What is end plate neuromuscular junction?
Neuromuscular junctions, also called motor end plates, are specialised chemical synapses formed at the sites where the terminal branches of the axon of a motor neuron contact a target muscle cell. It contains multiple mitochondria and synaptic vesicles where the transmitter acetylcholine is stored.
What is the role of the neuromuscular end plate?
The endplate depolarization by the released acetylcholine is called an endplate potential (EPP). The endplate potential is thus responsible for setting up an action potential in the muscle fiber which triggers muscle contraction.
What is motor endplate?
The specialized postsynaptic region of a muscle cell. The motor endplate is immediately across the synaptic cleft from the presynaptic axon terminal. Among its anatomical specializations are junctional folds which harbor a high density of cholinergic receptors.
What is endplate depolarization?
Depolarization of the motor end plate occurs when both receptors bind acetylcholine, causing a conformational change in the channel complex, opening it to the inward flow of positive ions (Figure 19-2).
What are the steps of neuromuscular transmission?
Neuromuscular transmission may be divided into three processes: (1) presynaptic terminal depolarization and ACH release; (2) ACH binding and ion channel opening; and (3) postsynaptic membrane depolarization and muscle action potential generation.
What channels are in the motor end plate?
There are two types of ion channels involved in the neuromuscular junction and end plate potentials: voltage-gated ion channel and ligand-gated ion channel. Voltage gated ion channels are responsive to changes in membrane voltage which cause the voltage gated ion channel to open and allows certain ions to pass through.
Why is the motor end plate folded?
The motor end-plate has folds in the sarcolemma, called junctional folds, that create a large surface area for the neurotransmitter to bind to receptors.
What is motor end plate fatigue?
In nervous system disease: Motor end plate. Where fatigue and weakness are the symptoms, the underlying cause of disease may be a failure of motor nerve impulses to cross to the muscle end plate at the neuromuscular junction.
What increases neuromuscular transmission?
Neuromuscular transmission depends on a high concentration of acetylcholine receptors (AChRs) in the muscle membrane close to the sites of ACh release from the nerve. Whereas fetal fibers express AChR genes as part of their developmental program, AChR expression in the adult is suppressed by muscle activity.
What is neuromuscular transmission failure?
Definition. Neuromuscular transmission depends on the release of acetylcholine from synaptic vesicles that are stored in the terminal boutons of the motor nerve axon (Fig. However, if there is a an abnormally low end plate potential amplitude, failure of neuromuscular transmission may occur.
How do neuromuscular junctions work?
Neuromuscular junction, also called myoneural junction, site of chemical communication between a nerve fibre and a muscle cell. Upon stimulation by a nerve impulse, the terminal releases the chemical neurotransmitter acetylcholine from synaptic vesicles. …
Which is part of the neuromuscular junction is the motor end plate?
The part of the muscle fiber that is connected or interacts with the motor neuron in the neuromuscular junction is called the motor end plate. There are 3 parts of the neuromuscular junction. They are the presynaptic neuron (motor neuron), synaptic cleft and the motor end plate. Let us discuss all of them.
What causes muscle contraction in the motor end plate?
Muscle contraction occurs when motor nerve terminal impulse reaches a nerve ending, which in turn releases acetylcholine across the neuromuscular gap to the muscle signaling muscle contraction. Botulinum toxin blocks acetylcholine release. This blocking of acetylcholine occurs as a four-step process (Fig. 24-6 ).
What are the proteins in the motor end plate?
These muscles are rich in mitochondria and contain a (red) heme protein that helps bind and store oxygen.
What are the subneural clefts of the motor end plate?
Subneural clefts: Subneural clefts are also known as palisades or sub neutral apparatus or secondary synaptic clefts. They are the many folding of the sarcolemma membrane. They increase the surface area of the motor end plate.