Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Toxicology > Mechanisms of Toxicity 1 > Flashcards

Mechanisms of Toxicity 1 Flashcards

1
Q

understanding mechanisms allows

A

species comparisons
predictions for new compounds
risk assessments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

determines if there can be a toxic effect

A

disposition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

easiest compounds to absorb through membranes

A

lipid-soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

presystemic elimination can occur at

A

GI tract

liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

pumps that pump toxicants out of cells in the GI tract so they cant reach the systemic system, require ATP

A

P-glycol proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

produced in the liver to bind specifically to metals

A

metallothionein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

many chemicals are released as parent compound that is not toxic, but enzymatic activity changes or metabolizes the parent compound into a toxic compound

A

toxification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

compounds that want to take on an extra electron

A

electrophiles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

compounds that are willing to donate an electron

A

nuceophiles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the potential stages in development of toxicity after chemical exposure

A

delivery of chemical
interaction with target molecule or alteration of biological environment
cellular dysfunction, injury leading to toxicity
and potentially inappropriate repair and adaption causing toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

the transfer of a chemical from the site of exposure, usually an external or internal body surface into systemic circulation

A

absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

distribution of toxicant to specific target sites may be enhanced by

A
  1. porosity of the capillary endothelium
  2. specialized membrane transport
  3. accumulation in cell organelles
  4. reversible intracellular binding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

often formed through toxication, very reactive, can cause a lot of damage

A

free radicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

turns radicals into peroxide

A

superoxide dismutase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

three enzymes that can detox oxygen radicals

A

superoxide dismutase
glutathione peroxidase
catalase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

distributing toxicants to specific sites may be hindered by several processes

A

binding to plasma proteins
specialized barriers
distribution to storage sites such as adipose tissue
association with intracellular binding proteins
export from cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

the removal of xenobiotics from the blood and their return to the external environment

A

excretion

18
Q

major excretory organs such as kidney and liver can efficiently remove only____

A

highly hydrophilic usually ionized chemicals such as organic acids and bases

19
Q

three rather inefficient processes for eliminating non volatile, highly lipophilic chemicals

A

excretion by the mammary gland
excretion in bile in association with biliary micelles or phospholipid vesicles
intestinal excretion

20
Q

reabsorption by diffusion is dependent on

A

lipid solubility of the chemical

21
Q

radicals are formed by

A

accepting an electron
losing an electron
hemolytic fission of a covalent bond

22
Q

not only reactive electrophiles but also electron acceptors with the capacity to initiate redox cycling or oxidation of thiols and NADPH

A

quiniones

23
Q

a free radical of paramount toxicological significance generated by hemolytic fission

A

hydroxyl radical

24
Q

a relatively uncommon mechanism for activating toxicants

A

formation of nucleophiles

25
Q

biotransformation that eliminates an ultimate toxicant or prevents its formation

A

detoxication

26
Q

how are neucleophiles generally detoxified

A

conjugation at the nucleophilic functional group

27
Q

chemicals without functional groups are detoxified by..

A

adding a hydroxyl or carboxyl functional group by cytochrome p450 enzyme
then an endogenous acid is added by transferase

28
Q

how are electrophilic toxicants detoxified

A

conjugation with the thiol nucleophile glutathione

29
Q

peroxidase generated free radicals are eliminated by

A

electron transfer from glutathione

30
Q

detoxication can be insufficient for several reasons

A
  1. toxicants may overwhelm detoxication processes, leading to saturation of the detoxication enzymes
  2. reactive toxicant inactivates a detoxicating enzyme
  3. some conjugation reactions can be reversed
  4. sometimes detoxication generates potentially harmful byproducts
31
Q

interaction of the ultimate toxicant with the target molecule triggers the toxic effect, consideration is given to

A
  1. the attributes of target molecules
  2. the types of reactions between ultimate toxicant and target molecules
  3. the effects of toxicants on the target molecules
32
Q

what are the attributes of the target molecule

A

reactivity
accessibility
critical function

33
Q

what are the outcomes of the target molecule

A

dysfunction
destruction
neoantigen formation

34
Q

what are the reaction types with the target molecule

A 
noncovalent binding
covalent binding
hydrogen abstraction 
electron transfer
enzymatic reaction
35
Q

to conclusively identify a target molecule as being responsible for toxicity it should be demonstrated that the ultimate toxicant

A

reacts with the target and adversely affects its function
reaches an effective concentration at the target site
alters the target in a way that is mechanistically related to the observed toxicity

36
Q

due to apolar interactions or the formation of hydrogen and ionic bonds and is typically involved in the interaction of toxicants with targets such as membrane receptors, intracellular receptors, ion channels, and some enzymes

A

noncovalent binding

37
Q

practically irreversible this is of great toxicological importance because it permanently alters endogenous molecules

A

covalent binding

38
Q

an example is hydrolysis by snake venom

A

enzymatic reaction

39
Q

produced by neutral free radicals

A

hydrogen abstraction

40
Q

effects caused by the dysfunction of target molecules

A 
mimic of receptor ligand
inhibition of enzymes
blockage of ion channels
interference with cytoskeleton
break 3D structures of proteins (disulfide bridges)
cause DNA damage
41
Q

binding of toxicant to protein
new protein becomes “non self”
may cause autoimmune reaction

A

neoantigen formation

42
Q

what changes may occur to the microenvironment

A

no direct interaction with target molecule
pH changes
destruction of membrane lipids by solvents
occupying space

Toxicology (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions