Neuroscience: Electrophysiology, Synaptic Transmission, and Pharmacology

Vocabulary practice flashcards covering cellular neurobiology, synaptic transmission, postsynaptic potentials, and principles of neuropharmacology based on the lecture.

Absolute Refractory Period

The phase during repolarization where a neuron cannot fire another action potential at that specific location regardless of how large the stimulus or charge is.

Relative Refractory Period

The phase following an action potential during which the neuron can fire another action potential, but it requires an exceptionally large stimulus to reach threshold.

Saltatory Conduction

The process by which an action potential propagates down a myelinated axon by jumping from node of Ranvier to node of Ranvier.

Holding Zone

The area in the presynaptic terminal where vesicles containing quantile amounts of neurotransmitter are stored before release.

Calcium-Calmodulin Complex

A complex formed when calcium enters the presynaptic terminal via voltage-gated channels and binds to calmodulin, triggering synaptic vesicles to translocate from the holding zone to the active zone.

Active Zone

A thicker region of the presynaptic membrane where neurotransmitter-filled vesicles fuse during synaptic release.

Omega Body

The omega-shaped structural configuration formed when a synaptic vesicle fuses with the presynaptic active zone membrane.

Exocytosis

The cellular process wherein synaptic vesicles fuse with the presynaptic membrane to discharge their stored neurotransmitters into the synaptic cleft.

Endocytosis

A clearance mechanism in the synapse where transporters retrieve neurotransmitters from the synaptic cleft to be repackaged into vesicles.

Ligand-Gated Ion Channel

A membrane channel on the postsynaptic neuron that opens in response to the binding of a chemical messenger (ligand or neurotransmitter).

Excitatory Postsynaptic Potential (EPSP)

A graded depolarization on the postsynaptic membrane, predominantly caused by ligand-gated sodium channels opening, that brings the membrane potential closer to threshold.

Inhibitory Postsynaptic Potential (IPSP)

A graded postsynaptic response that inhibits neural firing by driving the membrane potential further from threshold or locking it down near resting potential.

Summation

The continuous integration of incoming EPSPs and subtraction of IPSPs occurring at the axon hillock to determine whether the membrane reaches threshold to fire an action potential.

Electrical Sink

An electrophysiological effect where an open ion channel (such as chloride channels with an equilibrium potential around $-70\,\text{mV}$) drains depolarization away and anchors the membrane potential near resting level.

Resting Membrane Potential

The electrical charge across the neuronal membrane (approximately $-70\,\text{mV}$) determined by the equilibrium potentials of the involved ions relative to their permeabilities.

Lidocaine

A local anesthetic and painkiller that blocks voltage-dependent channels along pain-sensing neurons, preventing the propagation of action potentials to the terminal.

Substance P

A specific neurotransmitter responsible for mediating pain signaling from peripheral pain neurons to the central nervous system.

Neurosteroids

Steroid molecules (such as allopregnanolone) that do not act like typical steroids altering gene transcription, but instead act as neurotransmitters by binding directly to neuronal receptors.

Allopregnanolone

A neurosteroid (3-alpha-hydroxy 5-alpha-pregnanolone) found in higher concentrations in females and during pregnancy, whose release is stimulated by alcohol.

Finasteride

A pharmacological compound used for pattern hair baldness that blocks the formation and effects of the neurosteroid allopregnanolone.

Intramuscular Administration

A route of drug delivery injected directly into muscle tissue, resulting in a slower absorption rate into the circulatory system compared to intravenous delivery.

Transdermal Administration

A route of drug administration absorbed slowly through the skin barrier into the bloodstream, such as through nicotine or estrogen replacement patches.