muscle tissues 3-27 friday

What connects a neuron to a skeletal muscle fiber at the neuromuscular junction?

A synaptic cleft separates the neuron and the skeletal muscle fiber.

What neurotransmitter is released at the neuromuscular junction?

Acetylcholine.

What happens when acetylcholine binds to its receptors on a muscle fiber?

It causes chemical gated sodium channels to open, allowing sodium to enter the cell.

What is the membrane potential when the cell is at resting state?

Resting potential is approximately -70 millivolts.

What is threshold potential?

Threshold potential is the membrane potential of about -55 millivolts required to trigger action potential.

What are the two types of gated channels mentioned?

Chemical gated channels and voltage gated channels.

What triggers the opening of voltage gated sodium channels?

The membrane potential reaching -55 millivolts.

What occurs first during action potential?

Depolarization, where sodium enters the cell.

What happens during repolarization?

Potassium exits the cell after voltage gated potassium channels open.

What is an action potential comprised of?

Depolarization followed by repolarization.

What process restores the original ion distribution after an action potential?

Sodium-potassium pumps return sodium outside and potassium inside the cell.

What is the term for the traveling wave of depolarization and repolarization in a muscle fiber?

Muscle impulse.

What are the two main cations involved in membrane potential changes?

Sodium (Na+) and Potassium (K+).

What part of the neuron is responsible for receiving signals?

Dendrites.

What is the role of myelin sheaths in neurons?

They insulate the axon to speed up signal transmission.

What ions are predominantly involved in generating action potentials?

Sodium (Na+) and Potassium (K+).

What is the function of the synaptic cleft?

It is the space between the presynaptic neuron and the postsynaptic cell.

What triggers the release of neurotransmitters from the presynaptic neuron?

An influx of calcium ions when action potentials reach the terminal.

What are excitatory postsynaptic potentials (EPSPs)?

Depolarizations that increase the likelihood of an action potential in the postsynaptic neuron.

What are inhibitory postsynaptic potentials (IPSPs)?

Hyperpolarizations that decrease the likelihood of an action potential in the postsynaptic neuron.

What is the all-or-nothing principle in action potentials?

An action potential will occur fully if the threshold is reached; it cannot be partial.

How do signals travel along the axon?

By the sequential opening of voltage-gated sodium channels.

What mechanism returns the membrane potential back to resting state after an action potential?

The activity of sodium-potassium pumps and voltage-gated channels.