Final answer:
Total body sodium content, ECF volume, and blood pressure are jointly regulated through mechanisms such as the renin-angiotensin-aldosterone system and antidiuretic hormone release.
Step-by-step explanation:
Total body sodium content, extracellular fluid (ECF) volume, and blood pressure are jointly regulated in mammalian systems. Sodium, as the major cation in the extracellular fluid, has a strong osmotic effect and attracts water. Changes in sodium levels can lead to alterations in fluid volume and blood pressure. The regulation of sodium and water balance is mediated by various mechanisms, including the renin-angiotensin-aldosterone system and the release of antidiuretic hormone. These regulatory processes help maintain homeostasis and ensure the proper functioning of the body.