Topic Resources Because sodium is the major osmotically active ion in the extracellular fluid (ECF), total body sodium content determines ECF volume. Deficiency or excess of total body sodium content causes ECF
volume depletion
Volume Depletion Volume depletion, or extracellular fluid (ECF) volume contraction, occurs as a result of loss of total body sodium. Causes include vomiting, excessive sweating, diarrhea, burns, diuretic use... read more or
volume overload
Volume Overload Volume overload generally refers to expansion of the extracellular fluid (ECF) volume. ECF volume expansion typically occurs in heart failure, kidney failure, nephrotic syndrome, and cirrhosis... read more . Serum sodium concentration does not necessarily reflect total body sodium. (See also
Water and Sodium Balance
Water and Sodium Balance Body fluid volume and electrolyte concentration are normally maintained within very narrow limits despite wide variations in dietary intake, metabolic activity, and environmental stresses. Homeostasis... read more .) Dietary intake and renal excretion
regulate total body sodium content. When total sodium content and ECF volume are low, the kidneys increase sodium conservation. When total sodium content and ECF volume are high, sodium excretion (natriuresis) increases so that volume decreases. The renin-angiotensin-aldosterone axis is the main regulatory mechanism of renal sodium excretion. In volume-depleted states, GFR and chloride delivery to the distal nephrons decreases, causing release of
renin. Renin cleaves angiotensinogen (renin substrate) to form angiotensin I. Angiotensin-converting enzyme (ACE) then cleaves angiotensin I to angiotensin II. Angiotensin II does the following: Increases sodium retention by decreasing the filtered load of sodium and enhancing proximal tubular sodium reabsorption Increases blood pressure (has pressor activity) Increases thirst Directly impairs water excretion Stimulates the adrenal cortex to secrete aldosterone, which increases sodium reabsorption via multiple renal mechanisms Several other natriuretic factors have been identified, including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and a C-type natriuretic peptide (CNP). ANP is secreted by cardiac atrial tissue. Concentration increases in response to ECF volume overload (eg, heart failure
Heart Failure (HF) Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read more
BNP is synthesized mainly in the atria and left ventricle and has similar triggers and effects to ANP. BNP assays are readily available. High BNP concentration is used to diagnose volume overload. CNP, in contrast to ANP and BNP, is primarily vasodilatory. Sodium overload requires higher sodium intake than excretion; however, because normal kidneys can excrete large amounts of sodium, sodium overload generally reflects defective regulation of renal blood flow and sodium excretion (eg, as occurs in heart failure Heart Failure (HF) Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read
more Click here for Patient Education  Copyright © 2022 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved. Which type of extracellular fluid ECF solution will cause a cell to gain water quizlet?The ECF becomes hypotonic. The ICF now has a higher osmotic pressure than the ECF. This causes the cell to gain water until the pressures are equalized. Hypertonic fluids cause water to move out of the cytosol and the cell shrinks.
What type of ECF solution will cause a cell to lose water?If a cell is placed in a hypertonic solution, there will be a net flow of water out of the cell, and the cell will lose volume. A solution will be hypertonic to a cell if its solute concentration is higher than that inside the cell, and the solutes cannot cross the membrane.
Which of the following is an excess accumulation of interstitial fluid?Edema is defined as the accumulation of excess fluid in the interstitium.
What condition accompanies Overhydration or hypotonic?Overhydration with hypotonic solutions will especially result in hyponatremia, if one of the other mechanisms is contributing as well, such as decreased circulating volume or excess ADH.
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Decreased volume and increased concentration of the extracellular fluid (ecf) is defined as:
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