Synaptic Transmission

Electrical synapses involve ___ whereas chemical synapses involve ___.

• direct electrical connections; release and reception of neurotransmitters

• direct electrical connections; release and reception of hormones

• indirect electrical connections; release and reception of neurotransmitters

• direct chemical connections; release and reception of hormones

• indirect chemical connections; release of electrical signals

Answer explanation

Electrical synapses involve direct electrical connections between neurons, allowing for rapid signal transmission. In contrast, chemical synapses rely on the release and reception of neurotransmitters to communicate between neurons.

What is the action of the neurotransmitter at a chemical synapse?

• It acts on receptors in the postsynaptic membrane.

• It electrically activates the presynaptic neuron

• It crosses the postsynaptic membrane and then activates ion channels in the postsynaptic neuron.

• It depolarizes the postsynaptic membrane by delivering an electrical charge.

• It transfers an action potential from the presynaptic neuron to the postsynaptic neuron.

Answer explanation

The correct choice is that the neurotransmitter acts on receptors in the postsynaptic membrane, initiating a response in the postsynaptic neuron. This is the primary function of neurotransmitters at chemical synapses.

Which event is the first in the series of events that take place during chemical synaptic transmission?

• Neurotransmitter binds to its receptors.

• Influx of Ca²⁺ in the presynaptic terminal.

• Voltage-gated Ca²⁺ channels open.

• Neurotransmitter is released into the synaptic cleft.

• Synaptic vesicles fuse with the presynaptic membrane.

Answer explanation

The first event in chemical synaptic transmission is the opening of voltage-gated Ca2+ channels. This allows Ca2+ to enter the presynaptic terminal, triggering subsequent events like neurotransmitter release.

At which point during signal transmission at a chemical synapse is exocytosis occurring?

• As neurotransmitter binds to its receptors.

• While Ca²⁺ enters the presynaptic terminal.

• As voltage-gated Ca²⁺ channels are opening.

• During neurotransmitter release into the synaptic cleft.

• During reuptake, as synaptic vesicles are reformed from the plasma membrane.

Answer explanation

Exocytosis occurs during neurotransmitter release into the synaptic cleft, where neurotransmitters are expelled from synaptic vesicles into the space between neurons, facilitating communication.

What is the main role of calcium ions in synaptic transmission?

• To block neurotransmitter release

• To trigger neurotransmitter release

• To store neurotransmitters

• To insulate the synaptic cleft

How do calcium ions enter the presynaptic neurone?

• Through sodium channels

• Through potassium channels

• Through voltage-gated calcium channels

• Through ligand-gated calcium channels

What is the chemical used by a neuron to transmit an impulse across a synapse to another nerve cell?

• Neurotransmitters

• Synapse

• Threshold

• Impulse

What is the general name for the chemicals in the nervous system that allow messages to be passed across the synapse?

• Amino Acid

• Enzyme

• Hormone

• Neurotransmitter

What is the primary function of the synaptic cleft?

• To store neurotransmitters

• To facilitate neurotransmitter diffusion

• To generate action potentials

• To insulate neurons

What is the synaptic cleft?

• A solid barrier between neurones

• A fluid-filled gap between neurones

• A storage area for neurotransmitters

• A type of receptor