Brain Bee Study Guide Official

You are about to initiate movement. The EPSP travels down your dendrites, summing at the axon hillock — your decision zone. Here, voltage-gated sodium channels wait. The membrane potential crosses threshold (-55 mV from resting -70 mV). Bang.

Your action potential speeds down your (courtesy of oligodendrocytes in the CNS). The myelin sheaths are interrupted by Nodes of Ranvier , where saltatory conduction leaps the signal from node to node — much faster than unmyelinated axons. Step 2: The Synapse You arrive at the presynaptic terminal . Depolarization opens voltage-gated calcium channels (VGCCs) . Calcium rushes in. This triggers synaptic vesicles — loaded with glutamate — to dock at the active zone via SNARE proteins (synaptobrevin on vesicle, syntaxin and SNAP-25 on membrane). brain bee study guide

The muscle fiber fires an action potential. on the T-tubule sense the voltage change and mechanically open ryanodine receptors (RyRs) on the sarcoplasmic reticulum. Calcium floods the cytosol. You are about to initiate movement

At the NMJ, the enzyme — sitting on the basal lamina — rapidly cleaves ACh into acetate and choline. Choline is taken back up into the LMN via the choline transporter (CHT1) , then reused. The membrane potential crosses threshold (-55 mV from