Bioaccumulation & Toxicokinetics

Question 1

accumulation phase

Answer 1

uptake is high in early phase and then excretion phase becomes more predominant and then a steady state is reached

Question 2

depuration phase

Answer 2

if you put the organism in a new medium the toxicity concentration decreases

Question 3

growth dilution

Answer 3

dilute concentration of toxicant because the rate of tissue growth is higher than the rate of uptake

Question 4

bioconcentration

Answer 4

contaminants are more concentrated in organisms relative to exposure medium (water)

Question 5

biomagnification

Answer 5

increase toxicity as you move up from lower trophic level to higher trophic level

Question 6

toxicokinetics

Answer 6

how the body metabolizes and eliminates the toxic agent

Question 7

toxicodynamics

Answer 7

effects a toxic agent causes

Question 8

what defines toxic effects

Answer 8

ADME
- absorption
- distribution
- metabolism
- excretion

Question 9

diffusion

Answer 9

molecules move from higher [] to lower [] or -ve charge molecules will move toward +ve molecules
- ex) Cd2+, Pb2+

Question 10

what determines how efficiently molecules move into the cell

Answer 10

lipophilicity
- the more lipophilic, the more efficiently molecules enter in the cell through simple diffusion

Question 11

simple diffusion

Answer 11

molecules diffuse unassisted through membrane

Question 12

facilitated diffusion

Answer 12

uptake through transporters that bind to the molecules and transport them across the membrane

Question 13

paracellular pathway

Answer 13

pass through the space between two adjacent cells

Question 14

how do the physical and chemical properties define their route of transport?

Answer 14

• for simple diffusion they need to be small, lipohilic
• electtrically charged molecules need a channel or transporter

Question 15

active transport

Answer 15

Na/K/ATPase pump
- transport against electricochemical gradient

Question 16

endocytosis

Answer 16

• large molecules
• release of molecules or infolding of cell membrane

Question 17

distribution (partitioning)

Answer 17

• blood distributes contaminants into different organs
• liver is the primary site of metabolism and contaminants go through the liver first
• lipophilic contaminants are stored and distributed in adipose tissue

Question 18

distribution/metabolism of trace elements in the bloodstream

Answer 18

when toxic metal ions are transported into targer tissue, they need to be complexed (metal detoxification) or else they are very reactive in their cation form (keep them in non-ionic form) to prevent toxicity

Question 19

metabolism of toxicants

Answer 19

• lipophilic molecules need to be converted into a water soluble entity to be excreted through kidney
• carbon and chlorne bonds are resistant to phase I and II metabolism and remain in the body