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