Physical & Electrical Properties of Cells in the Nervous System, Synaptic Transmission & Elbow/Forearm

Vocabulary flashcards reviewing cellular properties, action potentials, synaptic transmission, neurotransmitter functions, neurological disorders, and elbow/forearm anatomy.

Voltage

The measure of potential energy representing the difference in electrical charge across the cell membrane, measured in millivolts ($\text{mV}$).

Current

The flow of electricity from one point to another, consisting of the movement of positively and negatively charged ions across the cell membrane.

Resistance

Any obstacle that hinders the flow of electrical current, represented in nervous system cells by the cell membrane itself.

Resting Membrane Potential

The polarized state of a neuron loaded and waiting near $-70\text{ mV}$, maintained by the sodium-potassium pump moving three $\text{Na}^+$ out for every two $\text{K}^+$ in.

Voltage-Gated Channels

Ion channels that open when the electrical potential across the cell membrane changes, responsible for generating action potentials.

Ligand-Gated Channels

Ion channels on the postsynaptic membrane that open when a specific neurotransmitter or hormone binds to its receptor.

Modality-Gated Channels

Sensory neuron channels that open in response to specific physical stimuli such as stretch, touch, pressure, or temperature changes.

Saltatory Conduction

The rapid transmission process in myelinated axons where electrical current leaps between gaps in myelin called the nodes of Ranvier.

Electrical Synapse

A rapid, direct form of cell communication using gap junctions that allow ion current to flow immediately into neighboring cell cytoplasm without signal conversion.

Chemical Synapse

A precise form of communication that converts electrical signals into chemical neurotransmitters across a synaptic cleft and back into electrical signals.

Excitatory Postsynaptic Potential (EPSP)

A temporary local depolarization of the receiving neuron's membrane that moves it closer to the threshold of firing, typically caused by $\text{Na}^+$ influx.

Inhibitory Postsynaptic Potential (IPSP)

A temporary local hyperpolarization of the receiving neuron's membrane that moves it farther from the threshold of firing, typically caused by $\text{Cl}^-$ influx or $\text{K}^+$ efflux.

Temporal Summation

The addition of postsynaptic potentials occurring when a single presynaptic neuron fires repeatedly in rapid succession over a short window of time.

Spatial Summation

The addition of postsynaptic potentials occurring when multiple presynaptic neurons fire simultaneously onto different locations of the same postsynaptic neuron.

Presynaptic Facilitation

Axo-axonic modulatory input on a presynaptic terminal that prolongs depolarization and increases calcium entry, resulting in increased neurotransmitter release.

Presynaptic Inhibition

Modulatory input on a presynaptic terminal that reduces calcium entry, resulting in decreased neurotransmitter release.

Neurotransmitters

Fast, direct chemical messengers released into the synaptic cleft that open or close ion channels to produce immediate EPSPs or IPSPs.

Neuromodulators

Slow, widespread chemical messengers released into extracellular fluid that adjust how responsive neurons are to neurotransmitters over minutes to hours.

Acetylcholine (ACh)

The principal fast neurotransmitter at the neuromuscular junction that initiates skeletal muscle contraction, also involved in cortical arousal and reward.

Gamma-Aminobutyric Acid (GABA)

The principal fast inhibitory neurotransmitter of the central nervous system that prevents excessive neural activity.

Glutamate

The principal fast excitatory neurotransmitter of the central nervous system vital for learning and memory.

Dopamine

A slow neuromodulator produced in the substantia nigra that regulates movement control, decision-making, pleasure, and reinforcement circuits.

Serotonin

A slow neuromodulator in the central nervous system that regulates sleep, appetite, arousal, and mood.

Myasthenia Gravis

An autoimmune disorder characterized by destruction of acetylcholine receptors at the neuromuscular junction, leading to fluctuating muscle weakness and fatigue.

Parkinson's Disease

A neurodegenerative disorder caused by the destruction of dopamine-producing cells in the substantia nigra, leading to tremors, bradykinesia, and motor deficits.

Brachial Plexus

A nerve network formed by the ventral rami of $C5$ through $T1$ that supplies motor and sensory signals to the upper extremity via five terminal branches.

Humeroulnar Joint

An articulation of the elbow joint where the trochlea of the humerus articulates with the concave trochlear notch of the ulna.

Humeroradial Joint

An articulation of the elbow joint where the convex capitulum of the humerus articulates with the concave proximal radial head.