From the stomach, the chyme passes into the small intestine through the pyloric sphincter Proteins have not been completely broken down, carbohydrates are still being converted into simple sugars, and fats remain in large globules. In the small intestine the process of digestion is completed by the action of the bile, which is secreted by the liver and released by the gallbladder, and by the action of various enzymes which are secreted by the pancreas and walls of the small in testine Absorption of the products of digestion taken place mainly through the wall of the small intestine
The small intestine is the region within which the process of digestion is completed and its products are absorbed. Although its epithelial lining forms many small glands, they mainly produce mucus. Most of the enzymes present are secreted by the pancreas, whose duct, opens into the duodenum. Bile from the liver also enters the duodenum.
The absorption of the product's of digestion also takes place in the small intestine, although water, salts, and glucose are ab sorbed from the stomach and the large intestine.
The large intestine is chiefly concerned with the preparation, storage and evacuation of undigestible and unabsorbable food residue.
сhewing – жевание
saliva – слюна
to moisten – увлажнять
enzyme – фермент
carbohydrates – углеводы
stomach – живот
tongue – язык
hydrochloric acid – соляная кислота
absorption – поглощение
45. The digestive system: the function
46. The digestive system: liver and stomach. Sources of energy
47. The urinary system: embriogenesis
48. The urinary system: kidneys
49. The urinary system: kidney vascular sypply
50. The urinary system: ureters, uretra
51. The kidney`s function
52. Acute renal failure
53. Iron in the body
54. Atherosclerotic mechanisms
55. Advances in blood component separation and plasma treatment for therapeutics
56. Artificial oxygen carries
Digestion
Chewing movements of the teeth, tongue, cheeks, lips and lower jaw break down food, mix it with saliva and roll it into a moist, soft mass called a bolus, suitable for swallowing. Having been rendered suitable for swallowing the food is pushed back into the pharynx by the tongue, and enters the esopha gus to be transported rapidly down the neck and thorax, through the diaphragm to the stomach. The mucous membrane of the stomach is equipped with millions of glands secreting mucus, digestive enzymes and hydrochloric acid.The small intestine is the region within which the process of digestion is completed and its products are absorbed. Although its epithelial lining forms many small glands, they mainly produce mucus. Most of the enzymes present are secreted by the pancreas, whose duct, opens into the duodenum. Bile from the liver also enters the duodenum.
The absorption of the product's of digestion also takes place in the small intestine, although water, salts, and glucose are ab sorbed from the stomach and the large intestine.
The large intestine is chiefly concerned with the preparation, storage and evacuation of undigestible and unabsorbable food residue.
New words
process of digestion – процесс перевариваниясhewing – жевание
saliva – слюна
to moisten – увлажнять
enzyme – фермент
carbohydrates – углеводы
stomach – живот
tongue – язык
hydrochloric acid – соляная кислота
absorption – поглощение
45. The digestive system: the function
The digestive system, or gastrointestinal tract, begins with the mouth, where food enters the body, and ends with the anus, where solid waste material leaves the body. The primary function of the organs of the digestive system are threefold.
First, complex food material which is taken into the mouth must be digested mechanically and chemically, as it travels through, the gastrointestinal tract.
Second, the digested food must be absorbed by passage through the walls of the small intestine into the blood stream so that the valuable energy-carrying nutrients can travel to all cells of the body.
The third function of the gastrointestinal tract is to eliminate the solid waste materials which are unable to be absorbed by the small intestine.
In the man the food in the mouth is masticated, that is to say it is bitten and broken up by the teeth and rolled into the bolus by the tongue.
The act of swallowing is divided into three stages
The first stage is under voluntary control. The food which has been transformed into a soft, mass by the act of mastication is brought into position upon the root of the tongue, and by the action of the lingual muscles is rolled backwards towards the base of the tongue.
The second stage is brief and is occupied in guiding the food through the pharynx and past the openings that lead from it. The muscular movements during this stage are purely reflex in nature. The third stage involves the passage of the food down the eso phagus. The food is seized by peristaltic wave which, traveling along the esophagus, carries the material before it into the stomach. The cardiac sphincter which guards the lower end of the esophagus and which at other times is kept tonically closed re laxes upon the approach of the bolus which is then swept into the stomach by the wave of constriction which follows.
Peristalsis is a type of muscular contraction characteristic of the gut and consists in waves of contraction, these running along the muscles, both circular and longitudinal, towards the anus.
If the food is fluid it enters the stomach six seconds after the beginning of the act, but If It is solid it takes much long e r, up to fifteen minutes, to pass down the esophagus.
In the stomach the food is thoroughly mixed by the series of contractions, three or four a minute, the contraction waves passing from the middle of the stomach to the pylorus. These tend to drive the food in the same direction, but the pylorus being closed, there is axial reflex, owing to which the food is well mixed. After a time – a bout a minute when water has been swallowed – the pylorus relaxes at each wave, allowing some of the stomach contents to enter the duodenum. Fat stays in the stomach longer than carbo hydrate, but all food leaves generally in three or four hours. In the small intestine the food continues to be moved by peristalsis, the latter controlled by the deep nerve plexus. The small intestine undergoes segmentation movements, the food contents being thoroughly mired The wall becomes constricted into a number of segments and then about five seconds later the constrictions disappear, there being another set exactly out of phase with the first. The large intestine undergoes infrequent powerful contractions, food having entered it. From the large intestine the food enters the rectum.
soft – мягкий
mastication – перетирание
position – положение
root – корень
First, complex food material which is taken into the mouth must be digested mechanically and chemically, as it travels through, the gastrointestinal tract.
Second, the digested food must be absorbed by passage through the walls of the small intestine into the blood stream so that the valuable energy-carrying nutrients can travel to all cells of the body.
The third function of the gastrointestinal tract is to eliminate the solid waste materials which are unable to be absorbed by the small intestine.
In the man the food in the mouth is masticated, that is to say it is bitten and broken up by the teeth and rolled into the bolus by the tongue.
The act of swallowing is divided into three stages
The first stage is under voluntary control. The food which has been transformed into a soft, mass by the act of mastication is brought into position upon the root of the tongue, and by the action of the lingual muscles is rolled backwards towards the base of the tongue.
The second stage is brief and is occupied in guiding the food through the pharynx and past the openings that lead from it. The muscular movements during this stage are purely reflex in nature. The third stage involves the passage of the food down the eso phagus. The food is seized by peristaltic wave which, traveling along the esophagus, carries the material before it into the stomach. The cardiac sphincter which guards the lower end of the esophagus and which at other times is kept tonically closed re laxes upon the approach of the bolus which is then swept into the stomach by the wave of constriction which follows.
Peristalsis is a type of muscular contraction characteristic of the gut and consists in waves of contraction, these running along the muscles, both circular and longitudinal, towards the anus.
If the food is fluid it enters the stomach six seconds after the beginning of the act, but If It is solid it takes much long e r, up to fifteen minutes, to pass down the esophagus.
In the stomach the food is thoroughly mixed by the series of contractions, three or four a minute, the contraction waves passing from the middle of the stomach to the pylorus. These tend to drive the food in the same direction, but the pylorus being closed, there is axial reflex, owing to which the food is well mixed. After a time – a bout a minute when water has been swallowed – the pylorus relaxes at each wave, allowing some of the stomach contents to enter the duodenum. Fat stays in the stomach longer than carbo hydrate, but all food leaves generally in three or four hours. In the small intestine the food continues to be moved by peristalsis, the latter controlled by the deep nerve plexus. The small intestine undergoes segmentation movements, the food contents being thoroughly mired The wall becomes constricted into a number of segments and then about five seconds later the constrictions disappear, there being another set exactly out of phase with the first. The large intestine undergoes infrequent powerful contractions, food having entered it. From the large intestine the food enters the rectum.
