Hockenbury Discovering Psychology 5th txtbk

46 CHAPTER 2 Neuroscience and Behaviorcell bodyProcesses nutrients and provides energy forthe neuron to function; contains the cell’snucleus; also called the soma.dendritesMultiple short fibers that extend from theneuron’s cell body and receive informationfrom other neurons or from sensory receptorcells.axonThe long, fluid-filled tube that carries aneuron’s messages to other body areas.Characteristics of the NeuronMost neurons have three basic components: a cell body, dendrites, and an axon (seeFigure 2.1). The cell body, also called the soma, contains structures that manu -facture proteins and process nutrients, providing the energy the neuron needs tofunction. The cell body also contains the nucleus, which in turn contains the cell’sgenetic material—twisted strands of DNA called chromosomes.Extending from the cell body are short, branching fibers, called dendrites. Theterm dendrite comes from a Greek word meaning “tree.” If you have a good imagination,the intricate branching of the dendrites does often resemble the branches of atree. Dendrites receive messages from other neurons or specialized cells. Dendriteswith many branches have a greater surface area, which increases the amount of informationthe neuron can receive. Some neurons have thousands of dendrites.The axon is a single, elongated tube that extends from the cell body in most,though not all, neurons. (Some neurons do not have axons.) Axons carry informationfrom the neuron to other cells in the body, including other neurons, glands, andmuscles. In contrast to the potentially large number of dendrites, a neuron has nomore than one axon exiting from the cell body. However, many axons havebranches near their tips that allow the neuron to communicate information to morethan one target.Cell bodyprocesses nutrients andprovides energy forneuronNucleuscontains chromosomesDendritesreceive information fromother neurons andsensory receptorsFigure 2.1 The Parts of a Typical NeuronThe drawing shows the location and functionof key parts of a neuron. The photograph,made with the aid of an electronmicroscope, reveals actual cell bodies, dendrites,and axons in a cluster of neurons.The green coloring was added to providecontrast in the photograph to make theneurons more visible.Myelin sheathinsulates axon and increasescommunication speedNodes of Ranvierare gaps in themyelin sheathAxoncarries informationto other neurons,muscles, and glands