34 Questions
What is the half-life of the radioactive isotope 137Cs, which is similar to potassium in its behavior?
30 years
Compared to the Chernobyl disaster, what is the order of magnitude of the releases of iodine-131 and caesium-137 from Fukushima?
The same
What is the primary factor that affects the absorption of substances in the gastrointestinal tract?
Lipid solubility
What is the main reason for the rapid absorption of gases, vapors, and volatile liquids in the lungs?
All of the above
What must substances cross to reach blood vessels in the skin?
Several cell layers
What is the minimum distance from the Fukushima plant where radioactive caesium levels have been reported to be high enough to cause concern?
30 km
What is the primary factor that determines the rate of passive diffusion across a cell membrane?
Surface area of the membrane
What is the characteristic of a chemical that allows it to diffuse through the lipid bilayer of a cell membrane?
Lipophilicity
Which type of transport is characterized by the movement of molecules along a concentration gradient without the use of energy?
Passive transport
What is the minimum molecular size required for a molecule to move through cell pores?
0.4 nm
What is the characteristic of a molecule that is a substrate for facilitated transport?
Specific binding to a carrier protein
What is the primary difference between active transport and facilitated transport?
Energy requirement
Which of the following xenobiotics is sequestered in adipose tissue as depot stores?
Organochlorine compounds
What is the primary target tissue for blood lead toxicity?
Brain
What is the mechanism by which lead is sequestered in growing bone?
Through deposition in hydroxyapatite
What is the effect of pregnancy and breast feeding on sequestered organochlorine compounds?
Depot mobilization into blood
Which of the following xenobiotics produces effects on the nervous tissue?
Organophosphate
What is the primary factor affecting absorption through endothelial pores into the circulation?
Blood flow
What is the common characteristic of xenobiotics that produce effects on specific body tissues or organs?
They must be bioavailable to distribute from blood to target tissue
What is the bioavailability of a drug administered intravenously?
100%
Which of the following routes of exposure has the largest surface area?
Intraperitoneal
What is the primary reason for the low bioavailability of lidocaine?
All of the above
What is the main purpose of understanding the extent of absorption and bioavailability?
To determine the toxic effects of a drug
What is the term for the process by which a drug is destroyed in the gut and liver before reaching the systemic circulation?
First Pass Effect
What is the primary mechanism for the excretion of water-soluble toxicants from the body?
Passive transport through the kidney
What is the function of the liver in the elimination of toxicants?
To metabolize lipid-soluble toxicants to more water-soluble forms
Which of the following is NOT a major route of elimination for toxicants?
Spleen
What is the term for the process by which lipid-soluble toxicants are reabsorbed into the bloodstream?
Systemic toxicity
Which of the following is an example of active transport in the elimination of toxicants?
Biliary secretion
Why is mother's milk an important route of elimination for toxicants?
It allows for the transfer of toxicants from the mother to the baby
What is the primary mechanism for the excretion of gases and volatile liquids from the body?
Diffusion through the lung
What is the significance of the molecular weight of a toxicant in determining its route of elimination?
Water-soluble toxicants have a molecular weight of < 70,000
Which of the following is a minor route of elimination for toxicants?
Sweat
What is the term for the process by which toxicants are changed from lipid-soluble to more water-soluble forms?
Metabolism
Test your understanding of cell membranes, cell walls, and the transport of molecules across external and internal membrane barriers. This quiz covers passive and active transport, facilitated diffusion, and the factors that affect permeability.
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