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Kidney
Human kidneys viewed from behind with spine removed
Latin ren
Gray's subject #253 1215
Artery renal artery
Vein renal vein
Nerve renal plexus
MeSH Kidney
Dorlands/Elsevier k_03/12470097

The kidneys are complicated organs that have numerous biological roles. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Gray's Anatomy the Respiratory apparatus ( Apparatus Respiratorius Respiratory system Respiratory apparatus Arteries are Blood vessels that carry blood away from the Heart. The renal arteries normally arise off the side of the Abdominal aorta, immediately below the Superior mesenteric artery, and supply the Kidneys with In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel The renal veins are Veins that drain the Kidney. They connect the kidney to the Inferior vena cava. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. The renal plexus is formed by filaments from the Celiac plexus, the Aorticorenal ganglion, and the Aortic plexus. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group In Biology, an organ ( Latin: organum, "instrument tool" from Greek όργανον - organon "organ instrument Their primary role is to maintain the homeostatic balance of bodily fluids by filtering and secreting metabolites (such as urea) and minerals from the blood and excreting them, along with water, as urine. Homeostasis (from Greek: ὅμος hómos, "equal" and ιστημι istēmi, "to stand" lit Urea is an Organic compound with the Chemical formula ( N[[hydrogen H]]22 C[[oxygen O]] Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells such as nutrients and oxygen—and transports Waste products Excretion is the process of eliminating waste products of Metabolism and other non-useful materials Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as Urine is a liquid waste product of the body secreted by the Kidneys by a process of filtration from Blood and Excreted through the Urethra. Because the kidneys are poised to sense plasma concentrations of ions such as sodium, potassium, hydrogen, oxygen, and compounds such as amino acids, creatine, bicarbonate, and glucose, they are important regulators of blood pressure, glucose metabolism, and erythropoiesis (the process by which red blood cells (erythrocytes) are produced). Blood plasma is the Liquid component of Blood, in which the Blood cells are suspended Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are Creatine is Nitrogenous Organic acid that occurs naturally in Vertebrates and helps to supply energy to Muscle and nerve cells In Inorganic chemistry, bicarbonate ( IUPAC -recommended nomenclature hydrogencarbonate) is an intermediate form in the Deprotonation Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Blood pressure is also the title of a short story by Damon Runyan in Guys and Dolls and Other Stories Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. Erythropoiesis is the process by which Red blood cells (erythrocytes are produced Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood The medical field that studies the kidneys and diseases of the kidney is called nephrology[1]. A disease is an abnormal condition of an organism that impairs bodily functions and can be deadly Nephrology (from Greek nephros, " Kidney " and λόγος Logos, "speech" lit The prefix nephro- meaning kidney is from the Ancient Greek word nephros (νεφρός); the adjective renal meaning related to the kidney is from Latin rēnēs, meaning kidneys. The Ancient Greek language is the historical stage in the development of the Hellenic language family spanning the Archaic (c In Grammar, an adjective is a word whose main syntactic role is to modify a Noun or Pronoun, giving more information about the Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. [2]

In humans, the kidneys are located in the posterior part of the abdomen. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species In Vertebrates such as Mammals the abdomen (belly constitutes the part of the body between the Thorax (chest and Pelvis. There is one on each side of the spine; the right kidney sits just below the liver, the left below the diaphragm and adjacent to the spleen. In Human anatomy, the vertebral column ( backbone or spine) is a column of 34 Vertebrae the Sacrum, Intervertebral The liver is a vital organ in the human body and is present in Vertebrates and some other animals For other types of diaphragm see Diaphragm. In the Anatomy of Mammals the thoracic diaphragm is a sheet of Muscle The spleen is an organ found in all Vertebrate animals In humans the spleen is located in the abdomen of the body where it functions in the destruction of redundant Red Above each kidney is an adrenal gland (also called the suprarenal gland). In Mammals the adrenal glands (also known as suprarenal glands) are the triangle-shaped Endocrine glands that sit on top of the Kidneys their The asymmetry within the abdominal cavity caused by the liver results in the right kidney being slightly lower than the left one while the left kidney is located slightly more medial.

