AP Lab

Peripheral Nervous System (PNS)

Divided into the Somatic Nervous System and the Autonomic Nervous System, responsible for voluntary and involuntary body functions.

Somatic Nervous System (SNS)

Controls voluntary movements and sensory information, involving sensory and motor neurons.

Autonomic Nervous System (ANS)

Regulates involuntary body functions, further divided into Sympathetic, Parasympathetic, and Enteric Nervous Systems.

Resting Membrane Potential

The electrical charge difference across a neuron’s membrane when not transmitting a signal, typically around -70mV.

Na⁺/K⁺ Pump

A mechanism that actively transports 3 sodium ions out and 2 potassium ions into the cell to maintain resting membrane potential.

Concentration Gradient for Sodium (Na⁺)

Higher concentration of Na⁺ outside the cell than inside.

Concentration Gradient for Potassium (K⁺)

Higher concentration of K⁺ inside the cell than outside.

Action Potential

A rapid rise and fall in membrane potential that consists of several phases: resting state, depolarization, repolarization, and hyperpolarization.

Depolarization Phase

The phase of action potential when sodium channels open and Na⁺ rushes into the neuron.

Repolarization Phase

The phase when potassium channels open and K⁺ flows out of the neuron, restoring the negative internal charge.

All or None Principle

Once the threshold is reached, an action potential fires at full strength, and its size and speed do not vary with stimulus strength.

Absolute Refractory Period

Period during which no new action potential can be initiated regardless of stimulus strength due to inactivation of sodium channels.

Relative Refractory Period

Period during which a stronger-than-usual stimulus is required to generate another action potential.

Factors Increasing Action Potential Conduction

Myelination and larger axon diameter both contribute to faster conduction of action potentials.

Saltatory Conduction

The process by which action potentials jump from one node of Ranvier to the next in myelinated axons, speeding up transmission.

Compound Action Potential (CAP)

The sum of electrical potentials from multiple nerve fibers; recorded in muscles like the adductor pollicis to assess nerve function.

Axon Diameter and Conduction Velocity

Larger diameter axons conduct action potentials faster due to reduced resistance to ion flow.