1. Electrical synapsis and signaling are communicated by
(1) Neurotransmitters
(2) hormones
(3) Gap junctions
(4) membrane proteins

Electrical synapses represent a critical mechanism by which neurons communicate rapidly and directly in the nervous system. Unlike chemical synapses that rely on neurotransmitters to transmit signals, electrical synapses communicate through specialized structures called gap junctions. These gap junctions form direct cytoplasmic connections between neurons, allowing electrical current and ions to pass instantaneously from one cell to another, enabling fast, bidirectional signaling vital for synchronized neural activities.

At the core of electrical synapses are gap junctions—clusters of channel-forming proteins called connexons. Each connexon comprises six connexin protein subunits arranged in a hexagonal pattern forming a pore. When two connexons from adjacent neurons align, they create a continuous channel bridging the small intercellular space (about 3.8 nanometers) between the cells. This gap junction channel permits the free flow of ions, ATP, metabolites, and signaling molecules directly between cells, facilitating rapid electrical transmission that chemical synapses, with their reliance on neurotransmitter release and receptor binding, cannot match.

Electrical synapses are particularly important in physiological contexts requiring immediate and coordinated responses. For instance, they are found in cardiac muscle tissue, where synchronized contractions depend on the swift propagation of electrical impulses. Similarly, electrical synapses are involved in certain brain areas such as the retina, hippocampus, and brainstem respiratory nuclei, coordinating neuronal network synchronization and rhythmic activities like breathing and heartbeat.

Another distinguishing feature of electrical synapses mediated by gap junctions is their bidirectional nature. Electrical signals can travel in both directions across the synapse, allowing neurons to simultaneously influence one another. This contrasts sharply with most chemical synapses, which typically convey signals in a single direction from the presynaptic to the postsynaptic cell.

However, electrical synapses via gap junctions also have limitations compared to chemical synapses. They do not provide the same level of signal modulation or plasticity and are mostly limited to transmitting simple electrical signals. Chemical synapses, though slower, allow for complex signaling through a variety of neurotransmitters and receptor types, supporting learning, memory, and intricate neural processing.

In summary, electrical synapses communicate via gap junctions—membrane protein channels formed by connexins—that enable rapid, direct, and bidirectional current flow between neurons. This system plays an essential role in fast, synchronized activities in the nervous system and other tissues, standing apart from neurotransmitter-based chemical synapses in both structure and function. Therefore, when asked how electrical synapses and signaling are communicated, the correct answer is unequivocally:

(3) Gap junctions

This direct electrical connectivity through gap junctions underpins fast and efficient neural communication, crucial for many physiological processes requiring near-instantaneous signal transmission.