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Titel    Kidney
Verlag    (Wikipedia)
Datum    14. May 2007
URL    http://en.wikipedia.org/w/index.php?title=Kidney&oldid=130822064

Literaturverz.   

no
Fußnoten    no
Fragmente    4


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[1.] Dsa/Fragment 013 03 - Diskussion
Zuletzt bearbeitet: 2016-03-18 14:05:09 Graf Isolan
Dsa, Fragment, Gesichtet, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Wikipedia Kidney 2007

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1. Introduction

1.1. Kidney anatomy

The kidneys are organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. The medical field that studies the kidneys and diseases of the kidney is called nephrology (nephro- meaning kidney is from the Ancient Greek word nephros; the adjective renal meaning related to the kidney is from Latin rēnēs, meaning kidneys). In humans, the kidneys are located in the posterior part of the abdomen. 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. Above each kidney is an adrenal gland (also called the suprarenal gland). 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, which means they lie behind the peritoneum, the lining of the abdominal cavity. They are approximately at the vertebral level T12 to L3. The upper parts of the kidneys are partially protected by the eleventh and twelfth ribs, and each whole kidney is surrounded by two layers of fat (the perirenal and pararenal fat) which help to cushion it. Congenital absence of one or both kidneys, known as unilateral or bilateral renal agenesis can occur. In a normal human adult, each kidney is about 10 cm long, 5.5 cm in width and about 3 cm thick, weighing 150 grams. Together, kidneys weigh about 0.5% of a person's total body weight. The kidneys are "bean-shaped" organs, and have a concave side facing inwards (medially). On this medial aspect of each kidney is an opening, called the hilum, which admits the renal artery, the renal vein, nerves, and the ureter. The outer portion of the kidney is called the renal cortex, which sits directly beneath the kidney's loose connective tissue/fibrous capsule. Deep to the cortex lies the renal medulla, which is divided into 10-20 renal pyramids in humans. Each pyramid together with the associated overlying cortex forms a renal lobe. The tip of each pyramid (called a papilla) empties into a calyx, and the calices empty into the renal pelvis. The pelvis transmits urine to the urinary bladder via the ureter.

Blood supply

Each kidney receives its blood supply from the renal artery, two of which branch from the abdominal aorta. Upon entering the hilum of the kidney, the renal artery divides into smaller interlobar arteries situated between the renal papillae. At the outer medulla, the interlobar arteries branch into arcuate arteries, which course along the border between the renal medulla and cortex, giving off still smaller branches, the cortical radial arteries (sometimes called interlobular arteries). Branching off these cortical arteries are the afferent arterioles supplying the glomerular capillaries, which drain into efferent arterioles. Efferent arterioles divide into peritubular capillaries that provide an extensive blood supply to the cortex. Blood from these capillaries collects in renal venules and leaves the kidney via the renal vein. Efferent arterioles of glomeruli closest to the medulla (those that belong to juxtamedullary nephrons) send branches into the medulla, forming the vasa recta. Blood supply is intimately linked to blood pressure.

In anatomy, urinary system, the kidneys filter wastes (such as urea) from the blood and excrete them, along with water, as urine. The medical field that studies the kidneys and diseases of the kidney is called nephrology (nephro- meaning kidney is from the Ancient Greek word nephros; the adjective renal meaning related to the kidney is from Latin rēnēs, meaning kidneys).

In humans, the kidneys are located in the posterior part of the abdomen. 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. Above each kidney is an adrenal gland (also called the suprarenal gland). 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, which means they lie behind the peritoneum, the lining of the abdominal cavity. They are approximately at the vertebral level T12 to L3. The upper parts of the kidneys are partially protected by the eleventh and twelfth ribs, and each whole kidney is surrounded by two layers of fat (the perirenal and pararenal fat) which help to cushion it. Congenital absence of one or both kidneys, known as unilateral or bilateral renal agenesis can occur.

[...]

