Electrical synapses have two main characteristics. First, they transmit signals through specialized tunnels between cells called gap junctions. Gap junctions facilitate movement of molecules and ions between cells. This movement enables transmission of signals between adjacent cells. Second, electrical synapses have a much higher speed of signal transmission than chemical synapses. This occurs because the signals in electrical synapses are transmitted directly from one cell to the next via gap junctions. In chemical synapses, however, signals are transmitted indirectly via neurotransmitters, which decreases the speed of signal transmission.

A chemical synapse is a type of synapse that uses neurotransmitters to transmit signals. A presynaptic neuron receives an action potential, which prompts neurotransmitters to be released into the synaptic cleft. These neurotransmitters traverse across the synaptic cleft and bind to receptors on the postsynaptic neuron. Binding of neurotransmitters initiates a signal pathway in the postsynaptic neuron.

One of the characteristics of a chemical synapse is that it is unidirectional. This means that the signal can only be propagated in one direction. The signal is always transmitted from the presynaptic to the postsynaptic neuron, never the other way around.

Chemical synapses are indeed more common than electrical synapses. Most nerves, neuromuscular junctions, and major organs in the body use chemical synapses to transmit action potentials. The only major exception is the heart; cardiac cells in the heart use electrical synapses to transmit signal from one cell to the other.

In a chemical synapse, the presynaptic neuron transmits a signal to the adjacent postsynaptic neuron. The postsynaptic neuron receives this signal via neurotransmitters. Recall that a neuron has directionality, with dendrites on one end and an axon on the other end. Dendrites receive an outside signal (signal enters neuron), whereas an axon transmits the signal to an adjacent neuron or muscle (signal exits neuron). This means that the axon end of the presynaptic neuron transmits the signal to the dendrite end of the postsynaptic neuron via a chemical synapse.

During the absolute refractory period, no action potential can occur. In the relative refractory period, an action potential can occur with more stimulation than is normally required.

Saltatory conduction is the property that allows an action potential to jump from one node to the next along a neural axon. This is accomplished by the presence of myelin, a non-conducting sheath around the axon. Myelin interrupts the flow of current down the membrane, forcing it to skip from one region of membrane to the next, rather than fluidly traveling down the entire axon length.

Depolarization is the stage of action potential transmission in which sodium channels are opened, and sodium rushes into the cell down its concentration gradient. The resting potential of the neural membrane is roughly . The rapid influx of positive sodium ions causes this potential in increase to at the action potential peak.

Repolarization is the stage of action potential transmission in which potassium channels of a cell are opened, and potassium moves out of the cell. This event re-establishes the negative resting membrane potential. 

The refractory period is the obligatory temporal gap between action potentials. After an action potential, the primary gating mechanism of the voltage-gated sodium channels causes the channels to close and deactivate. This constitutes the absolute refractory period, during which no stimulus is capable of producing an action potential. The relative refractory period follows, during the cell repolarization, when potassium efflux causes the membrane potential to drop below the resting potential. This state of hyperpolarization means that a greater stimulus is required to reach threshold, and constitutes the relative refractory period.

The proteins responsible for allowing ionic flow into and out of axons are most likely to be found at Nodes of Ranvier, where there is no myelin and ions can move freely. Action potentials travel via saltatory conduction, meaning that the ion channels are only stimulated a certain points on the membrane. The majority of the impulse is conducted through the interior of the axon without further external stimulation.

Saltatory conduction is defined as the method by which action potentials are propagated along axons in myelinated neurons. The method by which they do this is by the generation of action potentials at each node of Ranvier. The only places along the myelinated axon that display ion flow are the nodes of Ranvier. The myelinated portions do not display ion flow, allowing the electrical stimulus to rapidly jump down the axon from one node to the next rather than slowly flow down the full axon length.

Schwann cells are types of cell that make up the myelin coated sheath for select neurons.

Sodium channels have an inactivation gate, as well as a voltage gate. This allows the sodium channels to be turned off, even while voltage changes persist, thereby facilitating repolarization. This dual gate structure also causes the refractory period.

Potassium is the major species that repolarizes a neuron following depolarization. After sodium has entered the cell to create depolarization, repolarization is driven by potassium ion efflux.

The presence of potassium leak channels in the membrane allows potassium to drive the resting cell membrane potential nearer to its equilibrium potential than to sodium's.

The equilibrium potential is the electric potential that would exaclty balance the competing forces of concentration and electrical gradients. High potassium concentration in the cytosol drives potassium out of leak channels in the membrane, toward the extracellular space, but the inside develops a negative charge as a result. When this negative charge pulling positive potassium ions back in is enough to exactly cancel the concentration forces pushing potassium out, the equilibrium potential has been reached.