NS102 Lecture 4 review 10/10/06 seheekim Pseudounipolar neuron Increases velocity THE NEURON Cell Types Unipolar Bipolar Multipolar Psuedounipolar Golgi type I Golgi type II Axon trajectory and length # of projections From the soma n axo ing om Inc soma Trajectory and Length of Axon Golgi type I Golgi type II dendrites soma dendrites soma Gray Matter axon axon axon UNIPOLAR None in the vertebrate NS Nervous system Most frequent neuron in invertebrates Single axonal projection BIPOLAR Single dendritic projection Single axonal projection MULTIPOLAR Multiple dendritic projections Single axonal projection Golgi Type I &quot;long&quot; distance axon Axon leaves the gray matter and enters the white Golgi Type II &quot;short&quot; distance axon Axon does not enter the white matter Local circuit cells Important for higher cognitive activity PSEUDOUNIPOLAR Pain Touch Temperature C N S Central process THE NEURON Structure Endocellular Comonents Skeletal components Peripheral process Found primarily in the PNS Located in the sensory ganglia/ dorsal root ganglia Provide sensory input to spinal cord and brain stem 1 Receptacle for presynaptic input Presynaptic Terminals that end up on the spines are facilitatory Terminals that end up on the shaft are inhibitory DENDRITIC SPINES DENDRITE + DENDRITIC SPINES DENDRITE Schwann cells (PNS) and Oligos (CNS) lay down myelin in an outside-in manner Increases conductance Nodes of Ranvier are the periodic interruptions in the <a href="/keyword/myelin-sheath/" >myelin sheath</a> MITOCHONDRIA ENDOPLASMIC RETICULUM AXON HILLOCK MITOCHONDRIA ENDOPLASMIC RETICULUM AXON HILLOCK <a href="/keyword/myelin-sheath/" >myelin sheath</a> NODES OF RANVIER <a href="/keyword/myelin-sheath/" >myelin sheath</a> NODES OF RANVIER SYNAPTIC TERMINAL SYNAPTIC TERMINAL Some other structures... DENDRITIC SPINES DENDRITE Energy source for neuron SMOOTH ER lacks ribosomes so role is not in protein synthesis Calcium ion buffering/manipulation Lysosomes little bags of chemicals when released specifically break down or destroy components of the cytoplasm. MITOCHONDRIA ENDOPLASMIC RETICULUM AXON HILLOCK GOLGI BODIES Also a cisternal structure believed to be a derivative of smooth ER Packages the proteins made by the RER add glucose (glycosylation) Complex 3D maze of cisterns Outer lamina of the cisterns are lined with ribosomes These are the sites Synthesis of protein from RNA Ribosomes are rich in RNA and are scattered throughout soma <a href="/keyword/myelin-sheath/" >myelin sheath</a> NODES OF RANVIER Pigment granules SYNAPTIC TERMINAL DENDRITIC SPINES DENDRITE Point of emergence (axon from soma) Where propogating spike potential is generated SKELETAL COMPONENTS MICROTUBULES 25nm MITOCHONDRIA ENDOPLASMIC RETICULUM AXON HILLOCK NEUROFILAMENTS 10nm cytokeratins Most numerous of the skeletal components ALSO important in maintaining structure and shape MICROFILAMENTS 5nm actin Control placement and movement of proteins that float in the membrane Tubulin Important for axonal transport Maintains cell structure <a href="/keyword/myelin-sheath/" >myelin sheath</a> NODES OF RANVIER SYNAPTIC TERMINAL 2 SKELETAL COMPONENTS HOLE FILLER MICROTUBULES 25nm Tubulin Important for axonal transport Maintains cell structure ASTROCYTES Fill up holes in the nervous system and form a scar They are active synthesizers of glutamate help adjacent neurons (good!!) Epileptigenic (bad) D GLYCOGEN REPOSITORY K Neurons will call on glycogen reserve of astrocytes (glycogen is converted to glucose) Axonal transport occurs along surface of microtubules Powerful ATPases carry molecular masses along surfaces kinesin &amp; dynein SPONGE Sops up and absorbs extra glutamate and potassium in the environment MAINTAIN BLOOD BRAIN BARRIER ORTHOGRADE Fast (300mm/day) Kinesin system RETROGRADE Slow (1-2mm/day) Supported by dynein system &quot;sucker feet&quot; Maintain tight junctions of endothelial cells that line the capillaries Maintain tightness of the BB barrier OLIGODENDROCYTES Neuroglia 1. Astrocytes 2. Oligodendrocytes 3. Microglia Oligos in white matter Responsible for making white matter white! Laying down and maintenance of <a href="/keyword/myelin-sheath/" >myelin sheath</a> Oligos in gray matter physiological support for neurons OLIGODENDROCYTES Neuroglia NEURAL TUBE DERIVED 1. Astrocytes 2. Oligodendrocytes 3. Microglia MONOCYTE DERIVED Oligos in white matter Responsible for making white matter white! Laying down and maintenance of <a href="/keyword/myelin-sheath/" >myelin sheath</a> Oligos in gray matter physiological support for neurons CNS: oligodendrocytes NEURAL TUBE PNS: Schwann cells NEURAL CREST 3 MICROGLIA Derived from circulating white cells in the blood (monocytes) Sanitation Engineers of the nervous system Smallest and least abundant Part of the immune system of the CNS Engulf microorganisms of injured dead neurons plump up and become Gitter cells EPENDYMAL CELLS CILIA Single layer of cells that line the ventricles These cells are all that is left of the primitive neural epithelial cell mass METHODS...... NISSL Basic dyes Attracted to acidic components of nerve cells (DNA, RNA) Cellular type stain stains cell bodies GOLGI Silver Stain Exposure to chromates followed by exposure to silver Stains the nerve cell, its axons, dendrites... images the entire nerve cell It only stains ABOUT 2-3% of the cells in an area NAUTA Silver Stain Specific for degenerating axons 4