JК
Английский язык :: Беликова Елена
Страница: 54 из 68The 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 контроль
soft – 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.
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 контроль
soft – 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.