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2012-05-06 01:09:06
Exam three

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  1. Cell membrane - about
    • CA cells do not have a cell membrane
    • Cell membranes protect the cell
    • Limits cell growth
    • Determines what type of cell its gonna be
  2. What is CA?
    Malignant neoplasm - new growth or formation
  3. All normal cells share:
    • Nutrients
    • Oxygen
    • Carry out metabolism
    • Carry out excretion
    • Undergo a reproductive process
  4. Hypertrophy
    Increase in size of normal cells (heart muscle)
  5. Hyperplasia
    Increase in number of cells
  6. Cell growth - neoplasia
    Any new or continued cell growth NOT NEEDED for normal development or replacement of dead or damaged tissues is termed NEOPLASIA and is always considered abnormal
  7. Benign neoplasm
    • Slow growing
    • Localized
    • Encapsulated with well-defined borders
    • Easily removed
    • Non-malignant
  8. Malignant neoplasm
    • Aggressive growths that INVADE and DESTROY surrounding tissues
    • Can lead to death unless interventions taken
    • Own blood supply
    • Rapid growth
  9. Normal cell characteristics
    • *Have limited cell division
    • Undergo mitosis to develop normal tissue & replace lost or damaged normal tissue
    • Divide only when optimal body conditions & nutrition exist

    • *Show specific morphology
    • Each cell type has a distinct & recognizable appearance, size, & shape

    • *Have a small nuclear-cytoplasmic ratio
    • The nuclear space is small in proportion to the cytoplasmic space

    • *Perform specific differentiated functions
    • Every cell must perform at least one special function to contribute to whole body homeostasis

    • *Adhere tightly together
    • Cells make & secrete cell-surface proteins that allow cells to bind closely & tightly together (cling together)

    • *Are nonmigratory
    • Cells do not wander from one tissue to another
    • Exception - erythrocytes & leukocytes

    • *Are contact inhibited
    • A cell will divide only as long as it hase some surface that is not in direct contact with another cell
    • It no longer ungoes mitosis if it is in direct contact on all surface areas with another cell membrane
  10. Cell Cycle
    • G0 Phase: Resting - not in cell cycle
    • G1 Phase: preparing for division - taking extra everything - 18 hours
    • S Phase: DNA duplicates - DNA synthesis - 20 hours
    • G2 Phase: Protein & RNA synthesis
    • Mitosis: prophase, metaphase, anaphase, telophase - single cell splits into 2 identical cells
  11. Differentiation
    • Differentiated during embryonic development
    • This is a normal cell characteristic
    • Daughter cells - look just like mom - same characteristics
    • Increased specialization of cells & tissues
    • From immature to complex
    • A well-differentiated cell is mature & functions properly - looks like mom
    • An undifferentiated cell is immature & does not do its work - malignant
  12. Cancer Etiology
    Carcinogenesis - Activation of proto-oncogenes into oncogenes

    • Suppressor genes -
    • *Prevents cells from dividing
    • *Take control over proto oncogenes
    • *Maintains control over cell cycle

    Carcinogen meets up with suppressor gene DNA - alters it - turns proto oncogene into oncogene
  13. Proto-oncogenes
    • Genetic research has focused on proto oncogenes
    • These are genes that promote rapid growth in the undifferentiated cell of the fetus - as the cells begin to differentiate, these genes are "turned off"
    • They have no other apparent function in the life cycle
    • Mutation of proto oncogenes produces oncogenes
    • An oncogene (small segment of the DNA) can transform normal cells into malignant ones and activate the process of cell division
    • Proto oncogenes can be activated to become oncogenes by two processes
    • *Viral related - certain viruses can alter cell DNA control of the proto-oncogenes
    • *Carcinogenesis - some proto-oncogenes can become active oncogenes when spontaneous or chemically induced initiation occurs - this results in uncontrolled reproduction of mutant cells during the promotion phase
  14. How Does Cancer Develop
    The process of changing a cell with normal appearance & function into a cell with malignant characteristics (malignant transformation)

    • 4 Steps:
    • Initiation
    • Promotion
    • Progression
    • Metastasis
  15. Pathophysiology Carcinogenesis: Initiation
    • Initiators such as chemicals, physical factors, and biological agents escape normal enzymatic mechanisms and cause alterations in the genetic structure of the cellular DNA
    • Alterations are irreversible but usually not significant until the second step
  16. Pathophysiology Carcinogenesis: Promotion
    • Repeated exposure to promoting agents causes the expression of abnormal or mutant genetic information
    • The cells then begin to produce mutant cell populations
    • Agents that promote or initiate cellular transformation are referred to as carcinogens.