Study Guide 22

Study Guide 22 - Study Guide 22 J.W Via General Biology...

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Study Guide # 22 J.W. Via General Biology 1006 Neurons and the Nervous System How are physiological and developmental problems in organisms controlled? Short term control of movement, thought, organs functions are primarily under nervous control. Development, growth, reproduction are longer termed processes and are generally under hormonal control. Neuron- Functional unit of the nervous system. Transmits the nervous impulse. 1) Sensory Neurons- transfers signals from receptors to the central-nervous system. 2) Interneurons- - CNS (Central Nervous System) Neurons 3) Motor Neurons- transfers signal from the CNS to the Effectors e.g. glands, muscles. Anatomy of the Neuron - Dendrites = typically receive the impulse and transfer it to the Cell Body which is the nucleus of the cell and associated cytoplasm which then transfers the signal to the Axon which is the longest part of the neuron. Typically the signal is unidirectional in the pattern described above. Neurons are the longest cells of the body. Transmission of the Signal ( Nervous Impulse or Action Potential ) - Resting Nerves Active transport Concentrates Na + outside of the axon membrane of the neuron and K + inside of the cell membrane. This results in the Resting potential which is the polarized state of the neuron resulting from this difference in concentration. The cell in this state has a charge of -70mV with the inside less positive than the outside. Voltage is the way the potential of a nerve is measured. See your text for a good explanation of the importance of voltage. This is the polarized state. Action potential - (Nerve Impulse) is the wave of depolarization down a nerve fiber as measured electrically. This arises due to a change in the membrane permeability as a results of a stimulus which causes the influx if Na+ which
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Study Guide 22 - Study Guide 22 J.W Via General Biology...

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