Lecture 2

Lecture 2 - L2: Structure & Activity of the...

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Unformatted text preview: L2: Structure & Activity of the Nervous System 09/04/2007 19:00:00 jlambe@ucsd.edu Jackie Amy abissing@ucsd.edu Chapter 2 Brain cells: neurons and glia Neurons (100 billion) o Information processing units of nervous system o Communication with other cells Like other cells in the body, neurons contain the following structures: Membrane-separates the inside of the cell from the outside Nucleus-contains the chromosomes Mitochondria-perform metabolic activities Ribosomes-sites at which the cell synthesizes new protein molecules Distinctive features o Membrane Lipid bilayer with embedded proteins H2O, O2, CO2, urea pass freely across the membrane Elec. Charged or large molecules DO NOT (need ionic channels for K+, Na+, Cl-) Selectively permeable o Cell body (soma) contains nucleus with DNA o Dendrites INPUT structures Highly branched processes lined with synaptic receptors Receive chemical signals at synapses along length Dendritic spines contact points on dendrites, increase surface area for receiving chemical messages o Axon long process off soma, carries action potential (AP) Insulated with myelin sheath (some, not all) Transport material Nodes of Ranvier spaces between myelin sheath o Axon hillock at junction of axon and soma AP generate near here o Presynaptic terminal also terminal button end of axon, makes connections with other cells dentrites Releases neurotransmitter (NT) after AP o Synapse: presynaptic terminal gap/cleft, and dentrite Neurotransmitter across gap, contact post synaptic cell (dendrite) Types of neurons shape o Neurons are similar to other cells of the body but have a distinctive shape Motor neuron has its soma in the spinal cord and receives excitation from other neurons and conducts impulses along its axon to a muscle o Sensory neuron (at one end) connects to a receptor which highly sensitive to a particular type of stimulation (touch, temperature, odor, etc.) Bring info from receptors for external stimuli to the spinal cord and brain The Cells of the Nervous System o Terms used to describe neurons include the following Afferent axon (approach) refers to bringing information into a structure Efferent axon (exit) refers to carrying information away from a structure Interneurons or intrinsic neurons are those whose dendrites and axons are completely contained within a structure o Neurons vary in size, shape, and function The shape of a neuron determines its connections with other neurons The function is closely related to the shape...
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Lecture 2 - L2: Structure & Activity of the...

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