Action Potentials And Action Potentials

2033 Words 9 Pages
Abstract
Action potentials can be defined as the signals and the pathways sent through the nervous system. They are essential in carrying out various actions that are administered by the brain. This effect of action potentials help us to feel cold, warmth ,use the sensory actions of the eye etc. and the back forth signaling between the brain and the nerve cells helps the brain to carry the right action. Action potentials are housed by neuron structures which are made up of axons and dendrites. The synapses is the little gap between neurons across which they communicate with neurotransmitters. Every neuron usually has only one axon which can be short or long leaving the cell body however some of them can have many branches. The cell body receives
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Positively charged ions are pumped through the membrane creating a slightly more negative atmosphere inside the cell then the outside. This action causes the cell membrane to be polarized. Positively charged ions are kept out and only make it back in through special membrane gate channels which can open and close and these channels are distributed along the axons and dendrites. Changes in the environment stimulate the normally closed channels on the axon to swing open and allow positive charges to rush in through the action of depolarization. This activity causes the next area of the axon to become depolarized resulting in the opening of the neighboring gate. This pattern continues creating a wave of electrochemical potential changes that spread rapidly all the way down the axon known as an action potential. Action potentials follow the all or none rule where they fire at full strength or do not fire at all. Action potentials have also been discovered to be generated from both dendrites and axons however in the past scientist believed it was only generated from axons. The action potential speed is constant as it moves down an axon and depends on factors such as the diameter of an axon and the presence of myelin. Larger myelinated axons tend to be faster and the speed of action potentials can range from 0.2 meters per second to 120 meters per second. Myelin is a fatty substance that help in speeding up action …show more content…
They are important for the communication of information to and from and within the brain and complications with this can lead some bad conditions such as multiple sclerosis. The aid in the ability to laugh, cry, think, feel, see, hear, and move muscles. So it is quite impossible to live without it. There are various conditions that can result due to complications with the nervous system or action potential such as tetanus which results from low calcium levels and improper signaling of muscle cells causing severe cramps spasms or tremors. (Lippold, 1952)It can also be used to an advantage sometime where local anesthetics provide a reversible regional loss of sensation. The reduction in sensation reduces pain, thereby facilitating surgical procedures. Local anesthetics inhibit the depolarization of the nerve membrane by interfering with the sodium and potassium currents and the action potential is not propagated because the critical point or the threshold level is never attained. (Robyn Gmyrek, MD; 2013) Two theories have been proposed as to how this works i.e. the membrane expansion theory postulates. This theory suggest that the local anesthetic is absorbed into the cell membrane, expanding the membrane and leading to narrowing of the sodium channels. The second is the specific receptor theory which states that the local anesthetic diffuses across the cell

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