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Tox > midterm > Flashcards

midterm Flashcards

1
Q

Fractionation of a total dose so that the total amount administered is given over a period of time usually results in:

A

Decreased Toxicity

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2
Q

The quantity of a substance administered to an individual over a period of time or in several individual doses is known as the:

A

Total Dose

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3
Q

The usual dosage unit that incorporates the amount of material administered or absorbed in accordance with the size of the individual over a period of time is:

A

mg/kg/day

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4
Q

Knowledge of the dose-response relationship permits one to determine:

A

whether exposure has caused an effect, threshold for the effect, and the rate of buildup of
the effect with increasing dose levels.

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5
Q

The usual measure for variability of a toxic response is the standard deviation. One standard deviation represents:

A

68% of the responses.

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6
Q

The dose level at which a toxic effect is first encountered is known as the

A

Threshold Dose

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7
Q

The NOAEL, LOAEL, NOEL, and LOEL have great importance in the conduct of risk assessments.

A

The estimated dose level that will produce 50% deaths in groups of animals administered
a specific dose.

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8
Q

The Therapeutic Index is used to:

A

Compare the 50% response to a pharmaceutical in terms of therapeutically effectiveness
(ED50) and toxicity (LD50).

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9
Q

The Margin of Safety is:

A

A comparison of the minimally lethal dose (LD01) to the maximally effective dose
(ED99).

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10
Q

A drug that has a 99% effective dose of 20 mg/kg and a 1% lethal dose of 100 mg/kg has a margin of safety (MOS) of:

A

5

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11
Q

What is the LD50 for chemical XYZ, based on the figure below?

A

17mg

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12
Q

What is the NOAEL for chemical XYZ, based on the figure below?

A

30 mg

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13
Q

What is a target organ?

A

An organ that is damaged by the xenobiotic or its metabolite

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14
Q

What are the important factors that influence the degree of toxicity of a substance?

A

a. Innate chemical activity and the dosage of the chemical.
b. Absorption, distribution, metabolism and excretion.
c. Exposure route, species, age, sex, and the presence of other chemicals.
d. All of the above.

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15
Q

Metabolism of a xenobiotic:

A

May result in either detoxification (less toxic metabolites) or bioactivation (more toxic
metabolites).

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16
Q

The situation in which an antibiotic administered to humans kills bacteria in the human body but does not damage the human tissues is an example of:

A

Selective toxicity

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17
Q

The toxicity of pharmaceuticals to older persons and infants is generally:

A

Greater

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18
Q

Toxic effects are primarily of two general types:

A

systemic or specific target organ effects

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19
Q

The primary difference between acute and chronic toxicity is:

A

Acute toxicity appears soon after an exposure whereas chronic toxicity occurs many
months or years later.

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20
Q

Police respond to a 911 call in which two people are found dead in an enclosed bedroom heated by an unvented kerosene stove. There was no sign of trauma or violence, a likely cause of death is:

A

Acute toxicity due to carbon monoxide poisoning.

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21
Q

When toxicity occurs following several years’ exposure to a chemical, the effect is known as:

A

Chronic

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22
Q

The process whereby a normal body cell becomes a cancer cell is known as:

A

carcinogenicity

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23
Q

The difference between a benign tumor and a malignant tumor is:

A

A benign tumor grows only at the site of origin whereas a malignant tumor may invade
surrounding tissues and migrate to distant sites where it can spread.

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24
Q

Birth defects (teratogenic effects) are usually the result of:

A

Death or damage to critical cells of the developing fetus.

b. Mutations present in the parent’s germ cells.
c. Both of the above.

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25
Q

The term used to denote a substance that causes a change in the DNA of a cell is known as a:

A

Mutagen

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26
Q

Allergy is due to:

A

toxicity of the immune system

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27
Q

Antagonism refers to an interaction in which:

A

A reduction in a chemical’s toxicity occurs due to the presence of another chemical.

