FoundationalConceptsNeuroscience

selection now had a solid physical foundation and could be described in molecular terms. An important factor here, regarding the ...

CHAPTER 5 How Neurons Generate Signals It was on a dreary night of November, that I beheld the accomplishment of my toils. With ...

air about electricity. Our description of the microscopic nature of neural signaling begins with a discussion of the electrical ...

However, the phospholipid bilayer membrane of a nerve cell, like all biological membranes, is studded with protein molecules of ...

Figure 5.1. Lipid bilayer membrane with channel proteins. Sodium and chlo- ride ions distributed in water cannot pass through th ...

N Ss 0 o o «i fF tl I I N N HO—F—O—P—O-F —0 O OH OH OH H OH OH Adenosine triphosphate For the Na/K pump, one molecule of ATP wil ...

outside of neuron Nat Cl Ca Kt inside of neuron cat Kt Figure 5.2. Relative ion concentrations inside and outside a nerve cell, ...

the cell. If we examine a small region near the outside of the nerve cell membrane and add up all the positive and negative char ...

Figure 5.3. Cell membrane with ion-channel proteins. Present throughout the nerve cell membrane are various ion-channel proteins ...

channels. If the channel is open, then specific ions can flow through from one side of the cell membrane to the other. Some ion ...

ing K or Cl channels in a nerve cell at rest produces a hyperpolariz- ing effect on the cell membrane, as shown by the graph in ...

ol Time (milliseconds) Membrane^ potential (mV) BR Figure 5.4. Hyperpolarization (left) may result from opening potassium chan- ...

happens unless a depolarization large enough to reach about -50 mV takes place. When this occurs, things change abruptly and dra ...

Shortly after their initial publication, Great Britain was drawn full tilt into World War II and both Hodgkin and Huxley devoted ...

of the cell, carrying positive charge with it. The outflow of K causes the membrane voltage to become less positive (Fig. 5.7). ...

Figure 5.7. Actions of voltage-gated ion channels during an action potential. To summarize the important concept of a voltage-ga ...

end of the axon without stopping. No new input of energy is required to power the propagation of the action potential along the ...

entry, it will trigger sodium channels to open only in the downstream direction. The upstream sodium channels will be in their r ...

Dendrites “ Axon terminals Figure 5.8. Location of the axon hillock. Nodes of Ranvier Axon hillock Figure 5.9. Neuron with myeli ...

HO Cholesterol Several types of protein are also found in myelin. One function of the proteins is to link layers together, so th ...