UT Arlington BIOL 1334 - Lecture 9 - Nervous System (39 pages)

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Lecture 9 - Nervous System



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Lecture 9 - Nervous System

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Pages:
39
School:
University of Texas at Arlington
Course:
Biol 1334 - Introduction to Biology Ii
Introduction to Biology Ii Documents

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Biology 003 Organisms in Their Environment Lecture 9 Nervous System NERVOUS SYSTEM STRUCTURE AND FUNCTION 2012 Pearson Education Inc Figure 28 1A Sensory input Integration Sensory receptor Motor output Brain and spinal cord Muscle cells Peripheral nervous system PNS Central nervous system CNS Neurons are the functional units of the nervous system Neurons are cells specialized for carrying signals the functional units of the nervous system A neuron consists of a cell body and two types of extensions fibers that conduct signals dendrites axons Figure 28 2 Signal direction Cell body Nucleus Nodes of Ranvier Myelin sheath Dendrites Cell body Schwann cell Signal pathway Node of Ranvier Layers of myelin Synaptic terminals Nucleus Axon Schwann cell Nervous systems receive sensory input interpret it and send out appropriate commands The central nervous system CNS consists of the brain spinal cord vertebrates The peripheral nervous system PNS is located outside the CNS consists of nerves bundles of neurons wrapped in connective tissue and ganglia clusters of neuron cell bodies The nervous system receives sensory input interprets it and sends out appropriate commands Sensory neurons convey signals from sensory receptors to the CNS Interneurons are located entirely in the CNS integrate information and send it to motor neurons Motor neurons convey signals to muscle cells Figure 28 1B 1 Sensory receptor 2 Sensory neuron Brain Ganglion Motor neuron Spinal cord 3 Quadriceps muscles 4 Interneuron Flexor muscles Nerve PNS The knee jerk reflex CNS NERVE SIGNALS AND THEIR TRANSMISSION Nerve function depends on charge differences across neuron membranes At rest a neuron s plasma membrane has potential energy the membrane potential in which just inside the cell is slightly negative and just outside the cell is slightly positive The resting potential is the voltage across the plasma membrane of a resting neuron Ion atom with an electric charge due to the loss or gain of electrons e e g a



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