New words
voluntary control – добровольный контрольsoft – мягкий
mastication – перетирание
position – положение
root – корень
46. The digestive system: liver and stomach. Sources of energy
Liver, the pancreas and the kidneys are the organs primarily engaged in the intermediary metabolism of the materials resorbed from the gasro – intestinal tract and in the excretion of metabolic waste products Of these 3 organs the liver performs the most diverse functions. It acts as the receiving depot and distributing center for the majority of the products of intestinal digestion and plays a major role in the intermediary metabolism of carbohydrates, fats, proteins and purines.
It controls the concentration of cholesterol esters in the blood and utilizes the sterol in the formation of bile acid. The liver takes in the regulation of the blood volume and in water metabolism and distribution. Its secretion, the bile, is necessary for fat digestion
The liver is a site for the formation of the proteins of the blood plasma, especially for fibrinogen, and also forms heparin, also forms heparin, carbohydrate which prevents the clotting of the blood It has important detoxicating functions and guards the organism against toxins of in testinal origin as well as other harmful substances The liver in its detoxicating functions and manifold metabolic activities may well be соnsidered the most important gland of the body.
The normal position of the empty human stomach is not horizontal, as used to be thought before the development of rentgenology. This method of examination has revealed the stomach to be either somewhat J-shaped of comparable in outline to a reversed L. The majority of normal stomachs are J-shaped. In the J-shaped type the pylorus lies at a higher level than the lowest part of the greater curvature and the body of the stomach is nearly vertical.
The stomach docs not empty itself by gravity, but through the contraction of its muscular wall like any other part of the diges tive tube, of which it is merely a segment.
Gastric motility shows great individual variation; in some types of stomach the wave travels very rapidly, completing its journey in from 10 to 15 seconds. In others the wave takes 30 seconds or go to pass from its origin to the pylorus. The slow waves are the more common.
Carbohydrates are the principal source of energy in most diets. They are absorbed into the blood stream in the form of glucose. Glucose not needed for immediate use is converted into glycogen and stored in the liver. When the blood sugar concentration goes down, the liver reconverts some of its stored glycogen into glucose.
Pats make up the second largest source of energy in most diets. They are stored in adipose tissue and round the principal internal organs. If excess carbohydrate is taken in, this can be converted into fat and stored. The stored fat is utilized when the liver is empty of glycogen.
Proteins are essential for the growth and rebuilding of tissue, but they can also be utilized as a source of energy. In some diets, such as the diet of the Eskimo, they form the main source of energy. Proteins are first broken down into amino acids. Then they are absorbed into the blood and pass round the body. Amino acids not used by the body are eventually excreted in the urine in the form of urea. Proteins, unlike-car-bohydrates and fats, cannot be stored for future use.
principal source – основной источник
energy – энергия
glucose – глюкоза
glycogen – гликоген
stored – сохраненный
adipose – животный жир
amino acids – аминокислоты
It controls the concentration of cholesterol esters in the blood and utilizes the sterol in the formation of bile acid. The liver takes in the regulation of the blood volume and in water metabolism and distribution. Its secretion, the bile, is necessary for fat digestion
The liver is a site for the formation of the proteins of the blood plasma, especially for fibrinogen, and also forms heparin, also forms heparin, carbohydrate which prevents the clotting of the blood It has important detoxicating functions and guards the organism against toxins of in testinal origin as well as other harmful substances The liver in its detoxicating functions and manifold metabolic activities may well be соnsidered the most important gland of the body.
The normal position of the empty human stomach is not horizontal, as used to be thought before the development of rentgenology. This method of examination has revealed the stomach to be either somewhat J-shaped of comparable in outline to a reversed L. The majority of normal stomachs are J-shaped. In the J-shaped type the pylorus lies at a higher level than the lowest part of the greater curvature and the body of the stomach is nearly vertical.
The stomach docs not empty itself by gravity, but through the contraction of its muscular wall like any other part of the diges tive tube, of which it is merely a segment.
Gastric motility shows great individual variation; in some types of stomach the wave travels very rapidly, completing its journey in from 10 to 15 seconds. In others the wave takes 30 seconds or go to pass from its origin to the pylorus. The slow waves are the more common.
Sources of energy
The fuels of the body are carbohydrates, fats and proteins. These are taken in the diet.Carbohydrates are the principal source of energy in most diets. They are absorbed into the blood stream in the form of glucose. Glucose not needed for immediate use is converted into glycogen and stored in the liver. When the blood sugar concentration goes down, the liver reconverts some of its stored glycogen into glucose.
Pats make up the second largest source of energy in most diets. They are stored in adipose tissue and round the principal internal organs. If excess carbohydrate is taken in, this can be converted into fat and stored. The stored fat is utilized when the liver is empty of glycogen.
Proteins are essential for the growth and rebuilding of tissue, but they can also be utilized as a source of energy. In some diets, such as the diet of the Eskimo, they form the main source of energy. Proteins are first broken down into amino acids. Then they are absorbed into the blood and pass round the body. Amino acids not used by the body are eventually excreted in the urine in the form of urea. Proteins, unlike-car-bohydrates and fats, cannot be stored for future use.
New words
fuels – топливоprincipal source – основной источник
energy – энергия
glucose – глюкоза
glycogen – гликоген
stored – сохраненный
adipose – животный жир
amino acids – аминокислоты
47. The urinary system: embriogenesis
The urinary system is formed mainly from mesodermal and endodermal derivatives. Three separate systems form sequentially. The pronephros is vestigial; the mesonephros may function transiently, but then mainly disappears; the metanephros develops into the definitive kidney. The permanent excre tory ducts are derived from the metanephric ducts, the urogenital sinus, and surface ectoderm.
Pronephros: Segmented nephrotomes appear in the cervical intermediate mesoderm of the embryo in the fourth week. These structures grow laterally and canalize to form nephric tubules. Successive tubules grow caudally and unite to form the pronephric duct, which empties into the cloaca. The first tubules formed regress before the last ones are formed.
Mesonephros: In the fifth week, the mesonephros appears as «S-shaped» tubules in the intermediate mesoderm of the thoracic and lumbar regions of the embryo.
The medial end of each tubule enlarges to form a Bowman's capsule into which a tuft of capillaries, or glomerulus, invaginates.
The lateral end of each tubule opens into the meson-ephriс (Wolffian) duct.
Mesonephric tubules function temporarily and degenerate by the beginning of the third month. The mesonephric duct pesists in the male as the ductus epididymidis, ductus deferens, and the ejaculatory duct.
Metanephros: During the fifth week, the metanephros, or permanent kidney, develops from two sources: the ureteric bud, a diverticulum of the mesonephric duct, and the metan-ephricmas, from intermediate mesoderrn of the lumbar and sacral regions. The ureteric bud penetrates the metanephric mass, which cordenses around the diverticulum to form the metanephrogen cap. The bud dilates to form the renal pelvis. One-to-three million collecting tubules develop from the minor calyces, thus forming the renal pyramids. Penetration of collecting tubules into the metanephric mass induces cells of the tissue cap to form nephrons, or excretory units. The proximal nephron forms Bowman's capsule, wherea the distal nephron connects to a collecting tubule.
Lengtheningy of the excretory tubule gives rise to the proximal convoluted tubule, loop of Henle, and the distal convoluted tubule.
