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C1 > HUMAN BIOLOGY AND FUNDAMENTAL PRINCIPLES OF RADIOBIOLOGY > Flashcards

HUMAN BIOLOGY AND FUNDAMENTAL PRINCIPLES OF RADIOBIOLOGY Flashcards

1
Q

What is the primary result of X-rays interacting at the atomic level?

A

Molecular changes in tissue

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2
Q

The study of the effects of ionizing radiation on biological tissue

A

Radiobiology

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3
Q

What are the three stages of early radiation effects on humans?

A

Hematologic syndrome, gastrointestinal syndrome, central nervous system syndrome

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4
Q

What are the late effects of radiation on humans?

A

Leukemia, malignant diseases, local tissue damage, lifespan shortening, genetic damage

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5
Q

What are the effects of fetal irradiation?

A

Prenatal death, neonatal death, congenital malformation, childhood malignancy, diminished growth

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6
Q

What is the principal atomic composition of the human body?

A

60% hydrogen, 25.7% oxygen, 10.7% carbon, 2.4% nitrogen, and trace elements

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7
Q

What are the four principal macromolecules in the human body?

A

Proteins, lipids, carbohydrates, nucleic acids

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8
Q

What percentage of the human body is water?

A

80%

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9
Q

What is the most critical and radiosensitive target molecule in the body?

A

DNA

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10
Q

What are the primary functions of proteins in the body?

A

Provide structure, support, enzymes, hormones, and antibodies

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11
Q

What is the chemical formula for glucose?

A

C6H1206

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12
Q

Provide fuel for cell metabolism

A

carbohydrates

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13
Q

What is the main difference between DNA and RNA?

A

DNA has deoxyribose and thymine; RNA has ribose and uracil

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14
Q

What are the two principal types of nucleic acids?

A

DNA and RNA

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15
Q

What is the double-helix structure of DNA formed by?

A

Sugar-phosphate backbone and base pair bonding

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16
Q

What are the two major structures of a human cell?

A

Nucleus and cytoplasm

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17
Q

Acts as the “engine” of the cell, producing energy

A

mitochondria

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18
Q

Contain enzymes to digest cellular fragments and control intracellular contaminants

A

lysosomes

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19
Q

What is a codon in protein synthesis?

A

A series of three base pairs identifying an amino acid

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20
Q

What are the two general types of cells in the human body?

A

Genetic (germ) cells and somatic cells

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21
Q

What are the four phases of mitosis?

A

Prophase, metaphase, anaphase, telophase

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22
Q

Chromosomes align along the equator and are most visible

A

metaphase

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23
Q

A process of reduction division in genetic cells

A

meiosis

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24
Q

The exchange of chromosomal material between chromatids

A

crossover

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25
Q

What percentage of human tissue composition is muscle?

A

43%

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26
Q

What is the most radiosensitive cell type in humans?

A

Stem cells

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27
Q

What are the four types of tissues in the human body?

A

Epithelium, connective and supporting tissue, muscle, nervous tissue

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28
Q

Lines all exposed surfaces of the body

A

epithelium tissue

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29
Q

What are parenchymal and stromal tissues?

A

Parenchymal is functional tissue; stromal provides structure

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30
Q

Radiosensitivity depends on metabolic state, proliferation rate, and cell maturity

A

Law of Bergonie and Tribondeau

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31
Q

What are the physical factors affecting radiosensitivity?

A

LET, RBE, protraction, and fractionation

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32
Q

Rate at which radiation energy is transferred to soft tissue

A

linear energy transfer (LET)

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33
Q

What is the typical LET value for diagnostic X-rays?

A

3 keV/μm

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34
Q

What is the relative biological effectiveness (RBE) of diagnostic X-rays?

A

1.0

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35
Q

Ratio of radiation dose needed under anoxic vs. aerobic conditions

A

oxygen enhancement ratio (OER)

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36
Q

What are radiosensitizers?

A

Agents that enhance radiation effects

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37
Q

What are radioprotectors?

A

Agents that reduce radiation effects

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38
Q

What is the threshold dose in a dose-response relationship?

A

The dose below which there is no observed response

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39
Q

Response is directly proportional to dose, with no safe level

A

inear nonthreshold dose-response relationship

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40
Q

Response increases rapidly after a threshold dose is exceeded

A

sigmoid dose-response relationship

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41
Q

What is the principal aim of radiobiology?

A

To understand radiation dose-response relationships

42
Q

Delivering the total dose in equal portions at regular intervals

A

fractionation

43
Q

Delivering the dose continuously but at a lower dose rate

A

protraction

44
Q

What is hormesis in radiobiology?

A

The concept that low levels of radiation may be beneficial

45
Q

What is a deterministic (nonstochastic) radiation effect?

A

High-dose exposure causing early radiation response, e.g., skin burn

46
Q

Low-dose exposure causing late effects, e.g., cancer or genetic effects

A

stochastic radiation effect

47
Q

What are two characteristics of dose-response relationships?

A

They can be linear or nonlinear, and threshold or nonthreshold

48
Q

What is the most radiosensitive phase of the cell cycle?

