Changes

The total body content of sodium is regulated rather than the actual plasma concentration.  It would be impossible to regulate actual plasma concentration for 3 reasons:

The total body content of sodium is regulated rather than the actual plasma concentration.  It would be impossible to regulate actual plasma concentration for 3 reasons:

* When sodium is reabsorbed water follows it so the volume of the plasma is altered rather than the concentration of sodium changing

* When sodium is reabsorbed water follows it so the volume of the plasma is altered rather than the concentration of sodium changing

* [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Effects of Angiotensin 2 On Sodium|Angiotensin 2]] and [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Aldosterone|Aldosterone]] affect sodium but they also affect ECF volume so only quantity affected not concentration

* [[Renin Angiotensin Aldosterone SystemEffects of Angiotensin 2 On Sodium|Angiotensin 2]] and [[Aldosterone|Aldosterone]] affect sodium but they also affect ECF volume so only quantity affected not concentration

* [[Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland | ADH]] and thirst response also work together to dilute the ECF if concentrations of sodium are high so although there is more NaCl the actual concentration is not really changed.

* [[Pituitary Gland - Anatomy & Physiology #Posterior Pituitary Gland | ADH]] and thirst response also work together to dilute the ECF if concentrations of sodium are high so although there is more NaCl the actual concentration is not really changed.

* Takes 4-6 hours to respond

* Takes 4-6 hours to respond

* Allows fine control

* Allows fine control

* Influenced by [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Potassium|Aldosterone]]

* Influenced by [[Aldosterone|Aldosterone]]

=====GI excretion=====

=====GI excretion=====

* Makes up the other 10% of the chronic response

* Makes up the other 10% of the chronic response

* Also influenced by [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Potassium|Aldosterone]]

* Also influenced by [[Aldosterone]]

* Most important in renal failure

* Most important in renal failure

* However net reabsorption / secretion of potassium occurs in the distal tubule and first part of collecting duct

* However net reabsorption / secretion of potassium occurs in the distal tubule and first part of collecting duct

** Depends on bodies need

** Depends on bodies need

* Under the influence of [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Potassium|Aldosterone]]

* Under the influence of [[Aldosterone]]

* This is where the amount of potassium excreted is determined

* This is where the amount of potassium excreted is determined

* Reabsorption occurs in the final part of the collecting duct

* Reabsorption occurs in the final part of the collecting duct

===Potassium and Aldosterone===

===Potassium and Aldosterone===

* [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Potassium|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

* Increased potassium directly stimulates [[Important Hormonal Regulators of the Kidney - Anatomy & Physiology#Potassium|Aldosterone]] secretion

* Increased potassium directly stimulates [[Aldosterone]] secretion

* Increases the activity and number of Na⁺ / K⁺ ATPase in basolateral membranes of the principal cells in the collecting duct and distal tubule

* Increases the activity and number of Na⁺ / K⁺ ATPase in basolateral membranes of the principal cells in the collecting duct and distal tubule

* Potassium moves into the cells and is then excreted down an electro-chemical gradient

* Potassium moves into the cells and is then excreted down an electro-chemical gradient