RE: What do you know today that you didn't know yesterday?
December 19, 2023 at 12:26 am
(This post was last modified: December 19, 2023 at 12:46 am by Anomalocaris.)
I admit the claims were a bit disingenuous. Ionizing radiation and oxygen respiration both do damage by producing superoxides and hydroxyls in the cells. Oxygen respiration over a life time produces about 15000 times as much hydroxyls as a single chest x-ray, or 50 times as much as produced by all the ironizing radiation typically esperienced during a life time.
The disingenuousness comes from ignoring two factors to imply a more general equivalence.
1. Cells have evolved repair mechanisms against damages caused by superoxides and hydroxyls. The mechanism is able to more or less keep pace with the damages caused by normal respiration. However acute radiation exposure produces much more hydroxyls in small amount of time than respiration in normal atmosphere, so it overwhelms the repair mechanisms. The repair mechanisms can also be overwhelmed when breathing air with too much oxygen, this is the underlying reason for oxygen toxicity.
2. The Superoxides and hydroxyls produced by respiration occur primarily in cellular organelles involved, namely mitochondria. Hydroxyls and superoxides produced by radiation exposure occurs throughout the cell. So damage repair mechanisms operates more efficiently against damages produced by respiration than those by ionizing radiation.
The disingenuousness comes from ignoring two factors to imply a more general equivalence.
1. Cells have evolved repair mechanisms against damages caused by superoxides and hydroxyls. The mechanism is able to more or less keep pace with the damages caused by normal respiration. However acute radiation exposure produces much more hydroxyls in small amount of time than respiration in normal atmosphere, so it overwhelms the repair mechanisms. The repair mechanisms can also be overwhelmed when breathing air with too much oxygen, this is the underlying reason for oxygen toxicity.
2. The Superoxides and hydroxyls produced by respiration occur primarily in cellular organelles involved, namely mitochondria. Hydroxyls and superoxides produced by radiation exposure occurs throughout the cell. So damage repair mechanisms operates more efficiently against damages produced by respiration than those by ionizing radiation.