A

M phase (mitosis)

49
Q

What is the least radiosensitive phase of the cell cycle?

A

S phase (DNA synthesis)

50
Q

What is the lethal dose (LD) for single-cell organisms?

A

Measured in kilorads

51
Q

What is the lethal dose for human cells?

A

Less than 100 rad (1 Gy)

52
Q

Chromosomes disappear into DNA mass, and the nuclear membrane divides

A

telophase

53
Q

What are the two phases of the cell cycle according to geneticists?

A

M phase (mitosis) and interphase

54
Q

What occurs during the S phase of interphase?

A

DNA is replicated into two identical daughter molecules

55
Q

Chromosomes become visible and start to take structural form

A

prophase

56
Q

They connect chromatids to the poles of the nucleus

A

spindle fibers

57
Q

They contain enzymes capable of digesting cellular debris

A

lysosomes

58
Q

A state of equilibrium among tissues and organs

A

homeostasis

59
Q

Binds tissues and organs together and provides elasticity

A

connective tissue

60
Q

Site of protein synthesis

A

ribosomes

61
Q

What are the two principal types of radiation responses in humans?

A

Early effects (e.g., acute radiation syndrome) and late effects (e.g., cancer)

62
Q

What is the effect of radiation on immature (stem) cells compared to mature cells?

A

Stem cells are more radiosensitive than mature cells

63
Q

What happens during interphase in the cell cycle?

A

The cell grows and prepares for division

64
Q

What are the two types of RNA?

A

Messenger RNA (mRNA) and transfer RNA (tRNA)

65
Q

What is the configuration of RNA?

A

Single-helix

66
Q

What are the purines in DNA?

A

Adenine and guanine

67
Q

What are the pyrimidines in DNA?

A

Thymine and cytosine

68
Q

What is the sugar component in DNA?

A

Deoxyribose

69
Q

What is the sugar component in RNA?

A

Ribose

70
Q

A combination of base, sugar, and phosphate

A

nucleotide

71
Q

Control growth, development, and protein synthesis

A

nucleic acids

72
Q

What is the principal location of RNA in the cell?

A

Cytoplasm

73
Q

What is the oxygen enhancement ratio (OER) for low-LET radiation?

A

High OER

74
Q

What is the combined process of intracellular repair and repopulation called?

A

Recovery

75
Q

What is the most radioresistant age in humans?

A

Maturity

76
Q

What are examples of radiosensitizers?

A

Halogenated pyrimidines, methotrexate, vitamin K

77
Q

What are examples of radioprotectors?

A

Cysteine and cysteamine

78
Q

Why haven’t radioprotectors been applied in humans?

A

They require toxic levels to be effective

79
Q

What is the relationship between LET and RBE?

A

As LET increases, RBE increases

80
Q

What is the LET value for diagnostic X-rays?

A

3 keV/μm

81
Q

What is the RBE value for diagnostic X-rays?

A

1.0

82
Q

What is the function of the radiation weighting factor (WR)?

A

Adjusts for differences in biological effectiveness of various radiation types

83
Q

Cell death before replication

A

Interphase death

84
Q

What is the function of the mitochondria in radiation response?

A

Provides energy for cellular repair and survival

85
Q

What is a deterministic dose-response relationship?

A

Response increases with dose after a threshold is reached

86
Q

The response is directly proportional to the dose

A

linear dose-response relationship

87
Q

What is the principal use of linear nonthreshold models in radiology?

A

To establish radiation protection guidelines

88
Q

What phase of mitosis is best for analyzing chromosome damage?

A

Metaphase

89
Q

What tissues are classified as having high radiosensitivity?

A

Lymphoid tissue, bone marrow, gonads

90
Q

What are the primary effects of radiation on the central nervous system?

A

Edema, convulsions, and death at very high doses

91
Q

What is the typical dose range for intermediate radiosensitivity tissues?

A

1,000–5,000 rad (10–50 Gy)

92
Q

What organs have low radiosensitivity?

A

Muscle, brain, and spinal cord

93
Q

What is the purpose of dose-response curves in radiation therapy?

A

To design therapeutic treatments and set radiation safety guidelines

94
Q

What is the structure of a chromatid during the S phase?

A

Replicates from a two-chromatid to a four-chromatid structure

95
Q

Produces collagen and other fibers for structural support

A

fibroblasts

96
Q

What is the impact of radiation on intestinal crypt cells?

A

Highly radiosensitive, leading to gastrointestinal syndrome

97
Q

Chromosomes split at the centromere and migrate to opposite poles

A

anaphase

98
Q

Chromosomes become visible and take structural form

A

prophase

99
Q

What is the impact of low LET radiation on tissue damage?

A

Causes less biological damage than high LET radiation

100
Q

What is the difference between deterministic and stochastic effects?

A

Deterministic effects have a threshold; stochastic effects do not

101
Q

Modifies, sorts, and packages proteins

A

Golgi apparatus

102
Q

What are stem cells classified as?

A

Undifferentiated cells with high radiosensitivity

C1 (9 decks)

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