About Digestion 消化系统解说

 

Digestive System is essentially a long, twisting tube organ, it transform our food to body’s fuel. In a nutshell, it is start from mouth to the anus, approximately 30 feet (9 meters) complicated tube-type system. Before enter body circulation, food been digest, classified and reprocess. This is to provide energy for cell, cell regeneration and provide energy for muscle.

Digestion of the food on the plate need to be chew into soft yet sticky liquid to break down to its compartments like protein, carbohydrates, fats, vitamin and mineral. Teeth begin the digestion by chewing and grinding. The tongue pushes the food in ball shape to swallow.

Salivary gland in the lining of our mouth secretes the saliva to begin digestion chemically with enzyme, a special form of protein. The enzyme secreted from different digestive gland to break down the food to be absorbed by our body.

Digestion becomes involuntary when we start to swallow. Peristalsis which is waves of muscular contractions that moves along the stomach wall. Peristalsis starts when food passes from throat to esophagus.

Food then travel down the esophagus and into the stomach. Stomach is a large muscle pouch which mix food with various digestive fluid. For example, protease helps to digest protein and lipase helps to digest lipid. Gastric acid mainly breaking down proteins and killing the potential harmful bacteria and breaks down the food into a milky substance known as chime. After a few hours, the pyloric sphincter valves opens. The muscle contractions propel the chyme through the pyloric valve and into the first section of your small intestine (duodenum).

Small intestine divided into 3 portions, the first portion is duodenum. It secrete large amount of mucus to protect intestine wall from acidic chime. The length of small intestine is approximately 20-foot (6 meters), it is the main venue of digestion and absorption of the nutrients occurs. On the surface of small intestine, there is billion of tiny, fingers – like projection, villus. This villus transports the nutrients to bloodstream and then to the liver.

Whatever material is left goes into the large intestine. This is where water from the chyme is absorbed back into the body and feces are formed primarily from water (75 percent), dietary fiber and other waste products (dead cells). Feces are stored here until they are eliminated from the body through defecation.

消化系统是由一系列管状器官组成的,它将我们的食物转化为身体所需的燃料。总的说来,从口腔到肛门,有大约30英尺(9米)复杂的管道系统。一路上,在进入身体循环之前,食物被分解,分类和重新处理。作这些是为了给细胞提供能量,替换衰老细胞,给肌肉提供能量。

盘子里的食物为了被消化系统分解成它的组成部分,比如蛋白质,碳水化合物,脂肪,维生素和矿物质,需要被碾碎成又软又粘的液体。我们的牙齿通过咀嚼和碾磨每口食物最先开始这项工作。而舌头将食物卷成球状以便吞咽。

湿润的唾液从口腔附近的腺体分泌出来,他们通过一种叫做酶的特殊的蛋白质开始化学消化。酶从消化管道的不同的地方分泌出来,将大分子的食物降解成身体可以吸收的各种小分子。

一旦我们开始吞咽,消化就变成不自主的。蠕动指的是通过肌肉收缩将中空器官的内容物向前推进。食物从咽喉下降到食管,蠕动就是从这里开始的。

食管将食物排空到胃。胃是一个很大的肌肉空腔,它将食物和各种消化液混合。其中,包括分解蛋白的蛋白酶和分解脂肪的脂肪酶。胃酸主要帮助溶解胃内容物,杀死潜在的有害细菌。于是产生了半流质——食糜。它被胃用上下两个环状的括约肌封闭在胃腔内,数小时候,在短时间内迅速从胃释放到十二指肠。

小肠分为三段,十二指肠是第一段。十二指肠分泌大量黏液以保护肠壁不受酸性食糜侵害。小肠长约20英尺(6米),是消化和吸收的主要场所。小肠上有数百万细小的,手指状的称为绒毛的突起,这些绒毛把营养物质吸收到血液,然后运输到肝。

消化管道里的剩余物被排入大肠。在大肠,它们被数十亿无害的细菌吞噬后和死亡的细胞混在一起,形成固体粪便。水分被吸收,同时粪便移近肛门等待被排出。

关键器官
其他在消化过程中扮演重要角色的器官包括肝,胆囊和胰腺。胰腺是一个位于胃后的腺体,它将各种各样的酶释放到十二指肠。同时,有一个管道把十二场和胆囊连在一起。胆汁是肝脏消化完脂肪后排出的废弃物质。胆囊曾梨形,它挤出来自肝脏的棕绿色的胆汁。

肝脏本身是身体的主要化学工厂。它执行数百项不同功能。它处理由小肠分泌入血的营养物质,从碳水化合物合成可以提供能量的糖原,将食物中的蛋白质转化为我们血液需要的新的蛋白质。这些糖原,蛋白质以及维生素和矿物质在肝脏被储存起来,在需要时被释放。肝脏同时也降解一些不需要的化学物质,比如酒精就是在肝脏被解毒,然后作为废品排出体外。

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