RAD BIO EXAM 5

Acute radiation syndrome presents in four major response stages. In what order do these stages occur?

Prodromal → Latent period → Manifest illness → Recovery or death

Which of the following systems is the most radiosensitive vital organ system in human beings?

Hematopoietic

With regard to radiation exposure, which part of the gastrointestinal tract is most severely affected?

Small intestine

Which of the following correctly matches the radiation effect with its category?

Cataracts - Deterministic (Tissue Reactions)

Which statement correctly distinguishes somatic effects from genetic effects of radiation exposure?

Somatic effects occur in the irradiated individual, while genetic effects occur in future generations due to damaged germ cells.

Which of the following best defines somatic damage from radiation exposure?

Biologic damage sustained by living organisms as a direct result of ionizing radiation exposure

Which of the following best describes early tissue reactions to ionizing radiation?

They vary depending on the time after exposure, have a threshold dose, and the severity depends on the absorbed dose.

A whole-body radiation dose of approximately 6 Gyt can result in which of the following reactions?

Many manifestations of organic damage occurring in succession, known as acute radiation syndrome

Acute radiation syndrome (ARS) includes three separate dose-related syndromes as part of the total-body response. Which of the following is NOT one of the syndromes?

Respiratory syndrome

The hematopoietic syndrome of acute radiation syndrome typically occurs after a whole-body radiation dose of:

1 Gy to 10 Gy

In hematopoietic syndrome of acute radiation syndrome, damage to the body results in a decrease in which of the following?

Red blood cells, white blood cells, and platelets

Gastrointestinal syndrome of acute radiation syndrome typically occurs after a whole-body dose of:

10-50 Gy

In gastrointestinal syndrome, radiation primarily damages which of the following?

Intestinal lining, causing nausea, vomiting, diarrhea, and dehydration

In cerebrovascular syndrome, radiation primarily damages which of the following?

Central nervous system and cardiovascular system

Which of the following is defined as an analysis in which damage to tissues is used to estimate the amount of radiation exposure?

Biologic dosimetry

Which of the following statements is true regarding the term LD 50/60?

The whole-body dose of radiation that is lethal to 50% of the exposed population within 60 days

Why can cells exposed to sublethal doses of ionizing radiation often repair and recover?

Cells contain inherent repair mechanisms, such as repair enzymes

Regarding radiation-induced cellular damage, which of the following is correct?

Approximately 10% of damage is irreparable, while about 90% may be repaired over time.

Which of the following statements best describes the effect of oxygenation on cellular recovery from radiation?

Oxygenated cells recover better than hypoxic cells.

Which of the following statements is true?

Tissues with high radiosensitivity, rapid growth rates, and frequent cell reproduction are more likely to show radiation damage.

Which statement best describes the Law of Bergonié and Tribondeau regarding cell radiosensitivity?

Cells are more radiosensitive if they are immature, rapidly dividing, and have a high reproductive capacity

Why do the testes and ovaries respond differently to irradiation?

The method of cell production and maturation differs between the two organs.

What does the field of cytogenetics primarily study?

The study of cell genetics with emphasis on chromosomes

Which statement best describes deterministic effects of radiation?

Severity increases as dose increases, and a threshold must be reached before effects appear.

Cancer caused by radiation exposure is classified as which of the following? SELECT TWO

Late effect; Stochastic effect

Which of the following best describes stochastic effects?

Random effects with probability increasing as dose increases

Which statement best describes stochastic effects of radiation?

Probability increases with dose, but severity does not depend on dose.

What is the best definition of epidemiology?

The science that deals with the incidence, distribution, and control of disease in a population

What does a radiation dose-response curve represent?

The relationship between the observed biological effects and the dose of radiation received

What does a nonthreshold radiation dose-response relationship indicate?

Any amount of radiation, no matter how small, has the potential to produce a biologic effect

Which type of radiation dose-response relationship is currently recommended by radiation protection committees for estimating most types of cancer?

Linear nonthreshold curve

What does the linear nonthreshold (LNT) model imply about the relationship between radiation dose and biological response?

Biologic response is directly proportional to the dose received, with no safe threshold

Which type of dose-response curve is generally used in radiation therapy to demonstrate high-dose cellular responses in specific locations such as the skin, lens of the eye, or blood cells?

Sigmoid (S-shaped) nonlinear threshold curve

A patient receives a high dose of radiation to the abdomen during a therapeutic procedure and later develops nausea, vomiting, and temporary loss of white blood cells. Which type of radiation effect does this represent?

Somatic effect

Which of the following correctly distinguishes the two main categories of somatic effects? SELECT TWO

Stochastic effects - Probability depends on dose, severity does not; Tissue reactions - Both probability and severity depend on dose

A patient exposed to radiation develops cataracts after a high dose to the eye lens, while another patient exposed to low-dose radiation develops leukemia years later. Which statements correctly classify these effects?

Cataracts - Tissue reaction; Leukemia - Stochastic

Which of the following is true regarding late somatic effects of radiation?

They may be either stochastic effects or tissue reactions

What does the absolute risk model estimate in radiation epidemiology?

The specific number of malignancies expected to occur as a result of radiation exposure

Which of the following best describes the relative risk model in radiation epidemiology?

Predicts that radiation exposure will multiply the natural (baseline) incidence of cancer by a certain factor

Which of the following best describes a linear dose-response relationship in radiation epidemiology?

The risk per unit dose is constant, producing a straight-line progression

A patient receives a radiation dose to the eye lens below a certain level and does not develop cataracts, but higher doses cause cataracts with increasing severity. Which dose-response model does this example illustrate?

Linear threshold

A pregnant woman is exposed to a low dose of radiation 8 days after conception. During which stage of gestation did this exposure occur?

Preimplantation stage

A male radiation worker is exposed to ionizing radiation that damages the DNA in his sperm cells. If he has children afterward, what type of effect could occur, and why?

Genetic effect; because DNA alterations in germ cells can be passed to offspring

What is the definition of the doubling dose in radiation genetics?

The dose of radiation that doubles the number of spontaneous mutations in a generation

Which of the following is an example of a stochastic effect?

Leukemia

What does the symbol Z indicate when talking about atoms?

atomic number of an atom

During photoelectric absorption, an electron from which shell gets ejected?

Inner

Cataract formation and fibrosis are classified as __________ of ionizing radiation.

late tissue reactions

During an x-ray procedure, a patient receives an absorbed dose of 0.02 Gy to the lungs (0.12). What is the effective dose?

2.4 mSv

What is the annual equivalent dose limit for the lens of the eye of an occupational worker?

150 mSv

What is the annual effective dose (EfD) limit for an occupational worker?

50 mSv

Which of the following are classified as late tissue reactions (deterministic effects) caused by high-level radiation exposure that occur months or more after that exposure?

1 and 2 only

The embryo-fetus is particularly insensitive to radiation exposure.

False

Which of the following specialized cells in the bone marrow are the ones to produce antibodies?

B lymphocytes

How many different amino acids are involved in protein synthesis in humans?

22