Changes

==Overview==

==Overview==

Aldosterone is a steroid hormone which is secreted from the zona glomerulosa of the adrenal gland.  It has a mineralocorticoid activitiy and is the most important regulator of plasma potasium.  When plasma potasium increases increased stimulation of aldosterone occurs directly and as a result of [[Renin-Angiotensin-Aldosterone System (RAAS) - Anatomy & Physiology | Renin-Angiotensin-Aldosterone System (RAAS)]].  It is also the most important regulator of sodium excretion.

Aldosterone is a steroid hormone which is secreted from the zona glomerulosa of the adrenal gland.  It has a mineralocorticoid activity and is the most important regulator of plasma potassium.  When plasma potassium increases increased stimulation of aldosterone occurs directly and as a result of [[Renin-Angiotensin-Aldosterone System (RAAS) - Anatomy & Physiology | Renin-Angiotensin-Aldosterone System (RAAS)]].  It is also the most important regulator of sodium excretion.

==Release==

==Release==

* Total quantity of sodium is conserved not the actual plasma concentration

* Total quantity of sodium is conserved not the actual plasma concentration

** 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

** [[Renin-Angiotensin-Aldosterone System (RAAS) - Anatomy & Physiology| Angiotensin 2]] and [[Aldosterone]] affect scodium but they also affect ECF volume so only quantity affected not concentration

** [[Renin-Angiotensin-Aldosterone System (RAAS) - Anatomy & Physiology| Angiotensin 2]] and [[Aldosterone]] affect sodium but they also affect ECF volume so only quantity affected not concentration

** ADH and thirst response also work together to dilute the ECF if concentrations of sodium is high so although there is more NaCl the actual concentration is not really changed.

** 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.

* If there was no secretion of aldosterone a 20kg dog would excrete 15g per 24 hours

* If there was no secretion of aldosterone a 20kg dog would excrete 15g per 24 hours

* At maximal secretion no significant amount of sodium would be excreted

* At maximal secretion no significant amount of sodium would be excreted

* In cases of increased K⁺

* In cases of increased K⁺

* Increased Na⁺ / K⁺ ATPase pump activity increases the amount of K⁺ in cells to reduce plasa K⁺

* Increased Na⁺ / K⁺ ATPase pump activity increases the amount of K⁺ in cells to reduce plasma K⁺

* Generally not excreted

* Generally not excreted

* However if plasma K⁺ is still high aldosterone is stimulated

* However if plasma K⁺ is still high aldosterone is stimulated

* Causes pottassium secretion

* Causes potassium secretion

** Stimulates Na⁺ / K⁺ ATPases in the basolateral membrane of the principal cells

** Stimulates Na⁺ / K⁺ ATPases in the basolateral membrane of the principal cells

** Increased pottasium in the cells

** Increased potassium in the cells

** Pottassium leaves via apical leak channels  

** Potassium leaves via apical leak channels  

** Thanks to electro-chemical gradient

** Thanks to electro-chemical gradient

* Very tightly regulated system

* Very tightly regulated system