-Chemicals found within the axon terminal can be released into an exceedingly small gap
between the neurons, called a synaptic cleft, allowing the neuron to affect the excitability
of adjacent neurons.
-The region it self is called a synapse, and it consists of presynaptic membrane of the
axon terminal, the cleft, and the postsynaptic membrane of the ``target`` neurons.
-Pre—and post-synaptic membranes are ``glued`` together by way of interlocking
adhesion molecules that allow the tow membranes to work together as a functional unit
that resists separation by physical methods
-In the intra- and extracellular fluids are different concentrations of negatively and
positively charged ions.
-The four primary ions important for conduction are sodium Ca+, potassium K+, chloride
Cl-, and large negatively charged protein molecules.
-A fifth ion, a calcium ion with tow positive charges Ca++, it plays a vital role in a wide
variety of actions within the nervous system.
-There are two primary forces that influence the concentration of these ions across
- A concentration gradient force refers to the fact that when there are different
concentrations of molecules on the two sides of the membrane, they travel from high-
concentration region to the low-concentration region.
-Electrostatic pressure refers to the force exerted by the attraction of oppositely charged
ions or by the repulsion of similarly charged ions.
-Neurons can be in one of two states, one state is called the resting potential, although the
term resting is not really appropriate because the cell is actually expending ~ one quarter
of its totally energy maintain this state.
-In this state, there is much higher concentration of negatively charged ions on the inside
of the cell membrane than on the outside of the membrane.
- A potassium ion being pulled out of the cell because of concentration gradient pressure
and pulled in because of electrostatic pressure; a Chloride ion is being pulled into the cell
because of concentration gradient and pushed out because of electrostatic pressure; the
sodium ion being pulled into the cell by both electrostatic and gradient pressure.
-The large negatively charged protein ions are clustered close to the inside membrane,
and the positively charged sodium ions are clustered close to the outside membrane.
-The close proximity of these two ions on the two sides of the cell membrane and their
attraction for each other produces a considerable amount of pressure (voltage potential) at
-In the resting potential state, the cell is referred to as being polarized.
-In the other state, in which there is rapid exchange of ions across the neuron membrane,
the cell is referred to as being depolarized, a process resulting in what will be called an
-At rest, the neuron has an electrical potential of ~70mV