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Renal system anatomy and physiology
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Sodium is a positive ion or a cation noted with Na.
In the extracellular fluid, sodium has a concentration of about 135 milliequivalents (mEq) per liter.
Sodium is essential in maintaining water balance, as well as for nerve impulse conduction and muscle contraction.
Now, osmolality refers to the total solute concentration in a certain amount of solvent or water.
By affecting plasma osmolality, sodium determines plasma and blood volume.
So, at the end of the day, it’s important to maintain the sodium concentration in order to keep enough blood inside our arteries.
This blood is called the effective arterial blood volume or EABV, and it’s what ends up perfusing our various organs and tissues.
Okay, now, sodium comes from our diet.
The daily recommended sodium intake is about 2.3 grams per day which is the equivalent of a teaspoon of salt per day.
Once ingested, sodium is absorbed in the blood by the GI tract, and travels through the bloodstream unbound to plasma proteins.
At the other end, some sodium is eliminated from the body through sweat and through feces, but most of it comes out, along with water, as pee.
So the kidneys are the cornerstone of sodium homeostasis.
The renal corpuscle, in turn, is made up of the glomerulus, which is a tiny clump of capillaries, and Bowman’s capsule surrounding it.
Sodium homeostasis refers to the regulation of sodium levels in the body. Sodium is an important electrolyte mainly found in extracellular fluid, which helps maintain fluid balance, blood pressure, nerve impulse conduction, and muscle contraction. The body regulates sodium levels through hormones that control the reabsorption of sodium in the kidneys, as well as through thirst mechanisms. Factors that stimulate sodium reabsorption include the renin-angiotensin-aldosterone system, ADH, and the sympathetic nervous system. Factors that stimulate sodium excretion include PTH, and peptides like ANP. An imbalance in sodium levels can lead to health problems such as edema, hyponatremia, and hypernatremia.
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