Neurobiology and Neural Communication Vocabulary

Comprehensive vocabulary flashcards covering glial cells, neuron anatomy, passive and active conduction, action potential dynamics, synaptic mechanisms, and subcortical brain structures based on lecture notes.

Astrocyte

A star-shaped glial cell in the central nervous system that provides support structures for the brain and forms the blood-brain barrier.

Oligodendrocyte

A central nervous system glial cell that wraps myelin sheaths around multiple axons.

Microglial cell

A phagocytotic glial cell in the central nervous system responsible for removing damaged cells.

Schwann cell

A peripheral nervous system glial cell that forms myelin around only a single axon segment.

Neurites

Protruding processes or extensions extending from the neuronal cell body, which include both dendrites and axons.

Dendrites

Neuronal processes with a rough surface (dendritic spines) that convey information to the cell body, contain ribosomes to build proteins, lack myelin, and branch near the soma.

Axon

Typically a single, smooth-surfaced process longer than dendrites that conveys information away from the cell body, contains no ribosomes, branches further from the soma, and may be insulated by myelin.

Psuedounipolar neuron

A neuronal classification common in the peripheral nervous system characterized by a single neurite that branches early from the cell body.

Directional Flow of Information in Most Neurons

The sequential pathway of signal transmission: synapse $\rightarrow$ dendrite $\rightarrow$ soma $\rightarrow$ axon $\rightarrow$ synapse.

Axon hillock

The junction between the cell body and the axon where threshold depolarization must be reached to generate an action potential.

Electrotonic conduction

Passive, decremental conduction of electrical potential where signal strength decays as a function of the distance it travels along an axon.

Action potential

A brief electrical impulse that propagates along an axon without depleting or changing shape when depolarization exceeds the threshold of excitation.

Threshold of excitation

The value of depolarization at the axon hillock required to trigger an action potential.

Graded potential

Sub-threshold changes in membrane potential whose magnitude is directly related to the strength of incoming stimuli.

Depolarization

A change in electrical charge in the positive direction relative to the resting state (a decrease in negativity).

Hyperpolarization

A change in electrical charge in the negative direction relative to the resting state (an increase in negativity).

All-or-None Response

The characteristic of neurons to either fire an action potential at full amplitude and speed or not fire at all, independent of stimulus intensity once threshold is met.

Rate coding

The process by which neurons represent the strength of a stimulus through the firing rate of action potentials.

Phases of the Action Potential

The sequence of ion channel activity: $\text{Na}^+$ channels open (A), $\text{K}^+$ channels open (B), $\text{Na}^+$ channels become refractory (C), $\text{K}^+$ leaves the cell (D), $\text{K}^+$ channels close while $\text{Na}^+$ channels reset (E), and extra extracellular $\text{K}^+$ diffuses away (F).

Reuptake

A mechanism for modulating neurotransmitter levels in the synaptic cleft where neurotransmitter molecules are taken back into the presynaptic terminal.

Enzymatic deactivation

A synaptic mechanism where neurotransmitters in the cleft are broken down and inactivated by enzymes.

Limbic System

A network implicated in emotion, motivation, learning, memory, and autonomic responses regulating automatic bodily processes like breathing and digestion.

Hippocampus

A bilateral structure named after the Latin word for seahorse that plays a vital role in learning.

Basal Ganglia

Structures located beneath the cortex that modulate action through reciprocal interactions with the frontal lobes.

Hypothalamus

A small brain region critical for emotional behavior and maintaining homeostasis, working alongside the pituitary and adrenal glands.

Sympathetic nervous system

The branch of the autonomic nervous system involved in fight-or-flight responses when an organism is under threat.

Parasympathetic nervous system

The branch of the autonomic nervous system active when an organism is not under threat.