What is Glomerular Filtration? How is the Glomerular Filtration Rate (GFR) determined? What regulatory mechanisms help control and stabilize GFR?
Glomerular Filtration
Full Answer Section
The GFR is a measure of kidney function. A low GFR can indicate kidney disease. There are a number of regulatory mechanisms that help control and stabilize the GFR. These mechanisms include:- Autoregulation: The kidney can adjust the GFR to maintain a constant level of filtration even when the blood pressure changes.
- Hormonal regulation: Hormones such as angiotensin II and aldosterone can affect the GFR.
- Nephron adaptation: The kidneys can adapt to changes in the GFR by increasing or decreasing the number of nephrons that are functioning.
- The glomerulus is a ball of capillaries that is surrounded by a capsule called the Bowman's capsule. The blood pressure in the glomerulus is much higher than the blood pressure in the rest of the body. This high blood pressure forces water and solutes out of the blood and into the Bowman's capsule.
- The solutes that are filtered into the Bowman's capsule include water, glucose, amino acids, and electrolytes. The proteins in the blood are too large to be filtered.
- The filtered fluid then passes through the rest of the nephron, where it is further processed and eventually excreted as urine.
- The GFR is a measure of the amount of fluid that is filtered by the glomerulus each minute. It is a very important measure of kidney function. A low GFR can indicate kidney disease.
Sample Answer
Glomerular filtration is the process by which water and solutes are filtered from the blood into the nephron, the functional unit of the kidney. The glomerulus is a tuft of capillaries located in the kidney that is responsible for filtration. The GFR is the rate at which the glomerulus filters blood. The GFR is determined by a number of factors, including:- Blood pressure: The blood pressure in the glomerulus is the driving force for filtration.
- Glomerular permeability: The permeability of the glomerular membrane determines which solutes can be filtered.
- Protein concentration: The concentration of proteins in the blood affects the GFR. Proteins are too large to be filtered, so their concentration in the blood determines the amount of water that can be filtered.