Chapter 44 - Chapter 44: Neurons and Nervous System I....

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Chapter 44: Neurons and Nervous System I. Nerve Cells a. Neurons i. Excitable ii. Carry nerve impulses (action potentials) iii. Nodes of Ranvier – space between myelinated parts of axons 1. Clusters of voltage-gated ion channels 2. Fire APs only at nodes, but don’t travel into myelin covered membrane a. Instead + charges flowing in at node travel down axon b. Current gets to next node and another AP fired 3. Saltatory conduction a. Rapid impulse spreading b. Glia i. Support neurons 1. Physically 2. Immunologically 3. Metabolically ii. Orient neurons iii. Supply w/nutrients iv. Maintain extracellular homeostasis v. Eat foreign objects vi. Insulate axons vii.CNS = oligodendrocytes viii. PNS = Schwann cells ix. Myelin – white 1. APs faster with myelin bc less ions leak out 2. Faster bc current faster in cytoplasm, not channels x. Astrocytes 1. Surround smallest/most permeable blood vessels in brain 2. Help blood-brain barrier from toxins c. Nerve = bundle of axons II. Types of Neurons a. Afferent i. Sensory info (APs) into nervous system 1. From sensory neurons b. Efferent i. Carry commands to effectors (muscles) c. Interneurons i. Regulate info between sensors and effectors III. Networks a. Clusters of neurons = ganglia i. Largest = brain b. CNS – spinal cord/brain c. PNS – branches off CNS
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IV.Structure of neuron a. Cell body i. Nucleus b. Dendrites – off cell body i. Bring info to cell body c. Axon i. Carry info (APs) away from cell body d. Axon terminal i. Synapse w/ target cell
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This note was uploaded on 01/27/2011 for the course BIOSC 0150 taught by Professor Lydiadaniels during the Fall '08 term at Pittsburgh.

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Chapter 44 - Chapter 44: Neurons and Nervous System I....

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