Chapter 7: Molecular and Cellular Radiation Biology Flashcards
1
Q
Branch of biology concerned with the effects of ionizing radiation on living systems
A
Radiation Biology
2
Q
What does Radiation Biology include of:
A
- The sequence of events occurring after the absorption of energy from ionizing radiation
- The action of the living system to compensate for the consequences of this energy assimilation
- Injury to the living system that may occur from irradiation
3
Q
is a complex interconnected living system composed of very large numbers of various types of cells, most of which may be damaged by radiation.
A
The human body
4
Q
Damages living systems by ionizing the atoms comprising the molecular structure of these systems
A
Ionizing radiation
5
Q
what does ionization mean?
A
removal of an electron
5
Q
free radicals are considered your what
A
your biological damage
6
Q
Biologic damage begins with the ionization produced by various types of radiation such as:
A
- x-rays
- gamma rays
- alpha particles
- beta particles
- protons
7
Q
Ionized atoms will not what?
A
ionized atoms will not bond properly in molecules
8
Q
x-rays are considered
A
man made and can penetrate through more
9
Q
gamma rays, alpha particles, and beta particles are considered
A
natural
10
Q
Can only travel so far
- effect heavier
- more superficial can’t penetrate
A
alpha particles
11
Q
is composed of two protons and two neutrons and therefore carries an electric charge of +2
has a number of 20
A
Alpha particles
11
Q
what charge do electrons have?
A
electrons have a negative charge
12
Q
What 3 things varies among the different types of radiation?
A
- charge
- mass
- energy
*These attributes determine the extent to which different radiation modalities transfer energy into biologic tissue.
13
Q
What are the three important concepts that help us to understand the way ionizing radiation causes injury and how the effects may vary in biologic tissue?
A
- Linear energy transfer (LET)
- Relative biologic effectiveness (RBE)
- Oxygen enhancement ratio (OER)
14
Q
What kind of relationship does LET and RBE have?
A
directly proportional
14
Q
AS LET increases
A
RBE also increases
15
Q
As LET increases
A
biological damage also increases
16
Q
The average energy deposited per unit length of track by ionizing radiation as it passes through and interacts with a medium along its path
A
Linear Energy Transfer (LET)
17
Q
What does LET stand for
A
Linear Energy Transfer
18
Q
what units is LET described in
A
Is described in units of keV/μm
19
Q
Is a very important factor in assessing potential tissue and organ damage from exposure to ionizing radiation
A
LET
19
Q
Radiation categories according to LET:
A
Low-linear energy transfer radiation
High-linear energy transfer radiation
20
Q
1 micron [µm] =
A
10 ^−6 m
21
Examples of Low LET radiation:
-X-rays
- Gamma Rays
- Electrons
21
Low LET has?
Low RBE
Higher energy
22
Low LET are able to
pass through not a lot is deposited less damaging
23
Examples of high LET Radiation:
-alpha particles
-ions of heavy nuclei
-charged particles released from interactions between neutrons and atoms
-low energy neutrons
24
High LET has
high RBE
less energy
24
High LET is
deposited energy as it goes through its path more damaging
25
When LET increases, the chance of a significant biologic response in the radiosensitive DNA macromolecule also
increases
25
Because of a property known as wave-particle duality, x-rays and gamma rays, can also be referred to as streams of moving particles called photons, each of which has
no mass* and no charge
26
When low-LET radiation interacts with biologic tissue, it causes damage to a cell primarily through an indirect action that involves the production of molecules called
free radicals
27
Because low-LET radiation generally causes sub-lethal damage to DNA,
repair enzymes can usually reverse the cellular damage.
28
High-LET radiation includes particles that possess substantial:
mass and charge.
29
For radiation protection, high-LET radiation is of most significant concern when internal contamination is possible, that is, when a radionuclide has been:
* Implanted
* Ingested
* Injected
* Inhaled
29
Describes the relative capabilities of radiation with differing LETs to produce a particular biologic reaction
Relative Biologic Effectiveness (RBE)
30
What does RBE stand for
Relative Biologic Effectiveness
31
is the ratio of the dose of a reference radiation (conventionally 250-kVp x-rays) to the dose of radiation of the type in question that is necessary to produce the same biologic reaction in a given experiment. The reaction is produced by a dose of the test radiation delivered under the same conditions.
