homework review Flashcards
a single absorbed dose of 2 Gy can cause skin erythema within
24-48 hours
what is the correct order of the major response stages of ARS
prodromal, latent, manifest, death/recovery
absolute risk model estimates
malignancies that will occur as a result of irradiation
as radiation dose increases, the severity of early tissue reactions
also increases
which of the following systems is most radiosensitive?
cerebrovascular
gastrointestinal
hematopoietic
skeletal
hematopoietic
somatic cells divide through the process of
mitosis
cancer and genetic defects are examples of
stochastic effects
true/false: a normal human has 46 different chromosomes composed of 23 pairs in each somatic cell
true
true/false: the embryo-fetus has a large numbers of mature, specialized cells and therefore is relatively radioresistant
false
true/false: organogenesis lasts approximately from 10 days to 12 weeks postconception
true
experiments with mice show that cataracts may be caused by doses as low as
0.1 Gy (humans can be 0.5 Gy)
Gastrointestinal syndrome has a threshold dose of
6 Gy
based on current data, what is a safe radiation dose for the gonads of both males and females?
0 Gy
which of the following are considered low LET radiation?
x-rays and gamma rays
antibodies are protein molecules created by specialized cells in the bone marrow called
B lympocytes
During mitosis, what phase of the cellular life cycle is the actual DNA synthesis period?
S phase
How many different amino acids are involved in protein synthesis in humans?
22
in general, which of the following can human cells do?
1. Move, grow, react, and protect themselves
2. Repair damage and regulate life processes
3. Reproduce
all of the above
Inorganic materials are compounds that
do not contain carbon
What is any chemical reaction in which atoms lose electrons called?
oxidation
Which of the following are major tasks of the cytoplasm?
1. Accepts and builds up unrefined materials and assembles from these materials new substances such as carbohydrates, lipids, and proteins.
2. Breaks down organic materials to produce energy.
3. Packages substances for distribution to other areas of the cell or to various sites in the body through the circulation.
4. Eliminates waste products.
all of the above
Which of the following serves as a prototype for messenger RNA (mRNA)?
1. DNA
2. Potassium and Sodium
3. Nitric acid
4. tRNA
DNA
The cell components that contain the centrioles are the
centrosomes
In the human body mineral salts are necessary for
1. proper cell function.
2. creation of energy.
3. conduction of impulses along nerves.
all of the above
Because the genetic information to be passed on to future generations is contained in the strict sequence of nitrogenous bases, the loss or change of a base in the DNA chain represents a (an)
mutation
Direct action may occur after exposure to any type of radiation, but it is much more likely to occur after exposure to
high LET radiation such as alpha particles
The radiation dose required to produce mitotic death is
less than the dose needed to produce apoptosis in slowly dividing cells or nondividing cells.
When free radicals previously produced by the interaction of radiation with water molecules act on a molecule such as DNA, the damaging action of ionizing radiation is indirect in the sense that the radiation is not the immediate cause of injury to the macromolecule. What is the immediate cause of this damage
The free radicals produced by the interaction of radiation with water molecules
Which of the following curves illustrates the radiation sensitivity of a particular type of cell?
cell survival curve
Which of the following groups of cells is most radiosensitive?
a. Erythrocytes
b. Muscle cells
c. Lymphocytes
d. Adult nerve cells
lymphocytes
Which of the following humans is most radiosensitive?
a. An embryo-fetus during the first trimester of pregnancy
b. A fetus during the third trimester of gestation
c. A mature adult
d. A 5-year-old child
a. An embryo-fetus during the first trimester of pregnancy
Which of the following statements is true concerning patients who receive radiation exposure from a routine radiographic procedure such as a chest x-ray?
patients are not expected to sustain appreciable damage to either the blood or the blood-forming organs as a consequence of the examination.
A term that is synonymous with loss of hair is
epilation
Chromosomal damage can be caused by
both low and high radiation doses.
During the major response stages of acute radiation syndrome after the prodromal stage and a period of false calm that may last for several days, the stage when symptoms that affect the hematopoietic, gastrointestinal, and cerebrovascular systems occurs, this stage is called
manifest illness
Which of the following is not a form of acute radiation syndrome?
Carcinogenic syndrome
The term LD 50/30 signifies the whole-body dose of radiation that can be lethal to
50% of the exposed population within 30 days
Some local tissues suffer immediate consequences from high radiation doses. Examples of such tissues include
1. bone marrow.
2. male and female reproductive organs.
3. skin.
all of the above
If a person receives radiation exposure sufficient to cause the gastrointestinal syndrome, fatality occurs primarily as a result of
catastrophic damage to the epithelial cells that line the gastrointestinal track.
Moist and dry desquamation can be caused by
high radiation doses
The prodromal stage of acute radiation syndrome is actually the
beginning stage
Currently, evidence of radiation-induced hereditary effects has not been observed in persons employed in diagnostic imaging or in patients undergoing radiologic examinations. Even with this information, it is still recommended that
all radiation exposure be maintained as low as reasonably achievable (ALARA)
During the 1950s and 1960s, the Navajo people of Arizona and New Mexico who mined uranium for fuel for nuclear weapons and power plants developed lung cancer years after their exposure. This provides an example of which of the following?
Late stochastic effects
During the preimplantation stage of development, the fertilized ovum divides and forms a ball-like structure containing undifferentiated cells. If this structure is irradiated with a dose in the range of 0.05 to 0.15 Gyt which of the following will result?
embryonic death
Genetic mutations at the molecular level are called
point mutations
Genetic effects from exposure to ionizing radiation occur as a result of radiation-induced damage to the DNA molecule in which of the following?
a. Sperm of a man
b. Ova of a woman
c. Both A and B
d. Somatic cells of men and women
both A and B
Which of the following late effects caused by exposure to ionizing radiation is considered to be most significant?
cancer
When a prediction is made that the number of excess cancers will increase as the natural incidence of cancer increases with advancing age in the population, the risk is considered to be
relative
What is the mean value of the radiation doubling dose for humans, as determined from studies of the children of the atomic bomb survivors of Hiroshima and Nagasaki?
1.56 Sv
Some mutations in genetic material occur spontaneously, without a known cause. In humans, a hereditary disorder is present in approximately _________ of all live births in the United States.
10%
Radiation-induced cataracts in humans follow a ______ dose–response relationship.
threshold, nonlinear
