Nervous Tissue with px~(2008)

Nervous Tissue with - Nerve Tissue and the Nervous System Chapter 12 pages 318-363 1 Nervous System network of 10 billion nerve cells grouped in

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Nerve Tissue and the Nervous System : Chapter 12; pages 318-363 1. Nervous System: network of 10 billion nerve cells grouped in circuits. Irritability, conductivity. Cannot divide. Rapid response to external stimuli; regulates the function of internal organs. a. Central Nervous System: brain and spinal cord b. Peripheral Nervous System: cranial and spinal nerves, ganglia, and motor and sensory nerve endings 2. Embryology of nervous system: Figure 5.37, page 136. Neuroectoderm 3. Composition of nervous tissue a. nerve cell – functional unit of the nervous system b. supporting cells- non-conducting cells that are in intimate physical contact with neurons. 4. Neurons: reception, transmission, processing of stimuli; trigger certain cell activities; release of neurotransmitters.
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a. Neuron Anatomy: Figure 12.1, page 320 (1) Dendrite: direct extension of perikaryon; Nissl bodies; free ribosomes an occasional Golgi; gemmules (projections which act as synaptic sites) (2) Perikaryon, cell body or soma: trophic center; 5-150 micrometers in dia.; may receive stimuli aa. Nucleus: Large (up to 20 micrometers), central, euchromatic; prominent nucleolus bb. Organelles: axolemma; mitochondria (small and ovoid), Golgi complex (large and perinuclear); primary and secondary lysosomes; Nissl bodies (stacks of RER); neurofibrils (microtubules and neurofilaments) (3) Axon: single process; 1-20 micrometer in dia.; axon hillock which contains no nissl; lack RER; lacks Golgi; smooth exterior; proteins are product of perikaryon; contains mitochondria and neurofibrils; axonal transport of newly synthesized molecules (antegrade and retrograde transport) aa. Terminal arborization: distal and usually branched 1. End bulbs or boutons: terminal dilations bb. Synapse: may be chemical or electrical; transmission of stimulusto next cell; unidirectional; neurotransmitters. The components of the chemical synapse include: 1. Presynaptic component: formed by axon terminal
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2. Postsynaptic component: a part of another cell where new impulse is generated; receptors for neurotransmitters. 3. Synaptic cleft: intercellular space between pre- and post-synaptic membrane; 20-30 nm space 4. Axosomatic synapse: Figure 12.6, page 325; axon with cell body 5. Axodendritic synapse: axon with dentrite 6. Axoaxonic synapse: axon with axon 7. Dendrodendritic synapse: dendrite with dendrite 8. Chemical synapse: nerve impulse transmitted by neurotransmitters from pre-synaptic neuron to post-synaptic neuron/or effector, requires receptors; includes acetylcholine, norepinephrine, and serotonin. Produced by perikaryon and stored in vesicles in presynaptic region. Depolarization of membrane at the bouton causes voltage-gated calcium gates to open with an influx of calcium into the cell – the result is the fusion of vesicles with the pre-synaptic membrane and the release of neurotransmitter. Neurotransmitter is removed by enzymatic breakdown, diffusion or endocytosis by presynaptic membrane. Extra membranes recycled into membrane
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This note was uploaded on 04/21/2008 for the course BIOL 101 taught by Professor Kilgen during the Spring '08 term at Nicholls State.

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Nervous Tissue with - Nerve Tissue and the Nervous System Chapter 12 pages 318-363 1 Nervous System network of 10 billion nerve cells grouped in

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