BIO 110 Ch 41 Notes.docx - BIO 110 Chapter 41 Neuroscience l Cells of the Nervous System Nervous System Central nervous system(CNS brain and spinal cord

BIO 110 Ch 41 Notes.docx - BIO 110 Chapter 41 Neuroscience...

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BIO 110 Chapter 41 Neuroscience l: Cells of the Nervous System Nervous System Central nervous system (CNS) – brain and spinal cord Peripheral nervous system (PNS) – all neurons and projections of their plasma membranes that are outside of the CNS In certain invertebrates with a simple nervous system, the distinction is not clear or not present Neurons and glial cells don’t divide Types of Cells Neurons Cells in the nervous system that send and receive electrical and chemical signals to and from other neurons throughout the body All animals except sponges have neurons Number varies widely as a function of size and behavioral complexity Neuron Structure (fig. 41.2) Cell body (or soma) – contains nucleus and organelles Dendrites – Extensions of plasma membrane o Receive signals o May be single or branching Axons – Extensions of plasma membrane (long tail) o Typically single o Send outgoing signals o Axon Hillock near cell body o Terminal branches or nerve terminal at far end 3 Types of Neurons (fig, 41.3) Sensory neurons (afferent) – transmit signals to CNS Motor neurons (efferent) – send signals away from CNS Interneurons – form complex interconnections between other neurons Glia Perform various support functions 10 – 100 times more numerous than neurons Oligodendrocytes (CNS) and Schwann cells (PNS) make myelin sheath Astrocytes – metabolic support and blood brain barrier Microglia – remove cellular debris
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Radial glia – form tracks for neuronal migration in embryos Astrocytes and radial glia function as stem cells to produce more glial cells and neurons Reflex Arc (fig. 41.4) Stimulus from sensory neurons sent to CNS, little or no interpretation, signal transmitted to motor neurons to elicit response Electrical Properties Membrane potential – difference in charge inside and outside the cell o Plasma membrane barrier separating charges o Ion concentrations differ between the inside and outside of the cell o Polarized
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