regulation of electrolyte balance
The body buffers the extra potassium by equilibrating it within the cells. Adjustments in the respiratory and renal functions allow the body to regulate the levels of these ions in the extracellular fluid (ECF). It is present as an organic salt, while sodium is added as NaCl. In the face of phosphate depletion, the kidneys usually conserve phosphate, but during starvation, this conservation is impaired greatly. Additionally, because phosphate is a major constituent of the ICF, any significant destruction of cells can result in the dumping of phosphate into the ECF. Calcium is a very important electrolyte. Cell electrolytes: This diagram illustrates the mechanism for the transportation of water and electrolytes across the epithelial cells in the secretory glands. The major physiological controller of aldosterone secretion is the plasma angiotensin II level that increases aldosterone secretion. The most serious electrolyte disturbances involve abnormalities in the levels of sodium, potassium, and/or calcium. In a healthy individual, this multilevel coordinated control of fluid and electrolyte … The former can lead to seizures, while the latter can lead to osmotic cerebral edema upon rapid rehydration. For example, during heavy exercise electrolytes are lost through sweating, particularly sodium and potassium, and sweating can increase the need for electrolyte (salt) replacement. Bone and teeth bind up 85 percent of the body’s phosphate as part of calcium phosphate salts. Hypochloremia, or lower-than-normal blood chloride levels, can occur because of defective renal tubular absorption. Ninety-nine percent or more is deposited in the bones and the remainder plays a vital role in nerve conduction, muscle contraction, hormone release, and cell signaling. Contents Introduction Body Fluids Source Functions Composition Movements of Body Fluids Fluid Balance Regulation of Body Water Electrolytes Electrolyte balance Homeostasis Imbalance disorders Acid –Base Balance conclusion Chloride maintains proper hydration and functions to balance the cations in the ECF to keep the electrical neutrality of this fluid. The body contains a large variety of ions, or electrolytes, which perform a variety of functions. Bicarbonate is transported in the blood and once in the lungs, the reactions reverse direction, and CO2 is regenerated from the bicarbonate to be exhaled as metabolic waste. In hypotonic dehydration, intravascular water shifts to the extravascular space and exaggerates the intravascular volume depletion for a given amount of total body water loss. The usual amount of phosphate in the diet is about 1 g/d but not all of it is absorbed. Describe the mechanisms by which sodium balance is regulated. Therefore, a person with an acidosis (pH 7.1) and a plasma K+ of 6.5 mmol/l could be depleted of total body potassium. The excretion of ions occurs mainly through the kidneys, with lesser amounts of ions being lost in sweat and in feces. Deficits of water or electrolytes can be compensated for by increases in intake and retention, whereas excesses are compensated for by increases in urinary excretion. Many prescription medications disrupt electrolyte balance. It is usually considered that regulation of water excretion determines osmolality, and regulation of electrolyte excretion (principally NaCl) determines fluid volume; however, regulation of water excretion influences fluid volume and osmolality. Bicarbonate as a buffering system: In the lungs, CO2 is produced from bicarbonate and removed as metabolic waste through the reverse reaction of the bicarbonate bidirectional equation. Every biological chemical process involves a balance between water and the electrolytes in the intracellular fluid (ICF) and the extracellular fluid (ECF). The solubility product of Ca and P is close to saturation in plasma. Other ions help to stabilize protein structures in enzymes. As oral rehydration is less painful, less invasive, less expensive, and easier to provide, it is the treatment of choice for mild dehydration. Riassorbimento bicarbonati e respirazione cellulare. Movement of water between compartments: osmotic pressure The body has a potent sodium -retaining mechanism: the rennin– angiotensin system. In states of sodium depletion, aldosterone levels increase; in states of sodium excess, aldosterone levels decrease. This hormone also causes phosphate to leach out of the bones. Regulation of electrolyte Intake & output Electrolyte intake: Electrolytes are usually obtained in sufficient quantities in response to hunger and thirst mechanism. There is a constant loss of calcium by the kidney even if there is none in the diet. A low renal perfusion pressure stimulates the release of renin, which forms