CH 1.2 Summary Flashcards
The action potential transmits information without loss of intensity over distance.
The cost is a delay between the stimulus and its arrival in the brain.
The inside of a resting neuron has a negative charge with respect to the outside
Mainly because of negatively charged proteins inside the neuron.
The sodium–potassium pump moves
Sodium ions out of the neuron, and potassium ions in.
When the membrane is at rest, both the electrical gradient and the concentration gradient would act to
Move sodium ions into the cell, except that its gates are closed.
The electrical gradient tends to move potassium ions into the cell, but the concentration gradient tends to move it out.
The two forces almost balance out, but not quite, leaving a net tendency for potassium to exit the cell.
The all-or-none law
For any stimulus greater than the threshold, the amplitude and velocity of the action potential are independent of the size of the stimulus that initiated it.
When the membrane is sufficiently depolarized to reach the cell’s threshold
Sodium and potassium channels open.
Sodium ions enter rapidly, reducing and reversing the charge across the membrane.
This event is known as the action potential.
After the peak of the action potential, the membrane returns toward its original level of polarization because of
The outflow of potassium ions.
The action potential is regenerated at successive points along the
Axon as sodium ions flow through the core of the axon and stimulate the next point along the axon to its threshold.
The action potential maintains a
Constant magnitude as it passes along the axon.
In axons that are covered with myelin, action potentials form only in the nodes that separate myelinated segments.
Transmission in myelinated axons is faster than in unmyelinated axons.
Immediately after an action potential, the membrane enters a refractory period during which it is
Resistant to starting another action potential.
Local neurons are small, with no axon.
They convey information over short distances.
Contrary to a popular belief
People use all of their brain, not some smaller percentage.
