Sodium Management

Sodium

Managing sodium(Na⁺): Major ECF cation; important for fluid balance, nerve function. is the major function of the kidney. Of course this is true because sodium is the most abundant cation in your ECF. It’s the major cation in the plasmaThe liquid component of blood. and in the interstitial fluids. Not the ICF, though, potassium(K⁺): Major ICF cation; essential for muscle and nerve function. gets that compartment. Think of all the ways that the kidney uses sodium as a feedback mechanism to regulate filtrationThe process by which fluid moves out of capillaries into surrounding tissues due to hydrostatic pre.

The sodium content of the body may change. You might eat a salty meal, for example, raising the amount of sodium in your plasma. However the concentration of sodium in the ECF will remain stable. Instead of lowering sodium, the waterThe universal solvent essential for life. volume is adjusted to maintain the sodium concentration. This is called a fluid shift. Instead of moving around sodium, you move around water between fluid compartmentsDivisions of body water: intracellular, extracellular, and transcellular..

Your body will respond by raising the volume of water in the plasma when you eat a salty meal. This happens as a result of the increase in sodium content. This can be accomplished via thirst. Adding more water is like adding more water to a water balloon – the pressureThe force exerted by gases in the respiratory system, affecting airflow and gas exchange. increases. But, the water doesn’t stay in the plasma. It seeps into the interstitial fluids. This increases the volume of that fluid compartment. The IF overflows into the ICF, increasing the water pressure in each and every one of your cellsThe basic structural and functional units of life..

Water balance is strongly coupled with the control of water volume and by consequence, blood pressure. There are two important hormones that play a part in regulating sodium: aldosteroneA hormone that increases sodium and water reabsorption in the kidneys, helping regulate blood pressu and ADH. There are other hormones that regulate sodium, but those are the two major ones.

Hyponatremia & Hypernatremia

Hyponatremia and hypernatremiaHigh sodium levels in the blood. are the disorders that result from too little or too much salt. Remember that your body manages water by using sodium to create gradients.

Hypernatremia is a condition in which the sodium (Na⁺) concentration in the blood is higher than normal—typically above 145 mEq/L. One common cause is dehydrationA condition in which fluid loss exceeds intake, leading to a decrease in total body water., especially in elderly individuals or people with limited access to water. For example, if a person loses a lot of water through sweating or diarrhea, and they don’t replace it with fluids, the sodium concentration in the blood increases. They sweat or suffer from diarrhea. If they do not replace it with fluids, the sodium concentration in the blood increases. This happens because there’s less water to dilute it. Hyponatremia can cause muscle twitching. This occurs because the IF concentration of sodium is really high. It allows a lot of sodium to leak into cells using the leak channelsProtein passages in the cell membrane that allow specific molecules to pass through.. The treatment involves slowly rehydrating the person, usually with IV fluids that are hypotonic (low in sodium), such as 0.45% saline. The goal is to gradually restore the balance of water and sodium—too rapid correction can cause brain swelling (cerebral edemaExcess fluid in interstitial spaces.).

Hyponatremia occurs when blood sodium levels fall below normal, usually less than 135 mEq/L. A classic example is water intoxication. This can happen if someone drinks excessive amounts of water in a short period. This often occurs during endurance sports. It happens when electrolytes lost are not replaced. The excess water dilutes sodium in the blood. Muscle cramps or weakness. Treatment depends on the cause and severity. Mild cases may only need fluid restriction. Severe cases are treated with hypertonicA solution with a higher solute concentration than the inside of a cell, causing water to leave th saline (3% NaCl). The administration is done carefully. This is to avoid correcting sodium levels too quickly. Rapid correction could cause osmotic demyelination syndrome in the brain.

Hormonal Sodium Management

Aldosterone is released by the cortex of the adrenal glad and acts on the DCT of the nephronThe functional unit of the kidney that filters blood and produces urine.. This allows the DCT to reabsorb sodium, moving it from the filtrateThe fluid that is filtered from the blood into the nephron and will eventually become urine. to the blood in reabsorptionThe process of fluid moving back into capillaries from surrounding tissues due to colloid osmotic p. As the sodium moves, water follows it, ultimately increasing the volume of your ECF. So, again, the concentration of sodium is held constant by affecting movements in water. There is a disease called Addison’s disease where you basically generate tons and tons of aldosterone. To satisfy the kidney’s desires under that much aldosterone, you have to consume lots of salt and water. You spend your life bloated and uncomfortable. Surgery to remove part of the adrenal cortices helps Addison’s.

Estrogen mimic aldosterone causing the same type of bloating. Gluccocorticoids act like super-aldosterone and promote edema.

Angiotensin II controlsVariables that remain constant to ensure a fair test. the release of aldosterone from the adrenal cortexOuter portion of the adrenal glands producing corticosteroids.. Remember that the granular cellsSpecialized cells in the juxtaglomerular apparatus that secrete renin in response to low blood press of the afferent arterioleThe small artery that carries blood into the glomerulus of the nephron. release reninAn enzyme secreted by the juxtaglomerular cells that helps regulate blood pressure by triggering the. This renin is then processed into Angiotensin II. This occurs when there is decreased sodium or low blood pressure in the systemic circuitThe part of the circulatory system that carries oxygenated blood from the heart to the body and retu.