PYB102 Lecture 4: Cells in the Nervous System and Neural Communication

A comprehensive collection of vocabulary flashcards covering basic neural anatomy, resting potential, action potential dynamics, synaptic transmission, key neurotransmitters, and drug mechanisms based on PYB102 Lecture 4.

Neurons

The basic functional units of the nervous system, specialised for communication with each other.

Glial cells

Cells that nourish, protect, physically support, and facilitate neurons and neural communication, and are critical in brain development.

Oligodendrocyte

A specific type of glial cell that covers the axons of neurons with myelin.

Myelin

A substance that covers and insulates some axons to promote efficient transmission and increase the speed of propagation of the action potential.

Dendrites

Neuronal structures that function principally to receive messages from other neurons and transmit that information to the soma.

Soma (cell body)

The cell body of a neuron that contains mechanisms controlling cell metabolism and maintenance, and collates messages from other neurons.

Axon

A neuronal extension that carries messages, called action potentials, away from the soma towards communicating cells.

Terminal buttons

Structures located at the ends of axon branches that secrete neurotransmitters to affect the activity of other cells.

Lipid bilayer

Two layers of fatty (lipid) molecules forming the cell membrane of the neuron, within which specialised proteins float.

Resting potential

The electric potential of a neuron at rest, approximately equal to $-70\,mV$, resulting from relative ion concentrations inside and outside the membrane.

Action potential

A brief reversal in the resting charge of the neuron triggered by an exchange of ions across the neuron membrane.

Threshold of excitation

The depolarisation level of about $-55\,mV$ required for a neuron to fire an action potential.

All-or-none principle

The rule stating that if threshold depolarisation is reached, an action potential of a fixed size will always fire; otherwise, no action potential fires.

Nodes of Ranvier

Gaps in the myelin sheath where sodium channels are concentrated and where action potentials are generated.

Saltatory conduction

Rapid conduction along a myelinated axon where the action potential jumps from one break in the myelin (Node of Ranvier) to the next.

Synaptic cleft

The small space or gap separating neurons across which neurotransmitters diffuse.

Vesicles

Small sacs within the terminal button that store neurotransmitters before they are released into the synaptic cleft.

Receptors

Specialised protein molecules on the postsynaptic membrane that bind with neurotransmitters, opening ion channels.

Excitatory neurotransmitter

A neurotransmitter that depolarises the membrane upon binding, increasing the likelihood that the receiving neuron will fire an action potential.

Inhibitory neurotransmitter

A neurotransmitter that hyperpolarises the membrane upon binding, making the receiving neuron less likely to fire an action potential.

Acetylcholine (ACh)

A neurotransmitter that activates motor neurons controlling skeletal muscles and contributes to attention, arousal, and memory regulation.

Dopamine (DA)

A neurotransmitter contributing to voluntary movement control, reward, motivation, and pleasurable emotions.

Serotonin (5-HT)

A neurotransmitter important in emotional states, impulsiveness, and dreaming.

GABA

A widely distributed inhibitory neurotransmitter in the nervous system.

Endorphins

Chemicals resembling opiate drugs in structure and effects that contribute to pain relief and pleasurable emotions.

Reuptake

A termination process where the entire neurotransmitter molecule is reabsorbed back into the releasing axon terminal.

Deactivation (Degradation)

A termination process where a specific enzyme alters the neurotransmitter structure so it can no longer bind to receptors.

Acetylcholinesterase

The enzyme that breaks down acetylcholine into choline and acetate within the synaptic cleft.

Agonistic drug effects

Drug mechanisms that enhance or increase the synthesis, release, or postsynaptic impact of neurotransmitters.

Antagonistic drug effects

Drug mechanisms that decrease or block the synthesis, release, or postsynaptic receptor binding of neurotransmitters.