Introduction
A synapse is a link between two neurons or a neuron and a target or effector cell, such as a muscle cell. It permits the transfer of electrical or chemical impulses. A synapse is created between presynaptic and postsynaptic neurons. The neuromuscular junction is the connection that links a neuron to a muscle. A synapse is a structure that lets nerve impulses travel from the axon terminal of one neuron to the dendrites of the next. It could be electrical or chemical. Chemical and electrical synapses are specialized biological structures that join neurons and convey signals between neurons in the nervous system. Synapses are recognized in the nervous system. They may convey electrical or chemical signals. The two primary types of synapses that may be categorized based on the kind of signal are electrical and chemical synapses. In summary, A chemical synapse is a gap between two neurons through which information is transferred chemically in the form of neurotransmitter molecules.
An electrical synapse is a gap between two neurons with channel proteins joining them, so the electrical signal may move straight through the synapse. Electrical synapses are speedier, but they lack gain. After a synapse, the electrical signal stays steady or declines, but chemicals may amplify the signal. Electrical synapses must also be much smaller for channel proteins to travel from one cell to another. Electrical synapses are generally present in systems that demand fast responses, such as instincts and defence, and chemical synapses in less binding regions. Synapses are brain connections that allow neurons to relay information to particular target cells.
Chemical Synapse vs Electric Synapse
The significant distinction between a chemical synapse and an electrical synapse is that the nerve impulse in a chemical synapse is transmitted chemically through neurotransmitters. In contrast, an electrical synapse is linked via channel proteins. The membranes of pre-and postsynaptic neurons are in intimate contact at electrical synapses. Electric current may flow straight from one neuron to the next across these synapses, mimicking impulse conduction through a single axon. The ionic current signal then travels passively via the gap junction, allowing the call to be conveyed.
Connexons, protein channels, are used to construct a gap junction. Chemical synapses are formed when the membranes of pre-and postsynaptic neurons are separated by a fluid-filled region known as the synaptic cleft. Neurotransmitters are at work here. These substances bind to receptors on the postsynaptic membrane. Their binding opens ion channels, allowing ions to enter and produce new potential in postsynaptic neurons. Chemical synapse connections may form between two neurons or between a neuron and a nonneuronal cell. The three components are the presynaptic element, the synaptic cleft, and the postsynaptic element.
Nerve impulses travel through the axon membrane as an electrical signal. In the situation of the former, a chemical synapse turns an electrical signal into a chemical signal. In contrast, an electrical synapse may convey the impulse via ions. As a consequence, electrical synapses are significantly quicker than chemical synapses.
Difference Between Chemical Synapse and Electric Synapse in Tabular Form
| Parameters of Comparison | Chemical Synapse | Electric Synapse |
| Definition | A chemical synapse is a cell-to-cell link via which neurotransmitters convey nerve impulses in one direction alone. | An electrical synapse is a cell connection between two nerve cells where ions are used to swiftly convey nerve impulses. |
| Modification of Signals | Signals are altered during transmission. | Signals are not altered during transmission. |
| Occurrence | Chemical synapses exist in higher mammals. | Electrical synapses exist in lower vertebrates and invertebrates. |
| Chemo-receptors | Chemo-receptors are present on the post-synaptic membrane of chemical synapses. | On the post-synaptic membrane of electrical synapses, chemo-receptors do not exist. |
| One-way/Two-way | Messages are only delivered in one way at a chemical synapse. | Messages are delivered in both ways at an electrical synapse. |
| Energy Consumption | Energy is required for signal transmission. As a result, it is a dynamic process. | Signal transmission occurs without the need for energy. As a result, it is a passive process. |
What is Chemical Synapse?
A chemical synapse is a biological structure between two neurons or between a neuron and a nonneuronal cell that allows them to interact through chemical messengers. Neurotransmitters are the chemical messengers that carry messages between neurons. Synaptic vesicles are tiny vesicles that generate and package neurotransmitters. A chemical synapse is a cell connection that allows nerve impulses to be passed in one direction through neurotransmitters. Presynaptic and postsynaptic membranes are the two kinds of plasma membranes. The presynaptic membrane is located in the presynaptic cell, whereas the postsynaptic membrane is located in the postsynaptic cell. The synaptic cleft is located between the pre-and postsynaptic membranes. Chemically produced synapses are more prevalent. Neurotransmitters are bound by receptors in the postsynaptic membrane. This opens voltage-gated channels and allows ions to pass. As a consequence, the polarity of the postsynaptic membrane shifts, and an electric signal is sent across the synapse.
Chemical synapses are cell connections that allow neurotransmitters to convey nerve impulses in one direction. Chemical synapses are connections formed by two neurons or a neuron and a nonneuronal cell. The synaptic complex is the fundamental non-reducible unit of each chemical synapse, representing the bare minimum for effective chemical synaptic transmission. It is made up of three parts: a presynaptic element, a synaptic cleft, and a postsynaptic element. When an action potential is sensed at the terminal of the presynaptic membrane, the voltage-gated calcium channels of the presynaptic membrane open. These neurotransmitters pass across the synaptic cleft and bind to postsynaptic membrane receptors. They cause an action potential to be produced on the membrane of the postsynaptic neuron. Signal transduction at chemical synapses, as the name indicates, includes the translation of electrical impulses arriving at the presynaptic bouton into chemical signals seen by the postsynaptic cell. These chemical signals or substances, known as neurotransmitters, are released into the synaptic cleft by the presynaptic bouton and act to initiate a second electrical signal in the postsynaptic cell by binding to and opening postsynaptic ligand-gated ion channels known as neurotransmitter receptors, as discussed in detail below.
