Tubuloglomerular feedback
Tubuloglomerular feedback
Tubuloglomerular feedback (pronunciation: /ˌtjuːbjuːloʊˌɡlɒməˈrʊlər ˈfiːdbæk/) is a mechanism in the kidney that involves the juxtaglomerular apparatus in regulating the glomerular filtration rate (GFR).
Etymology
The term "tubuloglomerular" is derived from the words "tubule" and "glomerulus", referring to the renal tubule and the glomerulus in the kidney, respectively. The term "feedback" is used to describe the process of information or signals returning to their source or to a point in a system or process.
Function
The tubuloglomerular feedback mechanism is responsible for maintaining a constant glomerular filtration rate in the kidneys. It does this by sensing the concentration of sodium chloride (NaCl) in the distal tubule and adjusting the diameter of the afferent arteriole and the glomerular mesangial cells, which control the filtration rate of the glomerulus.
Mechanism
When the concentration of sodium chloride in the distal tubule is high, this indicates that the glomerular filtration rate is too high. The macula densa cells in the juxtaglomerular apparatus respond by releasing adenosine, which causes the afferent arteriole to constrict and the mesangial cells to contract. This reduces the glomerular filtration rate.
Conversely, when the concentration of sodium chloride in the distal tubule is low, this indicates that the glomerular filtration rate is too low. The macula densa cells respond by releasing nitric oxide, which causes the afferent arteriole to dilate and the mesangial cells to relax. This increases the glomerular filtration rate.
Related Terms
- Juxtaglomerular apparatus
- Glomerular filtration rate
- Afferent arteriole
- Macula densa
- Mesangial cells
- Adenosine
- Nitric oxide
External links
- Medical encyclopedia article on Tubuloglomerular feedback
- Wikipedia's article - Tubuloglomerular feedback
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