Toxicology

Question 1

Toxicology- Def.

Answer 1

Study of poisons/toxicants and their occurrence, effects, properties, regulation and how to detect

Question 2

Goals of Toxicology

Answer 2

Toxicant Identification, Intoxication Prevention, Mode of Action, Intoxication Management

Question 3

Intoxication Prevention

Answer 3

Eliminate, Minimize Exposure, Maximize Tolerance

Question 4

Mode of Action

Answer 4

Target Organs, Cells Affected, Molecular Site

Question 5

Intoxication Management

Answer 5

Regulate Dose, Treatment

Question 6

Does toxicology intersect with different fields of study

Answer 6

Yes: immunology, nutrition, chemistry

Question 7

What is nutritional toxicology?

Answer 7

a subfield of toxicology that targets the study of poisons delivery through oral exposure

Question 8

What are the routes of oral exposure?

Answer 8

water, diet, accidental ingestion

Question 9

Nutritional Toxicology also looks at:

Answer 9

effects on nutrient utilization, effects on production/health, mitigation of toxicant effects

Question 10

Challenges of Nutritional Toxicology

Answer 10

Route of Exposure: Orally

Question 11

Why is Oral exposure challenging?

Answer 11

diet complexity

Question 12

What are the general principles of toxicology?

Answer 12

Factors Affecting Toxicity, Doses Response Concept, Phases of Toxicity, Risk Assessment

Question 13

What are the factors affecting Toxicity?

Answer 13

exposure, dose, rate/extent of absorption, target species, sex, physiological status, nutritional status, elimination, distribution, bioaccumulation

Question 14

What is bioaccumulation?

Answer 14

toxicant accumulating in bones, fat, or the body: happens often when exposed during growth
usually occurs over multiple exposures and often due to low rate of elimination

Question 15

What are the general toxicant properties?

Answer 15

qualitative and quantitative

Question 16

What are qualitative toxicant properties?

Answer 16

mode/mechanism of action (carcinogen, vasoconstrictor), primary target tissues (hepatotoxin, neurotoxin)

Question 17

What is the Central Concept of Toxicology?

Answer 17

The dose response

Question 18

What is the dose response?

Answer 18

All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy. - Paracelsus

Question 19

Dose Response Relationship

Answer 19

Response Due to Chemical, Response changes with dose, method for response

Question 20

What does response changing with dose affect?

Answer 20

molecular target site, target site dose changes with change in dose administered, response related to target site dose

Question 21

What are the two types of Dose Responses?

Answer 21

Graded Dose Response, Quantal Dose Response

Question 22

What is Graded Dose Response?

Answer 22

dose response elicited by an INDIVIDUAL animal; characterized by dose related changes in the severity of toxic response (weight loss, decreased production)

Question 23

What is Quantal Dose Response?

Answer 23

dose response typically utilized when studying population to a toxicant response
ALL or NONE
characterized by dose related changes in the number of individuals of a population responding (death rate, pregnancy rate)

Question 24

Potency vs Efficacy

Answer 24

straight line- more effective

curved line- more potent

Question 25

Potency

Answer 25

the strength of a toxicant at a given dose

Question 26

Dose Response may affect:

Answer 26

tolerance

Question 27

What is tolerance?

Answer 27

state of decreased responsiveness to toxic effect of a chemical as result of a prior exposure to the chemical

Question 28

What is tolerance?

Answer 28

state of decreased responsiveness to toxic effect of a chemical as result of a prior exposure to the chemical

Question 29

What are the two types of tolerance?

Answer 29

Dispositional, Reduced Responsiveness

Question 30

What is dispositional tolerance?

Answer 30

decrease in amount of toxicant reaching target site

Question 31

What is reduced responsiveness?

Answer 31

target tissue less responsive to toxicant: metabolism, toxicant ejection, molecular site become refractory to the toxicant

Question 32

What is the threshold dose?

Answer 32

dose below which no adverse effect occurs

Question 33

What is the region of no effect?

Answer 33

the normal range, often termed the therapeutic range

Question 34

What must happen for a chemical to elicit a toxic effect in the animal?

