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Essential Ion and Compound Balance and Homeostasis - Anatomy & Physiology (view source)
Revision as of 20:47, 4 November 2010
, 20:47, 4 November 2010→Potassium
==Potassium==
==Potassium==
===Importance of Regulation===
===Importance of Regulation===
====Decreased Extracellular Potassium====
====Decreased Extracellular Potassium====
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.
====Increased Extracellular Potassium====
====Increased Extracellular Potassium====
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.
===Sources===
===Sources===
* 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]]
===Potassium and Aldosterone===
===Potassium and Aldosterone===
* [[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
===Factors Influencing Potassium Excretion===
===Factors Influencing Potassium Excretion===
====Sodium====
====Sodium====
* High sodium = increased potassium excretion
* High sodium = increased potassium excretion
** More sodium into cells
** More sodium into cells
====Potassium====
====Potassium====
* High potassium = increased potassium excretion
* High potassium = increased potassium excretion
* Triggers aldosterone
* Triggers aldosterone
====Acid-Base====
====Acid-Base====
* 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