Radiation Biophysics, 7 April 2003: Second Midterm

  1. (5 points)   Define potentially lethal damage.
    Answer: Working definition: Potentially lethal damage is damage to cells which, if left unrepaired, will result in [clonogenic] death.
    Formal definition: Potentially lethal damage is injury that will kill the cell unless intervention occurs to change the outcome.

  2. (5 points)   Define radiation-induced cell progression delay.
    Answer: Radiation-induced cell progression delay is the phenomenon wherein the progression of a cell through its maturation cycle is interrupted or slowed by exposure to radiation.

  3. (5 points)   Define a stem cell population.
    Answer: A stem cell population is a group of relatively undifferentiated cells that are capable of division and maturation into a functional group of cells.

  4. (5 points)Define a functional subunit and give two examples.
    Answer: A functional subunit of an organ is a volume of tissue that can be regenerated from a single surviving cell without loss of functional integrity. The nephron is the FSU of the filtration system of the kidney; the alveolus is the FSU of the lung.