Action Potentials Week 6

What is membrane potential?

The difference in electrical charge between the inside and outside of a cell, measured in millivolts.

What causes action potentials in the body?

The presence of different ions in bodily fluids leads to polarization, which initiates action potentials.

At what voltage does a voltage-gated sodium channel open?

-50 mV.

What is the resting membrane potential value?

-70 mV.

What role do Na/K pumps play in the membrane potential?

They restore the resting membrane potential.

What happens during depolarization?

Voltage-gated sodium channels open, allowing sodium to move down its gradient into the cell.

What occurs during repolarization?

Potassium exits the cell, making the cell more negative.

What is hyperpolarization?

A phase where sodium channels close and voltage-gated potassium channels remain open, making the cell more negative than its resting potential.

How does continuous propagation occur in unmyelinated axons?

It occurs as a slow wave-like step-by-step depolarization along the entire membrane.

What is saltatory propagation and where does it occur?

Saltatory propagation occurs in myelinated axons, where the action potential jumps between Nodes of Ranvier, resulting in faster conduction.

What do muscle spindles do?

They monitor changes in muscle length and help coordinate movements without visual feedback.

What is the function of the Golgi tendon organ?

It monitors changes in muscle tension at the junction between muscle and bone (tendons) to prevent excessive stretching.

What are the components of the sensory (ascending) pathway?

First-order neuron, second-order neuron, and third-order neuron.

What is the primary role of the autonomic nervous system?

To manage involuntary bodily functions.

What are the primary functions of the sympathetic division?

To support rapid ATP production and prepare the body for stress responses (fight/flight).

What are the primary functions of the parasympathetic division?

To conserve and restore energy (rest/digest).

Where are the ganglia located in the sympathetic division?

Near the spinal cord.

Characterize the preganglionic and postganglionic fibers in the sympathetic nervous system.

It has short preganglionic fibers and long postganglionic fibers.

What neurotransmitter is primarily used at target organs by the sympathetic division?

Norepinephrine (NE).

Where are the ganglia located in the parasympathetic division?

Near the effectors.

Characterize the preganglionic and postganglionic fibers in the parasympathetic nervous system.

It has long preganglionic fibers and short postganglionic fibers.

What neurotransmitter is primarily used at target organs by the parasympathetic division?

Acetylcholine (ACh).