Study sets, textbooks, questions
Upgrade to remove ads
Chapter 7 - Molecular & Cellular Radiation Biology
Terms in this set (174)
branch of biology concerned with the effects of ionizing radiation on living systems
includes: sequence of events, action of the living system, and injury to the living system
areas of study
Because we administer radiation ot humans for medical purposes, it is necessary that we have a basic understanding of cell ___, ___, and ___ as well as the adverse effects.
structure, composition, and function
Ionizing radiation damages living systems by removing ___.
What is able to interact with orbital electrons?
x-rays, gamma rays, alpha and beta particles, and protons
Biologic damage begins with the ___ produced by various types of radiation.
What are the 3 important concepts that must be studied to understand the way ionizing radiation causes injury and how the effects my vary? (abbreviations)
LET, RBE, and OER
This states that ionizing radiation may interact with a material as it passes through and deposit energy.
Linear Energy Transfer (LET)
The average energy deposited per unit of length of path traveled.
Linear Energy Transfer (LET)
X-rays and Gamma rays are forms of low/high LET radiation?
This is electromagnetic radiation that is sparsely ionizing, interacts randomly, doesn't give up all of it's energy quickly, and causes damage through indirect actions
Low LET radiation
Low LET radiation causes damage primarily through the formation of free radicals which is what type of action?
What can usually reverse cellular damage caused by low LET?
Alpha particles are a form of low/high LET radiation?
What includes particals that have substantial mass and charge that cause dense ionization and loses energy quickly?
High LET radiation
Which form of LET is more destructive to biologic tissue?
The probability of an electron interacting with DNA rather than an alpha particle is ___
These particles have a low probability of interacting with DNA because they do not interact as often and they travel farther.
These particles have a high probability of interacting with DNA because they interact often and they do not travel far.
Biologic damage produced by radiation ___ as the LET of radiation increases.
This describes the relative capabilities of radiation with differing LETs to produce a certain biologic reaction
Relative Biologic Effectiveness (RBE)
The ratio of the dose of reference radiation to the dose that is necessary to produce the same biologic reaction.
Relative Biologic Effectiveness (RBE)
Dose in Gy from 250 kVp x-rays/ dose in Gy of test radiation (abbrev.)
As LET increases, RBE ____
Low-LET have __ RBE
High-LET have ___ RBE
Diagnostic x-rays have a RBE of __?
Why is RBE not practical for specifying radiation protection dose levels in humans?
cells and tissues differ in biologic response
What is similar to RBE and used to calculate equivalent dose
Radiation Weighting Factor (Wr)
This describes the response of biologic tissue to radiation is greater when irradiated in an oxygenated state than when irradiated in an oxygen deprived state
Oxygen Enhancement Ratio (OER)
Dose required without O2/ Dose required with O2
Oxygen Enhancement Ratio (OER)
OER is most pronounced in ___ radiation
The presence or absence of oxygen does not matter with what type of radiation?
a solitary atom or most often a combination of atoms that behaves as an extremely reactive single entity as a result of the unpaired electrons
Free radicals dramatically ___ the amount of biologic damage
The presence/absence of oxygen in tissue makes bioligic damage produced by free raddicals permaninet
The presence of O2 makes damage permanent by producing ____, which makes nonrestrable changes in the chemical composition
organic peroxide compounds
Bioligic damage from ionizing radiation can be observed on which 3 levels?
molecular, cellular, and organic
The structures of a cell's constituent molecules determines ___
Exposure to radiation can alter cell structures and disturbe the cell's ____ & ultimately the way it operates
Irradiation of ____ ___ may disrupt body processes
Irradiation of ____ ___ may be passed to future generations in the form of genetic mutations
When radiation interacts with a cell, ionizations or excitations occur in ___ or ____?
DNA or water
The action of radiation on the cell is classified based on the ___ __ _____.
site of interaction
interaction with master molecules (DNA)
interaction that occurs in water molecules
This type of action may occur after exposure to any type of radiation but is MUCH more likely with high LET radiation
When ionizing particles interact directly with DNA, RNA, proteins and/or enzymes the reasult is breakage of ____ ____, which makes them abnormal both structurally and functionally.
this typeo f action occurs when radiation interacts with water which produces free radicals
If free radicals interact with DNA the damage to the DNA is what type of action?
what type of action is more likely to occur?
Indirect action involves the breakdown of a water molecule in to smaller molecules, producing what?
ions and free radicals
If an interaction with water occurs, what ion pair is formed from the water molecule?
HOH+ and e-
How much damage is caused when HOH+ and e- recombine?
Positive and negative water molecules are ___, or they will break apart into smaller molecules.
what makes free radicals highly reactive?
if Hydrogen and hydroxyl ions recombine the form what? (no harm)
normal water molecule
What are the 4 effets of ionizing radiation on DNA?
single-strand break, double-strand break, mutation, and covalent cross-links
Which effect on DNA occurs in low LET radiations and breaks into 2 sugar-phosphate chain that repair enzymes can reverse
when a DNA breaks into 1 sugar-phosphate chain
Which effect on DNA occurs when one ore more breaks in both sugar-phosphate chains occur and is more common with high LET.
