Glomerular Filtration Rate

Definition

Glomerular filtration rate (GFR) is a measure of the kidney's ability to filter waste and excess water from the blood. It represents the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit of time and is a key indicator of kidney function.

5 Must Know Facts For Your Next Test

1. Glomerular filtration rate is the best overall indicator of kidney function and is used to detect, evaluate, and monitor kidney disease.
2. GFR is influenced by factors such as renal blood flow, glomerular hydrostatic pressure, and the permeability of the glomerular membrane.
3. A normal GFR range is 90-120 mL/min/1.73m^2 in young adults, but it decreases with age and other factors like chronic kidney disease.
4. Decreased GFR can lead to the accumulation of waste products in the blood, which can have serious health consequences if left untreated.
5. Measurement of GFR is important for dosing medications that are primarily eliminated by the kidneys and for monitoring the progression of kidney disease.

Review Questions

• Explain the relationship between glomerular filtration rate and the microscopic anatomy of the kidney.
  • The glomerular filtration rate is directly related to the microscopic anatomy of the kidney, specifically the glomeruli. The glomeruli are the site of the initial filtration of blood, where water and small solutes pass through the glomerular capillaries and into Bowman's capsule to form the primary urine. The number, size, and permeability of the glomeruli, as well as the renal blood flow, are key determinants of the glomerular filtration rate and overall kidney function.
• Describe how the glomerular filtration rate is involved in the physiology of urine formation.
  • The glomerular filtration rate is a crucial component of the physiology of urine formation. The filtered fluid that enters Bowman's capsule from the glomeruli becomes the primary urine, which then undergoes further modification as it passes through the renal tubules. The rate at which this filtration occurs, as measured by the GFR, determines the volume and composition of the final urine. A decreased GFR can lead to the retention of waste products and excess water, which can disrupt the body's homeostasis and contribute to the development of kidney disease.
• Analyze how the regulation of renal blood flow impacts the glomerular filtration rate and the urinary system's role in homeostasis.
  • The regulation of renal blood flow is a key factor in determining the glomerular filtration rate. Factors such as blood pressure, sympathetic nervous system activity, and the release of hormones like angiotensin II can influence renal blood flow and, consequently, the GFR. Changes in GFR affect the kidney's ability to filter waste and maintain fluid and electrolyte balance, which are essential for overall homeostasis. A decrease in GFR, as seen in kidney disease, can lead to the accumulation of waste products in the blood and disruptions in fluid and electrolyte levels, impacting the urinary system's role in regulating the body's internal environment. Therefore, the regulation of renal blood flow and its impact on GFR is a critical component in understanding the urinary system's contribution to homeostasis.

Related terms

Glomerulus: The glomerulus is the network of capillaries in the renal cortex of the kidney where the initial filtration of blood occurs to form the primary urine.

Bowman's Capsule:

Bowman's capsule is a cup-shaped structure that surrounds the glomerulus and receives the filtered fluid, which then becomes the primary urine.

Renal Blood Flow:

Renal blood flow is the volume of blood flowing through the kidneys per unit of time and is a crucial factor in determining the glomerular filtration rate.