Digestive and Excretory Systems
After food is broken into fragments by chewing and mixed with saliva, digestion begins. The food passes down the gullet into the stomach, where the process is continued by the gastric and intestinal juices. Thereafter, the mixture of food and secretions, called chime, is pushed down the alimentary canal by peristalsis, rhythmic contractions of the smooth muscle of the gastrointestinal system. Absorption of nutrients from chyme occurs mainly in the small intestine; unabsorbed food and secretions and waste substances from the liver pass to the large intestines and are expelled as feces. Water and water-soluble substances travel via the bloodstream from the intestines to the kidneys, which absorb all the constituents of the blood plasma except its proteins. The kidneys return most of the water and salts to the body, while excreting other salts and waste products, along with excess water, as urine.
- excretory [eksˈkri:təri] adj.排泄的
- fragment [ˈfræɡmənt] n.碎片
- chew [tʃu:] v. 咀嚼
- saliva [səˈlaivə] n.唾液
- digestion [diˈdʒestʃən] n.消化
- gullet [ˈɡʌlit] n.食管
- stomach [ˈstʌmək] n.胃
- gastric [ˈɡæstrik] adj.胃的
- intestinal [inˈtestinl] adj.肠的
- juice [dʒu:s] n.体液
- secretion [siˈkri:ʃən] n.分泌物
- chyme [kaim] n.食糜：部分消化的食物的稠状半流体物，从胃进入十二指肠
- alimentary canal [ˌæliˈmentəri - kənæl] n.消化道
- peristalsis [ˌperiˈstælsis] n.蠕动
- gastrointestinal [ˌɡæstrəuinˈtestənl] adj. 肠胃的
- absorption [əbˈsɔ:pʃən] n.吸收
- nutrient [ˈnju:triənt] n. 营养物质
- small intestine [smɔ:l - inˈtestin] n.小肠
- waste substance [weist - ˈsʌbstəns] n.废物
- liver [ˈlivə] n.肝脏
- large intestine [la:dʒ - inˈtestin] n.大肠
- expel [iksˈpel] v. 排出
- feces [ˈfi:si:z] n. 粪便
- water-soluble [ˈwɔ:tə - ˌsɔljəbəl] n.可溶于水的
- via [ˈvaiə] prep. 通过
- kidney [ˈkidni] n.肾
- constituent [kənˈstitjuənt] n.成分
- excrete [eksˈkri:t] v.排泄,分泌
- urine [ˈjuərin] n.尿
