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Casey Exam 1

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126 Terms
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The study of the effects of ionizing radiation on biological tissues.
radiobiology
The effects of x-rays on humans is the result of interactions at the ______ _____
atomic level
_____ are the building blocks of all matter
atoms
_____ are the building blocks of living matter
cells
______ _____ was the first person to identify the cell as the biological building block in 1665
Robert Hooke
_____ ___ __________ accurately described the cell with the aid of his microscopic observations.
Anton van Leeuwenhoek
_________ & _______ showed conclusively that in all plants & animals, cells are the basic functional units of life. (this is the cell theory)
Schneider & Schwann
The cell theory
1. All living organisms are composed of cells 2. Cells arise from pre-existing cells 3. The cell is the basic unit of life
In 1953 ______ & _____ described the structure of DNA.
Watson & Crick
In the year 2000, this project resulted in the precise mapping of the 40,000 human genes?
the Human Genome Project
What percentage of the body is made up of hydrogen & oxygen?
85%
A group of cells that have the same purpose/perform the same activity?
tissues
A Group of tissues working together in close association in order to perform a specialized function?
organ
What is the term defined as a group of organs that work together to perform a common function?
system
What is the term that describes the production of large molecules from smaller molecules?
Anabolism
What is the term that describes the process of breaking larger molecules down into smaller molecules?
Catabolism
Anabolism & catabolism are collectively known as?
metabolism
All metabolic activity takes place in the?
cytoplasm
This lipid-protein structure selectively allows small molecules & water to pass in & out of the cell
cell membrane
Proteins, lipids, carbohydrates, & nucleic acids are all calssified as what type of molecules?
organic molecules
An organic molecule is life supporting & contains?
carbon
What percentage of the body/cell is made up of water?
80%
What macromolecule comprises 15% of the molecular composition of the body/cell?
protein
What 2 macromolecules comprise 1% of the molecular composition of the body/cell?
carbohydrates & nucleic acid
What macromolecule comprises 2% of the molecular composition of the body/cell?
lipids
The chief function of this macromolecule in the human body is to provide fuel for cell metabolism.
carbohydrates
Carbohydrates are also called saccharides (monosaccharides & disaccharides) which are?
sugars
Simple/monosaccharides are?
glucose & fructose
Complex/disaccharides are?
lactose, maltose, & sucrose
Polysaccharides are?
starches
____ is the radiation-sensitive target molecule
DNA
DNA has what type of structural configuration?
double-helix
DNA is found where?
the nucleus
Besides DNA, what is the other type of nucleic acid found in the cell?
RNA
RNA is mostly located where?
the cytoplasm
Besides the cytoplasm, where else is the RNA housed?
the nucleolus
DNA & RNA are macromolecules and are classified as what type of organic molecule?
nucleic acids
What are the side rails of the DNA strain composed of?
sugar-phosphates
The nitrogen-containing bases adenine & guanine are classified as?
purines
The nitrogen-containing bases thymine & cytosine are classified as?
pyrimidines
Cytosine is always paired with which nitrogen-contiaining base?
Guanine
The nitrogen-containing base Adenine is always paired with what other base?
Thymine
What is the name of the channels that allow the nucleus to communicate with the cytoplasm?
endoplasmic reticulum
What is the name of the large, bean-like structure, also known as the "engines of the cell"?
mitochondria
Small dot-like structures that consist of 2/3 RNA & 1/3 protein are known as?
Ribosomes
Ribosomes are the site of?
protein synthesis
What is the name of the tubes/channels that extend from the nucleus to the cell membrane & serve as a connection to the outside of the cell?
golgi apparatus
The small pea-like sacs that are resposible for digesting cellular wates & are known as the "garbage disposals".
lysosomes
The act of a single cell or group of cells reproducing and multiplying in number.
cell proliferation
What cells of the human body undergo mitosis?
somatic cells
Genetic/reproductive cells undergo what type of cell proliferation?
meiosis
This phase of the cell cycle is made up of G1, S, & G2 phases & is known as a period of growth & rest of the cell between divisions?
interphase
This phase of the cell cycle is also known as the pre-DNA synthesis phase?
G1 phase
During the cell cycle, which phase is considered to be the DNA synthesis phase?
S phase
What is the name of the cell cycle phase that is considered post-DNA synthesis?
G2 phase
This phase starts the division process, the nucleus swells & the DNA becomes more prominent.
prophase
During this phase, chromosomes appear & are lined up along the equator of the nucleus.
metaphase
During this phase, the chromosomes are split & pulled to their respective poles.
anaphase
What attaches to the chromatids & pulls them to their respective poles?
mitotic spindles
The final phase of mitosis is known as _________, whish is when the nucleus starts taking shape & the cytoplasm divides equally.
telophase
Mitosis results in?
2 daughter cells
During what phase of mitosis can the process be stopped & chromosomes can be studied?
metaphase
Somatic cells contain how many total chromosomes?
46
Meiosis is the process whereby genetic cells undergo what?
reduction division
Genetic cells contain how many chromosomes?
23
Meiosis results in what?
