midterm

Question 1

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

Answer 1

Decreased Toxicity

Question 2

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

Answer 2

Total Dose

Question 3

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:

Answer 3

mg/kg/day

Question 4

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

Answer 4

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

Question 5

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

Answer 5

68% of the responses.

Question 6

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

Answer 6

Threshold Dose

Question 7

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

Answer 7

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

Question 8

The Therapeutic Index is used to:

Answer 8

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

Question 9

The Margin of Safety is:

Answer 9

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

Question 10

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:

Answer 10

5

Question 11

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

Answer 11

17mg

Question 12

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

Answer 12

30 mg

Question 13

What is a target organ?

Answer 13

An organ that is damaged by the xenobiotic or its metabolite

Question 14

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

Answer 14

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.

Question 15

Metabolism of a xenobiotic:

Answer 15

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

Question 16

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:

Answer 16

Selective toxicity

Question 17

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

Answer 17

Greater

Question 18

Toxic effects are primarily of two general types:

Answer 18

systemic or specific target organ effects

Question 19

The primary difference between acute and chronic toxicity is:

Answer 19

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

Question 20

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:

Answer 20

Acute toxicity due to carbon monoxide poisoning.

Question 21

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

Answer 21

Chronic

Question 22

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

Answer 22

carcinogenicity

Question 23

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

Answer 23

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.

Question 24

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

Answer 24

Death or damage to critical cells of the developing fetus.

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

Question 25

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

Answer 25

Mutagen

Question 26

Allergy is due to:

Answer 26

toxicity of the immune system

Question 27

Antagonism refers to an interaction in which:

Answer 27

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

Question 28

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:

Answer 28

Additivity

Question 29

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:

Answer 29

Synergism

Question 30

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

Answer 30

Absorption

Question 31

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

Answer 31

pass through several cell membranes

Question 32

The basic structure of the cell membrane consists of:

Answer 32

a bilayer of phospholipids with scattered proteins within the layers

Question 33

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:

Answer 33

simple diffusion

Question 34

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:

Answer 34

pinocytosis

Question 35

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

Answer 35

pH

Question 36

The primary routes for absorption of environmental agents are:

Answer 36

gastrointestinal tract, respiratory tract, and skin

Question 37

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

Answer 37

Small intestinal

Question 38

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

Answer 38

high water solubility and small particle size

Question 39

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

Answer 39

tracheobronchial region

Question 40

The main barrier to dermal absorption is the:

Answer 40

stratum corneum

Question 41

The two primary factors that can increase dermal penetration are:

Answer 41

increasing hydration and disruption of the stratum corneum

Question 42

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

Answer 42

intravenous injection

Question 43

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

Answer 43

to allow slow-release over a long period of time

Question 44

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

Answer 44

interstitial fluid

Question 45

The apparent volume of distribution (VD ) represents:

Answer 45

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

Question 46

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

Answer 46

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

Question 47

Disposition models describe:

Answer 47

how a toxicant moves within the body with time

Question 48

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

Answer 48

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

Question 49

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

Answer 49

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

Question 50

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

Answer 50

adipose tissue, bone, liver, and kidney

Question 51

The term "biotransformation" refers to:

Answer 51

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

Question 52

Detoxification is a biotransformation process in which:

Answer 52

metabolites of lower toxicity are produced

Question 53

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

Answer 53

enzymes

Question 54

The convention used to name specific enzymes consists of:

Answer 54

combining the substrate name with the type of chemical reaction

Question 55

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

Answer 55

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

Question 56

The difference between oxidation and reduction reactions is:

Answer 56

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

Question 57

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

Answer 57

glucuronide conjugation

Question 58

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

Answer 58

Liver

Question 59

The "first pass" phenomenon pertains to:

Answer 59

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

Question 60

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

Answer 60

differences in capability to biotransform the xenobiotic

Question 61

The three major routes of excretion are:

Answer 61

urinary excretion, fecal excretion, and exhaled air

Question 62

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

Answer 62

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

Question 63

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

Answer 63

its polarity

Question 64

Substances excreted in the bile are primarily:

Answer 64

comparatively large, ionized molecules

Question 65

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

Answer 65

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

Question 66

Xenobiotics are eliminated in exhaled air by:

Answer 66

passive diffusion

Question 67

The following are minor routes of excretion:

Answer 67

sweat and saliva

Question 68

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

Answer 68

Homeostasis

Question 69

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:

Answer 69

receptor

Question 70

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

Answer 70

Tissues

Question 71

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

Answer 71

cardiovascular system

Question 72

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

Answer 72

endocrine system

Question 73

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

Answer 73

Epithelial tissue

Question 74

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

Answer 74

Ribosomes

Question 75

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

Answer 75

Mitochondria

Question 76

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

Answer 76

Organic compound

Question 77

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

Answer 77

DNA

Question 78

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

Answer 78

Physiological adaptation

Question 79

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

Answer 79

Hyperplasia

Question 80

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:

Answer 80

Dysplasia

Question 81

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

Answer 81

Apoptosis

Question 82

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

Answer 82

Labile cells

Question 83

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

Answer 83

malignant tumor

Question 84

Most cancers are thought to be due to the following:

Answer 84

Lifestyle

Question 85

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

Answer 85

initiation phase

Question 86

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:

Answer 86

Tumor suppressor gene aka anti-oncogenes

Question 87

The two fundamental anatomical divisions of the nervous system are:

Answer 87

The central nervous system and the peripheral nervous system

Question 88

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

Answer 88

Neurons and glial cells

Question 89

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

Answer 89

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

Question 90

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

Answer 90

Motor neuron

Question 91

The primary cause of death to neurons and glial cells is

Answer 91

anoxia

Question 92

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

Answer 92

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

Question 93

What are the two basic types of synapses

Answer 93

Those between two neurons and a neuron and effector