The kidneys develop in the pelvis but appear to «as-cend» into the abdomen as a result of fetal growth of the lumbar and sacral regions.
The upper and largest part of the urogenital sinus becomes the urinary bladder, which is initially continuous with the allantois. Later the lumen of the allantois becomes obliterated. The mucosa of the trigone of the bladder is formed by the incorporation of the caudal mesonephric ducts into the dorsal bladder wall. This mesodermal tissue is eventually replaced by endodermal epithelium so that the entire lining of the bladder is of endodermal origin. The smooth muscle of the bladder is derived from splanchnic mesoderm.
Mile urethra is anatomically divided into three portions: prostatic membranous, and spongy (penile).
The prostatic urethra, membranous urethra, and proximal penile urethra develop from the narrow portion of the urogenital sinus below the urinary bladder. The distal spongy urethra is derived from the ectodermal cells of the glans penis.
Fimale urethra: The upper two-thirds develops from the esonephric ducts, and the lower portion is derived from the ogenital sinus.
kidneys – почки
bladder – мочевой пузырь
excretory ducts – выделительные трубочки
pronephros – первичная почка
urogenital – мочеполовой
Pronephros: Segmented nephrotomes appear in the cervical intermediate mesoderm of the embryo in the fourth week. These structures grow laterally and canalize to form nephric tubules. Successive tubules grow caudally and unite to form the pronephric duct, which empties into the cloaca. The first tubules formed regress before the last ones are formed.
Mesonephros: In the fifth week, the mesonephros appears as «S-shaped» tubules in the intermediate mesoderm of the thoracic and lumbar regions of the embryo.
The medial end of each tubule enlarges to form a Bowman's capsule into which a tuft of capillaries, or glomerulus, invaginates.
The lateral end of each tubule opens into the meson-ephriс (Wolffian) duct.
Mesonephric tubules function temporarily and degenerate by the beginning of the third month. The mesonephric duct pesists in the male as the ductus epididymidis, ductus deferens, and the ejaculatory duct.
Metanephros: During the fifth week, the metanephros, or permanent kidney, develops from two sources: the ureteric bud, a diverticulum of the mesonephric duct, and the metan-ephricmas, from intermediate mesoderrn of the lumbar and sacral regions. The ureteric bud penetrates the metanephric mass, which cordenses around the diverticulum to form the metanephrogen cap. The bud dilates to form the renal pelvis. One-to-three million collecting tubules develop from the minor calyces, thus forming the renal pyramids. Penetration of collecting tubules into the metanephric mass induces cells of the tissue cap to form nephrons, or excretory units. The proximal nephron forms Bowman's capsule, wherea the distal nephron connects to a collecting tubule.
Lengtheningy of the excretory tubule gives rise to the proximal convoluted tubule, loop of Henle, and the distal convoluted tubule.
The kidneys develop in the pelvis but appear to «as-cend» into the abdomen as a result of fetal growth of the lumbar and sacral regions.
The upper and largest part of the urogenital sinus becomes the urinary bladder, which is initially continuous with the allantois. Later the lumen of the allantois becomes obliterated. The mucosa of the trigone of the bladder is formed by the incorporation of the caudal mesonephric ducts into the dorsal bladder wall. This mesodermal tissue is eventually replaced by endodermal epithelium so that the entire lining of the bladder is of endodermal origin. The smooth muscle of the bladder is derived from splanchnic mesoderm.
Mile urethra is anatomically divided into three portions: prostatic membranous, and spongy (penile).
The prostatic urethra, membranous urethra, and proximal penile urethra develop from the narrow portion of the urogenital sinus below the urinary bladder. The distal spongy urethra is derived from the ectodermal cells of the glans penis.
Fimale urethra: The upper two-thirds develops from the esonephric ducts, and the lower portion is derived from the ogenital sinus.
New words
urinary system – мочевая системаkidneys – почки
bladder – мочевой пузырь
excretory ducts – выделительные трубочки
pronephros – первичная почка
urogenital – мочеполовой
48. The urinary system: kidneys
The urinary system is the major system involved in the excretion of metabolic waste products and excess water from the body It is also important in maintaining a homeostatic balance of fluids and electrolytes. The urinary system consists of two kidneys, two ureters, the urinary bladder, and the urethra. Urine is produced by the kidneys and is then transmit ted via the ureters to the bladder for temporary storage The urethra is the final pathway that conveys urine to the exterior. This system also has an important endocrine function in the production of renin and erythropoietin, which influence blood pressure and red blood cell (RBC) formation, respec tively.
Each kidney is composed of stroma and parenchyma. The stroma consists of a tough fibrous connective tissue capsule and a delicate interstitial connective tissue com posed of fibroblasts, wandering cells, collagen fibrils, and a hydrated proteoglycan extracellular matrix, which is collec tively called the renal interstitium The parenchyma consists of more than one million elaborate uriniferous tubules that represent the functional units of the kidney.
The kidney contains a hilum, a cortex, and a medula. The hilum is located medially and serves entrance as the point of entrance and exit for the renal artery, renal veins, and ureter. The renal pelvis, the expanded upper, divides into two or three entrance into the kidney. These, in turn, divide into eight minor calyces.
The cortex forms the outer zone of the kidney.
The medulla appears as a series of medullary pyramids. Two or three pyramids may unite to form a papilla. Uriniferous tubules consist of two functionally related portions called the nephron and the collecting tubule
Glomerulus is made up of several anastomotic capillary loops interposed between an afferent and an efferent arteriole. Plasma filtration occurs in the glomerulus.
Bowman's capsule consists of an inner visceral layer and an outer parietal layer. The space between these layers, the urinary space, is continuous with the renal tubule.
Visceral layer is apposed to the glomerulus and closely follows the branches of the glomerular capillaries. The visceral layer is composed of a single layer of epithelial cells resting on a basal lamina, which is fused with the basal lamina of the capillary endothelium. The cells of the visceral layer, call podocytes.
Cytoplasmic extensions of podocytes rest on the basal lamina.
Between adjacent pedicles, a thin slit diaphragm assists in preventing large plasma proteins from escaping from the vascular system.
In fact, most of the components of the glomerular filtrate are reabsorbed in the proximal tubule. Loop of Henle is a hairpin loop of the nephron that extends into the medulla and consists of thick and thin segments. The thick proximal portion of Henle's loop, or the descending thick segment, is a direct medullary continuation of the cortical proximal convoluted tubule.
The thick distal portion of the loop of Henle, the ascending thick segment, ascends to the cortex and is continuous with distal convoluted tubule. The major function of the distal tubule is to reabsorb soduim and chloride from the tubular filtrate. Collecting tubules consist of arched and straight segments.
stroma – строма
parenchyma – паренхима
fibrous capsule – волокнистая капсула
delicate – тонкий
interstitial – промежуточный
Each kidney is composed of stroma and parenchyma. The stroma consists of a tough fibrous connective tissue capsule and a delicate interstitial connective tissue com posed of fibroblasts, wandering cells, collagen fibrils, and a hydrated proteoglycan extracellular matrix, which is collec tively called the renal interstitium The parenchyma consists of more than one million elaborate uriniferous tubules that represent the functional units of the kidney.
The kidney contains a hilum, a cortex, and a medula. The hilum is located medially and serves entrance as the point of entrance and exit for the renal artery, renal veins, and ureter. The renal pelvis, the expanded upper, divides into two or three entrance into the kidney. These, in turn, divide into eight minor calyces.
The cortex forms the outer zone of the kidney.
