Although it is essential that the kidneys reabsorb vital ions and compounds back from the filtrate in order to maintain there levels within the body, it is also important that the kidneys are able to further secrete ions and compounds. These compounds may not be able to be filtered, such as those bound to protein, or may on the whole need to be reabsorbed but tightly regulated so some secretion takes place such as [[Potassium Homeostasis - Physiology#Absorption/Secretion Mechanisms Along The Nephron|potassium]] and [[Acid Base Balance By The Kidney - Anatomy & Physiology#Secretion of H+|hydrogen]]. Secretion can take place via [[Active Transport - Physiology#Primary Active Transport|primary]] or [[Active Transport - Physiology#Secondary Active Transport|secondary active transport]]. | Although it is essential that the kidneys reabsorb vital ions and compounds back from the filtrate in order to maintain there levels within the body, it is also important that the kidneys are able to further secrete ions and compounds. These compounds may not be able to be filtered, such as those bound to protein, or may on the whole need to be reabsorbed but tightly regulated so some secretion takes place such as [[Potassium Homeostasis - Physiology#Absorption/Secretion Mechanisms Along The Nephron|potassium]] and [[Acid Base Balance By The Kidney - Anatomy & Physiology#Secretion of H+|hydrogen]]. Secretion can take place via [[Active Transport - Physiology#Primary Active Transport|primary]] or [[Active Transport - Physiology#Secondary Active Transport|secondary active transport]]. |