Neurotransmission Basics Lecture

Vocabulary flashcards summarizing key terms and concepts discussed in the lecture on neurotransmission, vesicular transport, and ion channels.

Neuron

Basic functional cell of the nervous system that transmits information through electrical and chemical signals.

Cell Body (Soma)

Central part of a neuron containing the nucleus and organelles where proteins and lipids are synthesized.

Axon

Long projection of a neuron that conducts action potentials from the cell body toward synaptic terminals.

Axonal Transport

Movement of vesicles, proteins, and other cargoes along the axon via molecular motors to and from the cell body.

Synaptic Terminal (Axon Terminal)

Distal end of an axon where neurotransmitters are stored and released.

Synaptic Vesicle

Small (~30–40 nm) membrane-bound vesicle containing fast-acting neurotransmitters like glutamate or GABA.

Large Dense-Core Vesicle

Larger (~80–200 nm) vesicle that stores and slowly releases neuropeptides or hormones.

Neurotransmitter

Chemical messenger released from presynaptic neurons that binds receptors on a postsynaptic cell to transmit signals.

Neuropeptide

Small peptide molecule functioning as a neuromodulator or neurotransmitter, typically packaged in dense-core vesicles.

Exocytosis

Fusion of a vesicle with the plasma membrane leading to release of its contents into the extracellular space.

Synaptic Cleft

Narrow (~20–40 nm) extracellular gap between pre- and postsynaptic cells where neurotransmitters diffuse.

Postsynaptic Receptor

Protein on the membrane of the receiving cell that specifically binds a neurotransmitter and initiates a response.

Ion Channel

Transmembrane protein forming a pore that allows selective passage of specific ions across a membrane.

Selectivity Filter

Structural region of an ion channel that confers ion specificity by coordinating certain ions while excluding others.

Potassium Channel

Tetrameric ion channel that selectively conducts K⁺ ions, playing key roles in repolarization and resting potential.

Sodium Channel

Ion channel that selectively allows Na⁺ ions to enter a cell, crucial for the depolarizing phase of action potentials.

Calcium Channel

Voltage-gated channel permitting Ca²⁺ influx, which triggers synaptic vesicle fusion.

Membrane Potential

Electrical voltage difference between the inside and outside of a cell resulting from ionic charge separation.

Depolarization

Reduction in membrane potential making the inside of the cell less negative, often due to Na⁺ entry.

Hyperpolarization

Increase in membrane potential making the inside of the cell more negative than the resting level.

Action Potential

Rapid, transient electrical signal along a neuron produced by sequential opening of voltage-gated Na⁺ and K⁺ channels.

Spatial Summation

Additive effect of simultaneous inputs at different locations on a neuron’s membrane.

Temporal Summation

Additive effect of sequential inputs occurring in rapid succession at the same synapse.

Sodium-Potassium Pump (Na⁺/K⁺-ATPase)

ATP-driven membrane pump that moves 3 Na⁺ out and 2 K⁺ into the cell to restore ion gradients after firing.

Active Transport

Energy-requiring movement of substances across membranes, often against their concentration gradient.

Passive Transport

Movement of substances across membranes without energy input, driven by concentration or electrochemical gradients.

Patch Clamp Technique

Electrophysiological method using a glass micropipette to measure ionic currents through individual channels.

Endoplasmic Reticulum (Rough ER)

Organelle with ribosomes where membrane and secretory proteins of neurons are synthesized.

Golgi Complex

Organelle that modifies, sorts, and packages proteins into vesicles destined for transport.

Vesicular Transport

Process by which membrane-bound vesicles carry cargo through the cytoplasm, including toward synaptic terminals.

Retrograde Transport

Movement of vesicles or materials from the axon terminal back to the neuronal cell body for recycling or degradation.

Excitatory Neurotransmitter

Chemical signal that increases the likelihood of the postsynaptic neuron firing, e.g., glutamate.

Inhibitory Neurotransmitter

Chemical signal that decreases the likelihood of the postsynaptic neuron firing, e.g., GABA.

Modulatory Neurotransmitter

Chemical messenger that alters neuronal responsiveness or network activity without directly causing excitation or inhibition.