The kidneys are retroperitoneal and range from 9 to 13 cm in diameter; the left slightly larger than the right. The retroperitoneum (adj retroperitoneal) is the anatomical space in the Abdominal cavity behind ( retro) the Peritoneum. They are approximately at the vertebral level T12 to L3. A vertebra (plural vertebrae) is an individual Irregular bone in the spinal or Vertebral column ( aka ischis a flexuous and flexible column The upper parts of the kidneys are partially protected by the eleventh and twelfth ribs, and each whole kidney and adrenal gland are surrounded by two layers of fat (the perirenal and pararenal fat) and the renal fascia which help to cushion it. In Vertebrate Anatomy, ribs ( Latin costae) are the long curved Bones which form the ribcage. In Mammals the adrenal glands (also known as suprarenal glands) are the triangle-shaped Endocrine glands that sit on top of the Kidneys their The Kidney and the Adipose capsule are enclosed in a sheath of fibrous tissue continuous with the Subperitoneal fascia, and named the renal fascia (also Congenital absence of one or both kidneys, known as unilateral or bilateral renal agenesis, can occur. The absence of one (unilateral or both (bilateral Kidneys at birth

Contents

Functions

Main article: Renal physiology

Excretion of waste products

The kidneys excrete a variety of waste products produced by metabolism, including the nitrogenous wastes: urea (from protein catabolism) and uric acid (from nucleic acid metabolism) and water. Renal physiology is the study of the Physiology of the Kidneys Functions of the kidney The functions of the kidney can be divided into two groups Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. Urea is an Organic compound with the Chemical formula ( N[[hydrogen H]]22 C[[oxygen O]] Uric acid (or urate) is an Organic compound of Carbon, Nitrogen, Oxygen and Hydrogen with the formula C5H4N4O3

Homeostasis

The kidney is one of the major organs involved in whole-body homeostasis. Homeostasis (from Greek: ὅμος hómos, "equal" and ιστημι istēmi, "to stand" lit Among its homeostatic functions are acid-base balance, regulation of electrolyte concentrations, control of blood volume, and regulation of blood pressure. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium Blood volume is the Volume of Blood (both Red blood cells and plasma) in a person's Circulatory system. Blood pressure is also the title of a short story by Damon Runyan in Guys and Dolls and Other Stories The kidneys accomplish these homeostatic functions independently and through coordination with other organs, particularly those of the endocrine system. The endocrine system is an integrated system of small organs that involve the release of extracellular signaling molecules known as Hormones The endocrine system is instrumental The kidney communicates with these organs through hormones secreted into the bloodstream.

Acid-base balance

The kidneys regulate the pH of blood by adjusting H+ ion levels, referred as augmentation of mineral ion concentration, as well as water composition of the blood. pH is the measure of the acidity or alkalinity of a Solution.

Blood pressure

Main article: Renin-angiotensin system

Sodium ions are controlled in a homeostatic process involving aldosterone which increases sodium ion reabsorption in the distal convoluted tubules. The renin-angiotensin system (RAS or the renin-angiotensin-aldosterone system (RAAS is a hormone system that regulates Blood pressure and water ( fluid Aldosterone is a hormone that causes the tubules of the kidneys to retain sodium and water

Plasma volume

Any significant rise or drop in plasma osmolality is detected by the hypothalamus, which communicates directly with the posterior pituitary gland. Plasma osmolality is a measure of the concentration of substances such as Sodium, Chloride, Potassium, Urea, Glucose, and other The hypothalamus links the Nervous system to the Endocrine system via the Pituitary gland (hypophysis The posterior pituitary (or neurohypophysis) comprises the Posterior lobe of the Pituitary gland and is part of the Endocrine system. A rise in osmolality causes the gland to secrete antidiuretic hormone, resulting in water reabsorption by the kidney and an increase in urine concentration. Arginine vasopressin ( AVP) also known as vasopressin, argipressin or antidiuretic hormone ( ADH) is a Hormone found in The two factors work together to return the plasma osmolality to its normal levels.

