BIOL 121 Lecture Notes - Lecture 23: Motor Neuron, Nicotinic Acetylcholine Receptor, Foodborne Illness
Document Summary
The smallest functional unit of muscle contraction. 1 somatic motor neuron and all of its fibers is innervates. Each motor neuron innervates 10 to several thousand fibers. An ap in a motor neuron will excite every fiber within the motor unit. The synapse between somatic motor neuron axon terminals and the motor end plate region on the sarcolemma (muscle membrane) Surface area of synapse is very large. Ap in motor neuron leads to ach release at nmj. Ach binds to nicotinic receptors, opening cation channels. If na influx depolarizes motor end plate to threshold, an ap is triggered. Ap propagates along membrane and down t-tubules. Single ap in a motor neuron will cause an ap in each and every fiber within its motor unit. Binds to but doesn"t activate nicotinic receptors. Doesn"t let ach bind to nicotinic receptor. Lead to death due to paralysis of breathing muscles. Muscle becomes paralyzed because the membrane cant become repolarized.
