Chapter 8: Neurotransmitter Systems I: Acetylcholine & the Amino Acids
The cell bodies for neurons that synthesize and release acetylcholine (ACh), called cholinergic neurons, are located in
A. only the brainstem and spinal cord.
B. only the autonomic nervous system.
C. only the central nervous system (CNS).
D. only the peripheral nervous system (PNS).
E. Cholinergic neurons are located in the brainstem and spinal cord (lower somatic motor neurons and preganglionic autonomic neurons), interneurons in the brain (basal forebrain, striatum, and brainstem), and autonomic ganglia (majority of postganglionic parasympathetic neurons).
A neurologist selects a drug that has properties similar to γ-aminobutyric acid (GABA) for the treatment of temporal lobe epilepsy. This neurotransmitter (NT) serves important functions within the CNS. Which of the following accurately characterizes a basic property of this NT?
A. GABA is known to have equal inhibitory and excitatory properties in the adult CNS.
B. The associated receptor channel is permeable to Cl- ions.
C. GABA is formed directly from serine.
D. Increased GABA is associated with the generation of seizure activity.
E. GABA is present mainly in the spinal cord.
B. GABA has predominantly inhibitory actions in the adult CNS (it has some excitatory actions in the developing brain). The GABA receptor is a ligand-gated Cl– channel, which when open, usually leads to Cl– influx and hyperpolarization of the membrane potential and inhibition. GABA is formed from glutamate. Decreased GABA function is associated with seizures. GABA is present in both the brain and spinal cord, whereas glycine is found mainly in the spinal cord.
A patient with a history of depression is treated with a novel compound that acts mainly upon N-methyl-D-aspartate (NMDA) receptors. Which of the following best describes a basic property associated with the NMDA receptor?
A. The NMDA receptor–associated channel is blocked by the presence of Mg2+ at the resting membrane potential.
B. It controls a high-conductance anion channel.
C. NMDA is selective for metabotropic receptors.
D. Insufficient amounts of glutamate, acting through NMDA receptors, may cause neuronal cell death.
E. Current flow is blocked in the presence of glutamate, leading ...