spread
Seeding, Implantation & Metastasis
