Sodium tends to remain in the extracellular space , that is , in the fluid that surrounds cells and tissues , and in the blood . Cells actually pump out more sodium than retain it , but that ' s an entire ELI 5 in itself . And sodium doesn ' t remain in the blood forever . Your kidneys are capable of sensing how much sodium is present , and will adjust the reabsorption of sodium from the urine accordingly on a more or less minute to minute basis . Your heart can also detect sodium concentrations , though indirectly , The only time this will happen is if the heart is failing , and can ' t pump properly and increases Na excretion in the urine by secreting special peptides . <| sep |> Afsoning med internet er ikke afsoning