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25 Cards in this Set

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Drugs can be moved across membranes into and/or out of cells and thus across cell layers by three very different types of Transport Mechanism:
Endocytosis/Exocytosis, Protein Transporters and Diffusion
Endocytosis (aka pinocytosis) and Exocytosis, both of which require?
significant structural alterations of the cell to move drug molecules into or out of the cell, Protein Transporters and Diffusion.
Endocytosis, Exocytosis, Protein Transporters and Diffusion
While these are important mechanisms in physiological processes, they are not important in?
terms of movement of drugs across cell layers:
drugs may ("target" and) affect these processes to produce therapeutic benefit in some clinical situations.
Endocytosis (aka pinocytosis) and Exocytosis, Protein Transporters and Diffusion
Drugs can be moved across membranes into and/or out of cells and thus across cell layers by three very different types of Transport Mechanism:

Endocytosis (aka pinocytosis) and Exocytosis, both of which require what significant structural alterations of the cell to move drug molecules into or out of the cell,
Protein Transporters and Diffusion.
Endocytosis, Exocytosis, Protein Transporters and Diffusion
While these are important mechanisms in physiological processes, they are not important in?
terms of movement of drugs across cell layers:
drugs may ("target" and) affect these processes to produce therapeutic benefit in some clinical situations.
Endocytosis (aka pinocytosis) and Exocytosis, Protein Transporters and Diffusion
What is Exocytosis?
Drug molecules are moved from the cytoplasm into the extracellular space by being packaged into vesicles and the subsequent release of vesicular contents into the extracellular space after vesicle-plasma membrane fusion.
This is the process by which neurotransmitters and protein hormones are released from cells and is therefore physiologically extremely important.
Exocytosis
Exocytosis and Endocytosis of drugs as the mechanism to move drugs across cell layers is?
relatively rare (or at least not well documented).
These two processes are certainly energy dependent (that is, energy is expended) and can be used to move drug molecules up or down a concentration gradient across the membrane for that drug.
Exocytosis and Endocytosis
Exocytosis is a critical physiological mechanism used by cells to?
secrete molecules into the extracellular space and may be modulated (increased or decreased) by some drugs.
What is Endocytosis
Drug molecules are moved into the cytoplasm from the extracellular space by being enveloped by a membrane invagination which engulfs a small volume of extracellular fluid (containing the drug molecules) and brings this fluid into the cell within a vesicle (sphere of membrane).
During endocytosis, the drug in each vesicle is within the cell but can not be described as being free in the cytoplasm. To set the drug molecules free in the cytoplasm the drug-containing vesicle must?
be destroyed.
What are Protein Transporters
Drug molecules are moved across membranes after binding to a transporter molecule embedded in the plasma membrane.
Protein transporters are protein molecule and may be considered to be?
a receptor based on affinity and action of drugs on activity of the transporter.
The transport process may be energy independent or energy requiring.
Protein Transporters
In some situations, the transporter protein will transport?
a single or primary type of molecule or ion and other, secondary molecules or ions are co-transported.
Co-transported molecules and ions may do what?
be moved in the same direction or the opposite direction as the primary transported molecule or ion.
These transport processes can permit movement of molecules and ions down a concentration gradient - from a compartment with high concentration (of transported molecules or ions) to a compartment with low concentration - or up a concentration gradient - from a compartment with low concentration (of transported molecules or ions) to a compartment with high concentration.
Protein transporters
These membrane embedded transporters are rarely the mechanism for significant transmembrane movement of drug molecules but are the therapeutically relevant target of some types of drug.
Protein transporters
What is Diffusion
Drug molecules may move across the membrane by moving within the phospholipid bilayer.
This drug transport movement is energy independent.
Diffusion
Rate of movement of drug molecules depends on several factors.
Net movement of drug molecules requires that there is?
a difference of concentration of the drug on each side of the membrane and will occur until drug concentration on each side of the membrane is the same.
what drug molecule movement process across the membrane occurs in both directions - even when concentration of the drug is the same on each side of the membrane.
Diffusion