The medulla appears as a series of medullary pyramids. Two or three pyramids may unite to form a papilla. Uriniferous tubules consist of two functionally related portions called the nephron and the collecting tubule
Glomerulus is made up of several anastomotic capillary loops interposed between an afferent and an efferent arteriole. Plasma filtration occurs in the glomerulus.
Bowman's capsule consists of an inner visceral layer and an outer parietal layer. The space between these layers, the urinary space, is continuous with the renal tubule.
Visceral layer is apposed to the glomerulus and closely follows the branches of the glomerular capillaries. The visceral layer is composed of a single layer of epithelial cells resting on a basal lamina, which is fused with the basal lamina of the capillary endothelium. The cells of the visceral layer, call podocytes.
Cytoplasmic extensions of podocytes rest on the basal lamina.
Between adjacent pedicles, a thin slit diaphragm assists in preventing large plasma proteins from escaping from the vascular system.
In fact, most of the components of the glomerular filtrate are reabsorbed in the proximal tubule. Loop of Henle is a hairpin loop of the nephron that extends into the medulla and consists of thick and thin segments. The thick proximal portion of Henle's loop, or the descending thick segment, is a direct medullary continuation of the cortical proximal convoluted tubule.
The thick distal portion of the loop of Henle, the ascending thick segment, ascends to the cortex and is continuous with distal convoluted tubule. The major function of the distal tubule is to reabsorb soduim and chloride from the tubular filtrate. Collecting tubules consist of arched and straight segments.
New words
urea – мочаstroma – строма
parenchyma – паренхима
fibrous capsule – волокнистая капсула
delicate – тонкий
interstitial – промежуточный
49. The urinary system: kidney vascular sypply
Vascular supply begins with the renal artery, enters the kidney the hilum, and immediately divides into interlobar arteries The arteries supply the pelvis and capsule before passing direct between the medullary pyramids to the corticomedullary junction The interlobar arteries bend almost 90 degrees to form shoarching, arcuate arteries, which run along the corticomedullary junction. The arcuate arteries subdivide into numerous fine interlobul arteries, which ascend perpendicularly to the arcuate arteries through the cortical labyrinths to the surface of the kidney. Each interlobular artery passes midway between two adjacent medullary rays.
The interlobular arteries then give off branches that become the afferent arterioles of the glomeruli.
As the afferent arteriole approaches the glomerulus, some its smooth muscle cells are replaced by myoepithelioid cells, which are part of the juxtaglomerular apparatus. The juxtaglomerular apparatus consists of juxtaglomerular cells, polkissen cells, and the macula densa.
Cells of the distal convoluted tubule near the afferent arteriole are taller and more slender than elsewhere in the distal tubule.
The juxtaglomerular cells secrete an enzyme called renin, which enters the bloodstream and converts the circulating polypeptide angiotensinogen into angiotensin I. Angiotensin I is converted to angiotensin II, a potent vaso constrictor that stimulates aldosterone secretion from the adrenal cortex. Aldosterone increases sodium and water reabsorption in the distal portion of the nephron.
Their nuclei are packed closely, so the region appear darker under the light microscope. The macula densa is thought to sense sodium concentration in the tubular fluid.
Polkissen cells are located between the afferent and ef-fer ent arterioles at the vascular pole of the glomerulus, adja cent to the macula densa.
Their function is unknown. Efferent glomerular arteriole divides into a second system of capillaries, the peritub-ufar plexus, which forms a dense net work of blood vessels around the tubules of the cortex.
Arterial supply of the medulla is provided by the efferent arte rioles of the glomeruli near the medulla. The arterio-lae rectae and the corresponding venae rectae with their respective capillary networks comprise the vasa recta, which supplies the medulla. The endothelium of the venae rectae is fenestrated and plays an important role in maintaining the osmotic gradi ent required for concentrating urine in the kidney tubules.
renal veins – почечные вены
expanded upper – расширенный верхний
minor calyces – незначительные чашечки
to supply – снабжать
arcuate arteries – дугообразные артерии
to subdivide – подразделять
numerous – многочисленный
interlobul – междолевой
to ascend – поднимать
perpendicularly – перпендикулярно
arcuate arteries – дугообразные артерии
The interlobular arteries then give off branches that become the afferent arterioles of the glomeruli.
As the afferent arteriole approaches the glomerulus, some its smooth muscle cells are replaced by myoepithelioid cells, which are part of the juxtaglomerular apparatus. The juxtaglomerular apparatus consists of juxtaglomerular cells, polkissen cells, and the macula densa.
Cells of the distal convoluted tubule near the afferent arteriole are taller and more slender than elsewhere in the distal tubule.
The juxtaglomerular cells secrete an enzyme called renin, which enters the bloodstream and converts the circulating polypeptide angiotensinogen into angiotensin I. Angiotensin I is converted to angiotensin II, a potent vaso constrictor that stimulates aldosterone secretion from the adrenal cortex. Aldosterone increases sodium and water reabsorption in the distal portion of the nephron.
Their nuclei are packed closely, so the region appear darker under the light microscope. The macula densa is thought to sense sodium concentration in the tubular fluid.
Polkissen cells are located between the afferent and ef-fer ent arterioles at the vascular pole of the glomerulus, adja cent to the macula densa.
Their function is unknown. Efferent glomerular arteriole divides into a second system of capillaries, the peritub-ufar plexus, which forms a dense net work of blood vessels around the tubules of the cortex.
Arterial supply of the medulla is provided by the efferent arte rioles of the glomeruli near the medulla. The arterio-lae rectae and the corresponding venae rectae with their respective capillary networks comprise the vasa recta, which supplies the medulla. The endothelium of the venae rectae is fenestrated and plays an important role in maintaining the osmotic gradi ent required for concentrating urine in the kidney tubules.
New words
renal artery – почечная артерияrenal veins – почечные вены
expanded upper – расширенный верхний
minor calyces – незначительные чашечки
to supply – снабжать
arcuate arteries – дугообразные артерии
to subdivide – подразделять
numerous – многочисленный
interlobul – междолевой
to ascend – поднимать
perpendicularly – перпендикулярно
arcuate arteries – дугообразные артерии
50. The urinary system: ureters, uretra
The calyces, renal pelves, and ureters constitute the main excretory ducts of the kidneys. The walls of these structures, in particular the renal pelvis and ureter, consist of three coats: an inner mucosa, middle muscularis, and an outer adventitia.
Mucosa of the calyces and ureter is lined by a transitional epithelium, which varies in thickness with the distention of the ureter. In the collapsed state, the cells are cuboidal with larger с shaped cells in the superficial layer. In the relaxed state, the lumen of the ureter is thrown into folds that generally disappear when the organ dilates during urine transport. Muscularis consists of an inner longitudinal and an outer circular layer of smooth muscle. In the distal ureter, an additional discontinuous outer longitudinal layer is present.