angiotensin I that is converted to angiotensin II. The most common cause of electrolyte disturbances is renal failure. Hyperphosphatemia, or abnormally increased levels of phosphates in the blood, occurs if there is decreased renal function or in cases of acute lymphocytic leukemia. The concentration of Ca++ in the cytoplasm is < 10–6 mmol/l but the concentration of Ca++ in the cell is much higher as calcium is taken up (and is able to be released from) cell organelles. Electrolyte balance. Overall electrolyte regulation is dependent on what and how much you eat and drink and the level of functioning of the kidneys. Hormonal regulation of fluid and electrolyte balance during exercise Fluid balance during exercise is critical for optimal metabolic, cardiovascular, and thermoregulatory function. The perfusion pressure to the adrenal gland has little direct effect on aldosterone secretion and the low blood pressure operates to control aldosterone via the renin–angiotensin system. Bicarbonate ‘s main role is to maintain the body’s acid–base balance through a buffer system. Overall electrolyte regulation is dependent on what and how much you eat and drink and the level of functioning of the kidneys. The kidney accomplishes this by altering urine volume and osmolarity. Regulation of Daily Water Input. Fluid and Electrolyte Balance. The cell sodium concentration is about 15 mmol/l, but it varies in different organs; it has an intracellular volume of 30 liters and about 400 mmol are inside the cell. The kidneys regulate the salt balance in the blood by controlling the excretion and the reabsorption of various ions. the intracellular fluid is double the size of the extracellular fluid. Atrial peptide causes the loss of sodium by the kidneys: it is secreted from the heart in high sodium states due to excess intake or cardiac disease. In the typical Australian diet, there is about 1200 mg/d of calcium. This page outlines key regulatory systems involving the kidneys for controlling volume, sodium and potassium concentrations, and the pH of bodily fluids. In an unprocessed diet potassium is much more plentiful than sodium. The acid–base status controls the distribution between plasma and cells. Severe vomiting or diarrhea will also cause a loss of chloride and bicarbonate ions. Chronic laxative abuse or severe diarrhea or vomiting (gastroenteritis) can lead to electrolyte disturbances combined with dehydration. Sodium is lost through the kidneys, sweat, and feces. Even if it was all soluble it is not all absorbed as it combines with phosphates in the intestinal secretions. Potassium is mainly an intracellular ion. The mechanisms involved in regulating water input and output are intertwined with those controlling electrolyte balance. Body water constitutes approximately 60% of total body weight in adults (a higher proportion in infants and children). Only a small amount of CO2 can be dissolved in body fluids; thus, over 90 percent of the CO2 is converted into bicarbonate ions, HCO3-, through the following reactions: The bidirectional arrows indicate that the reactions can go in either direction depending on the concentrations of the reactants and products. This change of distribution with the acid–base status means that the plasma K+ may not reflect the total body content. This page was last modified on 20 March 2014, at 11:16. Most measurements of electrolyte concentration are of the extracellular fluid such as blood or urine. Bicarbonate ions result from a chemical reaction that starts with the carbon dioxide (CO2) and water (H2O) molecules that are produced at the end of aerobic metabolism. Calcium absorption is controlled by vitamin D, and calcium excretion is controlled by the parathyroid hormones. It is usually considered that regulation of water excretion determines osmolality, and regulation of electrolyte excretion (principally NaCl) determines fluid volume; however, regulation of water excretion influences fluid volume and osmolality. Phosphate is a major constituent of the intracellular fluid, and it is important in the regulation of metabolic processes and as a buffering agent in animal cells. Any excess is excreted by the kidney and this excretion is increased by the parathyroid hormone. Water Balance (ECF/ICF volumes) 2. People suffering from bulimia or anorexia nervosa are especially at high risk for an electrolyte imbalance. Renin–angiotensin system: The regulation of sodium via the hormones renin, angiotensin, and aldosterone. Electrolytes are minerals in your body that have an electric charge. In addition, phosphate is found in phospholipids, such as those that make up the cell membrane, and in ATP, nucleotides, and buffers.
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12th November 2018