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Unformatted text preview: NERVOUS SYSTEM
Neurophysiology Functions of the Nervous System Sensory function: detect internal and external stimuli Various type of receptors Integrative function: interpretation of sensory input Motor function: respond to stimuli by activating effectors Effectors = muscles, glands Organization of the Nervous System Central Nervous System Brain Spinal cord Integration of input to determine appropriate output Peripheral Nervous System Sensory (Afferent) neurons provide input to CNS from receptors Efferent (Motor) neurons provide output from CNS to effectors Efferent Neurons Somatic: CNS Skeletal muscle Autonomic: CNS Smooth muscle Cardiac muscle Glands Autonomic Neurons Sympathetic "Fight or Flight" Parasympathetic "Resting and Digesting" Organization of neurons differs May differ in chemical signal (neurotransmitter) Most effectors are innervated by both Antagonistic control (Enteric NS) Neurons in the wall of the digestive tract Mostly controlled by autonomic division Controls glands + smooth muscle Some autonomy in controlling local digestive functions Figure 8-1 Nervous Tissue
2 cell types: Neurons excitable cells
Transmit electrical signals Long-lived, amitotic, and have a high metabolic rate Neuroglia or glial cells - supporting cells
Different types in CNS and PNS Do NOT conduct electrical impulses Mitotic Figure 8-3e Neuron Structure Cell body, Dendrites, Axon Cell body (soma) Nucleus + typical organelles (no centrioles = amitotic) Dendrites Highly branched processes Receptive regions Conduct electrical signals (graded potentials) toward the cell body Axons Slender processes, arise from axon hillock Variation: <1" to 3-4 feet Nerve fibers Axonal terminals branched distal ends containing synaptic vesicles (chemicals stored here) Generate and transmit action potentials away from cell body Figure 8-3e Terms reflecting organization of neurons Collection of cell bodies CNS nucleus PNS ganglion Collection of axons CNS tract PNS - nerve Functional Classification of Neurons Sensory (afferent) Receptors to CNS Motor (efferent) CNS to effectors Interneurons (association neurons) Sensory to motor neurons (within CNS) Structural Classification of Neurons Multipolar -- 3+ processes Many dendrites, one axon Bipolar -- 2 processes One dendrite, one axon Unipolar -- 1 process (divided) Figure 8-3 - Overview Figure 8-5 (3 of 3) Neuroglia (CNS) Astrocytes Support and brace neurons (foot processes) Anchor neurons to t...
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This note was uploaded on 04/29/2009 for the course BIOL 425 taught by Professor Tondi during the Fall '08 term at George Mason.
- Fall '08