RBE of the type of radiation being used
31
What is the mathematical expression for RBE?
RBE= dose in Gyt from 250 kvp x-rays (reference radiation) over dose in Gyt of test radiation
31
math equation for RBE
bigger number over smaller number
31
least resistant means
most sensitive
32
Most resistant means
least sensitive
33
the concept of RBE alone is not practical for specifying radiation protection dose levels in humans. To overcome this limitation, a radiation weighting factor (WR) is employed to calculate the equivalent dose (EqD) to determine the ability of a dose of any kind of ionizing radiation to cause biologic damage.
True or false
True
33
The ratio of the radiation dose required to cause a particular biologic response of cells or organisms in any oxygen-deprived environment to the radiation dose required to cause an identical response under normal oxygenated conditions
Oxygen Enhancement Ratio (OER)
33
when the radiation dose is high, how much OER does xrays and gamma rays have
In general, x-rays and gamma rays have an OER of about 3.0 when radiation dose is high.
33
when the radiation dose is low, how much is the OER
ER may be less (approximately 2.0) when radiation doses are below 2 Gyt.
34
the more oxygen that is present in the cell
the more sensitive it is to radiation
35
What is the OER ratio
radiation dose required to cause biologic responce without O2 over Radiation dose required to cause biologic response with O2
35
OER math formula
without oxygen over with oxygen
36
without oxygen is called
anoxic
37
low oxygen
hypoxic
38
cells that are anoxic are
3x more resistent least sensitive
39
high LET have an OER of
1.0
39
blood cells have a lot of oxygen meaning
they are more sensitive
39
blood cells have a count of
0.25
40
blood cells are easily repaired but once they get to the muscle tissue
they are not easily repaired
40
In living systems, biologic damage stemming from exposure to ionizing radiation may be observed on three levels:
* Molecular
* Cellular
* Organic systems
41
Any visible radiation-induced injuries of living systems at the cellular or organic level always begin with damage at what level
at the molecular level.
41
results in the formation of structurally changed molecules that may impair cellular functioning.
Molecular Damage
41
what happens to the energy as there is an increase in LET and increase in RBE
decrease in energy
42
what happens to energy when there is a decrease in LET and RBE
increase in energy
43
somatic
yourself
44
genetic
future generations
45
Three things that can happen in the molecular, cellular, or organic systems:
1. it can be repaired if there's no damage
2. it can be repaired but (mutated)
3. cell death
46
Because energy from ionizing radiation can alter a human cell’s constituent molecules, such exposure may disturb the cell’s chemical balance and ultimately the way it operates. The affected cell can then no longer perform its normal task.
Effects of Irradiation on Somatic and Genetic Cells
47
If a sufficient quantity of somatic cells are affected,
entire body processes may be disrupted.
47
If radiation damages the germ cells, the damage may be passed
on to future generations in the form of genetic mutations.
47
Cells of the human body are highly what? Each cell has a predetermined task to perform, and each cell’s function is governed and defined by the structures of its constituent molecules.
highly specialized
48
There are two classifications of ionizing radiation interaction on a cell.
Direct action (e.g., in DNA)
Indirect action (e.g., in H2O)
48
directly hitting DNA (more common with Alpha particles)
Direct action
48
is high LET direct or indirect
direct action
48
hitting something else not DNA more likely to get because our body is made of 80% of water
indirect action
48
is low LET direct or indirect
indirect action
49
when you have an indirect hit you create what
free radicals which creates biological damage
50
is direct or indirect more likely to happen
Indirect —-Because the human body is 80% water and less than 1% DNA, essentially all effects of low-LET irradiation in a living cell result from indirect action.