Adventitia consists of loose connective tissue with many large blood vessels. It blends with the connective tissue of the surrounding structures and anchors the ureter to the renal pelvis. The urinary bladder functions as a strong organ for urine. The structure of the wall of the bladder is similar to but thicker than of the ureter. Mucosa of the urinary bladder is usually folded, depending the degree of the bladder distention. The epithelium is transitional and the number of apparent layers depends on the fullness of the bladder. As the organ becomes distended, the superficial epithelial layer and the mucosa become flattened, and the entire epithelium becomes thinner. At its fullest distention, the bladder epithelium maybe only two or three cells thick. Lamina propria consists of connective tissue with abundant elastic fibers. Muscularis consists of prominent and thick bundles of smooth muscle that are loosely organized into three layers. Adventitia covers the bladder except on its superior part, where serosa is present. Male urethra serves as an excretory duct for both urine and semen. It is approximately 20 cm in length and has three anatom ic divisions. The prostatic portion is lined by transitional epithelium similar to that of the bladder. The prostatic urethra is surrounded by the fibromuscular tissue of the prostate, which normally keeps the urethral lumen closed. In the membranous and penile portions, the epithelium is pseudostratified up to the glans. At this point, it becomes stratified squamous and is continuous with the epidermis of the external part of the penis. The membranous urethra is encircled by a sphincter of skeletal muscle fibers from the deep transverse perineal muscle of the urogenital diaphragm, which also keeps the urethral lumen closed. The wall of the penile urethra contains little muscle but is surrounded and supported by the cylindrical erectile mass of corpus spongiosum tissue. Female urethra is considerably shorter than that of the male urethra. It serves as the terminal urinary passage, conducting urine from the bladder to the vestibule of the vulva. The epithelium begins at the bladder as a transitional variety and becomes stratified squamous with small areas of a pseudostratified columnar epithelium. The muscularis is rather indefinite but does contain both circu lar and longitudinal smooth muscle fibers. A urethral sphincter is formed by skeletal muscle as the female urethra passes through the urogenital diaphragm.
renal pelvis – почечная лоханка
calyces – чашечки
urethra – уретра
Mucosa of the calyces and ureter is lined by a transitional epithelium, which varies in thickness with the distention of the ureter. In the collapsed state, the cells are cuboidal with larger с shaped cells in the superficial layer. In the relaxed state, the lumen of the ureter is thrown into folds that generally disappear when the organ dilates during urine transport. Muscularis consists of an inner longitudinal and an outer circular layer of smooth muscle. In the distal ureter, an additional discontinuous outer longitudinal layer is present.
Adventitia consists of loose connective tissue with many large blood vessels. It blends with the connective tissue of the surrounding structures and anchors the ureter to the renal pelvis. The urinary bladder functions as a strong organ for urine. The structure of the wall of the bladder is similar to but thicker than of the ureter. Mucosa of the urinary bladder is usually folded, depending the degree of the bladder distention. The epithelium is transitional and the number of apparent layers depends on the fullness of the bladder. As the organ becomes distended, the superficial epithelial layer and the mucosa become flattened, and the entire epithelium becomes thinner. At its fullest distention, the bladder epithelium maybe only two or three cells thick. Lamina propria consists of connective tissue with abundant elastic fibers. Muscularis consists of prominent and thick bundles of smooth muscle that are loosely organized into three layers. Adventitia covers the bladder except on its superior part, where serosa is present. Male urethra serves as an excretory duct for both urine and semen. It is approximately 20 cm in length and has three anatom ic divisions. The prostatic portion is lined by transitional epithelium similar to that of the bladder. The prostatic urethra is surrounded by the fibromuscular tissue of the prostate, which normally keeps the urethral lumen closed. In the membranous and penile portions, the epithelium is pseudostratified up to the glans. At this point, it becomes stratified squamous and is continuous with the epidermis of the external part of the penis. The membranous urethra is encircled by a sphincter of skeletal muscle fibers from the deep transverse perineal muscle of the urogenital diaphragm, which also keeps the urethral lumen closed. The wall of the penile urethra contains little muscle but is surrounded and supported by the cylindrical erectile mass of corpus spongiosum tissue. Female urethra is considerably shorter than that of the male urethra. It serves as the terminal urinary passage, conducting urine from the bladder to the vestibule of the vulva. The epithelium begins at the bladder as a transitional variety and becomes stratified squamous with small areas of a pseudostratified columnar epithelium. The muscularis is rather indefinite but does contain both circu lar and longitudinal smooth muscle fibers. A urethral sphincter is formed by skeletal muscle as the female urethra passes through the urogenital diaphragm.
New words
ureter – мочеточникrenal pelvis – почечная лоханка
calyces – чашечки
urethra – уретра
51. The kidney`s function
The kidneys are filters which remove waste products from the blood. In the human each is a bean-shaped organ, some four inches long and about two inches wide. The two are situated high up on the posterior abdominal wall behind the peritoneum and in front of the lats ribs and the upper two lunbar transverse processes. Each is invested by a fibrous capsule surrounded by more or less perinephric fat. On the upper pole of each is a supra-renal gland. On the medical side is a notch called the hilum where the vessels and the ureter are attached.
Vertical selections through a kidney discloses three more or less concentric zones. The other light-colored zone is the renal cortex, within this is the darker renal medulla and within this again is a space – the renal sinus which is normally occurred by a fibrous bag called the renal pelvis. The pelvis opens below into the ureter. The cortex extends inwards in a series of renal columns which divide the medulla into a number of renal pyramids. Each pyramid has a free rounded projection – a renal papilla – which lies in a cap – like extension, of the pelvis cal led a renal calyx. The pelvis is lined by transitioual epithelium, which extends the calyces and covers the papillae
Within the cortex each minute artery presents along its course a convoluted knot, called a glomerulus; the branch which enters the knot is the afferent vessel, that which leaves is she efferent vessel. Each glomerulus project into the dilated end of its corresponding renal tubule, from which it is separated by a thin layer of cells called glomerular (Bowman s) capsule; glomerulus plus capsule form a renal (Nalpighian) corpuscle. The cortex contains multitudes of such corpuscles, each giving rise to a tubule which passes down into the medul la and back again in the so-called loop of Henle. Back in, the cortex loop ends in a functional tubule which joins а larger collecting tube. Ultimately, a number of collecting tubes combine to form an excretory tube, which opens at the ареx of a papilla into a renal calyx. The efferent vessel from the glomerulus accompanies the loop of Henle, supply ing the tubule on the way and finally ends in a small vein. A renal corpuscule plus its complement of tubules and blood vessels is called a renal unit, or nephron; there are said to be one million such units in each kidney, their tubing totaling a length of some twenty miles.
four inches long – 4 дюйма в длину
two inches wide – 2 дюйма в ширину
peritoneum – брюшина
lumbar – поясничный
renal cortex – корковый слой
renal medulla – мозговой слой
fibrous – волокнистая
dilated – расширенный
to be separated – быть разделенным
loop of henle – петля Генле
Vertical selections through a kidney discloses three more or less concentric zones. The other light-colored zone is the renal cortex, within this is the darker renal medulla and within this again is a space – the renal sinus which is normally occurred by a fibrous bag called the renal pelvis. The pelvis opens below into the ureter. The cortex extends inwards in a series of renal columns which divide the medulla into a number of renal pyramids. Each pyramid has a free rounded projection – a renal papilla – which lies in a cap – like extension, of the pelvis cal led a renal calyx. The pelvis is lined by transitioual epithelium, which extends the calyces and covers the papillae
Within the cortex each minute artery presents along its course a convoluted knot, called a glomerulus; the branch which enters the knot is the afferent vessel, that which leaves is she efferent vessel. Each glomerulus project into the dilated end of its corresponding renal tubule, from which it is separated by a thin layer of cells called glomerular (Bowman s) capsule; glomerulus plus capsule form a renal (Nalpighian) corpuscle. The cortex contains multitudes of such corpuscles, each giving rise to a tubule which passes down into the medul la and back again in the so-called loop of Henle. Back in, the cortex loop ends in a functional tubule which joins а larger collecting tube. Ultimately, a number of collecting tubes combine to form an excretory tube, which opens at the ареx of a papilla into a renal calyx. The efferent vessel from the glomerulus accompanies the loop of Henle, supply ing the tubule on the way and finally ends in a small vein. A renal corpuscule plus its complement of tubules and blood vessels is called a renal unit, or nephron; there are said to be one million such units in each kidney, their tubing totaling a length of some twenty miles.