Organization

In a normal human adult, each kidney is about 10 cm long, 5.5 cm in width and about 3 cm thick, weighing 150 grams.[1] Together, kidneys weigh about 0.5% of a person's total body weight. The kidneys are "bean-shaped" organs, and have a concave side facing inwards (medially). On this medial aspect of each kidney is an opening, called the hilum, which admits the renal artery, the renal vein, nerves, and the ureter.

The outer portion of the kidney is called the renal cortex, which sits directly beneath the kidney's loose connective tissue/fibrous capsule. Deep to the cortex lies the renal medulla, which is divided into 10-20 renal pyramids in humans. Each pyramid together with the associated overlying cortex forms a renal lobe. The tip of each pyramid (called a papilla) empties into a calyx, and the calices empty into the renal pelvis. The pelvis transmits urine to the urinary bladder via the ureter.

Blood supply

Each kidney receives its blood supply from the renal artery, two of which branch from the abdominal aorta. Upon entering the hilum of the kidney, the renal artery divides into smaller interlobar arteries situated between the renal papillae. At the outer medulla, the interlobar arteries branch into arcuate arteries, which course along the border between the renal medulla and cortex, giving off still smaller branches, the cortical radial arteries (sometimes called interlobular arteries). Branching off these cortical arteries are the afferent arterioles supplying the glomerular capillaries, which drain into efferent arterioles. Efferent arterioles divide into peritubular capillaries that provide an extensive blood supply to the cortex. Blood from these capillaries collects in renal venules and leaves the kidney via the renal vein. Efferent arterioles of glomeruli closest to the medulla (those that belong to juxtamedullary nephrons) send branches into the medulla, forming the vasa recta. Blood supply is intimately linked to blood pressure.


1. Martini F. Fundamentals of Anatomy and Physiology 5th edition. Prentice Hall International Inc. 2001.

Anmerkungen

The source is not mentioned.

Sichter
(Hindemith), Graf Isolan

[2.] Dsa/Fragment 014 01 - Diskussion
Zuletzt bearbeitet: 2016-08-02 08:04:58 WiseWoman
Dsa, Fragment, Gesichtet, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Wikipedia Kidney 2007

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Dsa 014a diss

Figure nr. 1 - Kidney structure.

Parts of the kidney: 1. Renal pyramid; 2. Efferent vessel; 3. Renal artery; 4. Renal vein; 5. Renal hilum; 6. Renal pelvis; 7. Ureter; 8. Minor calyx; 9. Renal capsule; 10. Inferior renal capsule; 11. Superior renal capsule; 12. Afferent vessel; 13. Nephron; 14. Minor calyx; 15. Major calyx; 16. Renal papilla; 17. Renal column.

The basic functional unit of the kidney is the nephron, of which there are more than a million within the cortex and medulla of each normal adult human kidney. Nephrons regulate water and solute within the cortex and medulla of each normal adult human kidney. Nephrons regulate water and soluble matter (especially electrolytes) in the body by first filtering the blood under pressure, and then reabsorbing some necessary fluid and molecules back into the blood while secreting other, unneeded molecules. Reabsorption and secretion are accomplished with both cotransport and countertransport mechanisms established in the nephrons and associated collecting ducts.

Collecting duct system

The fluid flows from the nephron into the collecting duct system. This segment of the nephron is crucial to the process of water conservation by the organism. In the presence of antidiuretic hormone (ADH; also called vasopressin), these ducts become permeable to water and facilitate its reabsorption, thus concentrating the urine and reducing its volume.

Dsa 014a source

Parts of the kidney:

1. Renal pyramid

2. Efferent vessel

3. Renal artery

4. Renal vein

5. Renal hilum

6. Renal pelvis

7. Ureter

8. Minor calyx

9. Renal capsule

10. Inferior renal capsule

11. Superior renal capsule

12. Afferent vessel

13. Nephron

14. Minor calyx

15. Major calyx

16. Renal papilla

17. Renal column

The basic functional unit of the kidney is the nephron, of which there are more than a million within the cortex and medulla of each normal adult human kidney. Nephrons regulate water and solute within the cortex and medulla of each normal adult human kidney. Nephrons regulate water and soluble matter (especially electrolytes) in the body by first filtering the blood under pressure, and then reabsorbing some necessary fluid and molecules back into the blood while secreting other, unneeded molecules. Reabsorption and secretion are accomplished with both cotransport and countertransport mechanisms established in the nephrons and associated collecting ducts.