50
what happens when free radicles comes in contact with DNA
there will be cell death
51
what does a indirect hit create
indirect hit creates free radicals, those free radicals cause more biological damage
51
most common form of biological damage
free radicals
52
biological damage occurs as a result of DNA inaccurate / functioning high LET
direct action
53
most are these interact with water ( 80 to 85 %) produce free radicals
indirect action
53
refers to the dissociation of molecules by ionizing radiation
Radiolysis
53
What are the steps of Radiolysis of water
Ionization of water molecules
Production of free radicals
Production of undesirable chemical reactions and biologic damage
Production of cell-damaging substances
Organic free radical formation
54
when it hits the water molecule it can ionize that water molecule if that happens there's no damage it can restabilize
ionization of water moleucles
55
ionization of water molecules has a charge of
positive charge
55
free radical is what kind of charge
negative charge
55
they are unstable and can break apart into smaller molecules
production of free radicals
55
radiation with water can form
ion pair
56
2/3ths of your radiation damage is caused by your
free radical
56
2/3ths of your radiation damage is caused by your free radical
production of undesirable chemical reactions and biologic damage
56
altered areas of chemical bond
point lesions
56
free radical hydroxyl
OH
56
hydrogen peroxide
production of cell damaging substances
57
chemical symbol for hydrogen peroxide
OH + OH = H2O2
57
hydrogen peroxide in the body is
extremely damaging when it comes to radiation cellular damage
58
very poisonous to the cell
hydrogen peroxide
59
are believed to be among the primary substances that produce biologic damage directly after the interaction of radiation with water.
hydroperoxyl radical and hydrogen peroxide
59
small scale change of disruption original molecule is destroyed and is replaced by radicals
organic free radical formation
60
only effecting the one side of rungs (DNA)
single strand break
61
Ionizing radiation interacts with DNA macromolecule, transfers energy, and ruptures one of the molecule’s chemical bonds possibly severing one of the sugar-phosphate chain side rails (called a point mutation)
- Repair enzymes are often capable of reversing this damage
single strand break
62
a single alteration along the sequence of nitrogenous bases can result in
a gene abnormality
62
Point lesions commonly occur with
Low-LET radiation
62
-can be cell death (not commonly repaired)
-usually happens with alpha what type of break?
double strand break
62
one chemical find side rail on strand
point mutation
low LET
repair enzyme can repair
DNA single strand break
62
high LET
not usually repaired what type of break?
double strand break
63
what type of radiation does Double strand break happen with
Occur more commonly with densely ionizing (high-LET) radiation.
64
Further exposure of the affected DNA macromolecule to ionizing radiation can lead to additional breaks in the sugar-phosphate molecular chain(s).
Breaks may also be repaired but are not repaired as easily as single-strand breaks.
If repair does not take place, further separation may occur in the DNA chains, threatening the life of the cell.
- getting it twice there's two breaks in it
- there could be cell death
Double strand break
65
some types of chromosomal damage that are caused explicitly by high-LET radiation are related to double-strand breaks of DNA. Because the chance of reversing this type of injury is meager, the possibility of a lethal alteration of nitrogenous bases within the genetic sequence is now far more significant.
double strand break
66
Result is a cleaved or broken chromosome with each new portion containing an unequal amount of genetic material
If damaged chromosome divides, each new daughter cell will receive an incorrect amount of genetic material culminating in the death or impaired functioning of the new daughter cell.
double strand break in same rung of dna
67
a double strand break in the same rung of the DNA molecular structure causes complete chromosomes breakage resulting in a cleaved or broken chromosome
low chance of survival cell death
67
Interactions of ionizing radiation with DNA molecules may cause the loss of or change in a nitrogenous base in the DNA chain.
Mutation
68
Direct consequence of this damage is an alteration of the base sequence,
a mutation
68
May not be reversible and may cause acute consequences for the cell
mutation
69
If cell remains viable, incorrect genetic information will be transferred to one of the two daughter cells when the cell divides.
mutation
69
Alteration of the nitrogen base sequence on the DNA chain caused by the action of ionizing radiation directly on a DNA molecule
is not going to function properly mutation
69
What does A bond with
A bonds with T
70
What does C bond with
C bonds with G
70
A + T
bond
70
C + G
bond
71
is U seen in DNA or RNA
RNA
72
T and A
mutation
73
is the process of chemically joining two or more molecules by a covalent bond, which is the sharing of one or more pairs of electrons between the molecules
covalent cross - links
73
Chemical unions created between atoms by the single sharing of one or more pairs of electrons
Initiated by high-energy radiation (alpha, beta)
Following irradiation, some molecules can fragment or change into small, spurlike molecules that become very interactive (sticky) when they themselves are exposed to radiation, causing these molecules to attach to other macromolecules or to other segments of the same macromolecule chain.