New words
bean-shaped organ – орган в форме бобаfour inches long – 4 дюйма в длину
two inches wide – 2 дюйма в ширину
peritoneum – брюшина
lumbar – поясничный
renal cortex – корковый слой
renal medulla – мозговой слой
fibrous – волокнистая
dilated – расширенный
to be separated – быть разделенным
loop of henle – петля Генле
52. Acute renal failure
The two major mechanisms may participate in association between intratubular hemorrage and nephron damage in acute renal failure. The first mechanism is direct nephrotoxicity from hemoglobin, because intratubular degradation of erythrocytes releases heme and iron which are toxic to cells. The second mechanism is hypoxic damage induced by regional vasoconstriction because heme avidly binds the potent vasodilator nitric oxide.
Intratubular degradation of hemoglobin releases heme containing molecules and eventually free iron. These breakdown products, also elaborated from myoglobin, probably play an important role in the pathogenesis of acute tubular necrosis. Endocytic reabsorption from the tubular him en of filtered free hemoglobin or myoglobin may be a major pathway to proximal tubular damage in pigment nephropathy. In addition, free iron promotes the formation of oxygen free radicals, lipid peroxidation and cell death Another source of toxic iron is from the breakdown of intracellular cytochrom P-450 under hypoxic condition. One of the most potent intrarenal vasodilator system is nitric oxide, produced from L-arginine in vascular endothelium. smooth muscle and tubular calls, causing Vascular smooth muscle relaxation through the induction of intracellular cyclic GMP. Blocking nitric oxide synthesis causes profound vascular constriction, systemic hypertension and a marked decline in renal blood flow. Endothelial dysfunction with reduced nitric oxid production may underlie the defective regional vasodilation in diabetes and atherosclerosis, predisposing to renal ischemia and nephrotoxic insult.
Hemoglobin avidly binds nitric oxide and ingibits nitrovasodilation. The presence of large pool of hemoglobin in the tubular lumen could therefore affect the vasomotor balance of kidney circulation: intrarenal vasoconstriction is likely to be most pronounced and most significant in the medulla., because the ratio of tubular mass to vessels surface may be particularly high in this region. The medulla normally functions at low oxygen tension, because of limited medulla blood flow and counter-current exchange of oxygen. Inhibinion of nitric oxide synthesis induces severe and prolonged outer medullary hypoxia and predisposes to tubular necrosis Unfortunately, biopsy specimens of glomerulonephritis associated with acute tubular necrosis do not provide the precise distribution of the tubular lesions.
In chronic glomerulonephritis tubulo-interstitiaJ damage has often been reported as correlate of kidney function and also its best prognostic marker. Glomerular obsolescence deprives the renal parenchyma from nutritional blood flow, leading to tubule-interstitial fibrosis in medullary rays and outer medulla. Proteinuria imposes to the proximal tubules a constant burden of reabsorption and catabolism of albumin and other proteins from the tubular lumen, which have been suggested to cause cellular injury.
intratubular – внутриканальцевый
heme – гем
tubular necrosis – канапьцевый некроз
reabsorption – реабсорбция
proteinuria – протеннурия
Intratubular degradation of hemoglobin releases heme containing molecules and eventually free iron. These breakdown products, also elaborated from myoglobin, probably play an important role in the pathogenesis of acute tubular necrosis. Endocytic reabsorption from the tubular him en of filtered free hemoglobin or myoglobin may be a major pathway to proximal tubular damage in pigment nephropathy. In addition, free iron promotes the formation of oxygen free radicals, lipid peroxidation and cell death Another source of toxic iron is from the breakdown of intracellular cytochrom P-450 under hypoxic condition. One of the most potent intrarenal vasodilator system is nitric oxide, produced from L-arginine in vascular endothelium. smooth muscle and tubular calls, causing Vascular smooth muscle relaxation through the induction of intracellular cyclic GMP. Blocking nitric oxide synthesis causes profound vascular constriction, systemic hypertension and a marked decline in renal blood flow. Endothelial dysfunction with reduced nitric oxid production may underlie the defective regional vasodilation in diabetes and atherosclerosis, predisposing to renal ischemia and nephrotoxic insult.
Hemoglobin avidly binds nitric oxide and ingibits nitrovasodilation. The presence of large pool of hemoglobin in the tubular lumen could therefore affect the vasomotor balance of kidney circulation: intrarenal vasoconstriction is likely to be most pronounced and most significant in the medulla., because the ratio of tubular mass to vessels surface may be particularly high in this region. The medulla normally functions at low oxygen tension, because of limited medulla blood flow and counter-current exchange of oxygen. Inhibinion of nitric oxide synthesis induces severe and prolonged outer medullary hypoxia and predisposes to tubular necrosis Unfortunately, biopsy specimens of glomerulonephritis associated with acute tubular necrosis do not provide the precise distribution of the tubular lesions.
In chronic glomerulonephritis tubulo-interstitiaJ damage has often been reported as correlate of kidney function and also its best prognostic marker. Glomerular obsolescence deprives the renal parenchyma from nutritional blood flow, leading to tubule-interstitial fibrosis in medullary rays and outer medulla. Proteinuria imposes to the proximal tubules a constant burden of reabsorption and catabolism of albumin and other proteins from the tubular lumen, which have been suggested to cause cellular injury.
New words
nephron – нефронintratubular – внутриканальцевый
heme – гем
tubular necrosis – канапьцевый некроз
reabsorption – реабсорбция
proteinuria – протеннурия
53. Iron in the body
It is accepted that the total amount of iron in the body is between 2 and 5 g., varying with body-weight and hemoglobin level; about two-thirds of this is in the form of hemoglobin and about 30 % is storage iron; iron in myо-globin and enzymes makes up the small remaining fraction together with iron in transport, which is only 0,12 %. There is a big difference between the sexes: in the adult male the total iron is about 50 mg. per kg. body-weight. But in the adult female the figure is only 35 mg. per kg., mainly be cause the normal blood-level of hemoglobin is lower than in the male. Iron exists in the body mainly in two forms: firstly, as heme in hemoglobin, and cytоchrome concerned with the utilization of oxygen; and secondly, bound to a protein without heme formation, as storage and transport iron. Iron in the body has a very rapid turnover, since some 3 million red blood cells are broken down per second and the greater part of the iron released is returned to the bone marrow and re-formed into fresh hemoglobin; some 6,3 g. of hemoglobin containing 21 mg. of iron is handled this way every 24 hours.
The amount of iron in the body is regulated by control of absorption, since excretion is very small. The amount of iron absorbed from food differs with different foodstuffs, so the com position of the diet is important. Absorption can be increased in the normal Individual when the blood-hemoglobin is lower than normal and is the iron stores are low. Iron stores are normally lower in women than men and so they tend to absorb more iron. Iron absorption can decrease in older persons, especially in those over 60. Many estimates have agreed that the average Western diet pro vides between 10 and 15 mg. of iron daily, of which only 5 – 10 % is absorbed.
Iron absorption takes place mainly in the upper jejunum, though some is absorbed in all parts of the small intestine and even in the colon. Iron in food is mostly in ferric form and must bе reduced to the ferrous form before it can be absorbed; this reduction begins in the stomach – though very little is absorbed there – and continues in the small intestine. The iron is absorbed via the brush-border of the intestine and then may take one of two paths; it is either passed into the blood, where it combines with a globulin, and passes to the marrow or to storage sites; or it combines with the protein, which is then deposited in the intestinal cells.
