Glomerular hydrostatic pressure

To determine the protein concentration Ce in the efferent blood we assume that filtration equilibrium is established before the blood leaves the glomerular capillaries, i.e., that the glomerular hydrostatic pressure minus the efferent colloid osmotic pressure Posm equals the tubular pressure. The experimentally determined relation between the colloid osmotic pressure and the protein concentration C can be described as [16] ... 

Glomerular filtration rate (GFR) is the volume of plasma-like fluid that is filtered per unit time across the glomerular capillary membranes to enter the tubular space. Filtrate formation is driven by the net filtration pressure that is equal to the capillary hydrostatic pressure diminished by the sum of capillary oncotic... 

Glomerular capillary pressure (PGC) is a hydrostatic pressure that pushes blood out of the capillary. The blood pressure in these capillaries is markedly different from that of typical capillaries. In capillaries elsewhere in the body, blood pressure at the arteriolar end is about 30 mmHg and at the venular end is about 10 mmHg (see Chapter 15). These pressures lead to the net filtration of fluid at the inflow end of the capillary and net reabsorption of fluid at the outflow end. 

Figure 29.3. (A) Glomerular capillaries are positioned between two arterioles that regulate hydrostatic pressure and blood flow through the capillaries, thereby controlling glomerular filtration rate. (B) The glomerular basement membrane consists of three layers the capillary endothelium, the capillary basement membrane, and podocytes from epithelial cells of Bowman s capsule. The capillary basement membrane also contains three layers the lamina rara interna (blood side), lamina densa, and lamina rara externa (epithelial side). (From Guyton, A. C., and Hall, J. E. Textbook of Medical Physiology, 11th ed. Elsevier Saunders Company, Philadelphia, 2006. Reproduced with permission.)...

Pccap = glomerular-capillary hydrostatic pressure IIbc - oncotic pressure in Bowman s capsule Pbc = hydrostatic pressure in Bowman s capsule Ifccap - oncotic pressure in the glomerular capillary... 

Angiotensin-converting enzyme inhibitors and nonsteroidal anti-inflammatory drugs are associated with hemodynamically-mediated renal failure, the pathogenesis of which is a decrease in glomerular capillary hydrostatic pressure. 

FIGURE 46-2. Normal glomerular autoregulation serves to maintain intraglomerular capillary hydrostatic pressure, glomerular filtration rate (GFR), and ultimately, urine output. This is accomplished by modulation of afferent and efferent arterioles. Afferent and efferent arteriolar vasoconstriction are primarily mediated by angiotensin II, whereas afferent vasodilation is primarily mediated by prostaglandins. 

The glomerular capillary wall is particularly susceptible to immune-mediated injury. Antigen and antibody tend to localize in the glomerulus, probably because of its high blood flow and capillary hydrostatic pressure. Parenchymal damage can be induced as a result of humoral- and cell-mediated immune reactions (Table 47-1). Antibodies and sensitized T lymphocytes are the primary mediators of glomerular injury. ... 

Heart failure results in edema either because of increased hydrostatic pressure in capillaries or because of a compensatory renal mechanism. As the effective output of the heart decreases, renal flow, and therefore glomerular filtration, also decrease. Reabsorption of sodium and water is more complete, resulting in increased tissue retention of both substances. Digitalis has a diuretic effect to the extent that it relieves the underlying factors in the heart. 

Blood is returned to the heart via series of veins connecting to the renal vein and then to vena cava. Renal perfusion with nutrients and oxygen is essentially for normal renal functions and this is dependent on adequate renal blood flow. This balance is controlled by several factors, including systemic blood pressure, glomerular capillary hydrostatic pressure, afferent/efferent arteriolar vasoconstriction, edema, plasma total protein and albumin concentration, glomerular ultraflltration rates, and permeability—all of which also will affect the glomerular filtration rate. 

Urine formation involves glomerular filtration, reabsorption, and tubular secretion. The capillaries of the glomeruli are inserted between two arteries. The hydrostatic pressure and the permeability of the glomeru-... 

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