Question: What Two Pressures Oppose Filtration And What Are Their Values?

What factors affect filtration rate?

Factors Affecting Filtration Rates and Cake MoisturesParticle Size of Solids.Ratio of slimes to coarser particles.Filter aids.Feed solids concentration.Filter Thickening.Slurry pH.Flocculation/Dispersion of fine solids.Slurry Age.More items…•.

How do we calculate GFR?

eGFR is estimated GFR calculated by the abbreviated MDRD equation : 186 x (Creatinine/88.4)-1.154 x (Age)-0.203 x (0.742 if female) x (1.210 if black). If you have an eGFR value calculated by a local laboratory, use that.

What drives filtration through a membrane?

Glomerular filtration is a process of bulk flow driven by the hydrostatic pressure of the blood. Small molecules pass rapidly through the filtration membrane, while large proteins and blood cells are kept out of the capsular space.

What does the filtration membrane consist of?

Pathophysiology/Pathogenesis. The glomerular filtration barrier consists of the fenestrated endothelium, the glomerular basement membrane, and the podocyte foot processes, which are connected by a slit-diaphragm.

Which of the following pressures oppose glomerular filtration?

Hydrostatic pressure is the glomerulus is the main driver for filtration to occur, which is opposed by the plasma osmotic pressure. Capsular hydrostatic pressure also opposes glomerular filtration.

What is effective filtration pressure?

The effective filtration pressure (EFP) is the total pressure that promotes filtration, is determine as follows: Glomerular blood hydrostatic pressure minus the colloidal osmotic pressure of blood and capsular hydrostatic pressure.

How does pressure affect filtration rate?

The glomerular filtration rate is directly proportional to the pressure gradient in the glomerulus, so changes in pressure will change GFR. GFR is also an indicator of urine production, increased GFR will increase urine production, and vice versa.

What three driving forces determine glomerular filtration rate?

glomerular filtration rate (GFR) – The total amount of plasma filtrate formed by all the nephrons of the kidneys per minute; it is determined physiologically by three factors: (1) the total surface area available for filtration, (2) the permeability of the filtration membrane, and (3) the net filtration pressure; …

What is tubular reabsorption?

Tubular reabsorption is the process that moves solutes and water out of the filtrate and back into your bloodstream. This process is known as reabsorption, because this is the second time they have been absorbed; the first time being when they were absorbed into the bloodstream from the digestive tract after a meal.

What force drives filtration at the glomerulus?

outward pressureThe rate at which kidneys filter blood is called the glomerular filtration rate. The main driving force for the filtering process, or outward pressure is the blood pressure as it enters the glomerulus.

What is the Bowman’s capsule?

Bowman’s capsule is a part of the nephron that forms a cup-like sack surrounding the glomerulus. Bowman’s capsule encloses a space called “Bowman’s space,” which represents the beginning of the urinary space and is contiguous with the proximal convoluted tubule of the nephron.

What is the main factor that determines the rate of glomerular filtration?

Renal blood flow is 3- to 5-fold greater than the perfusion to other organs because it drives glomerular capillary filtration. Both glomerular capillary hydrostatic pressure and renal blood flow are important determinants of the glomerular filtration rate (GFR).

What is normal GFR for age?

Following the classical way, we can assert that normal GFR values are largely over 60 mL/min/1.73 m2 in healthy subjects, at least before the age of 70 years. However, we know that GFR physiologically decreases with age, and in adults older than 70 years, values below 60 mL/min/1.73 m2 could be considered normal.

When the net filtration pressure is negative?

The net driving force (NDF) for fluid movement is the net pressure gradient determined by the sum of the individual hydrostatic and oncotic pressures, and is expressed in the units of mmHg. When the NDF is positive, there is net fluid filtration, and when it is negative, there is net fluid reabsorption.

What is kidney hydrostatic pressure?

Hydrostatic pressure is the pressure produced by a fluid against a surface. The blood inside the glomerulus creates glomerular hydrostatic pressure which forces fluid out of the glomerulus into the glomerular capsule.

What are the three components of the filtration membrane at the glomerulus?

This barrier has three major components: the fenestrated endothelial cell, the glomerular basement membrane (GBM), and the podocyte with their “slit diaphragms”.

What is the normal net filtration pressure?

NET FILTRATION PRESSURE (NFP) is the total pressure that promotes filtration. To calculate NFP, we subtract the forces that oppose filtration from the GBHP. A normal NFP (using the figures mentioned) would be: NFP=55-(15+30)=55-45=10mm Hg.

What increases Net filtration pressure?

The net filtration pressure is determined by the balance of the Starling forces (the hydrostatic pressure and the oncotic pressure within the glomerular capillaries and Bowman’s capsule). … An increase in renal arterial pressure (or renal blood flow) causes an increase in GFR.