Hormone secretion

The kidneys secrete a variety of hormones, including erythropoietin, urodilatin, renin and vitamin D. Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body Erythropoietin (ɨˌɹɪθɹoʊˈpɔɪɨtɨn /ɨˌɹɪθɹoʊˈpɔɪtən/ or /ɨˌɹiːθɹoʊ-/ or EPO is a Glycoprotein Hormone that controls Urodilatin is a Hormone that causes Diuresis through increasing Renal blood flow. Renin (pronounced "Ree-nin" or "Rē-nin" (ˈriːnɨn also known as Angiotensinogenase, is a circulating Enzyme that participates in the body's Vitamin D is a group of fat-soluble Prohormones, the two major forms of which are vitamin D2 (or Ergocalciferol) and vitamin D3 (or

Embryology

Main article: Development of the urinary and reproductive organs

The mammalian kidney develops from intermediate mesoderm. The development of the urinary and reproductive organs as a part of the Prenatal development, concerns the Urinary system and Sex organs. Intermediate mesoderm is a type of Mesoderm that is located between the Paraxial mesoderm and the Lateral plate. Kidney development, also called nephrogenesis, proceeds through a series of three successive phases, each marked by the development of a more advanced pair of kidneys: the pronephros, mesonephros, and metanephros. [3] (The plural forms of these terms end in -oi. )

Pronephros

Main article: Pronephros

During approximately day 22 of human gestation, the paired pronephroi appear towards the cranial end of the intermediate mesoderm. Pronephros the most primitive of the three excretory organs that develop in Vertebrates corresponding to the first stage of Kidney development Gestation is the carrying of an Embryo or Fetus inside a Female Viviparous Animal. In this region, epithelial cells arrange themselves in a series of tubules called nephrotomes and join laterally with the pronephric duct, which does not reach the outside of the embryo. In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body The nephrotome is a section of the Mesoderm. It gives rise to the Pronephros and eventually to the rest of the Kidney. The pronephric duct is the predecessor of the Wolffian duct. Development The development of the pronephric duct is a part of the Development of the urinary Thus the pronephros is considered nonfunctional in mammals because it cannot excrete waste from the embryo.

Mesonephros

Main article: Mesonephros

Each pronephric duct grows towards the tail of the embryo, and in doing so induces intermediate mesoderm in the thoracolumbar area to become epithelial tubules called mesonephric tubules. The mesonephros ( Latin for "middle Kidney " is one of three excretory organs that develop in Vertebrates It serves as the main excretory The mesonephros ( Latin for "middle Kidney " is one of three excretory organs that develop in Vertebrates It serves as the main excretory Each mesonephric tubule receives a blood supply from a branch of the aorta, ending in a capillary tuft analogous to the glomerulus of the definitive nephron. A glomerulus is a Capillary tuft surrounded by Bowman's capsule in Nephrons of the vertebrate Kidney. A nephron (from Greek νεφρός (nephros meaning "kidney" is the basic structural and functional unit of the Kidney. The mesonephric tubule forms a capsule around the capillary tuft, allowing for filtration of blood. This filtrate flows through the mesonephric tubule and is drained into the continuation of the pronephric duct, now called the mesonephric duct or Wolffian duct. The nephrotomes of the pronephros degenerate while the mesonephric duct extends towards the most caudal end of the embryo, ultimately attaching to the cloaca. In zoological anatomy a cloaca is the posterior opening that serves as the only such opening for the intestinal and urinary tracts of certain animal species The mammalian mesonephros is similar to the kidneys of aquatic amphibians and fishes. Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two

Metanephros

During the fifth week of gestation, the mesonephric duct develops an outpouching, the ureteric bud, near its attachment to the cloaca. The ureteric bud is a protrusion from the Mesonephric duct during the Development of the urinary and reproductive organs. This bud, also called the metanephrogenic diverticulum, grows posteriorly and towards the head of the embryo. The elongated stalk of the ureteric bud, the metanephric duct, later forms the ureter. In human Anatomy, the ureters are muscular ducts that propel Urine from the Kidneys to the Urinary bladder. As the cranial end of the bud extends into the intermediate mesoderm, it undergoes a series of branchings to form the collecting duct system of the kidney. The collecting duct system of the Kidney consists of a series of tubules and ducts that connect the Nephrons to the Ureter. It also forms the major and minor calyces and the renal pelvis. The renal pelvis is the funnel-like dilated proximal part of the Ureter in the Kidney.

