File Name: generation and conduction of nerve impulse .zip
Action potential , the brief about one-thousandth of a second reversal of electric polarization of the membrane of a nerve cell neuron or muscle cell. In the neuron an action potential produces the nerve impulse, and in the muscle cell it produces the contraction required for all movement. Sometimes called a propagated potential because a wave of excitation is actively transmitted along the nerve or muscle fibre, an action potential is conducted at speeds that range from 1 to metres 3 to feet per second, depending on the properties of the fibre and its environment. Before stimulation, a neuron or muscle cell has a slightly negative electric polarization; that is, its interior has a negative charge compared with the extracellular fluid. This polarized state is created by a high concentration of positively charged sodium ions outside the cell and a high concentration of negatively charged chloride ions as well as a lower concentration of positively charged potassium inside.
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The nerve impulse is the sum of mechanical, chemical and electrical disturbances created by a stimulus in a neuron. The conduction of the nerve impulse can be divided into two main phases — resting membrane potential and action membrane potential. Neurons are excitable cells. They may be stimulated by physical, mechanical, chemical or electrical stimuli. The axoplasm inside the axon contains a high concentration of potassium ions, negatively-charged proteins and a low concentration of sodium ions. On the contrary, the extracellular fluid outside the axon contains a low concentration of potassium and a high concentration of sodium.
This amazing cloud-to-surface lightning occurred when a difference in electrical charge built up in a cloud relative to the ground. When the buildup of charge was great enough, a sudden discharge of electricity occurred. A nerve impulse is similar to a lightning strike. Both a nerve impulse and a lightning strike occur because of differences in electrical charge, and both result in an electric current. A nerve impulse , like a lightning strike, is an electrical phenomenon. A nerve impulse occurs because of a difference in electrical charge across the plasma membrane of a neuron. How does this difference in electrical charge come about?
In physiology , an action potential AP occurs when the membrane potential of a specific cell location rapidly rises and falls:  this depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells , called excitable cells, which include neurons , muscle cells , endocrine cells, glomus cells , and in some plant cells. In neurons, action potentials play a central role in cell-to-cell communication by providing for—or with regard to saltatory conduction , assisting—the propagation of signals along the neuron's axon toward synaptic boutons situated at the ends of an axon; these signals can then connect with other neurons at synapses, or to motor cells or glands. In other types of cells, their main function is to activate intracellular processes. In muscle cells, for example, an action potential is the first step in the chain of events leading to contraction.
Generation and Conduction of Nerve Impulse
Having looked at the components of nervous tissue, and the basic anatomy of the nervous system, next comes an understanding of how nervous tissue is capable of communicating within the nervous system. Before getting to the nuts and bolts of how this works, an illustration of how the components come together will be helpful. Imagine you are about to take a shower in the morning before going to school. You have turned on the faucet to start the water as you prepare to get in the shower.
Neurons communicate with each other via brief electrical signals known as action potentials. They are brief changes in the voltage across the membrane due to the flow of certain ions into and out of the neuron. In this article, we will discuss how an action potential AP is generated and how conduction of an action potential occurs.
The Resting Membrane Potential
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Jia Published Materials Science. The form of the action electric-potential in nerve membranes in the nerve cell-membranes are first described, it is, in essence, a nerve impulse and can be formed by virtue of periodic and ruled changes of non-uniform distribution of the sodium and potassium ions in the inner and surface of nerve cell-membranes.
Халохот быстро убедился, что сад пуст, и поднял глаза вверх, на Гиральду. Вход на спиральную лестницу Гиральды преграждала веревка с висящей на ней маленькой деревянной табличкой. Веревка даже не была как следует натянута. Халохот быстро осмотрел стодвадцатиметровую башню и сразу же решил, что прятаться здесь просто смешно. Наверняка Беккер не настолько глуп.
На него сверху вниз смотрел прыщавый бритоголовый коротышка. Половина головы красная, половина - синяя. Как пасхальное яйцо. - Я сказал, что ты занял мое место.
Танкадо успел отдать его за мгновение до смерти.