conductivity ability to rapidly produce electrical

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Unformatted text preview: ctivity, secretion • Excitability= ability to respond to changes (stimuli) ability to Neurons Neurons 3 physiological properties (cont.)• Conductivity= ability to rapidly produce electrical signals that ability reach distant cells reach • Secretion= ability to secrete neurotransmitter @ synapse to ability stimulate next cell stimulate 3 functional classes of neurons- sensory (afferent), sensory interneurons (association), motor (efferent) interneurons • Sensory= specialized to detect stimuli (light, heat, pressure, specialized chemicals) & transmit info to CNS chemicals) • Afferent= conduction towards CNS • Some receptors are neurons (pain, smell), other receptors send Some info directly to sensory neurons (taste, hearing) info • Interneurons= all reside w/in CNS; receive signals from other all neurons, integrate info, & decide how to respond to stimuli to • Lie btw & interconnect incoming sensory & outgoing motor nerves Neuron Structure Neuron Neuron of spinal cord (typical structure)• Soma (cell body)= control center w/ nucleus & organelles • Neurofibrils (actin filaments) & microtubules make cytoskeleton • Nissl bodies= rough ER (stain dark) • Dendrites= primary site for receiving signals from other neurons • More dendrites, more info cell body can integrate & process • Axon hillock= mound in cell body leading to axon fiber • Axon= ‘‘nerve fiber’, process that rapidly transmits AP’s; nerve 1/neuron & usually much longer than dendrites (mm-m length) 1/neuron • Potentially few side branches= axon Potentially collaterals collaterals • Some retinal & brain neurons don’t have • Axoplasm= cytoplasm • Axolemma= plasma membrane • Terminal arborization= distal end w/ distal extensive fine branches each ending in a synaptic knob synaptic Variations in Neuron Structure Variations Terminal arborization (cont.)• S.knob forms a synapse w/ adjacent neuron/gland/muscle cell S.knob & houses synaptic vesicles containing a neurotransmitter synaptic neurotransmitter Neurons classified by # of processes extending from soma• Multipolar neurons: 1 axon, multiple dendrites; most...
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