Can occur in many different patterns
Covalent cross-links
74
Chemical unions created between atoms by the single sharing of one or more pairs of electrons
Initiated by high-energy radiation
(happens because of alpha, beta)
Covalent CROSS LINKS
75
between the same DNA strand
intrastrand cross link
76
between 2 different strands not going to function
interstrand cross link
77
creating cell death mutations. sticking to other cells
covalent cross links
78
same DNA strand
intrastrand
79
2 different ones
interstrand
80
Large-scale structural changes in a chromosome produced by ionizing radiation may be as grave for the cell as are radiation-induced changes in DNA.
Effects of Ionizing Radiation on Chromosomes
81
Radiation-induced chromosome breaks in both
somatic and reproductive cells
82
two or more chromosomal fragments are produced. Each of these fragments contains a fractured extremity. These broken ends are chemically very active and therefore have a strong tendency to adhere, or chemically combine, to another similar end.
Chromosomal fragments
83
The fractured fragments can:
* Rejoin in their original configuration
* Fail to rejoin and create an aberration (lesion or anomaly)
* Join to other broken fragments and thereby create new chromosomes that may not appear structurally altered compared with the chromosome before irradiation
84
seen in your metaphase stage
chromosome anomalies
85
Two types of chromosome anomalies have been observed at metaphase. They are:
Chromosome aberrations and
Chromatid aberrations
86
happens early interphase, break is visible in next mitosis phase
each daughter cell will have damage
chromosome aberrations
87
result when irradiation occurs early in interphase, before DNA synthesis takes place. In this situation, the break caused by ionizing radiation is in a single strand of chromatin, which is the original chromosome
chromosome aberrations
87
1 daughter cell is effected
chromotid abberations
88
Summary of structural changes caused by ionizing radiation
- A single-strand break in one chromosome
- A break in one chromatid
- A single-strand break in separate chromosomes
- A strand break in separate chromatids
- More than one break in the same chromosome
- More than one break in the same chromatid
- Chromosome stickiness, or clumping together
89
most sensitive stage
metaphase
90
the breaks rejoin in the original configuration with no visible damage. no injury to the cell occurs because the chromatid has been restored to its original condition. The process of healing by is believed to be how 95% of single-chromosome breaks mend.
restitution
91
a part of the chromosome or chromatid is lost at the next cell division, thus creating an aberration known as an acentric fragment , which results in a cell mutation.
- fully separated off
- forms differently
deletion
92
a grossly misshapen chromosome may be produced. Ring chromatids, dicentric chromosomes, and anaphase bridges are examples of such distorted chromosomes and chromatids . This results in a cell mutation.
- it can only divide up to a certain point then you will get cell death
Broken end ararrangment
93
whereby the chromatid’s genetic material has been rearranged, yet the chromatid appears normal. Translocations are examples of such rearrangements (Fig. 7.14). This results in a cell mutation
- they rebound with the opposites ones
Broken-end rearrangement without visible damage to the chromatids
94
Consequences to the cell from structural changes within the nucleus:
- Restitution
- deletion
- broken end rearrangment
- broken end rearrangment without visible damage to the chromatids
94
concept of radiation damage to specific sensitive locations resulting from discrete and random events is known as
target theory
94
molecule that maintains normal cell function is believed to be present in every cell.
a master or key molecule
95
what molecule is necessary for the survival of the cell
Master, or key, molecule is necessary for the survival of the cell.
95
what may be used to explain cell death and nonfatal cell abnormalities caused by exposure to radiation.
target theory
96
if master key gets hit
it will die
96
if your DNA dies then
the cell will die
97
DNA is directly or indirectly inactivated by exposure radiation to the cell will cause death. random event that causes radiation damage
target theory
97
Ionizing radiation can adversely affect
the cell
97
Damage to the cell’s nucleus reveals itself in one of the following ways:
- Instant death
- Reproductive death
- Apoptosis, or programmed cell death (interphase death)
- Mitotic, or genetic, death
- Mitotic delay
- Interference with function
98
indirect can be lasting/fixed with or without oxygen
without oxygen
99
-greater than diagnostic studies
-1000 Gy over period of seconds or minutes
- you will see it in a diagnostic study
instant death
99
results from exposure of cells to doses or ionizing radiation in the range of 1-10 Gy
more than 10 Gyt loses ability to procreate
reproductive death
100
programmed cell death
interphase death
dies without attempting to divide again
apopotosis
101
A non-mitotic, or non-division, form of cell death that occurs when cells die without attempting division during the interphase portion of the cell life cycle is
Apoptosis
101
what are the other names for apoptosis
programmed cell death (interphase death)
101
In apoptosis the cell shrinks and produces tiny membrane-enclosed structures called
blebs
102
occurs when a cell dies after one or more divisions. Even relatively small doses of radiation have a possibility of causing this type of cell death. The radiation dose required to produce mitotic death is less than the dose needed to produce apoptosis in slowly dividing cells or non-dividing cells.
