Sodium in biology mEq/liter (135 - 145 mmol/L). A serum sodium level of less than 135 mEq/L qualifies as hyponatremia, which is considered severe when the serum sodium level is below 125 mEq/L. The renin–angiotensin system and the atrial natriuretic peptide indirectly regulate the amount of signal transduction in the human central nervous system, which depends on sodium ion motion across the nerve cell membrane, in all nerves. Sodium is thus important in neuron function and osmoregulation between cells and the extracellular fluid; the distribution of sodium ions are mediated in all animals by sodium–potassium pumps, which are active transporter solute pumps, pumping
Fetal bovine serum which they can survive, grow, and divide. FBS is not a fully defined media component, and as such may vary in composition between batches. As a result, serum free and chemically defined media (CDM) have been developed as a matter of good laboratory practice. Fetal bovine serum is a by-product of the dairy industry. Fetal bovine serum, as with the vast majority of animal serum used in cell culture, is produced from blood collected at commercial slaughterhouses from dairy cattle that also supply meat intended for human consumption. The first stage of the production process for fetal bovine serum is