Iron is lost mostly through the gastrointestinal tract by way of red cells and intestinal cells containing iron lost in the constant desquamation from the intestinal mucosa.
varying – изменение
hemoglobin – гемоглобин
storage – хранение
myоglobin – миоглобин
fraction – фракция
together – вместе
body-weight – масса тела
desquamation – десквамация
The amount of iron in the body is regulated by control of absorption, since excretion is very small. The amount of iron absorbed from food differs with different foodstuffs, so the com position of the diet is important. Absorption can be increased in the normal Individual when the blood-hemoglobin is lower than normal and is the iron stores are low. Iron stores are normally lower in women than men and so they tend to absorb more iron. Iron absorption can decrease in older persons, especially in those over 60. Many estimates have agreed that the average Western diet pro vides between 10 and 15 mg. of iron daily, of which only 5 – 10 % is absorbed.
Iron absorption takes place mainly in the upper jejunum, though some is absorbed in all parts of the small intestine and even in the colon. Iron in food is mostly in ferric form and must bе reduced to the ferrous form before it can be absorbed; this reduction begins in the stomach – though very little is absorbed there – and continues in the small intestine. The iron is absorbed via the brush-border of the intestine and then may take one of two paths; it is either passed into the blood, where it combines with a globulin, and passes to the marrow or to storage sites; or it combines with the protein, which is then deposited in the intestinal cells.
Iron is lost mostly through the gastrointestinal tract by way of red cells and intestinal cells containing iron lost in the constant desquamation from the intestinal mucosa.
New words
iron – железоvarying – изменение
hemoglobin – гемоглобин
storage – хранение
myоglobin – миоглобин
fraction – фракция
together – вместе
body-weight – масса тела
desquamation – десквамация
54. Atherosclerotic mechanisms
Pivotal mechanisms involved in atherogenesis include.
1. Focal intimal influx and accumulation of plasma lipoproteins at lesion-prone sites.
2. Focal intimal monocyte-macrophage recruitment.
3. Generation within the intima of reactive oxygen species of free radicals by smooth muscle cells, macrophages and endothelial cells.
4. Oxidative modification of intimal lipoproteins by these reactive oxygen species to produce such oxidatively modified lipoproteins species as oxidized LDL and Lp(a).
5. Foam cell formation due to the uptake of oxidatively modified lipoproteins by the non-down-regulating macrophage scavenger receptors.
6. Foam cell necrosis, most likely due to the cytotoxic effects of oxidatively modified LDL. This process gives rise to the extracellular lipid core, and is an important event in the transition from the reversible fatty streak to the less readily reversible, more advanced atherosclerotic lesion.
7. Smooth muscle cell migration to and proliferation in the arterial intima, a process in which platelet-derived growth factor is believed to act as a chemo oattractant. Fibroblast growth factors likely regulate smooth muscle cell proliferation.
8. Plaque rupture, primarily at sites of greatest macrophage density. Proteolytic enzymes released by macrophages may stimulate plaque rupture, which ultimately leads to mural or occlusive thrombosis. Thrombosis contributes significantly to the stages of plaque growth.
9. Autoimmune inflammation, likely the result of anti-genic epitopes of oxidized LDL. Lipoproteins, such as LDL and Lp(a), enter the subendothelial space and intercept free radicals generated by endothelial cells. Following oxidation, these charge-modified lipoproteins are taken up by the non-down-regulating macrophage scavenger receptors pathway, resulting in lipid-rich, cholesteryl ester rich foam cells. Concurrently, circulating monocytes continue to attach to the endothelium, attracted by the chem oattractant MCP-1, and oxidized LDL. The expression and synthesis of MCP-1 by endothelial and smooth muscle cells is augmented by oxidatively modified lipoproteins, allowing the process to continue.
The next phase in atherogenesis is the development of the classic fatty streak as result of the continued uptake of oxidatively modified LDL by the macrophage scavenger receptors with continuing foam cell formation. A few smooth muscle cells can also be seen apparently entering the subendothelial space and proliferating within the intima during this phase. The transitional phase of atherogenesis is characterized by necrosis of the foam cells and the formation of an extracellular lipid core. In this stage, there is an increase in both smooth muscle cells proliferation and collagen synthesis, and lesions continue to grow. As long as elevated low density lipoproteins are present in the circulation, the atherosclerosis process continues. Among the additional changes taking place is the influx of Tlymphocytes. The involvenment of an autoimmune inflammatory component becomes obvious in the late stages of lesion development and is reflected by a prominent lymphocytic infiltration of the adventitia.
plaque – атеросклеротическая бляшка
lymphocytic – лимфотический
inflammatory – воспалительный
low density lipoproteins – липопротеины низкой плотности
1. Focal intimal influx and accumulation of plasma lipoproteins at lesion-prone sites.
2. Focal intimal monocyte-macrophage recruitment.
3. Generation within the intima of reactive oxygen species of free radicals by smooth muscle cells, macrophages and endothelial cells.
4. Oxidative modification of intimal lipoproteins by these reactive oxygen species to produce such oxidatively modified lipoproteins species as oxidized LDL and Lp(a).
5. Foam cell formation due to the uptake of oxidatively modified lipoproteins by the non-down-regulating macrophage scavenger receptors.
6. Foam cell necrosis, most likely due to the cytotoxic effects of oxidatively modified LDL. This process gives rise to the extracellular lipid core, and is an important event in the transition from the reversible fatty streak to the less readily reversible, more advanced atherosclerotic lesion.
7. Smooth muscle cell migration to and proliferation in the arterial intima, a process in which platelet-derived growth factor is believed to act as a chemo oattractant. Fibroblast growth factors likely regulate smooth muscle cell proliferation.
8. Plaque rupture, primarily at sites of greatest macrophage density. Proteolytic enzymes released by macrophages may stimulate plaque rupture, which ultimately leads to mural or occlusive thrombosis. Thrombosis contributes significantly to the stages of plaque growth.
9. Autoimmune inflammation, likely the result of anti-genic epitopes of oxidized LDL. Lipoproteins, such as LDL and Lp(a), enter the subendothelial space and intercept free radicals generated by endothelial cells. Following oxidation, these charge-modified lipoproteins are taken up by the non-down-regulating macrophage scavenger receptors pathway, resulting in lipid-rich, cholesteryl ester rich foam cells. Concurrently, circulating monocytes continue to attach to the endothelium, attracted by the chem oattractant MCP-1, and oxidized LDL. The expression and synthesis of MCP-1 by endothelial and smooth muscle cells is augmented by oxidatively modified lipoproteins, allowing the process to continue.
The next phase in atherogenesis is the development of the classic fatty streak as result of the continued uptake of oxidatively modified LDL by the macrophage scavenger receptors with continuing foam cell formation. A few smooth muscle cells can also be seen apparently entering the subendothelial space and proliferating within the intima during this phase. The transitional phase of atherogenesis is characterized by necrosis of the foam cells and the formation of an extracellular lipid core. In this stage, there is an increase in both smooth muscle cells proliferation and collagen synthesis, and lesions continue to grow. As long as elevated low density lipoproteins are present in the circulation, the atherosclerosis process continues. Among the additional changes taking place is the influx of Tlymphocytes. The involvenment of an autoimmune inflammatory component becomes obvious in the late stages of lesion development and is reflected by a prominent lymphocytic infiltration of the adventitia.
