what is the structure and function of the neuromuscular junction
Neuromuscular junction A neuromuscular junction (or myoneural junction) is a chemical synapse formed by the contact between a motor neuron and a muscle fiber.[1] It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.
Neuromuscular junction Acetylcholine is a neurotransmitter synthesized from dietary choline and acetyl-CoA (ACoA), and is involved in the stimulation of muscle tissue in vertebrates as well as in some invertebrate animals. In vertebrate animals, the acetylcholine receptor subtype that is found at the neuromuscular junction of skeletal muscles is the nicotinic acetylcholine receptor (nAChR), which is a ligand-gated ion channel. Each subunit of this receptor has a characteristic "cys-loop", which is composed of a cysteine residue followed by 13 amino acid residues and another cysteine residue. The two cysteine residues form a disulfide linkage which results in the "cys-loop" receptor that is capable of binding acetylcholine and other ligands. These cys-loop receptors are found only in eukaryotes, but prokaryotes possess ACh receptors with similar properties.[3] Not all species use a cholinergic neuromuscular junction; e.g. crayfish and fruit flies have a glutamatergic neuromuscular junction.[2]
Neuromuscular junction The neuromuscular junction is where a neuron activates a muscle to contract. Upon the arrival of an action potential at the presynaptic neuron terminal, voltage-dependent calcium channels open and Ca2+ ions flow from the extracellular fluid into the presynaptic neuron's cytosol. This influx of Ca2+ causes neurotransmitter-containing vesicles to dock and fuse to the presynaptic neuron's cell membrane through SNARE proteins. Fusion of the vesicular membrane with the presynaptic cell membrane results in the emptying of the vesicle's contents (acetylcholine) into the synaptic cleft, a process known as exocytosis. Acetylcholine diffuses into the synaptic cleft and can bind to the nicotinic acetylcholine receptors on the motor endplate.
Thalamus It is a midline symmetrical structure of two halves, within the vertebrate brain, situated between the cerebral cortex and the midbrain.