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Environmental Toxicology > Chapter 7 - Absorption of Toxicants > Flashcards

Chapter 7 - Absorption of Toxicants Flashcards

1
Q

What are some methods that a toxicant can enter to body after exposure?

A
  • respiratory inhilation
  • GI ingestion
  • skin dermal
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2
Q

What is the path of travel for toxicants once they enter the body?

A
  1. toxicant
  2. respiratory system
  3. GI system
  4. skin (integumetary)
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3
Q

Entry point for toxic gases, solvents aerosols, and particulates

A

respiratory system

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4
Q

Has a large surface area,

A

GI system

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5
Q

Not highly permeable to most water-soluble chemical, but lipid soluble compounds are well absored via passive diffusion.

A

skin (integumentary)

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6
Q

composed of phospholipid bilayer approximately 7-9nm thick

A

cell membranes

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7
Q

What function do most proteins have on a cell membrane?

A

structural, receptor, and enzymatic

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8
Q

What is the primary mechanism for movement of toxicants across a cell membrane?

A

simple diffusion

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9
Q

What factors can affect net diffusion?

A
  • molecule size
  • charge
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10
Q

Which proteins are particularly selective to size?

A

channel proteins

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11
Q

Which kind of membrane protein takes part in facilitated diffusion?

A

integral membrane protein

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12
Q

What does facilitaed diffusion typically transport across the membrane?

A

glucose

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13
Q

What is the driving force behind simple and facilitated diffusion?

A

concentration gradient

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14
Q

What kind of transport is very specific and uses ATP to bring molecules against the concentration gradient?

A

active transport

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15
Q

How is active transport driven?

A

phosphorylation and ATP binding

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16
Q

How can a cell bring in molecules into the cell via vesicles formed from the plasma membrane?

A

endocytosis

17
Q

Why is endocytosis used as a mode of transport into the cell?

A

it can bring in large toxins

18
Q

What is the outer layer of the skin called?

A

stratum corneum

19
Q

What are the degrees of absorption for the GI tract?

A
  • site
  • pH
  • time
  • physiochemical properties
20
Q

Why is absorption through the GI tract considered systemic?

A

it can cause toxicants to travel throughout the whole body

21
Q

Where is absorption poor during absorption through the GI tract?

A

oral and esophagus

22
Q

Where can toxicants accumulate in the GI tract?

A

liver

23
Q

How does the liver remove toxicants?

A
  • venous blood
  • excreted into bile
  • metabotically converted
  • stored
24
Q

What is the process of bile being reabsorbed in the small intestine via the hepatic portal vein?

A

enterhepatic circulation

25
Q

What are the different levels of the respiratory tract where toxicants can be absorbed?

A
  1. nasopharyngeal
  2. tracheobronchial
  3. alveolar
  4. lymph

less and less absorbed as you go down

26
Q

How is the respiratory tract efficient in transporting toxicants?

A

it is quick, lipophilic and low-molecular weight gases are quickly absorbed (lipophilicity)

hydrophilic chemicals rate of absorption increases with size

27
Q

What are some examples of rapidly absorbed compounds absorbed through the respiratory tract?

A
  • nitrous oxide
  • hydrocyanic acid
  • ether
  • chloroform
28
Q

lipophilic: higher the rate ____ the absorption
hydrophilic: higher the size ____ the absorption

A

greater; lower

29
Q

What kinds of substances can stay in the lungs for a long period of time?

A

asbestos and coal dust

30
Q

Material that remains in the respiratory tract can produce local toxicity in the forms of…

A
  • lung cancer
  • chronic bronchitis
  • lung fibrosis
  • emphysema
31
Q

For females ____L of lung capacity volume is standard.

A

2.5

32
Q

What do all the models of disposition integrate?

A
  • distribution
  • metabolism
  • elimination
33
Q

Which model is represented?
Toxicant is introduced to the body and transported to a single homogenous compartment

A

one-compartment model

34
Q

What is the most common compartment model system?

A

two or greater compartment models

35
Q

What model is represented?
Toxicant is distributed through the blood (central comp.) into a periphreal compartment where it can be eliminated or returned back to the blood.

A

two compartment model

36
Q

What is half-life?

A

time required to reduce the blood or plasma concentration by 50%

Environmental Toxicology (9 decks)

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