Answer 34

exposure to toxicant, absorption of toxicant, elicit action at molecular site

Question 35

What are the phases of toxicity?

Answer 35

exposure, toxicokinetic, toxicodynamic

Question 36

What does the phase toxicokinetic in phases of toxicity included?

Answer 36

absorption (active, passive, facilitated), distribution, metabolism (biotransformation), elimination

Question 37

What does the phase toxicodynamic in phases of toxicity include?

Answer 37

toxic action

Question 38

What is the rate of elimination?

Answer 38

how long it takes a substance to be eliminated (urinary, feces, metabolic)

Question 39

What does rate of elimination effect?

Answer 39

whether animal reaches toxic level in circulation and/or how long they will stay at toxic level

Question 40

What are the two phases of biotransformation?

Answer 40

Phase I (cytochrome P-450), Phase II (glucuronidation)

Question 41

What is Phase I of Biotransformation?

Answer 41

introduce a polar group (OH, NH, SH, COOH) into a compound

Question 42

What does introducing a polar group do?

Answer 42

increases water solubility

Question 43

Examples of Phase I of biotransformation

Answer 43

Cytochrome P450: mitochondrial, microsomal FAD containing monooxygenase: microsomal Nonmicrosomal oxidation systems: alcohol and aldehyde dehydrogenases

Question 44

What is Phase II of biotransformation?

Answer 44

conjugation reactions: sugars and amino acids are attached to chemicals to increase water solubility

Question 45

Examples of Phase II biotransformation

Answer 45

glucuronidation, sulfonation, amino acid

Question 46

Can Phase I biotransformation prepare substance for Phase II?

Answer 46

yes

Question 47

First Order Elimination

Answer 47

rate DEPENDENT on plasma level | Half-life INDEPENDENT of plasma level

Question 48

Zero Oder Elimination

Answer 48

Rate INDEPENDENT of plasma level | Half-life DEPENDENT on plasma level

Question 49

What order of elimination is saturable?

Answer 49

Zero Order

Question 50

What order of elimination has a curved line and which one as a straight line?

Answer 50

Curved: First order Straight: Zero Order

Question 51

Can a toxicant shift from zero order to first order?

Answer 51

Yes

Question 52

What are the types of Toxic Modes of Action?

Answer 52

Reversible interactions, Irreversible covalent interaction, Physical sequestration (accumulation in bone, fat)

Question 53

How does toxicant elect a response?

Answer 53

cell maintenance, cell regulation

Question 54

What is Xylitol?

Answer 54

5 carbon sugar alcohol sweating agent that is naturally occurring

Question 55

Xylitol may also function as a?

Answer 55

hapten (allergic reaction possible)

Question 56

Where can Xylitol in nature be found?

Answer 56

animal, plant (beechwood), fungal metabolite

Question 57

Xylitol is Derived from?

Answer 57

Xylose via reduction of carbonyl group to an alcohol

Question 58

True or False: Xylitol can cause Prevention of dental carries in humans

Answer 58

True

Question 59

What are human treat that have xylitol?

Answer 59

gum, candy, cookies, peanut butter (not all)

Question 60

What are some alternative names of Xylitol?

Answer 60

birch sugar, sylvite, zylatol, anhydroxylitol

Question 61

What is the toxicant action of xylitol?

Answer 61

xylitol is rapidly converted to glucose causing rapid insulin release which causes a rapid drop in blood glucose

Question 62

Xylitol leads to what and how quickly:

Answer 62

hypoglycemia, within 30 minutes and last as long as 28 hrs

Question 63

Why does Xylitol cause rapid glucose drop?

Answer 63

may have a direct effect on beta cells in pancreas

Question 64

Xylitol can lead to what:

Answer 64

Liver insufficiency/failure: only occurs in some dogs, mechanism is unknown (perhaps depletion of ATP in liver)

Question 65

What are common clinical signs of Xylitol Poisoning?

Answer 65

vomiting, lethargy, diarrhea, ataxia, seizure, restlessness, reduced food intake