miércoles, 2 de marzo de 2011

Apéndice humana

Intestino grueso

The large intestine, or colon, consists of ascending, transverse, descending, and sigmoid portions. The ascending portion extends from the cecum superiorly along the right abdominal wall to the inferior surface of the liver and bends sharply at a right angle to the left at a curve called the hepatic flexure. From there, it crosses the abdominal cavity as the transverse colon to the left abdominal wall at the splenic flexure and begins the descending colon which traverses inferiorly along the left abdominal wall to the pelvic region. The colon then forms an angle medially from the pelvis to form an s-shaped curve called the sigmoid colon. The last few inches of the colon is the rectum which is a storage site for solid waste which leaves the body by way of an external opening called the anus, controlled by muscles called sphincters. Substances which have not been absorbed in the small intestine enter the large intestine in the form of liquid and fiber. The large intestine or "bowel" is sometimes called the "garbage dump" of the body, because the materials that reach it are of very small use to the body and are sent on to be disposed of. The first half of the colon absorbs fluids and recycles them into the blood stream. The second half compacts the wastes into feces, secretes mucus which binds the substances, and lubricates it to protect the colon and ease its passage. Of the two to two and one-half gallons of food and liquids taken in by the average adult, only about twelve ounces of waste enters the large intestine. Feces are comprised of about three quarters water. The remainder is protein, fat, undigested food roughage, dried digestive juices, cells shed by the intestine, and dead bacteria. A common disorder of the large intestine is inflammation of the appendix, or appendicitis. Waste that accumulates in the appendix cannot be moved easily by peristalsis since the appendix has only one opening. The symptoms of appendicitis include muscular rigidity, localized pain in the right lower quarter of the abdomen, and vomiting. The chief danger of appendicitis is that is may rupture and empty its contents of fecal matter and waste into the abdominal cavity producing an extremely serious condition called peritonitis.

Intestino delgado

If the small intestine were not looped back and forth upon itself, it could not fit into the abdominal space it occupies. It is held in place by tissues which are attached to the abdominal wall and measures eighteen to twenty-three feet in the average adult, which makes it about four times longer than the person is tall. It is a three-part tube of about one and one-half to two inches in diameter and is divided into three sections: (1) the duodenum, a receiving area for chemicals and partially digested food from the stomach; (2) the jejunum, where most of the nutrients are absorbed into the blood and (3) the ileum, where the remaining nutrients are absorbed before moving into the large intestine. The intestines process about 2.5 gallons of food, liquids and bodily waste every day. In order for enough nutrients to be absorbed into the body, it must come in contact with large numbers of intestinal cells which are folded like gathered skirts. Each of these cells contain thousands of tiny finger-like projections called "villi," and each villus contains microscopic "microvilli". In one square inch of small intestine, there are about 20,000 villi and ten billion microvilli. Each villus brings in fresh, oxygenated blood and sends out nutrient-enriched blood. The villi sway constantly to stir up liquefied food and remove the nutrients which can be absorbed and then passed through the membranes of the villi into the blood and lymph vessels. The fatty nutrients go to the lymph vessels, and glucose and amino acids go to the blood and on to the liver. The muscles which encircle this tube constrict about seven to twelve times a minute to move the food back and forth, to churn it, knead it, and to mix it with gastric juices. The small intestine also makes waves which move the food forward, but these are usually weak and infrequent to allow the food to stay in one place until the nutrients can be absorbed. If a toxic substance enters the small intestine, these movements may be strong and rapid to expel the poisons quickly.


El intestino grueso, o colon, consiste en las porciones ascendente, transversal, descendente y sigmoide. La porción ascendente se extiende desde el intestino ciego y sube junto con la pared abdominal derecha hacia la superficie interior del hígado y hace una pronunciada curva llamada la flexión hepática. De ahí, cruza la cavidad abdominal con el nombre de colon transverso hacia la pared abdominal izquierda hasta la flexión esplénica. Ahí comienza el colon descendente, que baja por la pared abdominal izquierda hasta la pelvis para formar una "S", llamada el colon sigmoide. Las últimas pulgadas del colon es el recto, que es un sitio de almacenamiento para los desechos sólidos que dejan el cuerpo por medio de una abertura externa llamada ano, controlado por músculos llamados esfínteres las sustancias que han sido absorbidas por el intestino delgado entran en el intestino grueso en la forma de fibras o líquidos. El intestino grueso o "tripa" es a veces llamado el "tiradero de basura" del cuerpo, porque los materiales que llegan a él son muy poco útiles para el cuerpo y se llegan para ser expulsados. La primer mitad del colon absorbe fluidos y los recicla hacia el torrente sanguíneo. La segunda mitad convierte lo desecho en heces, secreta mucosa envuelve las sustancias y que lubrica el intestino para protegerlo y facilitar el paso de desechos. De los dos o dos y medio galones de comida y líquidos que ingiere el adulto promedio, sólo 12 onzas de desecho entran en el intestino grueso. Las heces están compuestas por tres cuartos de agua. Lo que resta es proteína, grasa, fibra de comida no digerida, jugos digestivos secos, células derramadas por los intestinos y bacterias muertas. Un desorden común en el intestino grueso es la inflamación del apéndice, o apendicitis. Los desechos acumulados en el apéndice no pueden quitarse fácilmente por medio de la peristalsis ya que el apéndice sólo tienen un abertiura. Los síntomas de la apendicitis incluyen rigidez muscular, dolor en el cuarto inferior derecho del abdomen y vómitos. El mayor peligro de la apendicitis es que se puede romper y vaciar su contenido o materia fecal hacia la cavidad abdominal produciendo un condición extremadamente seria llamada peritonitis.


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