01:119:115 Lecture Notes - Lecture 18: Central Nervous System, Axon Hillock, Peripheral Nervous System

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8 Jul 2015

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Insulate axons of neurons: regulate extracellular fluid surrounding neurons, 10x to 50x more glia than neurons in mammal brains d. Information processing by nervous system occurs in three stages and by different types of neurons. Figure 48. 4 and 48. 5 process of nervous system: sensory input when sensory neurons transmit information about external stimuli. Ions play an essential role in neuronal signaling a. Stimuli cause membrane potential of neurons to change: change occurs because gated ion channels open or close in response to stimuli. Figure 48. 9 gated ion channels: opening gated k channels in resting neuron causes net k outflow, causes shift in membrane potential towards ek (-90mv) ii. Inside of cell membrane is less negative: simple shifts in membrane potential because of hyper-polarization or depolarization = graded potential, graded potentials have magnitude that varies with strength of stimulus. Figure 48. 11: stimulus opens some gated na channels causing start of depolarization a.

Related Questions

Nerve cells that conduct messages are called (1) ____. (2) _____ cells, which support and nurture the activities of neurons, make up less than half the volume of the nervous system. (3) _______ neurons respond to specific kinds of environmental stimuli, (4) ______ connect different neurons in the spinal cord and brain, and (5) ______ neurons are linked with muscles or glands. All neurons have a (6) _______ ________ that contains the nucleus and the metabolic means to carry out protein synthesis. (7) _______ are short, slender extensions of the (6), and together these two neuronal parts are the neuronsâ âinput zoneâ for receiving (8) _____. The (9) _____ is a single long, cylindrical extension away form the (10) ______; in motor neurons, the (11) ______ has finely branched (12) ________ that terminate on muscle or gland cells and are âoutput zones,â where messages are sent on to other cells. A neuron at rest establishes unequal electric charges across its plasma membrane, and a(n) (13) ____ ____ is maintained. Another name for (13) is the (14) _____ _____ _____; it represents an ability for the membrane to be disturbed. Weak disturbances of the neuronal membrane might set off only slight changes across a small patch, but strong disturbances can cause a(n) (15) _______ ______, which is an abrupt, short-lived reversal in the polarity of charge across the plasma membrane of the neuron. For a fraction of a second, the cytoplasmic side of a bit of membrane becomes positive with respect to the outside. The (16) ______ that travels along the neural membrane is nothing more than short-lived changes in the membrane potential. A. Neurons H. Sensory B. Motor I. Endings C. Interneurons J. Disturbance D. Cell body K. Signals (stimuli) E. Axon L. Voltage differential F. Dendrites M. Resting membrane potential G. Neuroglial N. Action potential

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01:119:115 Lecture Notes - Lecture 18: Central Nervous System, Axon Hillock, Peripheral Nervous System

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