30 terms

The Nervous System


Terms in this set (...)

The principal job of the human nervous system is to
facilitate communication among the body systems.
The basic unit of the nervous system is
the neuron.
What is NOT true concerning sensory neurons?
They lie in the pathway between the interneurons and motor neurons.
The single long process that extends from a typical motor nerve cell is the
Within a single neuron, the direction an impulse follows is
dendrite >>> cell body >>> axon.
When an impulse passes from one neuron to the next, it
passes from axon to dendrite.
Neuroglial cells
all of these
Functionally speaking, a nerve impulse is
a series of changes in membrane potentials.
When a neuron is at rest
all of these
The resting potential of a neuron is approximately minus
70 millivolts.
The membrane-bound enzyme system that restores and maintains the resting membrane potential is which pump?
At rest, a nerve cell has a high concentration of potassium inside and a high concentration of
sodium inside.
Active transport
helps to establish the resting potential of a neuron, counters the process of diffusion, and allows transport of atoms across the plasma membrane of the neuron against the concentration gradient.
What is true concerning transport proteins in the neuron membrane
Energy moves ions against the concentration gradient.
What is the first response a neuron makes to a stimulus?
Sodium ions enter the cell.
For sodium to accumulate rapidly in a neuron,
a stimulus above the threshold must open sodium gates in an accelerating manner.
Disturbances in sensory neurons will result in an action potential if the
graded stimulus reaches a trigger zone.
What occurs first during an action potential?
A local disturbance triggers the resting voltage to exceed the threshold level.
What term most accurately describes the cellular activity associated with the actual passage of a nerve impulse?
wave of depolarization
What happens immediately following the closing of the sodium gates during an action potential?
Potassium ions leave the cell.
An action potential is brought about by
a local change in membrane permeability caused by a greater-than-threshold stimulus.
During the passage of a nerve impulse
all of these
The phrase "all or nothing," used in conjunction with discussion about an action potential, means that
nothing can stop the action potential once the threshold is reached.
Once a threshold is reached,
the opening of sodium gates and the accompanying flow of sodium ions is an example of positive feedback.
The occurrence of an action potential can best be compared to a
switch to turn a lamp on and off.
Which statement is false?
An action potential continues indefinitely until a quenching signal is released.
The recovery time from the passage of a nerve impulse is called the
refractory period.
During the recovery period between action potentials,
the sodium gates are shut and the potassium gates are opened.
Transmitter substances
are expelled from the presynaptic cells and interact with membrane receptors of the postsynaptic cells.
What is a junction between two neurons?
chemical synapse