Final answer:
Adding NaCl to the body increases ECF volume and blood pressure, suppresses RAAS and ADH, enhances ANP/BNP secretion, dampens thirst, reduces water intake, and results in more dilute urine with increased sodium excretion.
Step-by-step explanation:
When NaCl is added to the body, a series of physiological responses occur:
- a. Extracellular Fluid (ECF) volume increases, leading to higher blood pressure.
- b. Renin-Angiotensin-Aldosterone System (RAAS) is downregulated due to increased blood pressure and volume.
- c. Atrial Natriuretic Peptide (ANP)/Brain Natriuretic Peptide (BNP) levels increase to promote salt and water excretion and decrease blood pressure.
- d. Carotid Sinus baroreceptors detect increased blood pressure, leading to a decrease in sympathetic outflow and lowered heart rate.
- e. Urine Sodium Excretion is promoted by increased ANP/BNP and decreased RAAS activity.
- f. Antidiuretic Hormone (ADH) secretion is suppressed due to adequate hydration, leading to a decrease in water reabsorption.
- g. Thirst sensation is attenuated as the body is in a state of volume expansion.
- h. Urinary Osmolality (uOSM) decreases as less ADH is present, resulting in more dilute urine.
- i. Water intake is decreased due to reduced thirst and adequate ECF volume.