Divisions and Functions of the Nervous System

These flashcards cover key concepts related to the nervous system, including its divisions, neuron functions, ion concentrations, action potential phases, and conduction properties.

What are the two primary divisions of the nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

What is the function of sensory nerves?

Sensory (afferent) nerves carry information to the CNS.

What parts make up a neuron?

Cell body, dendrites, axon, terminal branches.

What is the concentration of sodium (Na+) inside vs outside a neuron?

Inside: low Na+; Outside: high Na+.

What is the function of the Na+/K+ ATPase pump?

Moves 3 Na+ out and 2 K+ in using ATP.

What is the resting membrane potential (RMP) of a neuron?

Around -70 mV.

What does the Nernst equation calculate?

The equilibrium potential for one ion.

Why is the resting membrane potential -70 mV and not -90 mV?

Because some Na+ leaks into the cell, raising the potential.

What is the role of voltage-gated channels in neurons?

They open in response to voltage changes and are key for action potential generation.

What happens during the depolarization phase of an action potential?

VG Na+ channels open, allowing Na+ influx, making the membrane potential positive.

What occurs during the repolarization phase of an action potential?

VG K+ channels open, allowing K+ efflux, returning the membrane to a negative potential.

What is the absolute refractory period?

A period during which no action potential is possible because the Na+ inactivation gate is closed.

What is the all-or-none property of action potentials?

If the threshold is reached, a full action potential fires; if not, no action potential occurs.

How does conduction differ between myelinated and unmyelinated axons?

Myelinated axons conduct action potentials rapidly via saltatory conduction, while unmyelinated axons conduct slowly by regenerating APs continuously.

What does AP frequency coding indicate?

A stronger stimulus results in more action potentials, not larger ones.