Inorganic ions include those of sodium, phosphorus and hydrogen. Describe how these and other inorganic ions are used in living organisms.
Inorganic ions in animals and plants are necessary for vital cellular activity. In body tissue they can also be called electrolytes, which are essential for electrical activity needed to support muscle contractions and neuron activation. Ions also effect how pH changes in the blood and other bodily functions. Ions are also incorporated into the structure of biological molecules.
Resting potentials require ions as they play a vital role in the process. In the surface membrane of a cell there are protein carriers. These actively pump Na+ ions out of the cytoplasm to the outside of the cell. At the same time, K+ ions are pumped from the outside in. This active pumping of Na+ and K+ ions requires ATP because the ions are being moved against their concentration gradients. K+ and Na+ ions diffuse back down their concentration gradient but K+ diffuses back out of the cell faster than Na+ can diffuse back in. Which means that there is a net movement of positive ions out of the cell making the inside of the cell negatively charged, relative to the outside. This charge is the resting potential of the cell and is about -70mV. Ions are also used in action potentials. When a receptor is stimulated, it will create a positive environment inside the cell. This is caused by a change in the concentrations of Na+ and K+ ions in the cell and happens when there is a change in permeability to Na+ and K+ in the cell surface membrane at the area of stimulation, which causes Na+ channels in that area to open, Na+ therefore floods into the cytoplasm down the concentration gradient. As this happens the membrane depolarizes. If this depolarisation reaches a certain level, called the threshold level then an action potential has been generated and an impulse will be fired. If it does not reach this level, nothing will happen. Once +40mV is reached...
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