Physiology

2 Pages 405 Words

The neuromuscular junction is the synaptic connection between a nerve cell and a skeletal muscle cell. The neurotransmitter present at the neuromuscular junction is acetylcholine, a cholinergic neurotransmitter. Acetylcholine is released from the pre-synaptic membrane to traverse the synapse and bind to the nicotinic receptors which lie on the membrane of skeletal muscle cells. When the neurotransmitter acetylcholine binds post-synaptically, it elicits a post-synaptic potential. This post-synaptic potential can either cause an action potential or prevent an action potential. Thus one of two results of acetylcholine binding post-synaptically can take place: there can be an inhibitory post synaptic potential, where the resting membrane potential is hyperpolarized, thus inhibiting an action potential from occurring (as it causes greater negativity than already present), or an excitatory post synaptic potential, where the membrane is hypopolarized and brought closer (less negative) to firing level for an action potential to occur. Respectively, these post synaptic potentials are more commonly referred to as IPSP (inhibitory post synaptic potential) and EPSP (excitatory post synaptic potential). (Rhoades and Pflanzer, 3rd Edition c1996).


Methods:

In regards to muscle, we measured and recorded the distance between stimulating and recording electrodes with a ruler. Then we stimulated the extensor muscles of the forearm and recorded with our recording electrode from the dorsal side of the wrist on the side of the thumb. By using this setup, we could determine the conduction velocity of the extensor muscles by figuring out how long it took to elicit a compound action potential after the stimulus artifact was observed.
In regards to nerve, we once again measured the distance between the stimulating electrode and recording electrode with a centimeter ruler. This time though, we were stimulating the ulnar nerve at the elbow and...