Chemical Messengers and Synaptic Transmission

A set of flashcards based on key concepts related to chemical messengers and synaptic transmission.

What are chemical messengers that transmit signals across synapses called?

Neurotransmitters.

How are neurotransmitters stored in the presynaptic axon terminal?

In tiny spherical bags called synaptic vesicles.

What triggers the release of neurotransmitters into the synaptic cleft?

The arrival of an action potential, which opens ion channels allowing calcium ions (Ca++) to enter.

What is the distance of the synaptic cleft that neurotransmitters must cross?

20 nanometres.

What type of receptor opens ion channels directly upon binding with neurotransmitters?

Ionotropic receptors.

What is an excitatory post-synaptic potential (EPSP)?

A change in membrane potential that moves it closer to the threshold for firing an action potential.

What are the two main inhibitory neurotransmitters mentioned?

GABA and glycine.

What is the effect of inhibitory post-synaptic potentials (IPSPs) on neuron membrane potential?

They cause a change that opposes depolarization and decreases the likelihood of action potential initiation.

How quickly does synaptic transmission occur?

Within approximately 1/1000 of a second.

What effect does dopamine have on the brain?

It makes certain situations rewarding by acting on brain centers associated with positive emotional features.

What is the role of acetylcholine in the nervous system?

It acts on both ionotropic and metabotropic receptors, functioning as a neurotransmitter and a neuromodulator.

What is neuromodulation?

The process by which metabotropic receptors adjust or modulate neuronal mechanisms without directly initiating action potentials.

Where are noradrenaline neurons primarily located in the brain?

In the locus coeruleus (LC) region.

What is the relationship between excitatory and inhibitory neurotransmitters?

Excitation of some neurons is paired with inhibition of others to coordinate nervous system activity.

What biochemical processes do metabotropic receptors initiate?

They trigger a series of biochemical events involving second messengers and can lead to long-lasting changes in neuronal function.

How do glial cells contribute to neurotransmitter recycling?

They clear neurotransmitters from the synaptic cleft and may process them for future use.