Chapter 3 - Absorption, Distribution, Excretion of Xenobiotics Flashcards Preview

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Flashcards in Chapter 3 - Absorption, Distribution, Excretion of Xenobiotics Deck (58):
0

Toxicants most likely to be reabsorbed after being filtered at the glomerulus are...

A. Organic anions

B. organic cations

C. Neutral polar molecules

D. Highly lipid-soluble molecules

D. Highly lipid-soluble molecules

1

A high urinary pH would favor the excretion of...

A. Organic acids

B. organic bases

C. Neutral organic compounds

D. None of the above

A. Organic acids

2

Diuretics can enhance the renal elimination of compounds that...

A. Are of a molecular weight greater than 70 kDa

B. are ion trapped in the tubular lumen

C. Are highly lipid soluble

D. Are highly protein bound

B. are ion trapped in the tubular lumen

3

The amt of a volatile liquid excreted by the lungs is...

A. Inversely proportional to its lipid-water partition coefficient

B. directly proportional to its vapor pressure

C. Directly proportional to its molecular weight

D. Inversely proportional to cardiac output

B. directly proportional to its vapor pressure

4

Kernicterus results from...

A. Enzyme induction leading to decreased glucocorticoid levels

B. excess ingestion of foods containing tyramine

C. Displacement of bilirubin from plasma proteins

D. Malabsorption of fat-soluble vitamins

C. Displacement of bilirubin from plasma proteins

5

All of the following could influence the gastrointestional absorption of xenobiotics except...

A. pH

B. intestinal microflora

C. Presence of food

D. Time of day

D. Time of day

6

The rate of diffusion of a xenobiotic across the GI tract is proportional to all of the following except...

A. Hepatic blood flow

B. surface area

C. Permeability

D. Residence time

A. Hepatic blood flow

7

Which of the following is not absorbed in the colon?

A. Water

B. sodium ions

C. Glucose

D. Hydrogen ion

C. Glucose

8

Nanoparticles are considered to have diameters smaller than...

A. 100 um

B. 10 um

C. 1 um

D. 0.1 um

D. 0.1 um

9

All of the following are true of nanoparticles except...

A. They are capable of exposing the lung to a large number of particles

B. they are capable of exposing the lung to large particle surface area

C. Because of turbulance, very few reach the alveoli

D. They are the focus of recent toxicologic research

C. Because of turbulance, very few reach the alveoli

10

All of the following are significantly stored in bone matrix except...

A. Lead

B. diaquat

C. Strontium

D. Fluoride

B. diaquat

11

All of the following can cross the placenta except...

A. Heparin

B. rubella virus

C. Spirochetes

D. IgG antibody

A. Heparin

12

Methylmercury crosses the BBB bycombining with cysteine and forming a molecule similar to
...

A. Glycine

B. glutamine

C. Taurine

D. Methionine

D. Methionine

13

Which of the following statements is true?

A. The BBB of a 70 year old is more permeable than that of a premature infant

B. chemicals/drugs can be excreted into the urine by active secretion

C. The kidney lacks cytochrome P450 enzymes

D. All mammalian placentas have the same number of tissue layers

B. chemicals/drugs can be excreted into the urine by active secretion

14

All of the following is true of breast milk except...

A. Acidic cmpds may be more conc in milk than plasma

B. Toxicants can be passed from mother to offspring

C. Toxicants can be passed from cows tohumans

D. DDT, PCBs, and PBBs can be found in human milk

A. Acidic cmpds may be more conc in milk than plasma

15

Active transport is characterized by all of the following except...

A. Movement against a concentration gradient

B. energy requirement

C. Nonsaturability

D. Competitive inhibition

C. Nonsaturability

16

All of the following are true of facilitated diffusion except...

A. Does not require energy

B. movement against a concentration gradient

C. Saturability

D. Involvement of a carrier

B. movement against a concentration gradient

17

A transport process that removes particles from alveoli is...

A. Phagocytosis

B. phospholipids

C. Mediated through BCRP

D. Mediated through MDR1/P-gp

A. Phagocytosis

18

P-gp, MRP2, and BCRP on enterocyte brush-border membranes function as...

A. Influx transporters

B. bile acid binders

C. Metal transporters

D. Efflux transporters

D. Efflux transporters

19

Substrates for P-gp include all of the following except...

