Edema excess fluid in the tissues – medical nail yeast infection physiology

Two conditions are especially prone to cause intracel-lular swelling: (1) depression of the metabolic systems of the tissues, and (2) lack of adequate nutrition to the cells. For example, when blood flow to a tissue is decreased, the delivery of oxygen and nutrients is reduced. If the blood flow becomes too low to maintain normal nail yeast infection tissue metabolism, the cell membrane ionic pumps become depressed. When this occurs, sodium ions that normally leak into the interior of the nail yeast infection cell can no longer be pumped out of the cells, and the excess sodium ions inside the cells cause osmosis nail yeast infection of water into the cells. Sometimes this can increase intra-cellular volume of a tissue area—even of an entire ischemic leg, for example—to two to three times normal. When this occurs, it is usually a prelude to death of the tissue.

Intracellular edema can also occur in inflamed tissues. Inflammation usually has a direct effect on the cell membranes nail yeast infection to increase their permeability, allowing sodium and other ions to diffuse into the interior nail yeast infection of the cell, with subsequent osmosis of water into the cells. Extracellular edema

Extracellular fluid edema occurs when there is excess fluid accumulation nail yeast infection in the extracellular spaces. There are two general causes of extracellular edema: (1) abnormal leakage of fluid from the plasma to the interstitial nail yeast infection spaces across the capillaries, and (2) failure of the lymphatics to return fluid from the interstitium nail yeast infection back into the blood. The most common clinical cause of interstitial fluid accumulation is nail yeast infection excessive capillary fluid filtration. Factors that can increase capillary filtration

Filtration = kf x (pc – pif – pc + pif), where kf is the capillary filtration coefficient (the product of the permeability and surface area of the nail yeast infection capillaries), pc is the capillary hydrostatic pressure, pif is the interstitial fluid hydrostatic pressure, pc is the capillary plasma colloid osmotic pressure, and pif is the interstitial fluid colloid osmotic pressure. From this equation, one can see that any one of the following changes nail yeast infection can increase the capillary filtration rate:

When lymphatic blockage occurs, edema can become especially severe because plasma proteins that leak nail yeast infection into the interstitium have no other way to be removed. The rise in protein concentration raises the colloid osmotic pressure nail yeast infection of the interstitial fluid, which draws even more fluid out of the capillaries.

Blockage of lymph flow can be especially severe with infections nail yeast infection of the lymph nodes, such as occurs with infection by filaria nematodes. Blockage of the lymph vessels can occur in certain types nail yeast infection of cancer or after surgery in which lymph vessels are nail yeast infection removed or obstructed. For example, large numbers of lymph vessels are removed during radical mastectomy, impairing removal of fluid from the breast and arm areas nail yeast infection and causing edema and swelling of the tissue spaces. A few lymph vessels eventually regrow after this type of nail yeast infection surgery, so that the interstitial edema is usually temporary. Summary of causes of extracellular edema

A large number of conditions can cause fluid accumulation in nail yeast infection the interstitial spaces by the abnormal leaking of fluid from nail yeast infection the capillaries or by preventing the lymphatics from returning fluid nail yeast infection from the interstitium back to the circulation. The following is a partial list of conditions that can nail yeast infection cause extracellular edema by these two types of abnormalities: I. Increased capillary pressure

Edema caused by heart failure. One of the most serious and most common causes of nail yeast infection edema is heart failure. In heart failure, the heart fails to pump blood normally from the veins nail yeast infection into the arteries; this raises venous pressure and capillary pressure, causing increased capillary filtration. In addition, the arterial pressure tends to fall, causing decreased excretion of salt and water by the kidneys, which increases blood volume and further raises capillary hydrostatic pressure nail yeast infection to cause still more edema. Also, diminished blood flow to the kidneys stimulates secretion of renin, causing increased formation of angiotensin II and increased secretion of nail yeast infection aldosterone, both of which cause additional salt and water retention by nail yeast infection the kidneys. Thus, in untreated heart failure, all these factors acting together cause serious generalized extracellular edema.

In patients with left-sided heart failure but without significant failure of the right nail yeast infection side of the heart, blood is pumped into the lungs normally by the right nail yeast infection side of the heart but cannot escape easily from the nail yeast infection pulmonary veins to the left side of the heart because nail yeast infection this part of the heart has been greatly weakened. Consequently, all the pulmonary vascular pressures, including pulmonary capillary pressure, rise far above normal, causing serious and life-threatening pulmonary edema. When untreated, fluid accumulation in the lungs can rapidly progress, causing death within a few hours.

As discussed earlier, most sodium chloride added to the blood remains in the nail yeast infection extracellular compartment, and only small amounts enter the cells. Therefore, in kidney diseases that compromise urinary excretion of salt and nail yeast infection water, large amounts of sodium chloride and water are added to nail yeast infection the extracellular fluid. Most of this salt and water leaks from the blood nail yeast infection into the interstitial spaces, but some remains in the blood. The main effects of this are to cause (1) widespread increases in interstitial fluid volume (extracellular edema) and (2) hypertension because of the increase in blood volume, as explained in chapter 19. As an example, children who develop acute glomerulonephritis, in which the renal glomeruli are injured by inflammation and nail yeast infection therefore fail to filter adequate amounts of fluid, also develop serious extracellular fluid edema in the entire body; along with the edema, these children usually develop severe hypertension.