Collecting duct system

[...]

The fluid flows from the nephron into the collecting duct system. This segment of the nephron is crucial to the process of water conservation by the organism. In the presence of antidiuretic hormone (ADH; also called vasopressin), these ducts become permeable to water and facilitate its reabsorption, thus concentrating the urine and reducing its volume.

Anmerkungen

The source is not mentioned. The illustration is by Piotr Michał Jaworski [1] and is under a CC-BY-SA license, meaning that the illustrator must be credited and any work using it must be under at least a CC-SA license. Thus, in addition to plagiarism, this fragment represents a copyright violation.

Sichter
(Hindemith), WiseWoman

[3.] Dsa/Fragment 015 01 - Diskussion
Zuletzt bearbeitet: 2016-08-02 08:19:22 WiseWoman
Dsa, Fragment, Gesichtet, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Wikipedia Kidney 2007

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Conversely, when the organism must eliminate excess water, such as after excess fluid drinking, the production of ADH is decreased and the collecting tubule becomes less permeable to water, rendering urine dilute and abundant. Failure of the organism to decrease ADH production appropriately, a condition known as syndrome of inappropriate ADH (SIADH), may lead to water retention and dangerous dilution of body fluids, which in turn may cause severe neurological damage. Failure to produce ADH (or inability of the collecting ducts to respond to it) may cause excessive urination, called diabetes insipidus (DI). A second major function of the collecting duct system is the maintenance of acid-base homeostasis. After being processed along the collecting tubules and ducts, the fluid, now called urine, is drained into the bladder via the ureter, to be finally excluded from the organism. Conversely, when the organism must eliminate excess water, such as after excess fluid drinking, the production of ADH is decreased and the collecting tubule becomes less permeable to water, rendering urine dilute and abundant. Failure of the organism to decrease ADH production appropriately, a condition known as syndrome of inappropriate ADH (SIADH), may lead to water retention and dangerous dilution of body fluids, which in turn may cause severe neurological damage. Failure to produce ADH (or inability of the collecting ducts to respond to it) may cause excessive urination, called diabetes insipidus (DI).

A second major function of the collecting duct system is the maintenance of acid-base homeostasis.

After being processed along the collecting tubules and ducts, the fluid, now called urine, is drained into the bladder via the ureter, to be finally excluded from the organism.

Anmerkungen

The source is not given.

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(Hindemith), WiseWoman

[4.] Dsa/Fragment 016 04 - Diskussion
Zuletzt bearbeitet: 2016-08-02 09:12:50 WiseWoman
Dsa, Fragment, Gesichtet, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Wikipedia Kidney 2007

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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.

Homeostasis

The kidney is one of the major organs involved in whole-body homeostasis. Among its homeostatic functions are acid-base balance, regulation of electrolyte concentrations, control of blood volume, and regulation of blood pressure. The kidneys accomplish these homeostatic functions independently and through coordination with other organs, particularly those of the endocrine system. The kidney communicates with these organs through hormones secreted into the bloodstream.

Acid-base balance

The kidneys regulate the pH, by eliminating H ions concentration called augmentation mineral ion concentration, and water composition of the blood. By exchanging hydronium ions and hydroxyl ions, the blood plasma is maintained by the kidney at a slightly alkaline pH of 7.4. Urine, on the other hand, is acidic at pH 5 or alkaline at pH 8. The pH is maintained through four main protein transporters: NHE3 (a sodium-hydrogen exchanger), V-type H-ATPase (an isoform of the hydrogen ATPase), NBC1 (a sodium-bicarbonate cotransporter) and AE1 (an anion exchanger which exchanges chloride for bicarbonate). Due to the polar alignment of cells in the renal epithelia NHE3 and the H-ATPase are exposed to the lumen (which is essentially outside the body), on the apical side of the cells, and are responsible for excreting hydrogen ions (or protons). Conversely, NBC1 and AE1 are on the basolateral side of the cells, and allow bicarbonate ions to move back into the extracellular fluid and thus are returned to the blood plasma.

