01:119:116 Lecture Notes - Lecture 19: Axon Hillock, Action Potential, Facilitated Diffusion

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orchidjackal213

11 Jan 2020

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Lecture 19 - nervous ii action potential: neurons, structure and function. Axon - transmit stimulus to effector or another nerve. Synaptic terminals - at the end of the branches. More sodium outside & 1 na inside. Passive - no energy used for the pump. Dynamic equilibrium - same number of positive and negative on both sides. Gated - closed until opened by a key . Voltage gated - opened by change in voltage. Ion movement can result in different % ions inside & outside cell membrane cell membrane. Rapidly change membrane potential by opening & closing gates channels. Non stimulated cell is at rest: resting potential. Resting potential (rp) is between -60 and -80 mv. 70mv - maintained by sodium potassium pump closed ion channels. At rest - gated ion channels are closed. Na+/k+ pump is pumping but k+ voltage gated channels leak so they are always slightly open. Membrane is 100x more permeable to k+ than na+

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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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01:119:116 Lecture Notes - Lecture 19: Axon Hillock, Action Potential, Facilitated Diffusion

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