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28
Q

A dose of 4 mg of an insecticide causes 20% toxicity whereas the same dose of another insecticide produces 30% toxicity. If 8 mg of a formulation containing both insecticides in equal concentrations causes 50% toxicity, the interaction is known as:

A

Additivity

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29
Q

Piperonyl butoxide added to pyrethrum insecticide results in a pyrethrum formulation having about 100 times the toxicity of pyrethrum alone. The interaction of this combination is:

A

Synergism

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30
Q

The process whereby a substance moves from outside the body into the body is known as:

A

Absorption

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31
Q

For a xenobiotic to move from outside the body to a site of toxic action requires that it

A

pass through several cell membranes

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32
Q

The basic structure of the cell membrane consists of:

A

a bilayer of phospholipids with scattered proteins within the layers

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33
Q

The membrane transport process by which large hydrophobic molecules cross membranes via the lipid portion of the membrane, follow the concentration gradient, and do not require energy or carrier molecules is known as:

A

simple diffusion

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34
Q

Endocytosis is a form of specialized membrane transport in which the cell surrounds the substance with a section of its cell membrane. The specific endocytosis process by which liquids or very small particles are engulfed and transported across the membrane is known as:

A

pinocytosis

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35
Q

The most important factor that determines whether a substance will be absorbed within the stomach is:

A

pH

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36
Q

The primary routes for absorption of environmental agents are:

A

gastrointestinal tract, respiratory tract, and skin

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37
Q

The site of the gastrointestinal tract where most absorption takes place is:

A

Small intestinal

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38
Q

An inhaled material will most likely be absorbed into the body if it has the following characteristics:

A

high water solubility and small particle size

39
Q

Particles of size 2-5 μM are most likely to settle out in which location of the respiratory tract?

A

tracheobronchial region

40
Q

The main barrier to dermal absorption is the:

A

stratum corneum

41
Q

The two primary factors that can increase dermal penetration are:

A

increasing hydration and disruption of the stratum corneum

42
Q

If an immediate therapeutic effect is needed, the route of exposure that would most likely be used is the:

A

intravenous injection

43
Q

A pharmaceutical may be implanted in the body for the following reason:

A

to allow slow-release over a long period of time

44
Q

When an ingested toxicant is absorbed, it passes through the cells lining the GI tract into the:

A

interstitial fluid

45
Q

The apparent volume of distribution (VD ) represents:

A

the total volume of body fluids in which a toxicant is distributed

46
Q

The main difference in distribution of a toxicant absorbed from the gastrointestinal tract from toxicants absorbed through the skin or from inhalation is:

A

the toxicant enters the systemic circulatory system after passing through the liver first

47
Q

Disposition models describe:

A

how a toxicant moves within the body with time

48
Q

Organs may differ greatly in the concentration of a toxicant in them, due primarily to:

A

volume of blood flow and the presence of special barriers to absorption

49
Q

The placental barrier protects the fetus from toxicants in the maternal blood because:

A

substances in the maternal blood must move through several layers of cells in order to
gain entrance to placental blood

50
Q

The areas of the body which most frequently store toxicants are:

A

adipose tissue, bone, liver, and kidney

51
Q

The term “biotransformation” refers to:

A

chemical reactions in the body that create a new chemical from another chemical

52
Q

Detoxification is a biotransformation process in which:

A

metabolites of lower toxicity are produced

53
Q

The substances in the body that accelerate chemical reactions are known as:

A

enzymes

54
Q

The convention used to name specific enzymes consists of:

A

combining the substrate name with the type of chemical reaction

55
Q

Biotransformation reactions are classified as Phase I and Phase II. The basic difference is:

A

Phase I reactions generally add a functional structure whereas Phase II reactions
conjugate the substance

56
Q

The difference between oxidation and reduction reactions is:

A

a substrate losses electrons from an oxidation reaction whereas it gains electrons by a
reduction reaction

57
Q

Which conjugation reaction is the most common in the biotransformation of xenobiotics?

A

glucuronide conjugation

58
Q

he organ that has the greatest ability to biotransform xenobiotics is the:

A

Liver

59
Q

The “first pass” phenomenon pertains to:

A

an anatomical arrangement in which xenobiotics absorbed from the intestine go to the
liver first rather than into the systemic circulation

60
Q

Selective toxicity refers to a difference in the toxicity of a xenobiotic to different species. This selective toxicity can usually be attributed to:

A

differences in capability to biotransform the xenobiotic

61
Q

The three major routes of excretion are:

A

urinary excretion, fecal excretion, and exhaled air

62
Q

The reason that much of the blood plasma filters into the renal tubule is due to:

A

the large amount of blood, under relatively high pressure, that flows through kidney
glomerulae whose capillaries have large pores

63
Q

In which area of the nephron does active secretion take place?

