PSY 100 Lecture Notes - Voltage-Gated Potassium Channel, Potassium Channel, Retina
Document Summary
Voltage-gated means these channels open and then close when specific membrane potentials are reached. Threshold of excitation (-55 mv) is reached due to incoming signals. Na+ rushes into cell and depolarizes it until +40 mv is reached; na+ ion entry activates adjacent na+ channels to cause a domino effect down the axon. Na+ channels close, and voltage gated k+ channels slowly open and k+ leaves the cell and repolarizes it to -70 mv. Overshoot of k+ leaves cell transiently hyperpolarized and refractory (unresponsive) Resting state is then maintained by the na+/k+ pump until the next action potential. Axons of the presynaptic neuron end in numerous knob-like structures called terminal buttons (or synaptic terminals) These terminals store vesicles full of neurotransmitters (nt) Action potential initiates release of nt into synapse to act on receptors on the receiving dendrite of the postsynaptic neuron. Nts are cleared from the synapse in 3 ways to end postsynaptic activation.