The loss or change in a nitrogenous ase on a DNA chain; the alteration of the base sequences
what is contained in the strict sequences of DNA bases?
If the cell divides, the mutation will be transfered to how many of the daughter cells?
1 or 2
Chemical unions created beween atoms by the single sharing of one or more pair of electrons; can occur in many different forms and are potentially fatal to the cell.
when changes occur in the DNA molecule what exhibits the alteration?
What are the 3 effects of Ionizing radiation on chromosomes?
radiation-induced chromosome breaks, chromosomal fragments, and chromosomal anomalies
What may be viewed microscopically (metaphase and anaphase) and can happen to the chromosomes of somatic and germ cells?
Radiation-induced chromosome breaks
During which phases of mitosis can you view radiation-induced chromosome breaks?
Metaphase and anaphase
What is produced by chromosome breakage and have a fractured extremity that have the ability to adhere to each other?
What are chromosome or chromatid aberrations that can be observed in metaphase?
During which phase of mitosis can you view chromosome anomalies?
Chromosome anomalies that result when radiation occurs before DNA synthesis; each daughter cell exhibits this
Chromosome anomalies that result when radiation occurs after DNA synthesis; only 1 daughter cell exhibits the aberration
break rejoins with no visible damage (structural change)
part of the chromosome or chromatid is lost at the next cell division (structural change)
grossly mis-shapen chromosome may be reproductive without visible damage to the chromosomes (structural change)
what does broken-end rearrangement result in?
Concept that DNA is the "master" molecule in a cell, andif it is inactivated by exposure to radiation, the cell will die.
Interactions occur only by ___
x-ray or gamma ray doses of about 1000 Gy in a matter of seconds or minutes
cell does not die, but cannot reproduce; 1-10 Gy
"interphase death" cells die without attempting division; occurs spontaneously in both normal tissue and in tumors
The doser required to cause apoptosis is governed by the cell's
"genetic death" occurs when a cell dies after one or more divisions
can occur from doses as small as .01 Gy
a potential outcome when radiation interacts with a DNA macromolecule; can occur in one or both strands and results in a loss of genetic material
A method of displaying the sensitivity of a particular type of cell to radiation
cell survival curve
A cell survival curve for low LET radiation shows ___ change in survival at low doses
A cell survival curve for low LET radiaton shows a ____ in survival as dose increases (linear portion)
A curve for high LET does not have a shoulder, meaning it is ___.
Immature cells are undifferentiated and rapidly dividing, therefore they are ___ radiosensitive.
Mature cells are highly differentiated and divide slowly if at all, therefore they are ___ radiosensitive.
LET affects cell ____.
Oxygen ___ the effects of ionizing radiation by increasing tissue radiosensitivity
Oxygen increases the ___ ____ ____ of radiation.
potential indirect damage
Established that radiosensitivity is a function of the metabolic state of the cell receiving exposre
Law of Bergonie and Tribondeau
Radiosensitivity of cells is ___ ___ to their reproductive activity.
Radiosensitivity of cells is ___ __ to their degree of differentiation.
The most pronounced radiation effects occur in cells with the ___ maturity and specialization and the ___ reproductive activity
Effect of ionizing radiation on human cells that is a decrease in the number of blood cells in circulation
Effect of ionizing radiation on human cells that is a decrease in the number of cells produced in bone marrow
depletion of Immature blood cells
This happens after some cells in the bone marrow recover
among the most sensative cells of the Hematpoeitic system
Humans receiving 5Gys may die within ___ __ due to depletion of stem cells of the hematopoietic system
stem cells are part of which system?
Dose that produces death in 50% of subjects in 30 days
Dose that prodices death in 50% of subjects in 60 days
Lethal dose for humans
white blood cells
subgroup of leukocytes that defend the body against foreign antigens by producing antibodies
Lymphocytes manufactured in ___ are the most radiosensitive blood cells in the human body
doeses of ____ depress the number of WBC
Type of WBC that plays an important role in fighting infection; dose of .5 Gy cand cause reduction
Scavenger type of WBC that fights bacteria and responds to irradiation by a sudden increase in number followed by a decrease
platelets that initiate blood clotting and prevent hemorrhage; .5 Gy depresses counts
Tissue found in the lining of intestines, mucous lining of respiratory tract, pulmonary alveoli, and lining of blood and lymphatic vessels that is very radiosensitive
tissue that is highly specialized, does not divide, and is relatively insensitive to radiation
tissue that is more radiosensitive in the embryo/fetus than in an adult
What is needed to cause temporary sterility of sperm and ova cells
What is needed to cause permanent sterility of sperm cells
5 or 6 Gy
Amount of radiation needed to cause permanent sterility of ova cells?
