Chapter 6: Radiation & Cancer Flashcards
Non-Ionizing Radiation
Heat, Sound, Radio, Visible
Generally SAFE
Ionizing Radiation
Cause DNA damage by ionizing atoms (X-Ray, Nuclear Radiation)
Is Ultraviolet light Ionizing radiation?
NO! It can BOTH heat and cause DNA damage by altering chemical bonds (cross linking DNA bases)
What are the 3 forms of skin cancer?
Basal Cell
Squamous
Melanoma
Which form of skin cancer rarely metastasizes?
Basal cell
Which form of skin cancer metastasizes in 1/20 patients and is linked to sunlight exposure?
Squamous
Which form of skin cancer has usually metastasized by the time of diagnosis?
Melanoma
Which form of skin cancer appears most often on the legs and back, non-exposed areas?
Melanoma
Why can melanomas appear in non-exposed areas?
Early childhood with severe sunburns, severe sunburns as an adult
Which class of UV is associated with Skin Cancer? Why?
UVB
Breaks covalent bonds in DNA
What compound has increased our exposure to UVB? Why?
Chlorofluorocarbons
Were used as refrigerants, but are now banned due to destruction of Ozone layer
How does UVB cause DNA mutations?
Creating pyrimidine dimers in DNA
What is the UVB signature in DNA? What gene is this signature in?
C-T substitutions at dipyrimidine sites
P-53 gene
UVB
P-53 mutations
Apoptosis
Tumor promotion
Is sunburn a protective mechanism against skin cancer?
YES! It is an attempt to destroy cells damaged by UV radiation
Is UVA considered an initiator or promoter?
Promoter as it stimulates division
Tanning Devices
Claim to be safer than sunlight because they use UVA to stimulate melanin production
People who use them have higher rates of skin cancer, than those who do not
X-Rays
Very penetrating through the body
Decrease in lifespan due to death from cancers - especially Leukemias
Nuclear radiation
Alpha particles
Beta particles
Gamma particles
Which form of nuclear radiation has the most energy and penetration?
Gamma Particles
Which form of nuclear radiation is the most damaging but least penetrating?
Alpha Particles
Radon Gas
Alpha emitter
Little penetration
Where does radon gas come from?
Radium and uranium
What radioactive element does radon decay to?
Polonium
Whee does radon gas in tobacco smoke come from?
Tobacco fertilizers continuing phosphate from crushed rocks w/ trapped radon gas
Why is Leukemia rate highest post atomic bomb?
Not as common as other cancers & latent period is generally shorter than other cancers, so they are first to be seen
Natural promoter event
Lymphocytes are stimulated to divide due to allergies and infection
What nuclear event caused the largest numbers of cancers of the thyroid ever caused by one single event?
Chernobyl 400X the radiation from bombing Japan
How does ionizing radiation cause cancer?
Initiating carcinogenesis by causing DNA damage
Reactive Oxygen Species
Hydroxyl radical, hydrogen peroxide, superoxide
Produced in biological systems and can be damaging and mutational
Enzyme systems
Neutralize free radicals and consume and synthesize molecules to scavenge them
Prevents many diseases (cancer, heart disease)
BERT
Background Equivalent Radiation Time
How many days of BERTS add up to one Chest X-Ray?
10 days
How many years of BERTS does the average smoked get from smoking one year?
10 years
What radioactive element is present in cigarette smoke following the decay of radon gas?
Polonium
Radiation
Energetic particles or waves
90% of exposure is natural and we have evolved repair mechanism
