HTHSCI 1H06 Chapter Notes -Depolarization, Cytosol, Extracellular Fluid
23 Sep 2013
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Document Summary
Neurons communicate using: graded potentials (short-distance communication, action potentials (long-distance communication within body, action potential in muscle fiber is muscle action potential, when action potential occurs in nerve cell, it is called nerve action potential. What happens when you touch a pen: graded potential builds in sensory receptor in fingertips, graded potential triggers axon to form nerve action potential, travels into. Positively charged cations move toward negatively charged area, and vice versa. Small buildup of negative ions in cytosol along inside of membrane, and equal buildup of positive ions in extracellular fluid along outside surface of membrane. In neurons, resting membrane potential ranges from -40 to -90mv. Typical value is -70mv, meaning inside of cell is negative relative to outside, and is polarized. Resting membrane results from: unequal distribution of ions in ecf and cytosol, inability of most anions to leave the cell, electrogenic nature of the na+/k+ atpases.