A single organism's nervous system has a massive number of chemical synapses. The central nervous system of an adult may include 1000 to 5000 trillion chemical synapses. This value varies with age. In general, the concentration of calcium ions in the synaptic cleft is 10-3 M, whereas the concentration within nerve cells is 10-7 M. Calcium ions are therefore transported from the synaptic cleft into the presynaptic neuron cell through calcium channels. This raises the calcium concentration inside the presynaptic nerve cell, enabling synaptic vesicles to fuse with the presynaptic membrane and exocytotic neurotransmitters into the synaptic cleft. They cause an action potential to be generated on the membrane of the postsynaptic neuron.
What is Electric Synapsis?
An electrical synapse is a cell connection between nerve cells that allows for the transmission of nerve impulses through ions. An electrical synapse has a tiny synaptic cleft, and the two plasma membranes of the neurons are joined by a gap junction. In an electrical synapse, the membranes of presynaptic and postsynaptic cells are linked by unique channels called gap junctions, which may pass an electric current and cause voltage changes in the presynaptic cell to induce voltage changes in the postsynaptic cell. Each channel pair forms a pore that is substantially larger than that of a normal ion channel. As a consequence, large molecules, in addition to ions, may travel across these gap junctions. In addition to the ions that carry this current, other molecules such as ATP may pass through the large gap junction pores. As a result, intracellular metabolites and second messengers may move between two neurons. In an electrical synapse, the presynaptic and postsynaptic neuron membranes come very near to each other and connect through a channel known as a gap junction. The signal, which is in the form of ionic current, then passes passively across the gap junction, permitting signal transmission. Connexons, which are protein channels, are used to produce gap junctions.
Connexons are protein tube-like structures that connect two neurons. Information is transferred between neurons through specialized junctions known as synapses. Neurons interact and employ primarily two channels in this synaptic space: the chemical synapse, where information is sent by releasing chemicals or neurotransmitters, and the electrical synapse. A neuron has a resting potential of -60 to -70 millivolts while at rest. This means that the cell's inside is negatively charged in comparison to the exterior. An electrical synapse allows action potentials to be sent in both directions. Furthermore, the pace of transmission of action potentials is very fast. Electrical synapses are primarily responsible for coordinating the activity of a set of neurons.
Electrical synapses connect neurons in the hypothalamus, allowing numerous neurons to fire action potentials at the same time. In addition to the ions that carry this current, another molecule such as ATP may pass through the large gap junction pores. Conversely, electrical synapses enable the action potential to be passively conveyed from one neuron to the next through the pores of the gap junctions. Electrical synapses are also required for rod and cone signal transmission and modulation in the retina. The retina changes the electrical connectivity between these AII amacrine cells depending on the intensity of light to balance the demands for sensitivity and spatial resolution in human vision. Electrical synapses provide a broader role by synchronizing electrical activity across groups of neurons. Electrical synapses, for example, link specific hormone-secreting neurons in the human hypothalamus.
Difference Between Chemical Synapse and Electric Synapse In Points
- Chemical and electrical synapses transfer messages in different ways: chemical synapses convey signals in the form of chemicals known as neurotransmitters, whilst electrical synapses send information in the form of electrical impulses without the need for chemicals. Chemical and electrical synapses have somewhat distinct architectures due to their diverse ways of action.
- Nerve impulses are transferred as a chemical signal through neurotransmitters at a chemical synapse, while nerve impulses are transmitted as an electrical signal via gap junctions or low resistance bridges at an electric synapse.
- Chemical synaptic knobs contain synaptic vesicles and a large number of mitochondria, while electrical synaptic knobs have no synaptic vesicles and just a few mitochondria.
- Chemoreceptors are found on the postsynaptic membrane of chemical synapses but not on the postsynaptic membrane of electrical synapses.
- Higher mammals have chemical synapses, while lesser vertebrates and invertebrates have electrical synapses.
- A chemical synapse only delivers signals in one direction, but an electrical synapse delivers messages in both directions.
- In a chemical synapse, the synaptic cleft is the larger gap between two neurons. Neurotransmitters go across the synaptic cleft to their target receptors. Two neurons are physically joined by gap junctions to form the electric synapse. As a consequence, the space between them is quite limited.
Conclusion
The two forms of gaps that arise between nerve cells are chemical synapses and electrical synapses. Synapses of both kinds send nerve impulses. Chemical synapses use neurotransmitters to convey nerve impulses. A synapse is a link between two neurons or a neuron and a target or effector cell, such as a muscle cell. It permits the transfer of electrical or chemical impulses. A synapse is created between presynaptic and postsynaptic neurons. The neuromuscular junction is the connection that links a neuron to a muscle. Although chemicals may enhance a signal, electrical signals are always the same or less following a synapse.
Chemical synapses and electrical synapses are the two types of gaps that occur between nerve cells. The chemical synapse has a bigger gap between two neurons, which is known as the synaptic cleft. Neurotransmitters diffuse across the synaptic cleft until they reach their appropriate receptors. The space is relatively tiny because two neurons in the electric synapse physically communicate with each other through gap junctions. Unlike chemical synapses, the function of an electrical synapse is determined by the relative voltage of the two cells linked, since it is essentially a hole connecting their cytoplasm. If cell A is hyperpolarized about cell B, it will inhibit it; if it is depolarized, it will stimulate it.’
References
- Synapse: Electrical and Chemical Synapse, Synaptic Polarization (collegedunia.com)
- Electrical Synapse - an overview | ScienceDirect Topics
- Chemical Synapse - an overview | ScienceDirect Topics
