The kidneys : Human kidneys viewed from behind with the spine removed. Resting on top of each kidney is an adrenal gland adrenal meaning on top of renal , which are involved in some renal system processes despite being a primarily endocrine organ. The upper parts of the kidneys are partially protected by lower ribs, and each whole kidney and adrenal gland are surrounded by two layers of fat the perirenal and pararenal fat and the renal fascia. The kidneys are located at the rear wall of the abdominal cavity just above the waistline and are protected by the ribcage.
They are considered retroperitoneal, which means that they lie behind the peritoneum, the membrane lining of the abdominal cavity. There are a number of important external structures connecting the kidneys to the rest of the body. The renal artery branches off from the lower part of the aorta and provides the blood supply to the kidneys. Renal veins take blood away from the kidneys into the inferior vena cava. The ureters are structures that come out of the kidneys, bringing urine downward into the bladder.
The cortex and medulla make up two of the internal layers of a kidney and are composed of individual filtering units known as nephrons. The renal cortex is a space between the medulla and the outer capsule. The renal medulla contains the majority of the length of nephrons, the main functional component of the kidney that filters fluid from blood.
The renal pelvis connects the kidney with the circulatory and nervous systems from the rest of the body. The kidneys are surrounded by a renal cortex, a layer of tissue that is also covered by renal fascia connective tissue and the renal capsule. The renal cortex is granular tissue due to the presence of nephrons—the functional unit of the kidney—that are located deeper within the kidney, within the renal pyramids of the medulla.
The cortex provides a space for arterioles and venules from the renal artery and vein, as well as the glomerular capillaries, to perfuse the nephrons of the kidney.
Erythropotein, a hormone necessary for the synthesis of new red blood cells, is also produced in the renal cortex. Kidney structure : The kidney is made up of three main areas: the outer cortex, a medulla in the middle, and the renal pelvis. The medulla is the inner region of the parenchyma of the kidney. The medulla consists of multiple pyramidal tissue masses, called the renal pyramids, which are triangle structures that contain a dense network of nephrons.
It surrounds a tuft of capillaries called the glomerulus that carries blood from the renal arteries into the nephron, where plasma is filtered through the capsule.
After entering the capsule, the filtered fluid flows along the proximal convoluted tubule to the loop of Henle and then to the distal convoluted tubule and the collecting ducts, which flow into the ureter. Each of the different components of the nephrons are selectively permeable to different molecules, and enable the complex regulation of water and ion concentrations in the body. The renal pelvis contains the hilium. The hilum is the concave part of the bean-shape where blood vessels and nerves enter and exit the kidney; it is also the point of exit for the ureters—the urine-bearing tubes that exit the kidney and empty into the urinary bladder.
The renal pelvis connects the kidney to the rest of the body. Because the kidney filters blood, its network of blood vessels is an important component of its structure and function. The arteries, veins, and nerves that supply the kidney enter and exit at the renal hilum. The renal arteries branch off of the abdominal aorta and supply the kidneys with blood. The arterial supply of the kidneys is variable from person to person, and there may be one or more renal arteries supplying each kidney.
Due to the position of the aorta, the inferior vena cava, and the kidneys in the body, the right renal artery is normally longer than the left renal artery. The renal arteries carry a large portion of the total blood flow to the kidneys—up to a third of the total cardiac output can pass through the renal arteries to be filtered by the kidneys. Renal blood supply starts with the branching of the aorta into the renal arteries which are each named based on the region of the kidney they pass through and ends with the exiting of the renal veins to join the inferior vena cava.
The renal arteries split into several segmental arteries upon entering the kidneys, which then split into several arterioles. The renal veins are the veins that drain the kidneys and connect them to the inferior vena cava. The renal vein drains blood from venules that arise from the interlobular capillaries inside the parenchyma of the kidney. The renal plexus are the source of nervous tissue innervation within the kidney, which surround and primarily alter the size of the arterioles within the renal cortex.
Input from the sympathetic nervous system triggers vasoconstriction of the arterioles in the kidney, thereby reducing renal blood flow into the glomerulus. The kidney also receives input from the parasympathetic nervous system, by way of the renal branches of the vagus nerve cranial nerve X , which causes vasodilation and increased blood flow of the afferent arterioles.
Due to this mechanism, sympathetic nervous stimulation will decrease urine production, while parasympathetic nervous stimulation will increase urine production.
Blood supply to the kidneys : The renal arteries branch off of the abdominal aorta and supply the kidneys with blood. The nephron of the kidney is involved in the regulation of water and soluble substances in blood. Renal medulla refers to the inner-most part of the kidney.
It is composed of renal pyramids. Renal pyramids are triangular structures, which consist of densely-packed network of nephron structures. The loops of Henle and the collecting tubules are located in the renal pyramids of the renal medulla. The U-shaped portion of a nephron is called the loop of Henle.
It re-filters water, sodium ions, and chloride ions from the filtrate. Renal medulla also contains collecting tubules of the nephrons. Collecting tubules concentrate the final filtrate or urine and transport it to the renal calyces. The distribution of a nephron in the renal cortex and medulla is shown in figure 2. Since both loop of Henle and collecting tubules reabsorb water from urine, the length of these structures determines the amount of water that is going to be absorbed from the urine.
If the two types of tubules are lengthy, a high amount of water is going to be absorbed from the urine. Renal Cortex: Renal Cortex refers to the part of the kidney that contains the glomeruli and the proximal and distal convoluted tubules. Renal Medulla: Renal medulla refers to the inner-most part of the kidney which is mainly composed of collecting tubules.
Renal Cortex: Renal cortex is the outer layer of the kidney, situated between the renal capsule and renal medullas. Renal Medulla: Renal medulla is the inner-most layer of the kidney. Renal Cortex: Renal cortex is pale brown or reddish color.
Renal Medulla: Renal medulla is dark, reddish-brown in color. The renal medulla contains the parts of the structures of the nephron which are responsible for maintaining the water and salt balance of the blood. These structures include vasa rectae, venular rectae, medullary capillary plexus, the loop of Henle and the collecting tubule. The renal medulla is hypertonic to the filtrate in the nephron that aids in maintaining water balance by the reabsorption of water.
Due to this, the water will be extracted through the tubule walls into the medulla. This process conserves most of the water in the body. So, the renal medulla is very important to maintain the salt and water balance in the body. The kidney is a bean-shaped, extremely important organ in the body. It is located just below the rib cage. The function of the kidney is to filter blood daily to produce urine that contains waste and extra fluids.
And from the bladder, these urines will be excreted out of the body through the urethra. It is divided into smaller sections called as renal pyramids. The difference between renal cortex and renal medulla is, the renal cortex is the outer portion of the kidney whereas renal medulla is the innermost part of the kidney. You can download PDF version of this article and use it for offline purposes as per citation note.
Available here. WikiJournal of Medicine 1 2. ISSN Samanthi Udayangani holds a B. Degree in Plant Science, M. Your email address will not be published. Figure Renal Cortex. Figure Renal Medulla. Leave a Reply Cancel reply Your email address will not be published.
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