A. Cyclosporin

B. paclitaxel

C. Ethanol

D. Colchicine

C. Ethanol

20

The transfer of toxicants by simple diffusion from areas of high concentration to areas of low conc is called...

A. Dalton's law

B. Priestley's law

C. Fick's law

D. Henderson's law

C. Fick's law

21

The fluid character of cell membranes is somewhat dependent on the amount of...

A. Saturated fatty acids

B. transmembrane proteins

C. Ion channels

D. Unsaturated fatty acids

D. Unsaturated fatty acids

22

Aqueous pores are primarily involved in the transport of...

A. Small hydrophobic molecules

B. large hydrophobic molecules

C. Small hydrophyllic molecules

D. Large hydrophyllic molecules

C. Small hydrophyllic molecules

23

The agent with the largest octanel/water partition coefficient is...

A. Paraquat

B. ethylene glycol

C. Acetic acid

D. TCDD

D. TCDD

24

In renal glomeruli, pores allow molecules to pass through that are smaller than...

A. 60 kDa

B. 30 kDa

C. 15 kDa

D. 5 kDa

A. 60 kDa

25

Most of the vital nutrients essential for fetal development are delivered by...

A. simple diffusion

B. facilitated diffusion

C. Active transport

D. Ion trapping

C. Active transport

26

Most toxicants cross the placenta by...

A. Simple diffusion

B. facilitated diffusion

C. Active transport

D. Ion trapping

A. Simple diffusion

27

All of the following protect the fetus from toxicant exposure except...

A. Tight endothelial cell junctions similar to BBB

B. multiple tissue layers in the placenta

C. Biotransformation ability of the placenta

D. Presence of transporter systems in the placenta

A. Tight endothelial cell junctions similar to BBB

28

All of the following statements are true of the P-gp, Mrp2, Mrp4, and BCRP transport systems that contribute to the BBB except...

A. They are located on the luminal side of the capillary endothelial cell

B. they can efflux uncharged molecules

C. They do not require energy from ATP

D. Some can efflux anionic or cationic molecules

C. They do not require energy from ATP

29

All of the following statements are true of the BBB except...

A. It is not fully developed at birth

B. it is remarkedly constant throughout all areas of the brain

C. Lipid-soluble chemicals will penetrate faster

D. Ionized chemicals will penetrate slower.

B. it is remarkedly constant throughout all areas of the brain

30

Elemental mercury is poorly absorbed orally because of...

A. Large particle size

B. efflux transporters

C. Formation of insoluble complexes with phosphate

D. All of the above

A. Large particle size

31

The higher pH of the infant GI tract causes infants to be more susceptible to...

A. Reflux disease

B. toxic megacolon

C. Methhemoglobinemia

D. GI erosions

C. Methhemoglobinemia

32

Grapefruit juice affects...

A. Activity of CYP3A4

B. function of P-gp

C. Absorption of lovastatin

D. All of the above

D. All of the above

33

Species differences in GI absorption are due to...

A. Anatomic factors

B. gastrointestional pH differences

C. Differences in GI microflora

D. All of the above

D. All of the above

34

All of the following are true of absorption of gasses in the lung except...

A. Lipid solubility is more important than in GI absorption

B. degree of ionization is less important than in GI absorption

C. Diffusion through cell membranes is usually not rate limiting

D. Very water soluble molecules can be removed by the nose before reaching the lungs

A. Lipid solubility is more important than in GI absorption

35

The most characterized transplacental carcinogen is...

A. Warfarin

B. phenytoin

C. Diethylstilbestrol

D. Vitamin A

C. Diethylstilbestrol

36

Enzymes in the intestinal microflora may hydrolyze conjugates of organic cmpds with...

A. UDP-glucuronic acid

B. sulfate

C. Both

D. Neither

C. Both

37

The process of hydrolysis of an organic conjugate in the gut and reabsorption of the liberated parent cmpd is called...

A. Gastric bypass

B. enterohepatic cycling

C. First-pass effect

D. Well-stirred effect

B. enterohepatic cycling

38

The substance with the highest bile-to-plasma concentration ratio is..,

A. Arsenic

B. albumin

C. Iron

D. Gold

A. Arsenic

39

All of the following are transporters involved in biliary excretion except...

A. P-gp

B. Mrp2

C. BCRP

D. ras

D. ras

40

The organ that receives the smallest percentage of cardiac output is...

