BIPN 105 Lecture Notes - Lecture 4: Alpha Motor Neuron, Neuromuscular Junction, Basal Lamina

• School: UCSD
• Department: Bioinformatics
• Course: BIPN 105
• Professor: Catalina Reyes Gonzalez

Document Summary

Chemical synapses: synaptic transmission, components of the synapse: presynaptic cell -> synaptic cleft (30 nm) -> postsynaptic cell, synaptic cleft filled with basal lamina: sponge-like with interstitial fluid, helping diffusion to occur. Non-viscous medium: neurotransmitters diffuse through synapse, neuromuscular junction: most well-known chemical synapse, a alpha motor neuron innervates skeletal muscle fiber. Has large surface area (folded) for more receptors. Steps of nmj transmission: action potential goes down axon of a alpha motor neuron, action potential depolarizes the membrane and signals p/q ca2+ channels to open, allowing ca2+ to enter. The ca2+ signals ach vesicles to fuse to membrane: ach released into synaptic cleft. Diffuses and bind to the receptors on motor end plate (2 per receptor), activating the ionotropic receptors. Channel opens and na+/k+ cross: na+ flows in and k+ exits. More na+ moves in due to higher driving force from membrane potential differences, creating an end plate potential (epp) (graded potential).