Circulatory System
In passing through the system, blood pumped by the heart follows a winding course through the right chambers of the heart, into the lungs, where it picks up oxygen, and back into the left chambers of the heart. From these it is pumped into the main artery, the aorta, which branches into increasingly smaller arteries until it passes through the smallest, known as arterioles. Beyond the arterioles, the blood passes through a vast amount of tiny, thin-walled structures called capillaries. Here, the blood gives up its oxygen and its nutrients to the tissues and absorbs from them carbon dioxide and other waste products of metabolism. The blood completes its circuit by passing through small veins that join to form increasingly larger vessels until it reaches the largest veins, the inferior and superior venae cavae, which return it to the right side of the heart. Blood is propelled mainly by contractions of the heart and arteries; contractions of skeletal muscle also contribute to circulation. Valves in the heart and in the veins ensure its flow in one direction.
- circulatory system [sə:kjuˈleitəri - ˈsistəm] n.循环系统
- pump [pʌmp] v. 输送
- winding [ˈwaindiŋ] adj. 弯曲的
- chamber [ˈtʃeimbə] n. 心室
- pick up [pik - ʌp] v. 获得
- oxygen [ˈɔksidʒən] n. 氧气
- artery [ˈɑ:təri] n.动脉
- aorta [eiˈɔ:tə] n.主动脉
- arteriole [ɑ:ˈtiriəul] n.小动脉
- vast [vɑ:st] adj. 大量的
- capillary [kəˈpiləri] n. 毛细血管
- give up [giv - ʌp] v. 把……输送到……
- nutrient [ˈnju:triənt] n. 营养品
- tissue [ˈtisju:] n.组织
- absorb [əbˈsɔ:b] v.吸收
- carbon dioxide [ˈka:bən - daiˈɔksaid] n.二氧化碳
- metabolism [məˈtæbəlizəm] n.新陈代谢
- circuit [ˈsə:kit] n. 一圈
- vein [vein] n.静脉
- vessel [ˈvesəl] n.血管
- inferior [inˈfiəriə] adj. 处于下方的
- superior [sjuˈpiəriə] adj. 处于上方的
- venae cavae [ˈvi:ni: - ˈkivi:] n.腔静脉(singular: vena [ˈvi:nə] cava ['ki:və])
- propel [prəˈpel] v. 推动
- circulation [ˌsə:kjuˈleiʃən] n. 循环
- valve [vælv] n.瓣膜
