Biological Psychology: Cells of the Nervous System

Anatomy of Neurons

External Features of Neuron * Cell Membrane: the semipermeable membrane that encloses the neuron * Cell Body: the metabolic center of the neuron; aka soma * Dendrites: the short processes emanating from the cell body, which receive most of the synaptic contacts from other neurons * Axon Hillock: the cone-shaped region at the junction between the axon and cell body * always singular * Axon: the long, narrow process that projects from the cell body * an axon always starts at the axon hillock * Myelin: the fatty insulation around many axons * insulation, protection; speeds up transmission or transfer of impulses (most important feature) * Nodes of Ranvier: gaps between sections of myelin * Terminal Buttons or Buttons: the buttonlike endings of the axon branches, which release chemicals into synapses * Synapses or Synaptic Gap or Cleft: the gaps between adjacent neurons across which chemical signals are transmitted
Internal Features of a Neuron * Mitochondria: sites of aerobic (oxygen-consuming) energy release; powerhouse * Nucleus: the spherical DNA-containing structure of the cell body * Endoplasmic Reticulum: a system of folded membranes in the cell body; rough portions (those with ribosomes) play a role in the synthesis of proteins; smooth portions (those without ribosomes) playa 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 * Endoplasmic Reticulum vs Golgi Complex: * Endoplasmic Reticulum: synthesize protein * Golgi Complex: smooth; packaging * Microtubules: tubules responsible for the rapid transport of material throughout neurons * transport of substances and nutrients happen * Synaptic Vesicles: spherical membrane packages that store neurotransmitter molecules ready for release near synapses * Neurotransmitters: molecules that are released from active neurons and influence the activity of other cells
Cell Membrane * The ^^cell membrane^^ is a lipid bilayer with signal proteins and channel proteins embedded in it * Lipid Bilayer: 2 layers of fat molecules * embedded are numerous protein molecules that are the basis of many of the cell membranes functional properties * Channel Proteins: through which certain molecules can pass * 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 * Unipolar Neuron: a neuron with one process extending from its cell body * cell body is smooth * Bipolar Neuron: a neuron with 2 processes extending from its cell body * Multipolar Neuron: a neuron with more than 2 processes extending from its cell body * one axon multiple dendrites; can receive or send out efferent axon away; away from axon (going out the neuron); motor or afferent to the neuron; sensory = accept; sensory * Multipolar Interneuron: neurons with a short axon or no axon at all * function is to integrate neural activity within a single brain structure, not to conduct signals from one structure to another * in between 2 other neurons; serves to conduct impulses through another neuron without the use of axon * Neurons and Neuroanatomical Structure * Nuclei (singular = nucleus): clusters of cell bodies in the central nervous system * Ganglia (singular = ganglion): clusters of cell bodies in the peripheral nervous system * Tracts: bundles of axons in the central nervous system * Nerves: bundles of axons in the peripheral nervous system

Glia: The Forgotten Cells

Glia: most common type of cells in the nervous system
Major Types of Glia * Oligodendrocytes: glial cells with extensions that around the axons of some neurons of the central nervous system * extensions are rich in myelin, a fatty insulating substance, and the myelin sheaths they form increase the speed and efficiency of axonal conduction * “cake roll” * Schwann Cells: similar function as oligodendrocytes in the peripheral nervous system * only Schwann cells can guide axonal regeneration (regrowth) after damage * “sandwich”
Major Types of Glia * Microglia: smaller than other glial cells * respond to injury or disease by multiplying, engulfing cellular debris or even entire cells, and triggering inflammatory responses * have immune system-like responsibilities in the brain, and they play a role in the regulating of cell death, synapse formation, and synapse elimination * rehabs the cell until cells are fully functional * Astroglia: largest of the glial cells; support and provide nourishment for neurons and form part of the blood-brain barrier * have the ability to contract or relax blood vessels throughout the brain * establish and maintain connections between neurons