Question

How do impulses travel across a synapse?

Answer 1

Hint: Conduction and transmission of a nerve impulse across a synapse take place with the help of two types of synapses they are electrical synapses and chemical synapses. It also involves a chemical substance called acetylcholine.

Complete answer:
The theory of synaptic transmission states that a chemical substance called acetylcholine is liberated at the synapse and it diffuses through the synaptic transmission occurs in the following way:

-When the nerve impulse passes through the first axon and reaches the dendrites at the end of the axon, chemical messengers called neurotransmitters are released.
-Neurotransmitters travel through the synapse between the axon and the dendrite of the next neuron and bind to the dendrite membrane.
-The Diffusion of this chemical substance, acetylcholine crosses the synaptic cleft.
-These chemicals diffuse across the synapse which is the gap between the two neurons. Chemicals bind to receptor molecules on the membrane of the second neuron.
-The receptor molecules on the second neuron can only bind to the specific neurotransmitters released from the first neuron.
-The binding of the neurotransmitter to the receptors stimulates the second neuron to transmit an electrical impulse along its axon. In this way, the signal has been carried from one neuron to the next neuron along the synapse.

Additional information:
The nerve impulse is the electrical signal that passes through the dendrites to produce a nerve impulse or an action potential. The action potential is due to the movement of ions in and out of the cell. Specifically, it includes sodium and potassium ions. They are moved in and out of the cell by the sodium and potassium channels and the sodium-potassium pump. Conduction of nerve impulses is due to the presence of active and electronic potentials along the conductors. The transmission of signals internally between cells is achieved via a synapse. Nerve conductors consist of relatively higher membrane resistance and low axial resistance. The electrical synapse is used in escape reflexes, the heart and the retina of vertebrates. They are primarily used if there is a need for rapid response and timing. Ionic currents pass through the two cell membranes as the action potential enters the stage of the synapse.

Note: Numerous small molecules synthesized in the axon terminal cytosol function as neurotransmitters in various chemical synapses. Neurotransmitters are stored in synaptic vesicles of uniform size, $$40-50$$ nm in diameter.