mitotic death
103
the failure of the cell to start dividing on time. After this delay the cell may resume its normal mitotic function.
- exposed as little as .01gy just before division
mitotic delay
103
Exposing a cell to as little as 10 cGyt of ionizing radiation just before it begins dividing can cause
Mitotic delay
104
reasons for mitotic delay:
1. Alteration of a chemical involved in mitosis
2. Proteins required for cell division not being synthesized
3. A change in the rate of DNA synthesis after irradiation
105
Permanent or temporary interference with cellular function independent of the cell’s ability to divide can also be brought about by exposure to ionizing radiation. If repair enzymes are able to repair the damage, the cell can recover and continue to function properly. Otherwise, the cell will be unable to reproduce or will die.
Interference with function
105
temporary or permanent repair enzymes come in to help
interference with function
105
mitotic death is less of a dose than
apoptosis
106
The segmenting of a chromosome due to the breaking of one or both of the sugar–phosphate chains of a DNA ladder-like structure, which is a potential outcome when ionizing radiation interacts with a DNA macromolecule.
- occurs with DNA is during mitosis permanent problems genetic mulatity
chromosome breakage
107
true or false
cells vary in their radiosensitivity
true
107
is a classic method of displaying the sensitivity of a particular type of cell to radiation.
cell survival curve
108
how is the cell survival curve obtained
Curve is constructed from data obtained by a series of experiments.
108
high LET is more damaging than
low LET
108
radiosensitivity of a certain type of cell
cell surviving curve
109
radiosensitive cells are considered
immature, have oxygen, sensitive to radiation, non specialized, rapid cell division germ cells and lymphocytes
110
examples of Radiosenistive cells
BASAL CELLS OF SKIN
BLOOD CELLS SUCH AS LYMPHOCYTES AND ERYTHROCYTES
INTESTINAL CRYPT CELLS
REPRODUCTIVE (GERM) CELLS
111
most sensitive part in your GI tract
111
radioinsensitive cells are considered to be
highly specialized, more mature, no oxygen, insensitive to radiation, divide slower rate, nerve and muscles
111
examples of radioinsensitive cells
brain cells
muscle cells
nerve cells
112
immature, nonspecialized, rapid cells division- germ cells, lymphocytes
radiosensitive
112
more mature, specialized divide slower rate- nerve, muscle
radioinsensitive
113
Amount of radiation energy transferred to biologic tissue
Plays a major role in determining the amount of biologic response
As LET increases, the ability of the radiation to cause biologic effects also generally increases until it reaches a maximal value.
LET can influence cell radiosensitivity.
CELL RADIOSENSITIVITY
113
Oxygen enhances the effects of ionizing radiation on biologic tissue by increasing tissue radiosensitivity.
During diagnostic imaging procedures, fully oxygenated human tissues are exposed to x-radiation or gamma radiation.
In radiotherapy, when radiation is used to treat certain types of cancerous tumors, high-pressure (hyperbaric) oxygen has sometimes been used in conjunction with it to increase tumor radiosensitivity.
OXYGEN ENHANCEMENT
113
the more oxygen
the more sensitive it is
113
if oxygen is present when a tissue is irradiated
more freeradicals will be formed in the tissue this increases the indirect damage potential of the radiation
114
oxygen present =free radicals
increased indirect damage
increased oxygen , increased radiosensitivity
oxygen enhancement
114
Observed the effects of ionizing radiation on testicular germ cells of rabbits they had exposed to x-rays
Law of Bergoiné and Tribondeau
114
Established that radiosensitivity was a function of the metabolic state of the cell receiving the exposure
Law of Bergoiné and Tribondeau
114
States that the radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation
Law of Bergoiné and Tribondeau
115
Although the law was initially applied only to germ cells, it is true for all types of cells in the human body.
