Neuromuscular Synapse

What is the resting membrane potential?

The resting membrane potential results from the distribution of various cations and anions inside and outside of the cell.

How can the resting membrane potential become depolarized?

By altering the movement of ions, specifically sodium ions.

Where does muscle contraction initiation occur?

At the neuromuscular junction.

What are the presynaptic and post-synaptic terminals in a neuromuscular synapse?

The presynaptic terminal is the neuron side, while the post-synaptic terminal is the muscle cell.

What is the synaptic cleft?

The small space where the axon terminal of a neuron connects with a muscle cell's membrane.

What neurotransmitter is involved in muscle contraction at the neuromuscular junction?

Acetylcholine.

What happens when an action potential reaches the axon terminal?

Synaptic vesicles release acetylcholine into the synaptic cleft.

What is the role of acetylcholine in muscle contraction?

It serves as the signal for muscle contraction.

What type of channel opens when acetylcholine binds to its receptor?

Ligand-gated sodium channel.

What occurs at the ligand-gated sodium channel when acetylcholine binds?

It opens, allowing sodium ions to flow into the muscle cell.

What is the concentration gradient for sodium ions in the synaptic cleft compared to the muscle cell?

Higher concentration in the synaptic cleft compared to the inside of the cell.

What is the effect of sodium ion influx on the muscle cell?

It depolarizes the muscle cell, bringing the membrane potential closer to zero.

What defines the resting membrane potential of a cell?

The distribution of cations and anions.

What does depolarization lead to?

The initiation of muscle contraction.

What is acetylcholine's role in neuromuscular transmission?

It is released from the presynaptic terminal to communicate with muscle cells.

Define the synaptic cleft.

The space filled with extracellular fluid between the presynaptic and postsynaptic terminals.

What is the function of synaptic vesicles?

To store and release neurotransmitters like acetylcholine.

What happens to sodium channels during resting potential?

They are closed.

What leads to muscle cell depolarization?

The influx of sodium ions through ligand-gated sodium channels.

Where does the flow of sodium ions occur from and to?

From a high concentration in the synaptic cleft to a low concentration in the muscle cell.

What initiates the process of muscle contraction?

The binding of acetylcholine to its receptors on the muscle cell.

What is the main ion involved in depolarizing the muscle cell?

Sodium ion.

What defines the presynaptic terminal in a neuromuscular junction?

It is where the neuron is located.

What does acetylcholine bind to on the muscle cell?

Its receptor on the muscle cell membrane.

What results from the binding of acetylcholine to its receptor?

Opening of ligand-gated sodium channels.

How does the initiation of muscle contraction occur?

Through depolarization of the muscle cell membrane.

What is the role of extracellular fluid in the synaptic cleft?

It contains a higher concentration of sodium ions.

How does action potential affect neurotransmitter release?

It triggers the release of acetylcholine from synaptic vesicles.

What is the consequence of muscle cell depolarization?

It signals the beginning of muscle contraction.

What happens to sodium concentration across the muscle cell membrane during contraction?

It increases as sodium flows into the cell.

Why is the neuromuscular junction important?

It is the site where neurons communicate with muscle cells to initiate contraction.

What happens to the muscle cell membrane during depolarization?

The membrane potential moves closer to zero.

What type of channel was referred to in this muscle contraction process?

Ligand-gated channel.

How does the movement of sodium ions compare inside and outside the muscle cell?

Higher concentration outside than inside before contraction.

What is acetylcholine's primary role in muscle cells?

To initiate contraction by binding to its receptors.

What happens to the muscle cell during the inflow of sodium ions?

It depolarizes.

What is the result of acetylcholine binding in the neuromuscular junction?

It opens sodium channels, allowing depolarization.

What initially prevents sodium ions from entering the muscle cell?

Closed sodium channels at resting potential.

What leads to the release of acetylcholine?

The arrival of an action potential at the axon terminal.

How is the balance of ions critical in maintaining resting membrane potential?

It reflects the concentrations of various cations and anions.

What key process occurs at the synaptic cleft in muscle contraction?

Release of neurotransmitters.

What is the importance of ion concentration differences in neural and muscular function?

They drive depolarization necessary for muscle contraction.

What is the physiological significance of the neuromuscular junction?

It facilitates communication between the nervous system and muscle tissue.