PSYC1101 Chapter Notes - Chapter 4: Enteric Nervous System, Peripheral Nervous System, Action Potential
Document Summary
The nerve impulse, or action potential, is a brief reversal in the electrical potential of the cell membrane from negative to positive as sodium ions from the surrounding fluid flow into the cell through sodium ion channels. The action potential obeys the all-or-none law, firing completely or not at all. The myelin sheath increases the speed of neural transmission. How neurons communicate: synaptic transmission: passage of the impulse across the synapse is mediated by chemical transmitter substances. Neurons are selective in the neurotransmitters that can stimulate them. Some neurotransmitters excite neurons, whereas others inhibit firing of the postsynaptic neuron. The nervous system requires a delicate balance of excitation and inhibition of neurons: psychoactive drugs such as caffeine, alcohol, nicotine and amphetamines produce their effects by either increasing or decreasing the action of neurotransmitters. Agonists can mimic or increase the action of neurotransmitters, whereas antagonists inhibit or decrease the action of neurotransmitters.
