Macula densa

Jump to: navigation, search

WikiDoc Resources for Macula densa

Articles

Most recent articles on Macula densa

Most cited articles on Macula densa

Review articles on Macula densa

Articles on Macula densa in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Macula densa

Images of Macula densa

Photos of Macula densa

Podcasts & MP3s on Macula densa

Videos on Macula densa

Evidence Based Medicine

Cochrane Collaboration on Macula densa

Bandolier on Macula densa

TRIP on Macula densa

Clinical Trials

Ongoing Trials on Macula densa at Clinical Trials.gov

Trial results on Macula densa

Clinical Trials on Macula densa at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Macula densa

NICE Guidance on Macula densa

NHS PRODIGY Guidance

FDA on Macula densa

CDC on Macula densa

Books

Books on Macula densa

News

Macula densa in the news

Be alerted to news on Macula densa

News trends on Macula densa

Commentary

Blogs on Macula densa

Definitions

Definitions of Macula densa

Patient Resources / Community

Patient resources on Macula densa

Discussion groups on Macula densa

Patient Handouts on Macula densa

Directions to Hospitals Treating Macula densa

Risk calculators and risk factors for Macula densa

Healthcare Provider Resources

Symptoms of Macula densa

Causes & Risk Factors for Macula densa

Diagnostic studies for Macula densa

Treatment of Macula densa

Continuing Medical Education (CME)

CME Programs on Macula densa

International

Macula densa en Espanol

Macula densa en Francais

Business

Macula densa in the Marketplace

Patents on Macula densa

Experimental / Informatics

List of terms related to Macula densa


In the kidney, the macula densa is an area of closely packed specialized cells lining the wall of the thick ascending limb of Henle (TALH) at the point of return of the nephron to the vascular pole of its parent glomerulus glomerular vascular pole.

The cells of the macula densa are sensitive to the ionic content and water volume of the fluid in the TALH, producing molecular signals that promote renin secretion by other cells of the juxtaglomerular apparatus.[1] The release of renin is an essential component of the renin-angiotensin-aldosterone system (RAAS), which regulates blood pressure and volume.

Histology

The cells of the macula densa cells are taller and have more prominent nuclei than surrounding cells of the thick ascending limb of Henle.

The close proximity and prominence of the nuclei cause this segment of the TALH wall to appear darker in microscopic preparations[2], hence the name macula densa.

Function

Schematic depicting how the RAAS works. Here, activation of the RAAS is initiated by a low perfusion pressure in the juxtaglomerular apparatus

A decrease in blood pressure results in a decreased concentration of sodium and chloride ions at the macula densa. (This is due to reduced filtration by the glomerulus: less filtrate is expelled into Bowman's space and the proximal convoluted tubule; the resulting fluid reaching the macula will have a lower sodium chloride concentration after the sodium chloride is removed along the thick ascending limb of Henle.)

In response, the macula densa cells release prostaglandins, which triggers granular juxtaglomerular cells lining the afferent arterioles to release renin into the bloodstream. (The juxtoglomerular cells can also release renin independently of the macula densa, as they are also triggered by baroreceptors lining the arterioles, and release renin if a fall in blood pressure in the arterioles is detected.) Furthermore, activation of the sympathetic nervous system stimulates renin release through activation of beta-1 receptors.

References

  1. Junqueira, Luiz C. (2003). Basic Histology. McGraw-Hill. ISBN 0071378294.  Unknown parameter |coauthors= ignored (help)
  2. Histology at Boston University 16010loa

External links

de:Macula densa

Linked-in.jpg