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| ==Potassium== | | ==Potassium== |
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| ===Importance of Regulation=== | | ===Importance of Regulation=== |
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| ====Decreased Extracellular Potassium==== | | ====Decreased Extracellular Potassium==== |
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| If the concentration of potassium in the ECF is reduced then the plasma membranes hyperpolarize resulting in decreased firing of action potentials. This causes skeletal muscle weakness and cardiac abnormalities. | | If the concentration of potassium in the ECF is reduced then the plasma membranes hyperpolarize resulting in decreased firing of action potentials. This causes skeletal muscle weakness and cardiac abnormalities. |
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| ====Increased Extracellular Potassium==== | | ====Increased Extracellular Potassium==== |
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| In this state the membrane is depolarised and is inappropriately triggered by action potentials. This can make the membrane insensitive to further stimulation causing cardiac abnormalities. | | In this state the membrane is depolarised and is inappropriately triggered by action potentials. This can make the membrane insensitive to further stimulation causing cardiac abnormalities. |
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| ===Sources=== | | ===Sources=== |
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| * Potassium is absorbed via passive diffusion from the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] | | * Potassium is absorbed via passive diffusion from the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] |
| * Also via active transport from the [[Colon - Anatomy & Physiology|colon]] | | * Also via active transport from the [[Colon - Anatomy & Physiology|colon]] |
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| ===Potassium and Aldosterone=== | | ===Potassium and Aldosterone=== |
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| * [[Aldosterone]] is the most important regulator of potassium | | * [[Aldosterone]] is the most important regulator of potassium |
| * It causes increased secretion of potassium | | * It causes increased secretion of potassium |
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| ===Factors Influencing Potassium Excretion=== | | ===Factors Influencing Potassium Excretion=== |
| ====Sodium==== | | ====Sodium==== |
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| * High sodium = increased potassium excretion | | * High sodium = increased potassium excretion |
| ** More sodium into cells | | ** More sodium into cells |
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| ====Potassium==== | | ====Potassium==== |
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| * High potassium = increased potassium excretion | | * High potassium = increased potassium excretion |
| * Triggers aldosterone | | * Triggers aldosterone |
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| ====Acid-Base==== | | ====Acid-Base==== |
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| * Potassium is exchanged for H<sup>+</sup> | | * Potassium is exchanged for H<sup>+</sup> |
| * Hypokalaemia = potassium to ECF and hydrogen to ICF | | * Hypokalaemia = potassium to ECF and hydrogen to ICF |