Chapter 3: The Biological Bases of Behavior Communication in the Nervous System Glia ? structural support and insulation Neurons ? communication Soma ? cell body Dendrites ? receive Axon ? transmit away Myelin sheath ? speeds up transmission Terminal Button ? end of axon; secretes neurotransmitters Neurotransmitters ? chemical messengers Figure 3.1 Structure of the neuron The Neuron at Rest Hodgkin & Huxley (1952) - giant squid Fluids inside and outside neuron Electrically charged particles (ions) Neuron at rest ? negative charge on inside compared to outside -70 millivolts ? resting potential The Action Potential Stimulation causes cell membrane to open briefly Positively charged sodium ions flow in Shift in electrical charge travels along neuron The Action Potential