Signalling at the Nerve-Muscle Synapse Flashcards
What does the stimulation of indirect ion-gate channels produce?
Second messengers, which are small, freely diffusible, intracellular metabolies such as cAMP or diacylglycerol
What do most second messangers activate?
Most second messengers activate protein kinases, which are enzymes that phosphorylate different substrate proteins.
Where does the motor neuron innervate at a muscle?
The motor neuron innervates the muscle at a specialized region of the muscle membrane called the endplate, where the motor axon loses its myelin sheath and splits into several fine branches
What is the function of acetylcholinesterase, and where is it located?
Acetylcholinesterase rapidly hydrolizes acetylcholine and is anchored to the collagen fibrils of the basal laminae
What is a nicotinic acetylcholine receptor and what is its function?
A nicotinic acetylcholine receptor is an integral membrane protein that booth binds acetylcholine and forms an ion channel
What is an excitatory postsynaptic potential?
An excitatory postsynaptic potential is the release of transmitter from the motor nerve terminal opening of acetylcholine receptor-channels in the muscle membrane at the endplate, and this action rapidly depolarizes the membrane
Why is an inward current confined to the endplate?
An inward current is confined to the endplate because the acetylcholine receptor-channels are concentrated there, opposite the presynaptic terminal from which transmitter is released.
What is the time course of an endplate current determined by?
The time course of an endplate current is directly determined by the rapid opening and closing of the acetylcholine receptor-channels.
