Lec 4: Human Neuropsychology - Neuronal Structure and Communication

Vocabulary flashcards covering key terms and concepts from Lecture 4 on Neuronal Structure and Communication.

Law of Dynamic Polarization

A principle formulated by Ramón y Cajal stating that information flows through a neuron in a single direction: collected by dendrites, integrated in the soma, conducted down the axon, and transmitted out via terminal buttons.

Dendrites

Neuronal structures that collect and receive input information from other cells, ranging from 1 to 20 per neuron with extensive branching.

Dendritic Spines

Small protrusions on dendrites that increase surface area and serve as the main sites for most excitatory synapses.

Soma

The cell body of a neuron that integrates incoming signals, contains the nucleus and organelles, and maintains cellular life.

Axon Hillock

The region at the junction of the soma and the beginning of the axon that integrates signals and triggers an action potential due to a high density of voltage-gated ion channels.

Axon

A single long extension of a neuron that conducts information internally, branching into axon collaterals and telodendria.

Terminal Button

The end foot of an axon branch that sends output signals to adjacent receiving cells across a synaptic gap.

Phospholipid Bilayer

A semipermeable membrane made of two opposing layers of phospholipids, featuring hydrophilic heads pointing outward and hydrophobic tails facing inward.

Golgi Body

A membranous cell structure that packages protein molecules received from the endoplasmic reticulum in a membrane and assigns them a shipping address for transport.

Sodium-Potassium Pump ($\text{Na}^+$--$\text{K}^+$ Pump)

A membrane protein pump that actively exchanges three $\text{Na}^+$ ions out of the cell for every two $\text{K}^+$ ions moved into the cell.

Resting Potential

The voltage difference across a neuron's membrane at rest, where the intracellular side is $-70\,\text{mV}$ relative to the extracellular side ($0\,\text{mV}$).

Concentration Gradient

The difference in concentration of a substance across a space that causes ions to diffuse from high concentration to low concentration.

Electrical Gradient

The difference in electrical charge across a membrane that causes opposite charges to attract and like charges to repel.

Graded Potentials

Localized, small voltage changes across the cell membrane caused by stimulation that rapidly decay and do not travel far.

Depolarization

A change in membrane potential that makes the inside of the cell less negative (closer to $0\,\text{mV}$), typically caused by an influx of $\text{Na}^+$ ions.

Hyperpolarization

A change in membrane potential that makes the inside of the cell more negative relative to rest, caused by an efflux of $\text{K}^+$ ions or influx of $\text{Cl}^-$ ions.

Threshold Potential

The specific membrane voltage (approximately $-50\,\text{mV}$) required to trigger an all-or-nothing action potential.

Action Potential

A brief, all-or-nothing electrical impulse in which the membrane potential swings from $-70\,\text{mV}$ to $+30\,\text{mV}$ and back within a few milliseconds.

Absolute Refractory Period

The period during an action potential when voltage-gated $\text{Na}^+$ channels are open or inactivated, making it impossible to generate another action potential.

Relative Refractory Period

The hyperpolarized phase following an action potential during which a stronger-than-normal electrical stimulus is required to initiate a new action potential.

Saltatory Conduction

The rapid propagation of an action potential along a myelinated axon as the signal jumps from one Node of Ranvier to the next.

Nodes of Ranvier

Unmyelinated gaps between adjacent myelin sheaths along an axon where voltage-gated ion channels are highly concentrated.

Oligodendroglia

Glial cells that form myelin sheaths around axons in the central nervous system (CNS).

Schwann Cells

Glial cells that form myelin sheaths around axons in the peripheral nervous system (PNS).

Ionotropic Receptor

A fast-acting, short-term neurotransmitter receptor that directly contains an ion channel pore which opens or closes upon ligand binding.

Metabotropic Receptor

A slow-onset, long-lasting neurotransmitter receptor without an intrinsic channel that activates a G protein to trigger intracellular metabolic pathways.

Reuptake

An inactivation mechanism where neurotransmitter molecules are transported back into the presynaptic terminal that released them.

Referred Pain

A phenomenon where visceral pain in an internal organ is perceived as coming from a somatic sensory area (dermatome).

Cranial Nerves

Twelve pairs of peripheral nerves originating directly from the brain that provide sensory and motor functions primarily to the head and neck.

Vagus Nerve (CN X)

The tenth cranial nerve, responsible for sensory and motor functions of the heart, blood vessels, viscera, larynx, and pharynx.

Transmitter Gases

A class of neurotransmitters including nitric oxide ($\text{NO}$), carbon monoxide ($\text{CO}$), and hydrogen sulfide ($\text{H}_2\text{S}$) that cannot be stored in vesicles and are synthesized as needed.