role in the synthesis of proteins; smooth portions (those without ribosomes) play a role in the synthesis of fats  Cytoplasm: the clear internal fluid of the cell  Ribosomes: internal cellular structures on which proteins are synthesized; they are located on the endoplasmic reticulum  Golgi complex: a connected system of membranes that packages molecules in vesicles  Microtubules: tubules responsible for the rapid transport of material throughout neurons  In the buttons: o Synaptic vesicles: spherical membrane packages that store neurotransmitter molecules ready for release near synapses o Neurotransmitters: molecules that are released from active neurons and influence the activity of other cells Neuron cell membrane  Composed of a lipid bilayer, or two layers of fat molecules  Protein molecules: o Embedded in the lipid bilayer o Basis of many of the cell membrane’s functional properties o Channel proteins: certain molecules can pass o Signal proteins: transfer a signal to the inside of the neuron when particular molecules bind to them on the outside of the membrane Classes of neurons  Multipolar neuron: a neuron with more than two processes extending from its cell body o Most neurons are multipolar  Unipolar neuron: a neuron with one process extending from its cell body  Bipolar neuron: a neuron with two processes extending from its cell body  Interneurons: neurons with a short axon or no axon o Their function is to integrate the neural activity within a single brain structure, not to conduct signals from one structure to another Neurons and neuroanatomical structure  Two kinds of gross neural structures: o Those composed primarily of cell bodies o Those composed primarily of axons  In the central nervous system o Nuclei: clusters of cell bodies  2 different neuroanatomical meanings o Tracts: bundle of axons

 In the peripheral nervous system o Ganglia: clusters of cell body o Nerves: bundles of axons Glial cells  Oligodendrocytes o Glial cells with extensions that wrap around the axons of some neurons of the central nervous system o Extensions are rich in myelin  The myelin sheaths they form increase the speed and efficiency of axonal conduction  Several myelin segments, often on more than one axon  Schwann cells o Similar function to the oligodendrocytes, but in the PNS o One myelin segment o Only schwann cells can guide axonal regeneration (regrowth) after damage  This is why effective axonal regeneration in the mammalian nervous system is restricted to the PNS  Microglia o Smaller than other glial cells o