Chemical Signalling by Neurotransmitters

Presynaptic Cell

A neuron that releases neurotransmitters into the synaptic cleft.

Synaptic Cleft

The space between the presynaptic neuron and the postsynaptic neuron where neurotransmitters are released.

Axodendritic Communication

Communication between neurons where an axon connects to a dendrite.

Criteria for Neurotransmitter Status

Set of standards to identify a substance as a neurotransmitter, including the need for presynaptic presence and postsynaptic receptors.

Acetylcholine (ACh)

A classical neurotransmitter involved in muscle activation and many other functions.

Gaseous Neurotransmitters

Types of neurotransmitters that include nitric oxide, carbon monoxide, and hydrogen sulfide, which are gaseous in nature.

Serotonin (5-HT)

An indoleamine neurotransmitter important for mood regulation.

Neuromuscular Junction

The synapse between a motor neuron and a muscle fiber.

Endocytosis

The process by which cells internalize substances; in neurons, it relates to vesicle recycling.

Ionotropic Receptors

Fast receptors that open ion channels when a neurotransmitter binds.

G Protein-Coupled Receptors (GPCRs)

A type of metabotropic receptor that activates G proteins to affect cell signaling.

Neurotrophic Factors

Proteins that support neuron growth, differentiation, and survival.

Inactivation of Neurotransmitters

Processes such as enzymatic breakdown or reuptake that terminate the action of neurotransmitters.

Agonist

A substance that binds to a receptor and initiates a biological response.

Antagonist

A substance that binds to a receptor but does not trigger a cellular response, blocking agonists.

Oxytocin

A hormone involved in childbirth and social bonding.

Vasopressin

Also known as antidiuretic hormone; regulates water retention in kidneys.

Second Messenger Systems

Intracellular signaling mechanisms activated by neurotransmitter binding that lead to various cellular effects.

Allosteric Modulators

Molecules that bind to sites other than the main ligand-binding site on a receptor to enhance or inhibit its function.

Neuropeptides

A type of non-classical neurotransmitter that includes substances like endorphins and substance P.

Electrical Synapse

A type of synapse where electric current flows through specialized protein channels.

Neuropeptides vs. Classical Neurotransmitters

Neuropeptides are often produced in the cell body and take longer to replenish compared to classical neurotransmitters made in axon terminals.

Rate of Firing

One of the mechanisms that controls neurotransmitter release.