A

its polarity

64
Q

Substances excreted in the bile are primarily:

A

comparatively large, ionized molecules

65
Q

many substances excreted in bile undergo enterohepatic circulation, which involves:

A

excretion into the intestinal tract and reabsorption and return to the liver by the portal circulation

66
Q

Xenobiotics are eliminated in exhaled air by:

A

passive diffusion

67
Q

The following are minor routes of excretion:

A

sweat and saliva

68
Q

The ability of the body to maintain relative stability and function even though drastic changes may take place in the external environment or in one portion of the body is known as

A

Homeostasis

69
Q

To maintain homeostasis, the body reacts to an abnormal change (induced by a toxin, biological organism, or other stress) and makes certain adjustments to counter the change (a defense mechanism). The component of the homeostasis process which detects the change in the environment is known as the:

A

receptor

70
Q

Groups of cells with similar structure and function are known as:

A

Tissues

71
Q

The organ system that transports oxygen and nutrients to tissues and removes waste products is the:

A

cardiovascular system

72
Q

The organ system that regulates body functions by chemicals (hormones) is known as the:

A

endocrine system

73
Q

There are only four types of tissues in the body. The type of tissue that is specialized to protect, absorb and secrete substances, detect sensations, covers every exposed body surface, and forms a barrier to the outside world is

A

Epithelial tissue

74
Q

There are several different types of cellular organelles. The very small structures (fixed to the endoplasmic reticulum or free within the cytoplasm) that consist of RNA and proteins, and function in protein synthesis, are

A

Ribosomes

75
Q

The organelle that produces nearly all (95%) of the energy required by the cell is the:

A

Mitochondria

76
Q

A substance in the body that contains covalently-bonded carbon and hydrogen is:

A

Organic compound

77
Q

The nucleic acid located in the nucleus, which makes up the chromosomes of cells, is:

A

DNA

78
Q

An increase in skeletal muscle cells in athletes due to exercise and increased metabolic demand is an example of:

A

Physiological adaptation

79
Q

A cellular response in which there is an increase in the number of cells in a tissue is known as

A

Hyperplasia

80
Q

A condition of abnormal cell changes or deranged cell growth in which the cells are structurally changed in size, shape, and appearance from the original cell type is known as:

A

Dysplasia

81
Q

The process of self-destruction of the cell nucleus (often referred to as “programmed cell death”) is known as:

A

Apoptosis

82
Q

The category of cells that routinely divide and replace cells that have a limited lifespan is known as:

A

Labile cells

83
Q

A body growth with the ability to metastasize or invade into surrounding tissues is known as a:

A

malignant tumor

84
Q

Most cancers are thought to be due to the following:

A

Lifestyle

85
Q

The initial stage in carcinogenesis in which there is an alteration of the DNA (mutation) is referred to as:

A

initiation phase

86
Q

The cellular gene which is present in most normal cells and serves as a balance to the genes for tumor expression is known as a:

A

Tumor suppressor gene aka anti-oncogenes

87
Q

The two fundamental anatomical divisions of the nervous system are:

A

The central nervous system and the peripheral nervous system

88
Q

The two major categories of cells found in the nervous system are:

A

Neurons and glial cells

89
Q

The propagation of an electrical impulse (action potential) down an axon consists of:

A

A continuous series of opening and closing of sodium-potassium channels and pumps

90
Q

The type of neuron that relays information from the CNS to other organs is a

A

Motor neuron

91
Q

The primary cause of death to neurons and glial cells is

A

anoxia

92
Q

A major mechanism that prevents the action potential (impulse) from moving down an axon is:

A

Blockage or interference with movement of sodium and potassium ions in and out of neuron membrane, changing the action potential

93
Q

What are the two basic types of synapses

A

Those between two neurons and a neuron and effector

Tox (2 decks)

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