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Nervous Tissue with px~(2008)

Nervous Tissue with px~(2008) - Nerve Tissue and the...

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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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