Chapter 7

Chapter 7 - 8.24.11 Chapter 7 The Nervous System(slide...

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8.24.11 Chapter 7 : The Nervous System (slide 1) -neurons as a cell The Nervous System (slide 3) -Two divisions of the nervous system -Central Nervous System (CNS) -brain and spinal cord -Peripheral Nervous System (PNS) -nervous tissue lying outside of brain and spinal cord -Overall structure of the CNS -7 major parts of the CNS -cerebral hemisphere (big brain), diencephalon (thalamus and hypothalamus), midbrain, pons, medulla oblongata, cerebellum (little brain), spinal cord -3 broad regions of the brain -forebrain, midbrain, hindbrain -Two cell types of the nervous system -glia (support cells) -neurons (basic functional unit of the nervous system) Anatomy of a Neuron (slide 4) -typical motor neuron -cell body/soma with nucleus -dendrites (finger like structures projecting from cell body, receives information) -axon hillock (deciding point, how many/frequent to fire off action potentials) -axon (impulses get out of neuron, direction of conduction) -myelin sheath (insulation for axon to conduct action potentials more quickly) Terminology (slide 5) -**Table 7.1 -CNS = brain and spinal cord -PNS = all nervous tissue outside of CNS -Functional classes of neurons -Aff erent neurons = sensory neurons -towards CNS, aff = towards -Eff erent neurons = motor neurons -eff = away, from CNS into PNS -somatic motor neurons (voluntary skeletal muscle movements) -autonomic motor neurons (involuntary muscle movements) -Inter neurons -inter= between, handle communication between neurons -most of the neurons -Nuclei (CNS) vs. ganglia (PNS) -“Fibers”: tracts (CNS) vs. nerves (PNS) (slide 6) -CNS (left) -PNS (right): anything outside of CNS
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-CNS and PNS anatomical distinctions -there are neurons that exist in both parts -somatic motor neuron: cell body in CNS and axon in PNS Morphological Classes of Neurons (slide 7) -identify them based on structure -names based on number of processes - pseudounipolar -only one (uni) -very quickly splits into dendrite and axon (pseudo) - bipolar -two processes (bi) -one is a dendrite and one is an axon -retina - multipolar -many dendrites, single axon -will see the most Supporting Cells: Glia (slide 9) -CNS glia - ependymal (specialized epithelial cells) -within lined ventricles of brain - microglia -scavenger, anti-inflammatory - astrocyte -looks like a star - oligodendrocyte -not as many processes Predominant Glia of Vertebrates (slide 10) -Astrocytes (CNS) -most abundant type of glial cell -mulitple functions via end-feet on capillaries & neurons - largely mediated by processes that are sent out -Oligodendroctyes (CNS) -function: insulation of central axons -one oligodendrocyte per ~15 internodes -don’t have to be on same axon -myelin sheath (“white matter”) -gray bodies is mostly composed of cell bodies -Schwann cells (PNS) -function: insulation of peripheral axons -one Schwann cell per internode -“Neurilemma” vs. “myelin sheath” Astrocytic Functions (slide 11) -yellow: top is presynaptic cell releases neurotransmitters, bottom is postsynaptic cell -glucose uptake from blood; lactate delivery to neurons -K + re-uptake -astrocytes will take up extra potassium
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Chapter 7 - 8.24.11 Chapter 7 The Nervous System(slide...

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