A. Liver

B. lung

C. Kidney

D. Skin

D. Skin

41

A major route for the excretion of TCDD is...

A. Urinary excretion

B. exhalation

C. Diffusion into fecal fat

D. Saliva

C. Diffusion into fecal fat

42

Xenobiotics can enter the gut by all of the following mechanisms except...

A. Secretion across the gut wall

B. patent ductus arteriosis

C. Elimination in the saliva

D. Elimination in pancreatic juice

B. patent ductus arteriosis

43

The two major plasma proteins that bind xenobiotics are...

A. Ferritin and transferrin

B. ceruloplasmin and renal-binding protein

C. Albumin and acid glycoprotein

D. Gamma globulin and fibrin

C. Albumin and acid glycoprotein

44

All of the following are true of the lung except...

A. It is a major barrier to the absorption of chemicals into the blood

B. it has a large surface area and a thin membrane

C. It is a major site of inactivation of certain peptides and prostaglandins

D. It has less capacity to metabolize foreign compounds than the liver does

A. It is a major barrier to the absorption of chemicals into the blood

45

All of the following contribute to the BBB except...

A. Low protein conc of brain interstitial fluid

B. tight junctions between endothelial capillary cells

C. significant endocytosis

D. Presence of efflux transporters

C. significant endocytosis

46

All of the following are true of the binding of xenobiotics to plasma protein except...

A. The total (bound plus free) conc is related to efficacy while only the free is related to toxicity

B. only the free conc is available to distrubute to tissues

C. Binding to plasma proteins could be saturable

D. Displacement interactions from plasma protein could lead to toxicity

A. The total (bound plus free) conc is related to efficacy while only the free is related to toxicity

47

An example of an uncommon covalent binding of a drug to a plasma protein is demonstrated by the drug...

A. Thiopental

B. captopril

C. Warfarin

D. Digoxin

B. captopril

48

All of the following statements are true of the ABC family of transporters except...

A. They all require ATP

B. They can bind 1 or 2 substrates

C. P-gp is an example

D. They are found only in liver and kidney in humans

D. They are found only in liver and kidney in humans

49

Which one of the following statements are true...

A. PAH clearance is a good indication of glomerular filtration rate

B. Organic anions and cations are transported by separate systems in the proximal convoluted tubule

C. Insulin clearance is a good indicator of renal blood flow

D. Biliary excretion is favored for molecules of 300 kDa or less

B. Organic anions and cations are transported by separate systems in the proximal convoluted tubule

50

Which of the following is most likely to require active transport processes for uptake into cells

A. Charged molecules

B. large hydrophobic molecules

C. Small hydrophobic molecules

D. Small highly-lipid soluble molecules

A. Charged molecules

51

Which of the following has the highest octanol/water partition coefficient?

A. Paraquat

B. DTT

C. asprin

D. Atropine

B. DTT

52

A weak acid with a pKa of 4 would be what percent unionized at pH 1 ?

A. 10%

B. 50%

C. 99%

D. 99.9%

D. 99.9%

53

Which of the following agents is rendered more toxic by bacteria in the GI tract?

A. 2,6 dinitrotoluene

B. benzene

C. Snake venom

D. Aniline

A. 2,6 dinitrotoluene

54

Which one of the following statements is false?

A. There are no aqueous pores in tight cellular junctions

B. glucose transport into the CNS occurs by facilitated diffusion

C. It is estimated that 5% of human genes are transporters

D. Metabolic inhibitors slow the rate of facilitated diffusion

D. Metabolic inhibitors slow the rate of facilitated diffusion

55

Which one of the following is false regarding interactions in metal transporter systems?

A. Thallium can be absorbed by the ion transporter

B. lead can be absorbed by the calcium transporter

C. Fluoride can compete with the glucose transporter

D. Lithium can compete with the sodium transport system

C. Fluoride can compete with the glucose transporter

56

Particles can be removed by the alveoli by all of the following except...

A. High fever

B. lymphatics

C. Phagocytosis

D. Mucociliary elevator

A. High fever

57

Which one of the following statements is true with respect to absorption of a toxicant through the skin?

A. The skin is incapable of xenobiotic metabolism

B. high solubility of a toxicant in a vehicle will increase skin absorption

C. All toxicants penetrate the stratum corneum by passive diffusion

D. There is little variability of dermal absorption between rodents and primates

C. All toxicants penetrate the stratum corneum by passive diffusion