Almost all multicellular organisms contain a nervous system, which allows them to sense changes in their environment or induce muscle contractions through electrical impulses. The majority of nerves cells that make up the nervous system are excitable cells, as they have the ability to produce an electric current to formrom an action potential from using a concentration gradient of ions across their membrane (Sherwood, 2013). The current generated by the flow of sodium (〖Na〗^+) and potassium ( K^+)ions is called an action potential and occurs in three steps: depolarization, repolarization, and hyperpolarization. First, a membrane potential 〖(V〗_m) is established by creating a concentration gradient of 〖Na〗^+ and K^+where there is a high concentration
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Initially, the sodium potassium pump creates the -70 mV V_m by pumping 〖Na〗^+ out of the cell and K^+ into the cell. After a stimulus is received, the 〖Na〗^+ ion channels open, allowing 〖Na〗^+ to flow into the cell and causing depolarization. Next, repolarization occurs as K^+ ion channels begin to open and K^+ ions flow out of the cell while the 〖Na〗^+ channels begin to close, which . eEstablishinges this a new V_m concentration of K^+ outside the cell and 〖Na〗^+ inside the cell is called repolarization. After repolarization, a new concentration gradient has been established where the K^+ concentration is highest outside the cell and the 〖Na〗^+concentration is highest inside the cell. The third step, hyperpolarization, occurs because of the K^+ channel’s slow response rate in comparison to that of the 〖Na〗^+ channels. During this period another action potential cannot be produced because the V_m has not been fully restored and more importantly because the potassium channels cannot be reopened immediately. The time interval before another action potential can be produced is called the refractory period (Sherwood,
Initially, the sodium potassium pump creates the -70 mV V_m by pumping 〖Na〗^+ out of the cell and K^+ into the cell. After a stimulus is received, the 〖Na〗^+ ion channels open, allowing 〖Na〗^+ to flow into the cell and causing depolarization. Next, repolarization occurs as K^+ ion channels begin to open and K^+ ions flow out of the cell while the 〖Na〗^+ channels begin to close, which . eEstablishinges this a new V_m concentration of K^+ outside the cell and 〖Na〗^+ inside the cell is called repolarization. After repolarization, a new concentration gradient has been established where the K^+ concentration is highest outside the cell and the 〖Na〗^+concentration is highest inside the cell. The third step, hyperpolarization, occurs because of the K^+ channel’s slow response rate in comparison to that of the 〖Na〗^+ channels. During this period another action potential cannot be produced because the V_m has not been fully restored and more importantly because the potassium channels cannot be reopened immediately. The time interval before another action potential can be produced is called the refractory period (Sherwood,