What are Renal Pyramids?
Renal pyramids (RP) are structures found in all kidney tissue. They consist of several layers: the outermost layer, which contains the glomeruli; the middle layer, containing tubules and filiform cells; and finally, the innermost layer, where most of the blood supply passes through. RP have been described in various organs such as liver, heart and brain. However, their exact functions remain unknown.
The term “pyramid” was first used to describe the structure of the human body when it was discovered that the kidneys were one of its main components. This discovery led to a better understanding of how these tissues work together and how they respond to different stimuli. Today, RP are known in many parts of the body including skin, lungs, gastrointestinal tract and other internal organs.
They are even found in some animals like insects and crustaceans.
How do Renal Pyramids Work?
In order to understand how RP work, it is necessary to look at them from the inside out. There are two major types of cells in the kidney: tubular epithelial cells (TECs), which make up the majority of these cells, and filiform cells (FCs).
Filiform cells have a large surface area and are supported by their surrounding TECs. They provide a protective barrier around the blood vessels in the RP, which makes filiform cells ideal for regeneration purposes. They typically live for about 20 days before they are replaced by new filiform cells.
Tubular epithelial cells make up the majority of the tubular region of the kidney. These cells are highly specialized since they can re-divide themselves and form new TECs. These new TECs are used to replace dying TECs elsewhere in the renal papilla.
The renal medulla is the inner region of the kidney, which contains a high concentration of blood vessels. The renal papilla is located at the peak of the “pyramid” and is where urine is stored before it is released into the ureters. The renal pelvis is the bottom part of the “pyramid”.
It has thick walls and is used to store urine between releases.
There are many factors affecting the way the kidney functions, such as age, diet and even genetics. In general, the renal system has a large degree of regeneration capabilities and can compensate for changes in metabolic rate. This makes it possible for these organs to handle a wide variety of waste substances.
What does Renal Pyramids Comprise?
The tubular epithelium is the most important constituent of the renal pyramid. Since this tissue has the ability to regenerate itself, it is possible to find several types of cells in the pyramids, each with a specific function. The glomerular filtration is regulated by these filiform cells, while the distal and proximal convoluted tubules are lined by TECs.
Sources & references used in this article:
Renal pyramids: focused sonography of normal and pathologic processes by A Daneman, OM Navarro, GR Somers, A Mohanta… – Radiographics, 2010 – pubs.rsna.org
Cystic disease of the renal pyramids by WP Mulvaney, WT Collins – The Journal of urology, 1956 – auajournals.org
Echogenic renal pyramids in children by S Jequier, BS Kaplan – Journal of clinical ultrasound, 1991 – Wiley Online Library
Renal cortical nephrocalcinosis by D Schepens, G Verswijvel, D Kuypers… – Nephrology Dialysis …, 2000 – academic.oup.com