Law of Bergoiné and Tribondeau
115
The most pronounced radiation effects occur in cells having the least maturity and specialization or differentiation, the greatest reproductive activity, and the longest mitotic phases.
Law of Bergoiné and Tribondeau
115
the embryo-fetus, which contains a large number of immature nonspecialized cells, is much more susceptible to radiation damage than is an adult or even a child
Law of Bergoiné and Tribondeau
115
the more immature it is
the more sensitive it is
116
the more mature it is
the less sensitiveit is
117
Equal doses of ionizing radiation produce different degrees of damage in different kinds of human cells because of differences in cell radiosensitivity.
The more mature and specialized in performing functions a cell is, the less sensitive it is to radiation.
Effects of ionizing radiation on human cells
118
immature/nonspecialized -more sensitive
Law of Bergoiné and Tribondeau
118
white blood cells are more sensitive than
nerve endings
119
Effects of ionizing radiation on human cells
Blood cells
-Hematologic depression
-Depletion of immature blood cells
-Repopulation after a period of recovery
-Effects on stem cells of the hematopoietic system
-Whole-body doses in excess of 5 Gyt
-Effects of ionizing radiation on lymphocytes
- Effects of ionizing radiation on neutrophils
120
.25 Gy whole body in a few days- exceeds dose for population
-blood tests not valid for dosimetry purpose
hemotologic depression
121
Most blood cells are manufactured in the bone marrow. Radiation causes a decrease in the number of immature blood cells (stem or precursor) produced in the bone marrow and hence a reduction, ultimately, in the number of mature blood cells in the bloodstream. The higher the radiation dose received by the bone marrow, the higher will be the resulting cell depletion
depletion of immature blood cells
122
after recovery , bone marrow can repopulate if wasnt destroyed
-recovery depends on dose
-less than 1Gy=weeks
-1-10 Gy + greater than 10 =
can cause permanent decrease
repopulation
122
If the bone marrow cells have not been destroyed by exposure to ionizing radiation, they can repopulate after a period of recovery. The time necessary for recovery depends on the magnitude of the radiation dose received. If a relatively low dose (less than 1 Gyt) of radiation is received, bone marrow repopulation occurs within weeks after irradiation. Large (1 to 10 Gyt) to very high (10 or more Gyt) doses, which severely deplete the number of bone marrow cells, require a more extended recovery period. Very high doses of radiation can cause a permanent decrease in the number of stem cells.
Repopulation after a period of recovery.
122
Radiation primarily affects the stem cells of the hematopoietic (blood-forming) system. Erythrocytes, also known as red blood cells because of their reddish color due to the presence of hemoglobin*, are the primary carriers of oxygen to the tissues and organs of the body. These transport cells are among the most radiosensitive of human cells. As with all cells, however, that develop from an immature, undifferentiated state to a mature, functional state, the mature red blood cells, which do not have a cell nucleus, are much less radiosensitive. Because the population of circulating red blood cells is high and their life span is long, depletion of red blood cells is not usually the cause of death in high-dose irradiation (i.e., several Gyt delivered to the whole body). Death, if it occurs, is typically caused by infection that cannot be overcome by the immune system because of the destruction of myeloblasts (an immature cell of bone marrow that is the most basic precursor of granulocyte* white blood cells) and internal hemorrhage resulting from destruction of megakaryoblasts (cells that are the ancestors of platelets
Effects on stem cells of the hematopoietic system.
123
this is your blood forming system
Effects on stem cells of the hematopoietic system.
124
red blood cells are called and what do they do
erythocytes
124
your white blood cells are called what and what do they do
leukocytes help fight off infections
124
RBC -oxygen to tissues and organs
-among most radiation (mature vs immature)
-not usually cause of death - Increase repopulation
erythrocytes (stem cells)
125
single most sensitive cell in body
lymphocyte
125
true or false
diagnostic xrays are considered low LET radiation
true
126
-defines the ability or aerobic conditions to enhance the effectiveness of radiation
-increasing the oxygenation of a cell increases the cells sensitivity to radiation
-is a numeric description of the oxygen effect. OER for human tissues has a max of approx. 3.0
oxygen effect
127
True or false
there is a master key in every cell
true
128
Cell death without attempting to divide
Apoptosis (interphase death) or programmed cell death
128
if there is a shoulder in the graph what does this mean?
can be repaired
128
if there is no shoulder in the graph what does this mean
cell death
128
Humans who receive whole-body doses above 5 Gyt may die within 30 to 60 days because of effects related to initial depletion of the stem cells of the hematopoietic system.
