Kidney Anatomy & Function - Gary's copy A&PII Labex 8 Flashcards
Glomerulus
In the kidney, a tiny ball-shaped structure composed of capillary blood vessels actively involved in the filtration of the blood to form urine. The glomerulus is one of the key structures that make up the nephron, the functional unit of the kidney. The glomerulus is the site in the nephron where fluid and solutes are filtered out of the blood to form a glomerular filtrate.
Erythropoietin
Hormone, erythropoietin: Erythropoietin is a substance produced by the kidney that leads to the formation of red blood cells in the bone marrow. Abbreviated: EPO. Convoluted tubules where filtration is performed.
The kidney cells that make EPO are specialized and are sensitive to low oxygen levels in the blood coming into the kidney. These cells release erythropoietin when the oxygen level is low in the kidney. Erythropoietin stimulates the bone marrow to produce more red blood cells which in turn increases the oxygen-carrying capacity of the blood.
EPO is the prime regulator of red cell production. Its major functions are to promote the differentiation and development of red blood cells and to initiate the production of hemoglobin, the molecule within red cells that transports oxygen.
EPO is produced not only in the kidney but also, to a lesser extent, in the liver. The EPO gene has been found on human chromosome 7 (in band 7q21). Different DNA sequences flanking the EPO gene act to control liver versus kidney production of EPO.
The measurement of EPO in the blood can indicate bone marrow disorders or kidney disease. Normal levels of EPO are 0 to 19 mU/ml (milliunits per milliliter). Elevated levels can be seen in polycythemia rubra vera, a disorder characterized by an excess of red blood cells. Lower than normal values of EPO are seen in chronic renal failure.
Using recombinant DNA technology, EPO has been synthetically produced for use in persons with certain types of anemia: anemia due to kidney failure, anemia secondary to AZT treatment of AIDS , and anemia associated with cancer.
EPO has been much misused as a performance-enhancing drug in endurance athletes such as reportedly cyclists (in the Tour de France), long-distance runners, speed skaters, and Nordic (cross-country) skiers. When misused in such situations, EPO is thought to be especially dangerous (perhaps because dehydration can further increase the viscosity of the blood, increasing the risk for heart attacks and strokes. EPO has been banned by the Tour, the Olympics, and other sports organizations.
Hilum
The renal hilum (Latin: hilum renale) or renal pedicle is the hilum of the kidney, that is, its recessed central fissure where its vessels, nerves and ureter pass. The medial border of the kidney is concave in the center and convex toward either extremity; it is directed forward and a little downward. Its central part presents a deep longitudinal fissure, bounded by prominent overhanging anterior and posterior lips. This fissure is a hilum that transmits the vessels, nerves, and ureter. From anterior to posterior, the renal vein exits, the renal artery enters, and the renal pelvis exits the kidney. The superior, middle, and inferior vessels enter or leave the hilum of kidney: from anterior to posterior is renal vein, renal artery and renal pelvis, respectively. The renal pelvis contains a hilium —the concave site in which the renal artery and vein and nerves enter the kidney and the ureter leaves the kidney.
Renal Parenchyma
the functional tissue of the kidney, consisting of the nephrons.
The solid part of the kidney, where the process of waste excretion takes place.
Renal Cortex
The outer layer of the parenchyma consisting of connective tissue. The renal cortex produces erythropotein. The kidneys are made up by three external layers, which include the renal fascia (the outermost layer), the perirenal fat capsule, and lastly, the innermost layer, the renal capsule, which then surround the space of the renal cortex. The outer region of the kidney, between the renal capsule and the renal medulla, that consists of a space that contains blood vessels that connect to the nephrons. The renal cortex is a space between the medulla and the outer capsule. 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.
Renal Medulla
Area of the kidney where filtration and concentration of wastes takes place, Henle’s loops, pyramids of converging tubules. The inner-most region of the kidney, arranged into pyramid-like structures, that consists of the bulk of nephron structure. The renal medulla contains the majority of the length of nephrons, the main functional component of the kidney that filters fluid from blood.
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.
At one end of each nephron, in the cortex of the kidney, is a cup-shaped structure called the Bowman’s capsule. 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.
Renal Columns
The renal column (or Bertin column, or column of Bertin) is a medullary extension of the renal cortex in between the renal pyramids. It allows the cortex to be better anchored.
Each column consists of lines of blood vessels and urinary tubes and a fibrous material.
A hypertrophied renal column (or renal pseudotumor) may be differentiated from an actual renal tumor with the help of a DMSA scan. The scan will show the area as one with normal activity if it is a pseudotumor or will show decreased uptake if it is a cystic or solid renal mass.
Major/Minor Calyx
Collecting area for urine within kidney before it is passed through to renal pelvis.
Renal Pelvis
Central collecting system of kidney. The renal pelvis connects the kidney with the circulatory and nervous systems from the rest of the body.
Nephron
Basic functional unit of kidney. Nephrons, masses of tiny tubules, are largely located in the medulla and receive fluid from the blood vessels in the renal cortex. The Bowman’s or renal capsule, located at one end of each nephron in the cortex of the kidney, is the blood-filtering region of the nephron. The basic structural and functional unit of the kidney that filters the blood in order to regulate chemical concentrations and produce urine.
Renal Corpuscle
Renal corpuscle, also called malpighian body, filtration unit of vertebrate nephrons, functional units of the kidney. It consists of a knot of capillaries (glomerulus) surrounded by a double-walled capsule (Bowman’s capsule) that opens into a tubule. Blood pressure forces plasma minus its macromolecules (e.g., proteins) from the glomerular capillaries into the Bowman’s capsule. This filtrate, called capsular urine, then passes into the tubule for further processing.
Renal Tubule
Etymology: L, ren, kidney, tubulus, small tube
the part of the kidney’s nephron that leads from the glomerulus to the collecting tubules. It consists of a looping segment and two convoluted sections. These canals resorb selected materials back into the blood and secrete, collect, and conduct urine.
The part of a nephron through which renal filtrate from the renal corpuscle flows and is changed to urine by reabsorption and secretion. The parts, in order, are the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule, and collecting tubule.
The proximal and distal tubules, the loop of Henle, and the collecting ducts are sites for the reabsorption of water and ions.The collecting duct and distal convoluted tubule are normally impermeable to water, but this is altered due to hormone stimulus during homeostasis.
