16 Questions
What is the primary effect of ionizing radiation in the physical stage?
Transfer of kinetic energy to atoms or molecules
During which stage of ionizing radiation do reactions between free radicals and intact molecules occur?
Chemical stage
What is the timespan for the development of processes of biological damage and reparative processes following ionizing radiation?
Seconds to years
In which stage of ionizing radiation are free radicals formed?
Physicochemical stage
What is the outcome of the displacement of absorbed energy of ionizing radiation into molecules and between them?
Formation of free radicals
In which stage does ionizing radiation lead to excitation and ionization of atoms and molecules?
Physical stage
What is the basic mechanism to trigger events that cause radiation damage to living tissues?
Excitation of atoms in key molecules resulting in bond breaks
What does ionization occur if particles or photons transfer sufficient energy to do?
Remove 1 e’ from inner to outer orbital shell
What is the result of excitation of atoms in key molecules?
Bond breaks
What are the effects of oxygen on free radical formation?
Enables creation of other free radical species with greater stability and longer lifetimes
What is the intermediary of radical formation and propagation in biological systems?
Water
What is the result of the absorption of energy from IR?
Damage to molecules by direct and indirect actions
What is the effect when IR impinges on biological systems?
Energy is transferred into the system according to fundamental physical principles
What does indirect action of radiation involve?
Transfer energy to atom with “decay” to free radical species
What does excitation occur if particles or photons transfer sufficient energy to do?
Remove 1 e’ from inner to outer orbital shell
What is the result of ionization at molecular level according to the text?
Inactivation or functional alteration of molecule.
Study Notes
Ionizing Radiation Stages
- The primary effect of ionizing radiation in the physical stage is the transfer of energy to atoms and molecules, leading to excitation and ionization.
Chemical Stage
- In the chemical stage, reactions between free radicals and intact molecules occur, triggering events that cause radiation damage to living tissues.
Biochemical Stage
- The timespan for the development of processes of biological damage and reparative processes following ionizing radiation can take a significant amount of time.
Formation of Free Radicals
- Free radicals are formed in the physical stage of ionizing radiation, when particles or photons transfer sufficient energy to displace absorbed energy into molecules and between them.
Energy Transfer
- Ionization occurs when particles or photons transfer sufficient energy to remove tightly bound electrons from atoms or molecules.
Excitation and Ionization
- Ionizing radiation leads to excitation and ionization of atoms and molecules, resulting in the formation of free radicals and highly reactive species.
Biological Damage
- The basic mechanism to trigger events that cause radiation damage to living tissues is the transfer of energy from ionizing radiation to biological molecules.
Effects of Oxygen
- Oxygen has a significant impact on free radical formation and propagation in biological systems, acting as an intermediary.
Biological Systems
- The absorption of energy from ionizing radiation (IR) leads to excitation of atoms in key molecules, resulting in the formation of free radicals.
- When IR impinges on biological systems, it leads to the formation of highly reactive species that can cause biological damage.
Indirect Action of Radiation
- Indirect action of radiation involves the formation of free radicals and highly reactive species that can interact with biological molecules, leading to radiation damage.
Test your knowledge about the biological effects of ionizing radiation at the molecular and cellular levels. Explore the 4 stages of ionizing radiation and their impact on atoms, molecules, and cells.
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