The portion of undifferentiated intermediate mesoderm in contact with the tips of the branching ureteric bud is known as the metanephrogenic blastema. Signals released from the ureteric bud induce the differentiation of the metanephrogenic blastema into the renal tubules. A nephron (from Greek νεφρός (nephros meaning "kidney" is the basic structural and functional unit of the Kidney. As the renal tubules grow, they come into contact and join with connecting tubules of the collecting duct system, forming a continuous passage for flow from the renal tubule to the collecting duct. In the Kidney, the collecting tubule ( CNT, or junctional tubule, or arcuate renal tubule) is a tubular segment of the renal Collecting duct Simultaneously, precursors of vascular endothelial cells begin to take their position at the tips of the renal tubules. These cells differentiate into the cells of the definitive glomerulus. A glomerulus is a Capillary tuft surrounded by Bowman's capsule in Nephrons of the vertebrate Kidney.

Terms

Microscopic photograph of the renal cortex.
Microscopic photograph of the renal cortex. The renal cortex is the outer portion of the Kidney between the Renal capsule and the Renal medulla.
Microscopic photograph of the renal medulla.
Microscopic photograph of the renal medulla. The renal medulla is the innermost part of the Kidney. The renal medulla is split up into a number of sections known as the Renal pyramids.

Diseases and disorders

Congenital

Acquired

drawing of an enlarged kidney by John Hunter
drawing of an enlarged kidney by John Hunter

The failing kidney

Generally, humans can live normally with just one kidney, as one has more functioning renal tissue than is needed to survive, possibly due to the nature of the prehistoric human diet. Renal failure or kidney Acute renal failure ( ARF) also known as acute kidney failure or acute kidney injury, is a rapid loss of Renal function due to damage to the Chronic kidney disease (CKD also known as chronic renal disease, is a progressive loss of renal function over a period of months or years Only when the amount of functioning kidney tissue is greatly diminished will Stage 5 Chronic Kidney Disease develop. Chronic kidney disease (CKD also known as chronic renal disease, is a progressive loss of renal function over a period of months or years If the glomerular filtration rate (a measure of renal function) has fallen very low ( Stage 5 Chronic Kidney Disease), or if the renal dysfunction leads to severe symptoms, then renal replacement therapy is indicated, either dialysis or kidney transplantation. Renal function, in Nephrology, is an indication of the state of the Kidney and its role in Renal physiology. Chronic kidney disease (CKD also known as chronic renal disease, is a progressive loss of renal function over a period of months or years Renal replacement therapy is a term used to encompass life-supporting treatments for Renal failure. In Medicine, dialysis (from Greek "dialusis" meaning dissolution "dia" meaning through and "lusis" meaning loosening is primarily Kidney transplantation or renal transplantation is the Organ transplant of a Kidney in a patient with End-stage renal disease.

Medical terminology

Histology

Human cell types found in the kidney include:

Animal kidneys as food

The kidneys of animals can be cooked and eaten by humans (along with other offal). Cooking is the process of preparing Food by applying Heat, selecting measuring and combining of ingredients in an ordered procedure for producing safe and edible Offal is the Entrails and Internal organs of a Butchered Animal. If prepared properly, they can be nutritious and pleasant tasting. Veal kidneys and lamb kidneys are particularly prized for their tenderness and flavour. Kidneys can be grilled or sautéed, though they become tough and unpleasant if overcooked.

See also

References

  1. ^ Nephrology. Kidney stones, also called renal calculi, are solid concretions (crystal aggregations of dissolved minerals in Urine; calculi typically form Kidney transplantation or renal transplantation is the Organ transplant of a Kidney in a patient with End-stage renal disease. Renal physiology is the study of the Physiology of the Kidneys Functions of the kidney The functions of the kidney can be divided into two groups The urinary system (also called Excretory system or the genitourinary system (GUS is the Organ system that produces stores and eliminates Urine. Dictionary. com. Retrieved on 2007-08-04. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 70 - The Destruction of the Second Temple in Jerusalem by the Romans.
  2. ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.  
  3. ^ Bruce M. Carlson (2004). Human Embryology and Developmental Biology, 3rd edition, Saint Louis: Mosby. ISBN 0-323-03649-X.  
  4. ^ mednote.co

External links

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Dictionary

kidney

-noun

  1. An organ in the body that produces urine.
  2. This organ (of an animal) cooked as food
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