BIOL 110

if the radiation response occurs within minutes or days after the radiation exposure, it is classified as… 5

early effect

if the human injury is not observed for months or years, its classified as 5

late effect

most human responses have been observed to occur after exposure to rather large radiation doses. However, we are cautious to assume… 5

that even a small dose is harmful

is considered to be the most critical and radiosensitive target molecule 6

DNA

Contains all the hereditary information that represents a cell… 6

DNA

serves as a command or control molecule for cell fuction 6

DNA

Located primarily in the cytoplasm, its also found in the nucleus 6

RNA

two types of RNA have been identified as… 6

messenger RNA (mRNA) and transfer (tRNA)

what is the most abundant molecule in the body, and it is the simplest. 6

water

center of the living cell 7

nucleus

DNA that is stored in its molecular structure 7

Nucleus

makes up the bulk of the cell 7

cytoplasm

channels the nucleus to communicate with the cytoplasm 7

endoplastic reticulum

large bean shaped structure. produces energy for the cell 7

mitochondria

When somatic cells proliferate or divide, they are undergoing… 9

mitosis

and genetic cells undergo…9

meiosis

mitosis is characterized of four sub-phases 9

PMAT: Prophase, metaphase, anaphase, and telophase

The nucleus swells and the DNA becomes more prominent and begins to take structural form 9

prophase

studied carefully under the microscope, radiation-induced chromosome damage is analyzed. 9

metaphase

characterized by splitting of each chromosome at the centromere. 9

anaphase

the final segment of mitosis 9

telophase

genetic cells begin with the same number of chromosomes as somatic cells 10

meiosis

meiosis has—- pairs and —- chromosomes 10

23, 46

are called undiffirentiated, precursor, or stem cells 10

immature cells

are more radiosensitive to radiation than mature cells 10

stem cells

younger tissue and organs are 11

radiosensitive

tissues with high metabolic activity are 11

radiosensitive

a high proliferation rate for cells and high growth rate fore tissues result in… 11

increased radiosensitivity

is expressed in units of kiloelectron volt of energy transferred per micrometer of track length in soft tissue 12

Linear energy transfer (LET)

if the dose is delivered continuously but at a lower dose rate, it is said to be… 13

protracted

if the dose is delivered, all separated by 24 hours, then it is said to be… 13

fractionated

what speciality uses dose fractionation more routinely? 13

radiation oncology

tissue is more sensitive to radiation when irradiated… 14.—- than when irrated under…

oxygenated, or aerobic state / anoxic(without oxygen) or hypoxic ( low oxygen)

what is the oxygen enhancement ratio equation 14

(OER) = Dose necessary under ANOXIC conditions to produce a GIVEN effect / Dose necessary under AEROBIC conditions to produce the SAME effect

what has been used in order to enhance the radiosensitivity of nodulars 14

hyperbaric (high-pressure) oxygen

At the whole body level, this recovery from radaition damage is assisted through… 15

repopulation by surviving cells

if a tissue or organ receives a sufficient radiation dose, it responds by… 15

shrinking

it occurs because some cells die and disintegrate and are carried away as waste products… 15

atrophy

recovery 15

recovery= intracellular repair + repopulation

what are agents that enhance effects of radiation called 16

sensitizing agents

what are examples of sensitizing agents 16

halogated pryrimidines, methotrexate, actinomycin D, hydroxyurea, vitamin K

radioprotective compounds include molecules that contain 16

sulfhydryl group (sulfur and hydrogen bound together) e

examples of radioprotectors 16

cysteine, and cysteamine

a little bit of radiation is good for you… 16

hormesis

ALARA 16

as low as reasonably achievable

early response to radiation exposure is called 17

deterministic l

late response to radiation exposure is called 17

stochastic

examples such as skin burns, represents what 17

deterministic e

examples such as cancer, leukemia, or genetic effects are considered what 17

stochastic

if the graph shows a linear dose-response relationship, it is because… 18

the response is DIRECTLY proportionate to the dose

In a nonthreshold dose-response relationship, any dose, regardless of its size, is … 18