New words
atherogenesis – атерогенезplaque – атеросклеротическая бляшка
lymphocytic – лимфотический
inflammatory – воспалительный
low density lipoproteins – липопротеины низкой плотности
55. Advances in blood component separation and plasma treatment for therapeutics
The separation of blood cells from plasma is done routinely by centrifugal techniques.
Membranes for plasma separation.
Membrane modules vary in surface area from about 0,15 to 0,8 m 2. Membrane plasma separation is a relatively simple process. At relatively low transmembrane pressure (generally less than 50 mm Hg), adequate plasma fluxes can be achieved. Equipment requirements are only minimal and the operation is much akin to that for other extracorporeal treatment technologies as hemodialysis, hemofiltration and hemoperfusion.
Membrane of on-line plasma treatment.
Plasma exchange whether by centrifugal or membrane techniques requires that the plasma discarded be replaced by physiological solution, which in most cases is en albumin solution. Because essential plasma components as well as pathological ones, are removed during plasma exchange, techniques designed to remove only the pathological components would be highly desirable. Review of the disease states treated by plasma exchange reveals that mane of the marker solutes ere of f molecular weight larger (generally greater than 100 000 daltons) than albumin, suggesting membrane filtration as physical separation techniques for their removal.
With presently available membranes, selective passage of albumin (near 70 000 daltons) and lower molecular weight solutes with complete retention of larger molecular weight solutes is difficult to achieve. However, such a complete separation may not be desirable since many higher molecular weight solutes are normal components of plasma To apply some selectivity in the separation of the marker solutes with a high return to the normal constituents of plasma and thus no requirement for plasma product infusion, the technique of cryofiltration was applied.
Cryofiltration is the on-line technique of plasma treatment consisting of plasma cooling followed by membrane filtration. By cooling the plasma, cryogel is deposited on the membrane during the Filtration process. The cryogel has been shown to contain concentrated quantities of the marker solutes. Response to therapy in the majority of patients with rheumatoid arthritis has been from good to excellent. In treatments, decreases in marker solutes have been noted coupled with improvement in clinical symptomology.
Membrane technology appears very promising in the separation and treatment of plasma on-line. Chronic treatment therapies appear safe and well tolerated by the patients.
plasma exchange – плазмообмен
therapeutic – терапевтический
metabolic – метаболический
multiple – множественный
extracorporeal – экстракорпоральный
Membranes for plasma separation.
Membrane modules vary in surface area from about 0,15 to 0,8 m 2. Membrane plasma separation is a relatively simple process. At relatively low transmembrane pressure (generally less than 50 mm Hg), adequate plasma fluxes can be achieved. Equipment requirements are only minimal and the operation is much akin to that for other extracorporeal treatment technologies as hemodialysis, hemofiltration and hemoperfusion.
Membrane of on-line plasma treatment.
Plasma exchange whether by centrifugal or membrane techniques requires that the plasma discarded be replaced by physiological solution, which in most cases is en albumin solution. Because essential plasma components as well as pathological ones, are removed during plasma exchange, techniques designed to remove only the pathological components would be highly desirable. Review of the disease states treated by plasma exchange reveals that mane of the marker solutes ere of f molecular weight larger (generally greater than 100 000 daltons) than albumin, suggesting membrane filtration as physical separation techniques for their removal.
With presently available membranes, selective passage of albumin (near 70 000 daltons) and lower molecular weight solutes with complete retention of larger molecular weight solutes is difficult to achieve. However, such a complete separation may not be desirable since many higher molecular weight solutes are normal components of plasma To apply some selectivity in the separation of the marker solutes with a high return to the normal constituents of plasma and thus no requirement for plasma product infusion, the technique of cryofiltration was applied.
Cryofiltration is the on-line technique of plasma treatment consisting of plasma cooling followed by membrane filtration. By cooling the plasma, cryogel is deposited on the membrane during the Filtration process. The cryogel has been shown to contain concentrated quantities of the marker solutes. Response to therapy in the majority of patients with rheumatoid arthritis has been from good to excellent. In treatments, decreases in marker solutes have been noted coupled with improvement in clinical symptomology.
Membrane technology appears very promising in the separation and treatment of plasma on-line. Chronic treatment therapies appear safe and well tolerated by the patients.
New words
centrifugal technique – центрифужные технологииplasma exchange – плазмообмен
therapeutic – терапевтический
metabolic – метаболический
multiple – множественный
extracorporeal – экстракорпоральный
56. Artificial oxygen carries
Artificial oxygen (O
2) carries aim at improving O
2delivery Artificial O
2carries thus may be used as alternative to allogeneic blood transfusions or to improve tissue oxygenation and function of organs with marginal O
2supply. Artificial O
2carries can be grouped into modified hemoglobin (Hb) solutions and perfluorocarbon (PFC) emulsions. The native human Hg molecule needs to be modified in order to decrease O
2affinity and to prevent rapid dissociation of the native tetramer into dimers. The O
2transport characteristics of modified Hb solutions and PFC emulsions are fundamentally different. The Hb solutions exhibit a sigmoidal O
2dissociation curve similar to blood. In contrast, the PFC emulsions are characterised by a linear relationship between O
2partial pressure and O
2content. Hb solutions thus provide O
2transport and unloading capacity similar to blood. This means that already at a relatively low arterial O
2partial pressure substantial amounts of O
2are being transported. In contrast, relatively high arterial O
2partial pressures are necessary to maximize the O
2transport capacity of PFC emulsions. Modified Hb solutions are very promising in improving O
2transport and tissure oxygenation to a physiologically relevant degree. Because cross-matching is unnecessary, these solutions hold great promise as alternative to allogeneic blood transfusions and as O
2therapeutics, which might be of great value also in the prehospital resuscitation of trauma victims or in specific situations in intensive care medicine. In patients with a reduced cardiac contractility and normal or elevated mean arterial pressure Hb infusion may increase systemic and pulmonary vascular resistances with consequent reduction in , cardiac output. In contrast, in a previously healthy trauma victim, suffering from severe hypovolaemia due to massive haemorrhage, the combined effects of volume replacement, added O
2transport capacity, and mild vasoconstriction due to the infusion of a modified Hb solution may be beneficial.
PFC are carbonfluorine compounds characterised by a high gas-dissolving capacity, low viscosity, and chemical and biological inertness. Manufacturing an emulsion with very specific characteristics is a great technologic challenge. After intravenous application, the droplets of the emulsion are being taken up by the reticular-endothelial system, droplets are slowly broken down, the PFC molecules are being taken up in the blood again and transported to the lungs, where the unaltered PFC molecules are finally excreted via exhalation. The ability of PFC emulsions to transport and efficiently unload O 2is undisputed. With the application of perflubron emulsion, cardiac output tender to increase.
emulsion – эмульсия
oxygen – кислород
solution – раствор
O 2transport – транспорт кислорода
tissure oxygenation – оксигенация тканей
physiological – физиологический
PFC are carbonfluorine compounds characterised by a high gas-dissolving capacity, low viscosity, and chemical and biological inertness. Manufacturing an emulsion with very specific characteristics is a great technologic challenge. After intravenous application, the droplets of the emulsion are being taken up by the reticular-endothelial system, droplets are slowly broken down, the PFC molecules are being taken up in the blood again and transported to the lungs, where the unaltered PFC molecules are finally excreted via exhalation. The ability of PFC emulsions to transport and efficiently unload O 2is undisputed. With the application of perflubron emulsion, cardiac output tender to increase.
New words
saturation – насыщение гемоглобина кислородомemulsion – эмульсия
oxygen – кислород
solution – раствор
O 2transport – транспорт кислорода
tissure oxygenation – оксигенация тканей
physiological – физиологический