um)
The oesophagus is a muscular tube, about 25cm long, with a sphincter (valve) at each end. Its function is to transport food and fluid, after being swallowed, from the mouth to the stomach. No absorption of nutrients takes place in the oesophagus. A mouthful of food which has been chewed and swallowed is called a bolus. This is propelled from the pharynx (throat) into the oesophagus, and is swept towards the stomach in peristaltic waves. These muscular contractions are involuntary, and cannot normally be felt. When food is not passing through, the oesophagus is folded in, or collapsed.
动物的消化系统
制作人： 周侠敏 张萌 周静雯
Digestive System
横隔膜 (Diaphragm)
肝脏 (Liver) 胆囊 (Gallbladder)
结肠 (Colon)
盲肠 (Calcum) 阑尾 (Appendix)
食管(Oesophagus) 脾(Spleen) 胃(Stomach) 胰腺 (Pancreas)
在胃里，食物得到暂时贮存，并与胃液混和，这时胃蛋白酶促使 食物中的一些蛋白质分解成多肽。
back
The small intestine is the longest section of the digestive tract, with an average length of about 6 metres. Although only 2.5 cm in diameter - which is why it is called the small intestine - its surface area for absorption covers the size of a tennis court. This is due to the numerous folds on its surface, covered in tiny projections known as villi, which in turn are covered in even tinier projections known as microvilli.
小肠是消化食物的主要场所，各种食物成份在小肠里受到多种消 化酶的作用，最终被分解成可吸收的小分子有机物，如淀粉被分 解成葡萄糖，蛋白质被分解成氨基酸，脂肪被分解成甘油和脂肪 酸。
back
The liver is the body's largest organ, weighing about 1.5 kgs, or 2.5% of body weight. Major functions involve the uptake of nutrients and other substances from the intestine, processing (metabolising), storing or distributing these to blood and bile. The liver is also important in removing unwanted or harmful chemicals (detoxification) including chemicals produced in the body, unwanted chemicals taken into the body (eg carcinogens), and medications. The liver is the 'powerhouse' of the body.
在口腔内，食物中的一小部分淀粉，在唾液淀粉酶的作用下，开 始分解成麦芽糖。
back
The stomach is a temporary storage organ for large quantities of food. It can easily hold 1.5 litres, with a maximum holding capacity of about 4 litres. Its three main compartments are called the fundus, the body and the antrum. The stomach is also an important site for mechanical and chemical breakdown of the food which enters it. Digestive juices are secreted from glands covering the entire stomach wall. When food is present, approximately every 20 seconds mixing waves combine the food with gastric juices to form chyme - a creamy, semi-fluid mass. This is gradually emptied into the small intestine through a narrowed region surrounded by a thick ring of muscle at the lower end of the stomach - the pyloric sphincter. Liquids empty from the stomach faster than solids, taking about 20 minutes. A mixed meal takes about 1.5 hours to be emptied.