let's learn about fluids and electrolytes sodium sodium is a very important electrolyte in the body sodium plays an important role in the proper function of many organs including muscles the brain heart and kidneys sodium accounts for 90 to 95% of the osmolarity or concentration of the extracellular fluid or ECF adults need an average of about a half a gram of sodium per day the typical American diet is high in sodium at about 3 to 7 gr per day sodium is regulated by a number of mechanisms these include aldosterone anti-diuretic hormone or ADH and atrial natriuretic peptide elderone is secreted by the adrenal gland elderone targets the kidneys to promote sodium retention the adrenal cortex secretes aldosterone in response to hormonal stimulation and by low plasma sodium the renin Angiotensin system promotes aldosterone secretion in response to low blood pressure anti-diuretic hormone has an effect on sodium concentration but does not affect the amount of sodium in the body ADH is secreted by the posterior pituitary gland in response to an increase in osmolarity or blood solute concentration as sensed by the hypothalamus ADH promotes water retention in the kidneys this in turn causes a decrease in plasma osmolarity atrial natriuretic peptide is a hormone secreted by the heart and responds to atrial stretch an increase in blood volume causes an increase in atrial stretch atrial natriuretic peptide targets the kidneys to inhibit sodium reabsorption sodium imbalances include hypernia or too high plasma sodium concentration and hyponatremia which is low sodium concentration in hypernia the plasma sodium concentration is greater than than 145 mil equivalents per liter hypernia can cause water retention hypertension and edema in hyponatremia the plasma sodium concentration is less than 135 mil equivalents per liter hyponatremia can cause nause and vomiting muscle problems seizures and coma I hope you've learned something about sodium imbalance and see you next time