What is the Renal Corpuscle?
An average human being has two kidneys which play a vital role in removing excess water, salts, and nitrogen waste from the body. Kidneys are covered by connective tissue capsule, and each kidney has two portions. The outer portion is referred to as the renal cortex, and the inner portion is the renal medulla. The functional unit of a kidney is referred to as the nephron, which is a coiled tubule made of a single cell layer. Each nephron includes the renal corpuscle, proximal convoluted tubule, the loop of Henle, distal convoluted tubule, and collecting duct. Each kidney may contain up to 1 to 4 million nephrons.
The renal corpuscle, also referred as the Malpighian corpuscle or body, is composed of the glomerulus and Bowman's capsule. Bowman's capsule is a cup-shaped structure that encloses a bunch of high-pressure capillaries referred to as glomerulus. Bowman's capsule is connected to a long tubule known as the proximal convoluted tubule. Generally, nephrons play a role in blood cleansing and maintaining a balance of blood constituents, including salt and nutrients. In addition, the renal corpuscle comprises vascular, mesangial, and epithelial components. The renal corpuscle is contained in the renal cortex portion of the kidney.
Renal Corpuscle Anatomy
Glomerulus and the Bowman's capsule are the main components of the renal corpuscle, though the mesangium is also a part.
The glomerulus is a network of capillaries. It is supplied by the afferent arteriole and emptied by the efferent arteriole. The afferent arteriole has a broader diameter than the efferent arteriole, which helps maintain a high pressure inside the glomerulus. The glomerulus capillaries have endothelial cells covered by a basement membrane. A basement membrane is a specialized extracellular matrix that is thin and complex, and it is essential in numerous body tissues arrangement, development, and maintenance. This basement membrane is surrounded by a particular type of cells known as podocytes. The basement membrane, attachment apparatus of podocytes (also known as podocytes foot processes), and the capillaries endothelium form the filtration barrier.
The Bowman's capsule is formed during embryonic development. It results from the pression of the glomerular capillaries against the closed end of the proximal convoluted tubule. The outer surface of this cup-like structure is made of parietal epithelium cells - flat, scale-like cells, also referred to as squamous epithelium cells. The podocytes form the visceral layer of the Bowman's capsule. These podocytes develop from the thickening of the epithelial cells that are in contact with the glomerular capillaries. There is a space between the visceral and parietal layers known as Bowman's space. This space forms the proximal convoluted tubule's lumen (inside space) from one end. This space also contains the renal filtrate, the fluid that eventually becomes the urine.
In addition, the renal corpuscle has another component known as the mesangium, an arborizing (branch freely and differently) structure comprised of mesangial matrix and mesangial cells. The mesangial cells are located adjacent to the glomerular capillaries, and they possess the ability to contract. Mesangial cells play several vital roles such as:
- It provides structural support of the glomerular capillaries.
- Production of immune systems proteins such as pro-inflammatory cytokines and prostaglandins.
- In addition, they also get rid of macromolecules within the mesangium through phagocytosis. Phagocytosis involves the ingestion and elimination of molecules or particles.
- These cells are also involved in the production of the extracellular matrix.
Some of the mesangial cells are located outside the glomerulus, i.e., they are found between the efferent and afferent arterioles. Such mesangial cells are referred to as extraglomerular mesangial cells.
Renal Corpuscle Diagram
The renal corpuscle comprises the glomerulus and Bowman's capsule, as shown in the diagram below. The afferent arteriole supplies the glomerulus while the efferent arteriole empties it.
Renal Corpuscle Function
The renal corpuscle is involved in the production of urine, where it plays a role in the filtration of the blood. Several features and components of the renal corpuscle make filtration of the blood possible. Some of these adaptations and features include:
1. The blood in the glomerular capillaries is supplied by an afferent arteriole and drained by an efferent arteriole. These two arterioles vary in size, with efferent arteriole having a smaller diameter than afferent arteriole. This creates a high pressure within the glomerular capillaries that facilitates the filtration process.
2. The endothelium of the glomerular capillaries is fenestrated, i.e., it is made up of pores that are 700 angstroms in size. These pores are referred to as fenestrae, and they are selectively permeable. Therefore, they only allow certain materials or substances to pass through them. For instance, water, creatinine, small proteins, and solutes such as sodium ions, urea, and glucose pass through these pores. However, blood cells (red blood cells, white blood cells, platelets) and large proteins cannot go through these pores. This phenomenon is mainly known as size exclusion filtration.
3. The podocytes and the basement membrane are separated from each other through gaps known as filtration slits. These slits play a role in size-selective filtration, where they minimize the filtration of proteins and large molecules that have already passed the basement membrane from entering the Bowman's space.
4. The ability of the mesangial cells to contract also regulates the glomerular filtration rate. This can be either through alteration of the glomerular capillaries surface area or blood flow regulation in the capillaries.
Kidneys are covered by connective tissue capsule, and each kidney has two portions. The outer portion is referred to as the renal cortex, while the inner portion is the renal medulla. The functional unit of a kidney is referred to as the nephron. Each nephron comprises renal corpuscle, proximal convoluted tubule, the loop of Henle, distal convoluted tubule, and collecting duct. The renal corpuscle is composed of the glomerulus and Bowman's capsule. The renal corpuscle is also referred to as the Malpighian corpuscle or body.
The glomerulus is a network of capillaries supplied by the afferent arteriole and emptied by the efferent arteriole. The capillaries of the glomerulus have endothelial cells that are covered by a basement membrane. Podocytes surround the basement membrane. The basement membrane, attachment apparatus of podocytes (also known as podocytes foot processes), and the capillaries endothelium form the filtration barrier. Bowman's capsule is a cup-shaped structure that encloses the glomerulus. The renal corpuscle is involved in blood filtration. The endothelium of the glomerular capillaries has pores that are referred to as fenestrae that allows selective filtration. Water, creatinine, small proteins, and solutes such as sodium ions, urea, and glucose pass through these pores. However, red blood cells, white blood cells, platelets, and large proteins cannot go through these pores. This type of filtration is referred to as size exclusion filtration.
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What structure is in the renal corpuscle?
The renal corpuscle is a structure comprised of the glomerulus and Bowman's capsule. The glomerulus is a bunch of capillaries, while the Bowman's capsule is a cup-shaped structure that encloses these capillaries.
What is the renal corpuscle's function?
The renal corpuscle is one of the nephron components. It is made up of the glomerulus and the Bowman's capsule. In addition, the renal corpuscle also has mesangium as its component. It helps to filter waste from the body.
What is the main function of the glomerular capsule?
The glomerular capsule is also referred to as the Bowman's capsule. It has a space known as the Bowman's space where the renal filtrate collects. This capsule also encloses the glomerulus, which performs the filtration of the blood.
Where do you find the renal corpuscles?
Renal corpuscles are contained in the renal cortex portion of the kidney. A kidney has two portions, the outer portion (renal cortex) and the inner (renal medulla).
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