Action potentials and synaptic transmission

This presentation will examine action potentials and synaptic transmission, with a focus on the factors establishing the neuron's resting membrane potential, and how this state enables rapid signaling. We'll explore the generation and propagation of action potentials, their key phases, and the role of myelination and refractory periods in signal transmission. Next, we'll discuss synaptic transmission, including neurotransmitter release and post synaptic integration of excitatory and inhibitory signals. Finally, we'll touch on how various drugs and diseases can affect each step of neural communication. Before a neuron can send signals, it sits at a resting membrane potential, typically around negative 70 millivolts. This state results from the interplay of ion gradients and selective permeability. There's more potassium inside and more sodium outside with the membrane more permeable to potassium at rest. The sodium potassium pump maintains these gradients, making the inside more negative. This polarization enables neurons to respond to stimuli and generate action potentials which form the basis of neural communication. An action potential is an all or none event triggered when the axon hillock reaches threshold voltage unfolding in key phases. First, depolarization occurs as voltage gated sodium channels open, letting sodium in and making the membrane more positive. At the peak, sodium channels close and potassium channels open, causing repolarization as potassium exits.