Question

Fill in the blanks with appropriate words.
The junction of two neurons is called .......... while the junction between a neuron and a muscle fiber is called a ..........

Answer 1

Hint: The junction between two neurons is a small gap present at the end of the neuron to help in signal transfer while the junction between a neuron and a muscle fiber is a chemical synapse between a motor neuron and a muscle fiber.

Complete answer:
The junction which is present between two neurons is called the synapse, on the other side the junction between a neuron and a muscle fiber is called a neuromuscular junction. A synapse is a structure in the nervous system that allows a nerve cell or neuron to pass an electrical or chemical signal to a different neuron or to the target effector cell. A neuromuscular junction which is also known as a myoneural junction is a chemical synapse that is present between a motor neuron and a muscle cell. It allows the motor neuron to transmit a type of signal to the muscle fiber, causing contraction.

Additional Information:
 Neuromuscular Junction- Synaptic transmission which occurs at the myoneural junction starts when a nerve impulse reaches the presynaptic terminal of an efferent neuron, which activates voltage-gated calcium channels to permit calcium ions to enter the neuron. Calcium ions bind to sensor proteins that are present on the synaptic vesicles, triggering vesicle fusion with the cell wall and subsequent neurotransmitter release from the efferent neuron into the synaptic cleft. It is seen that in vertebrates, motor neurons release the chemical acetylcholine, which is diffused across the synaptic cleft. After that it binds to nicotinic acetylcholine receptors on the cell wall of the muscle cell, also referred to as the sarcolemma. The binding of ACh to the receptor can depolarize the muscle cell, causing a cascade that eventually leads to contraction.
-Synapse- Synapses are very important for the functioning of the neuron. The neurons are the cells that are specialized to pass signals to individual target cells, and synapses are the means by which they are doing so. At a synapse, the cell wall of the signal-passing neuron comes into close opposition with the membrane of the target cell and the signals are transferred.

Note: Neuron is of two types on the basis of synapse i.e presynaptic and postsynaptic. At a chemical synapse, an action potential triggers the presynaptic neuron which further releases neurotransmitters. These molecules then bind to the receptors on the postsynaptic cell and create an action potential.