Edema caused by decreased plasma proteins. A reduction in plasma concentration of proteins because of either nail yeast infection failure to produce normal amounts of proteins or leakage of nail yeast infection proteins from the plasma causes the plasma colloid osmotic pressure nail yeast infection to fall. This leads to increased capillary filtration throughout the body as nail yeast infection well as extracellular edema.

One of the most important causes of decreased plasma protein nail yeast infection concentration is loss of proteins in the urine in certain nail yeast infection kidney diseases, a condition referred to as nephrotic syndrome. Multiple types of renal diseases can damage the membranes of nail yeast infection the renal glomeruli, causing the membranes to become leaky to the plasma proteins nail yeast infection and often allowing large quantities of these proteins to pass nail yeast infection into the urine. When this loss exceeds the ability of the body to nail yeast infection synthesize proteins, a reduction in plasma protein concentration occurs. Serious generalized edema occurs when the plasma protein concentration falls nail yeast infection below 2.5 g/100 ml.

Cirrhosis of the liver is another condition that causes a nail yeast infection reduction in plasma protein concentration. Cirrhosis means development of large amounts of fibrous tissue among nail yeast infection the liver parenchymal cells. One result is failure of these cells to produce sufficient nail yeast infection plasma proteins, leading to decreased plasma colloid osmotic pressure and the generalized nail yeast infection edema that goes with this condition.

Another way that liver cirrhosis causes edema is that the nail yeast infection liver fibrosis sometimes compresses the abdominal portal venous drainage vessels nail yeast infection as they pass through the liver before emptying back into nail yeast infection the general circulation. Blockage of this portal venous outflow raises capillary hydrostatic pressure nail yeast infection throughout the gastrointestinal area and further increases filtration of fluid nail yeast infection out of the plasma into the intra-abdominal areas. When this occurs, the combined effects of decreased plasma protein concentration and high nail yeast infection portal capillary pressures cause transudation of large amounts of fluid nail yeast infection and protein into the abdominal cavity, a condition referred to as ascites.

Tissues with relatively small additional increases in interstitial fluid hydrostatic nail yeast infection pressure. Thus, in the positive tissue pressure range, this safety factor against edema is lost because of the nail yeast infection large increase in compliance of the tissues. Safety factors that normally prevent edema

Even though many disturbances can cause edema, usually the abnormality must be severe before serious edema develops. The reason for this is that three major safety factors nail yeast infection prevent excessive fluid accumulation in the interstitial spaces: (1) low compliance of the inter-stitium when interstitial fluid pressure is in the negative pressure nail yeast infection range, (2) the ability of lymph flow to increase 10- to 50-fold, and (3) washdown of interstitial fluid protein concentration, which reduces interstitial fluid colloid osmotic pressure as capillary filtration nail yeast infection increases.

In chapter 16, we noted that interstitial fluid hydrostatic pressure in most loose nail yeast infection subcutaneous tissues of the body is slightly less than atmospheric nail yeast infection pressure, averaging about -3 mm hg. This slight suction in the tissues helps hold the tissues nail yeast infection together. Figure 25-7 shows the approximate relations between different levels of interstitial nail yeast infection fluid pressure and interstitial fluid volume, as extrapolated to the human being from animal studies. Note in figure 25-7 that as long as the interstitial fluid pressure is nail yeast infection in the negative range, small changes in interstitial fluid volume are associated with relatively nail yeast infection large changes in interstitial fluid hydrostatic pressure. Therefore, in the negative pressure range, the compliance of the tissues, defined as the change in volume per millimeter of mercury nail yeast infection pressure change, is low.

How does the low compliance of the tissues in the nail yeast infection negative pressure range act as a safety factor against edema? To answer this question, recall the determinants of capillary filtration discussed previously. When interstitial fluid hydrostatic pressure increases, this increased pressure tends to oppose further capillary filtration. Therefore, as long as the interstitial fluid hydrostatic pressure is in nail yeast infection the negative pressure range, small increases in interstitial fluid volume cause relatively large increases nail yeast infection in interstitial fluid hydrostatic pressure, opposing further filtration of fluid into the tissues.

Because the normal interstitial fluid hydrostatic pressure is -3 mm hg, the interstitial fluid hydrostatic pressure must increase by about 3 nail yeast infection mm hg before large amounts of fluid will begin to nail yeast infection accumulate in the tissues. Therefore, the safety factor against edema is a change of interstitial nail yeast infection fluid pressure of about 3 mm hg.

Importance of interstitial gel in preventing fluid accumulation in the nail yeast infection interstitium. Note in figure 25-7 that in normal tissues with negative interstitial fluid pressure, virtually all the fluid in the interstitium is in gel nail yeast infection form. That is, the fluid is bound in a proteoglycan meshwork so that nail yeast infection there are virtually no "free" fluid spaces larger than a few hundredths of a micrometer nail yeast infection in diameter. The importance of the gel is that it prevents fluid nail yeast infection from flowing easily through the tissues because of impediment from nail yeast infection the "brush pile" of trillions of proteoglycan filaments. Also, when the interstitial fluid pressure falls to very negative values, the gel does not contract greatly because the meshwork of nail yeast infection proteoglycan filaments offers an elastic resistance to compression. In the negative fluid pressure range, the interstitial fluid volume does not change greatly, regardless of whether the degree of suction is only a nail yeast infection few millimeters of mercury negative pressure or 10 to 20 nail yeast infection mm hg negative pressure. In other words, the compliance of the tissues is very low in the nail yeast infection negative pressure range.

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