What is anoxic
what is hypoxic
low oxygen conditions
What is the OER (oxygen enhancement ratio) for xrays and gamma rays when the radiation dose is high
3.0 (the OER may be less about 2.0 when radiation does are below 2 Gy about 200 rad
What is the oxygen fixation hypothesis
Without oxygen, damage produced by the indirect action of radiation of a biologic molecule may be repaired, but when damage occurs through an oxygen-mediated process, the end result is permanent, or fixed
What 3 levels can ionizing radiation be observed
molecular, cellular, and organic
What are short wavelength, high energy waves emitted by the nuclei of radioactive substances
what is the process whereby single chromosome breaks rejoin in their original configuration with no visible damage
with reference to human cells and the impact of ionizing radiation on them, this is a factor that is variable
tentacle like extensions from a nerve cell body that carry impulses toward the cell
what type of water molecule that forms when hydrogen and hydoxyl ions recombine
Particle composed of two protons and two neutrons
abbreviation for important factor used in assessing potential tissue and organ damage from exposure to ionizing radiation
scavenger type of white blood cells that fight bacteria
non specialized, rapidly dividing cells in the human body
type of delay that can be caused from exposing a cell to as little as 0.01 gray (1 rad) of ionizing radiation just before it begins dividing
what an ionized atom will not be able to do properly in molecules
what may be used to expain cell death and nonfatal cell abnormalities caused by exposure to ionizing radiation
what type of tissue considered relatively insensitive to radiation
______ action is more likely to happen after exposure to high-LET radiation
enzymes that are capable of reversing damage from a single strand break in a DNA macromolecule
a nonmitotic or nondivision form of cell death that occurs when cells die without attempting division during the interphase portion of the cell life cycle
blood cells that initiate clotting and prevent hemorrhage
what a therapeutic dose of ionizing radiation will cause in the blood count
a long single tentacle from a nerve cell body that carries impulses away from the cell
Atomic level of which biologic damage resulting from exposure to ionizing radiation begins
small head circumference
cross-link formed between two places on the same DNA strand
a type of breakage that is a potential outocme when ionizing radiation interacts with a DNA macromolecule
What are effects produced by reactive free radicals, which are created by the interaction of radiation with a water molecule
what is used to calculate the equivalent dose to determine the ability of a dose of any kind of ionizing radiation to cause biologic damage
radiation weighting factor (Wr)
States that the radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation.
law of Bergonie and Tribondeau
What is a genetic mutation in which the chromosome is not broken but the DNA within is damaged
What is the chemical unions created between atoms by the single sharing of one or more pairs of electrons
covalent cross links
What is the loss or change of a nitrogenous base in the DNA chain
What is OER
oxygen enhancement ratio
ratioof the radiation dose required to cause a particular biologic response of cells or organisms in an oxygen deprived environment to the dose required to cause an identical response under normal oxygenated conditions
programmed cell death
The cell dies if inactivation of the master molecule occurs as a result of exposure to ionizing radiation is called what
lesions that result when irradiation occurs early in interphase BEFORE DNA synthesis takes place
lesions that result when irradiation of individual chromatids occurs later in interphase, after DNA synthesis takes place
chromosome aberations happen when irradiation occurs in what phase
early in interphse
what may be used to expain cell death and non fatal cell abnormalities caused by exposure to radiation
what describes the ratio of the radiation dose required to cause a particular biologic response of cells or organisms in an oxygen deprived environment to the radiation dose required to cause an identical response under normal oxygenated conditions
ring chromosomes, dicentric chromosomes, and anaphase bridges are examples of what?
distorted chromosomes (in broken-end rearrangement)
For radiation protection purposes what kind of radiation is of the greatest concern when internal contamination is possible
Because the ovaries of young women are less sensitive than those of older women, what kind of dose of radiation is required to cause sterility in young women
a higher dose of radiation
Reproductive death generally results from exposure of cells to doses of ionizing radiation in the range of what
1 to 10 gray (100 to 1000rad)
What ions usually recombine to form a normal water molecule the existence of these ions as free agents in the human body is insignificant in terms of biologic damge
hydrogen and hydroxyl ions
Part of the chromosome or chromatid is lost at the next cell division, creating an aberration known as what
acentric fragment (deletion)
In apoptosis the cell shrinks and produces tiny membrane-enclosed structures called what
LD of what is more practical for human beings than LD 50/30
Sets found in the same folder
Chapter 8 - Early Deterministic Radiation Effects…
Chapter 6 - Overview of Cell Biology
Chapter 9 - Late Deterministic Radiation Effects o…
Chapter 3 - Interaction of X-Radiation with Matter
Other sets by this creator
Chest and Bony Thorax
Image Aquisition & Evaluation - Digital Imaging
Recommended textbook solutions
Kenneth R. Miller, Levine
Clinical Reasoning Cases in Nursing
Julie S Snyder, Mariann M Harding
Human Resource Management
John David Jackson, Patricia Meglich, Robert Mathis, Sean Valentine
Hole's Human Anatomy and Physiology
David N. Shier, Jackie L. Butler, Ricki Lewis