Toxicology Intro

Question 1

Xenobiotic definition

Answer 1

foreign substance introduced to body

Question 2

Toxic agent

Answer 2

chemical/physical compounds toxic at high doses

Question 3

Poison

Answer 3

chemical/physical compound toxic at a low dose

Question 4

Toxin

Answer 4

a toxic agent produced by biological systems

Question 5

Toxidrome

Answer 5

constellation of toxic effects comprising of a series of clinical fingerprints for a group of toxic chemicals

Question 6

6 ways of classifying in toxicology

Answer 6

1. use in public domain
2. target organ
3. physical state
4. effects
5. source
6. biochemical properties

Question 7

Route of exposure in toxicology

Answer 7

oral
intravenous
inhalation
parenteral

Question 8

how to define duration of use of substances

Answer 8

acute (single use)
subacute (repeated <1 month)
subchronic (repeated 1-3 months)
chronic (>3 months)

Question 9

graded dose response

Answer 9

relationship of test subject’s response to increasing dosage of a chemical

Question 10

quantal dose response

Answer 10

relationship of a population of test subjects against an increasing dosage of chemical agent

Question 11

Cell signalling dysfunction is caused by

Answer 11

1. changes in genetic expression
2. changes in the excitability of the cell

Question 12

reversible cell damage/injury

Answer 12

trauma to cell that heals, continuous or increased injury can lead to irreversible injury

Question 13

irreversible injury

Answer 13

leads to apoptosis or necrosis

Question 14

Cell injury or damage

Answer 14

occurs when injury exceeds to limits of an adapted cell

Question 15

Adaptation

Answer 15

cellular response to stress in the environment to maintain homeostasis in the body. It can be physiological or pathological.

Question 16

7 causes of cell injury

Answer 16

hypoxia
physical/chemical agents
immunologic agents
infectious agents
genetic derangement
nutritional imbalance
ageing

Question 17

ATP role in cellular injury

Answer 17

1. depletion of ATP leads to failure energy-dependent functions
2. causes dysfunction in mitochondria, leading to leakage of mitochondrial proteins, which is a signal for apoptosis

Question 18

Reactive oxygen species production

Answer 18

1. phagocytic leukocytes produce ROS (respiratory burst)
2. mitochondria when O2 is reduced to oxygen radical
3. mitochondria when hydrogen peroxide is reduced to hydroxyl radical

Question 19

Cell injury by ROS

Answer 19

1. lipid peroxidation
2. cross linking and protein changes
3. DNA mutation/damage

Question 20

signs of necrosis

Answer 20

1. severe cell swelling and rupture
2. denaturation and coagulation of cellular proteins
3. breakdown of cell organelles for lethally injured cell

Question 21

signs of apoptosis

Answer 21

cell shrinkage, chromatin condensation, cytoplasmic blebs, apoptotic bodies
phagocytosis

Question 22

intrinsic caspase activation via mitochondria

Answer 22

1. loss of survival signal caused by DNA damage + accumulation of misfolded protein
2. Inhibit Bcl-2 and Bcl x, leading to the release of apoptogenic molecules by destroying membrane
3. pro apoptotic proteins released to cytoplasm

Question 23

extrinsic caspase activation via death receptor

Answer 23

1. FasL of lymphocytes and cytotoxic T cells bind to FAS receptor on target cell
2. engage FAD receptor by ligands on adjacent cells
3. activate caspase
4. self phosphorylation -> activation
5. activate endonucleases and breakdown cytoskeleton