23 SINGULAR chromosomes
During the second division of meiosis, some chromosomal material is exchanged among chromatids through a process called?
crossing over
Human cells are most sensitive to radiation exposure during the M phase of mitosis. What is the next most sensitive phase of the cell cycle?
G1-S transition
What is the region on a chromosome that joins two sister chromatids?
centromere
These are the most sensitive types of cells in the body
stem cells
What are the names of the 2 French scientists who theorized & observed that the radiosensitivity of of living tissue varies with the maturity as well as the metabolic & proliferation rate?
Bergonie & Tribondeau
If a radiation response occurs within minutes or days after the exposure, it is classified as an?
early effect
If a radiation response occurs months or years after the exposure, it is classified as a?
late effect
What is the term that is defined as the relative constancy of the internal environment?
homeostasis
This term is defined as a measure of the rate at which energy is tranfered from ionizing radiation to soft tissue.
Linear Energy Transfer (LET)
What is the LET for diagnostic x-rays?
3 keV/micrometer
This term is defined as the ability of radiation to produce biologic damage.
Relative Biologic Effectiveness (RBE)
What is the RBE for diagnostic x-rays?
1
As LET _________, the ability to produce biologic damage _________.
increases; increases
LET & RBE have what type of relationship?
direct relationship
High LET is = to
high RBE
Low LET is = to
low RBE
______ hits are associated with high LET & they interact with the target molecule/DNA.
direct hits
________ hits are associated with low LET & they interact with water molecules.
indirect hits
If a dose is delivered CONTINUOUSLY but at a lower dose rate, it is classified as?
protraction
If a dose is delivered in equal portions at regular INTERVALS, it is classified as?
fractionation
Dose protraction & fractionation cause less effect becuase the longer irradiation time allows for?
intracellular repair & tissue recovery
This term describes the tissues response to radiation when irradiated in the oxygenated state.
Oxygen Enhancement Ratio (OER)
The presence of oxygen is going to increase the number of ________ hits.
indirect
What is the relationship between OER and LET?
high OER = low LET
List the biological factors that affect radiosensitivity:
OER, age, gender, inherent recovery, & chemical agents
Agents that enhance the effects of radiation are called?
radiosensitizers
When are humans most sensitive to radiation?
before birth
Females are more resistant to radiation than males by approximately what percent?
5-10%
If a cell is exposed during interphase & it is not able to recover, then it is known as?
interphase death
For chemical agents to be effective, they must be _______ at the time of exposure.
present
This vitamin is considered to be a radiosensitizer.
Vitamin K
Agents that protect against the effects of radiation are called?
radioprotectors
What type of drug group is considered to be a radioprotector?
sulfhydryl
This classification of radiation response usually follows a HIGH-dose exposure which produces an EARLY response. It can also be defined as a response that SEVERITY is increasing with the increaseing dose.
deterministic
This classification of radiation response usually follows a LOW-dose exposure which produces a LATE response. It can also be defined as a response that FREQUENCY is increasing with the increasing dose.
stochastic
The theory or belief that a little radiation is good for you.
Hormesis
On a dose-response chart, what type of curve demonstrates a directly proportional response to the increasing dose?
linear
Diagnostic x-ray follows what type of dose-response curve?
linear, non-threshold
For this type of dose-response relationship there must be a known dose.
threshold
For this type of dose-response it is assumed that a response to radiation exposure will occur at any dose regradless of size. (natural response)
non-threshold
S-type dose-response: when it starts to curve down is called?
inflection point
________ is the most prominent type of low dose exposure cancer.
leukemia
The breakage of the backbone of the long-chain macromolecule into smaller molecules is know as?
main-chain scission
How does main-chain scission effect the viscosity?
decreases it
This type of effect of radiation on macromolecules results in the production of spur-like structures.
cross-linking
How does cross-linking effect the viscosity?
increases it
Radiation interactions with macromolecules can also result in the disruption of chemical bonds which can produce what?
point lesions
When water is irradiated, it dissociates into smaller molecules; this action is called?
radiolysis of water
What are the 2 byproducts of water radiolysis?
hydrogen peroxide & hydroperoxyl
What is the principle effect/interacrion of radiation on humans?
indirect
When the ionizing event occurs on the target molecule, the effect of radiation is?
direct
The concept that the cell contains KEY sensitive molecules is termed?
target theory
With this process, the lethal effects of radiation are determined by observing cell survival & not cell death.
cell-survival kinetics
What type of cell survival model is applied to simple bacteria, enzymes, & viruses?
single target, single hit
What type of cell survival model is applied to more complex cells such as human somatic & genetic cells?
multi-target, single hit
Because radiation interacts randomly with matter, the probability of cell survival is governed by what law?
poisson distribution law
This acronym is a way of describing cellular radiosensitivity in which the dose results in a 37% survival?
D37
What is the acronym for the mean leathal dose?
D0
What does the acronym DQ represent?
recovery from a sub lethal dose
When looking at a cell survival chart, which type of shoulder would represent a cells ability to withstand or recover from more sublethal damage?
Wider shoulder