expected to produce a response ex cancer

shows that a large response results form a very small radiation dose

nonlinear nonthreshold

nonlinear, threshold is considered what.. 19

a deterministic response

What happens when macromolecules are irradiated? 20

main-chain scission, cross-linking, point lesions

is the breakage of the backbone of the long-chain macromolecule 20

main-chain scission

small, spur-like side structures that extend off the maihn chain 20

cross- linking

radiation interaction with macromolecules also can result in disruption of single chemical bonds, producing…l 21

point lesions

When water is irradiated, it dissociated into other molecular products, this is called 22

radiolysis or water

when an atom of water (H2O) is irradiated, … 22

it is ionized and dissociated into two ions. ion pair

what is highly reactive, unstable, can be transferred, and contain excess energy 23

free radicals

The OH free radical can join with a similar molecule to form… 23

hydrogen peroxide

hydrogen peroxide can be formed by the interaction of… 23

teo hydroperoxyl radicals

if the initial ionizing event occurs on the target molecule, the effect of radiation is… 23

direct

the principal effect of radiation on humans is… 23

indirect

radiation damage to such a molecule could affect the cell severely because.. 24

no similar molecules would be available as substitutes

for a cell to die after radiation exposure, its target molecule must be inactivated 24

this concept of sensitive key molecule serves as basis for the target theory

the ikey molecular target is 24

DNA

how are the lethal effects of radiation determined 25

by observing cell survival, not cell death

the multitarget, single-hit model applies to more complicated biologic systems, such as.. 25

human cells

in air, the alpha particles can travel approximately 27

5 cm

alpha radiation from an external source is nearly harmless because… 27

the radiation energy is deposited in the superficial layers of the skin

what can originate from the nuclei of radioactive atoms 27

beta particles

a beta particle may transverse … 27

10 to 100cm of air and approximately 1 to 2 cm of soft tissue

symptoms of early radiation sickness such as nausea, vomiting, diarrhea, and a reduction in the white cells of the peripheral blood (leukopenia) is called … 20

prodromal period

may last from a few hours to a couple of days 30

prodromal period

after the period of initial radiation sickness, a period of apparent well-being occurs, which is called 30

latent period

hematologic syndrome produce

200 to 1000 rad (2 to 10grt)

if the dose is not lethal, recovery begins in 2 to 3 weeks, but as long as 6 months may be required for… 30

full recovery

1000 to 5000 rad (10 to 50GYT) results in the 31

GI syndrome

Occurs principally because of severe damage to the cells lining the intestines 31

GI death

Dose in excess of approximatlly 5,000 rad (50gty) causes 31

centrl nercous system syndrome (CNS) syndrome

what is the LD 50/60 quantity for humans 32

350 rad (3.5 grt)

the manner in which local tissues respond depends on their intrinsic radiosensitivity and kinetics of cell proliferation and maturation 33

local tissues affected immediately are skin, gonads, and bone narrow

a sunburn-like redding of the skin 33

erythema

during radiation theraphy, the skin is exposed according to a fractioned scheme, usually aprox of… 33

200 rad/day (2grt/d), 5 days a week

are critically important target organs 34

human gonads

gonads are sensitive to radiation, responses as low as —- have been observed 34

10 rads

At fetal like and in early childhood the ovaries are… 34

especially sensitive

radiation doses as low as —— can reduce the number of spermatozoa 34

10 rad (100mgty)

what amount produces temporary infertility 34

200 rad. (2 gyt)

what amount produces permanent sterility 35

500 rad (5 gty)

what are the most radiosensitive cells in the body 35

lymphocytes and spermatogonia

what are less sensitive than other blood cells

erythocytes

why are erythrocytes less sensitive than the other blood cells 35

because of their very long lifetime in the peripheral blood

cyntogenetic analysis of chromosomes can be cut out like a paper doll and paired with its sister into a chromosome map, which is called a 36

karyotype

What represents a severe damage to the DNA 36

a chromosome hit