Question 1

All of the following substances are considered central nervous system neurotransmitters EXCEPT&#10;A) monoamines such as norepinephrine&#10;B) second messengers such as cyclic AMP&#10;C) amino acids such as glycine&#10;D) hormones such as vasopressin&#10;E) acetylcholine

Accepted Answer

Second messengers, such as cyclic AMP, are not considered central nervous system neurotransmitters. The other options are all types of neurotransmitters commonly found in the central nervous system.

Question 2

Drugs that must cross the blood brain barrier and enter the brain to exert therapeutic effects will be clinically useful if&#10;A) they are lipophilic&#10;B) they are hydrophilic but are able to enter the brain by active transport or facilitated diffusion&#10;C) they are not subject to active transport enzymes (efflux pumps) that move the drug out of the brain and back into the systemic circulation&#10;D) all the above&#10;E) none of the above

Accepted Answer

Lipophilic drugs are typically able to cross the blood brain barrier more easily. However, hydrophilic drugs may also be able to enter the brain through facilitated diffusion or active transport. Additionally, drugs must not be subject to efflux pumps that can move them back into the systemic circulation, otherwise their therapeutic effects may be limited. Therefore, drugs that are lipophilic or able to enter the brain through transportation mechanisms and are not subject to efflux pumps would be the most clinically useful option.

Question 3

Certain drugs are not able to pass from the bloodstream into the CNS because of the unique structure and function of the CNS capillaries,known commonly as the&#10;A) blood-brain barrier&#10;B) circle of Willis&#10;C) glomerulus&#10;D) septum pellucidum&#10;E) corpus callosum

Accepted Answer

The blood-brain barrier is a tight barrier system created by the endothelial cells of CNS capillaries, astrocytes, and pericytes that restricts the movement of certain substances, including some drugs, from the bloodstream into the brain and spinal cord. The circle of Willis is a ring of arteries at the base of the brain, the glomerulus is a structure in the kidney that filters blood, the septum pellucidum is a membrane that separates the two lateral ventricles of the brain, and the corpus callosum is a bundle of nerve fibers that connects the two hemispheres of the brain.

Question 4

Drugs can alter CNS neurotransmission by affecting neurotransmitter&#10;A) synthesis in the presynaptic terminal&#10;B) release from the presynaptic terminal&#10;C) degradation or breakdown at the synapse&#10;D) reuptake into the presynaptic terminal&#10;E) all the above are true

Accepted Answer

Drugs can affect neurotransmitter synthesis by blocking or enhancing the enzymes responsible for their production in the presynaptic terminal. They can affect neurotransmitter release by either promoting or inhibiting exocytosis of the neurotransmitter-containing vesicles. Drugs can also affect neurotransmitter degradation at the synapse by blocking the enzymes responsible for breaking them down, or they can enhance their breakdown by increasing the activity of these enzymes. Finally, drugs can affect neurotransmitter reuptake into the presynaptic terminal by blocking the transporters responsible for their reuptake, leading to increased extracellular levels of the neurotransmitter. Therefore, all of the options listed are true.

Deck 5: General Principles of Central Nervous System Pharmacology