Blood pressure

Sodium ions are controlled in a homeostatic process involving aldosterone which increases sodium ion reabsorption in the distal convoluted tubules.When [sic] blood pressure becomes low, a proteolytic enzyme called Renin is secreted by cells of the juxtaglomerular apparatus (part of the distal convoluted tubule) which are sensitive to pressure. Renin acts on a blood protein, angiotensinogen, converting it to angiotensin I (10 amino acids). Angiotensin I is then converted by the Angiotensin-converting enzyme (ACE) in the lung capillaries to Angiotensin II (8 amino acids), which stimulates the secretion of Aldosterone by the adrenal cortex, which then affects the kidney tubules.

Aldosterone stimulates an increase in the reabsorption of sodium ions from the kidney tubules which causes an increase in the volume of water that is reabsorbed from the tubule. This increase in water reabsorption increases the volume of blood which ultimately raises the blood pressure.

Plasma volume

Any significant rise or drop in plasma osmolality is detected by the hypothalamus, which communicates directly with the posterior pituitary gland. A rise in osmolality causes the gland to secrete antidiuretic hormone, resulting in water reabsorption by the kidney and an increase in urine concentration. The two factors work together to return the plasma osmolality to its normal levels.

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).

Homeostasis

The kidney is one of the major organs involved in whole-body homeostasis. Among its homeostatic functions are acid-base balance, regulation of electrolyte concentrations, control of blood volume, and regulation of blood pressure. The kidneys accomplish these homeostatic functions independently and through coordination with other organs, particularly those of the endocrine system. The kidney communicates with these organs through hormones secreted into the bloodstream.

Acid-base balance

The kidneys regulate the pH, by eliminating H ions concentration called augmentation mineral ion concentration, and water composition of the blood.

By exchanging hydronium ions and hydroxyl ions, the blood plasma is maintained by the kidney at a slightly alkaline pH of 7.4. Urine, on the other hand, is acidic at pH 5 or alkaline at pH 8.

The pH is maintained through four main protein transporters: NHE3 (a sodium-hydrogen exchanger), V-type H-ATPase (an isoform of the hydrogen ATPase), NBC1 (a sodium-bicarbonate cotransporter) and AE1 (an anion exchanger which exchanges chloride for bicarbonate). Due to the polar alignment of cells in the renal epithelia NHE3 and the H-ATPase are exposed to the lumen (which is essentially outside the body), on the apical side of the cells, and are responsible for excreting hydrogen ions (or protons). Conversely, NBC1 and AE1 are on the basolateral side of the cells, and allow bicarbonate ions to move back into the extracellular fluid and thus are returned to the blood plasma.[citation needed]

Blood pressure

[...]

Sodium ions are controlled in a homeostatic process involving aldosterone which increases sodium ion absorption in the distal convoluted tubules.

When blood pressure becomes low, a proteolytic enzyme called Renin is secreted by cells of the juxtaglomerular apparatus (part of the distal convoluted tubule) which are sensitive to pressure. Renin acts on a blood protein, angiotensinogen, converting it to angiotensin I (10 amino acids). Angiotensin I is then converted by the Angiotensin-converting enzyme (ACE) in the lung capillaries to Angiotensin II (8 amino acids), which stimulates the secretion of Aldosterone by the adrenal cortex, which then affects the kidney tubules.

Aldosterone stimulates an increase in the reabsorption of sodium ions from the kidney tubules which causes an increase in the volume of water that is reabsorbed from the tubule. This increase in water reabsorption increases the volume of blood which ultimately raises the blood pressure.

Plasma volume

Any significant rise or drop in plasma osmolality is detected by the hypothalamus, which communicates directly with the posterior pituitary gland. A rise in osmolality causes the gland to secrete antidiuretic hormone, resulting in water reabsorption by the kidney and an increase in urine concentration. The two factors work together to return the plasma osmolality to its normal levels.

Anmerkungen

The source is not mentioned.

Sichter
(Hindemith), WiseWoman

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