Whole-body doses in excess of 5 Gyt.
129
if you get a body dose of 5 or more gray you can die within
30 or 60 days because you are depleting your blood supply
129
The lethal dose in animals is usually specified as LD 50/30 (the dose that produces death in 50% of the subjects within 30 days
LD (lethal dose)
129
LD 50/60 what does it stand for
50 stands for % of the population and 60 represents # how many days
129
without medical treatment what is the lethal dose for humans
3.0 to 4.0 grays
129
what dose starts depleting white blood cells (lymphocytes)
0.25
130
what is the normal white blood cell count of an adult range
5000 to 10,000
130
if you lose your white blood cells
the body can't fight off infections
130
When significant numbers of lymphocytes are functionally damaged by radiation exposure, the body loses its natural ability to combat infection and becomes very susceptible to bacterial and viral antigens.
Effects of ionizing radiation on lymphocytes.
131
A whole-body dose of 0.5 Gyt of ionizing radiation will noticeably reduce the number of neutrophils present in the circulating blood, causing a person to be susceptible to infection.
Effects of ionizing radiation on neutrophils
131
another type of white blood cell
Neutrophils
131
A dose of radiation higher than 0.5 Gyt lessens the number of platelets in the circulating blood, A dose of radiation in the range of 1 to 10 Gyt, will significantly deplete these cells, and it will take approximately 2 months for them to repopulate. During this period wound clotting will be highly compromised.
effects of ionizing radiation on thrombocytes
132
inability to clot
hemophilia
132
A dose of radiation higher than 0.5 Gyt lessens the number of platelets
in the circulating blood
133
have received radiation doses within the diagnostic radiology range. Prime candidates for developing such irregularities are patients either for whom high-level fluoroscopy was employed or for whom very long fluoroscopic exposure times occurred (e.g., cardiac catheterization and other specialized invasive procedures)
Radiation exposure during diagnostic imaging procedures.
133
A therapeutic dose of ionizing radiation, especially doses delivered to locations that include blood-forming organs, decreases the blood count. Consequently, patients who are undergoing radiation therapy treatment are monitored frequently (in the form of weekly or biweekly complete blood counts, also known as CBCs) to determine whether all of their functioning blood constituent counts are adequate.
Monitoring of patients undergoing radiation therapy treatment.
134
wear radiation badge
Occupational radiation exposure monitoring.
135
is wearing your radiation badge a form of protection
no
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what is the occupational dose annually
50 milli sieverts
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covers your body tissue and highly sensitive to radiation
epithelial tissues
136
lines and covers body tissue. The cells of these tissues lie close together, with few or no substances between them. found in your intestine lining
epithelial tissue
136
contains fibers that affect the movement of an organ or part of the body. Since muscle tissue cells are highly specialized and do not divide, they are relatively insensitive to radiation. there's no oxygen
muscle tissue
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are men or women more sensitive to radiation
women
138
does not divide , they are mature , no oxygen
embryo more sensitive than human nerve tissue
nervous tissue
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The “young” spermatogonia, however, are unspecialized and divide rapidly, and therefore these germ cells are very radiosensitive
sperm
138
is reproduced every single day
sperm
138
is younger sperm or older ovaries more sensitive
younger sperm
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no oxygen they do not die
muscle tissue
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true or false
immature ova are more sensitive
true
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what dose causes more permanent sterility
5 to 6 gray
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what does it mean if its more immature
more sensitive
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what dose cause temporary sterility
2-3 gray
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what does it mean if its more mature
less sensitive
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is this lethal or survival
12 gray over a couple of days
survival
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is this lethal or survival
12 gray in 3 minutes
lethal
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(pulse in fluoro)
Small increments
-continuously amount of fluoro over time
protraction
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-Radiation therapy
-dosage over time
-break into several equal parts (period of recovering)
- a series of small dosage over time because there's a period of recovery in between
fractionation
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