英语翻译The interior of the heart is divided into four chambers:upper right and left atria and lower right and left ventricles.The atria contract and empty simultaneously into the ventricles,which also contract in unison.The walls of the atria ar

英语翻译The interior of the heart is divided into four chambers:upper right and left atria and lower right and left ventricles.The atria contract and empty simultaneously into the ventricles,which also contract in unison.The walls of the atria ar
英语翻译
The interior of the heart is divided into four chambers:upper right and left atria and lower right and left ventricles.The atria contract and empty simultaneously into the ventricles,which also contract in unison.The walls of the atria are reinforced with latticelike pestinate muscles.Contraction of these modified cardiac muscles ejects blood from the atria to the ventricles.Each atrium has an ear-shaped,expandable appendage called an auricle.The atria are separated from each other by the thin,muscular interatrial septum; the ventricles are separated from each other by the thick,muscular interventricular septum.Atrioventricular valves (AV valves) lie between the atria and ventricles,and semilunar valves are located at the bases of the two large vessels leaving the heart.Heart valves maintain a one-way flow of blood.
Grooved depressions on the surface of the heart indicate the partitions between the chambers and also contain cardiac vessels that supply blood to the muscular wall of the heart.The most prominent groove is the coronary sulcus that encircles the heart and marks the division between the atria and ventricles.The partition between the right and left ventricles is denoted by two (anterior and posterior) interventricular sulci.
The following discussion shows the sequence in which blood flows through the atria,ventricles,and valves.It is important to keep in mind that the right side of the heart (right atrium and right ventricle) receives deoxygenated blood (blood low in oxygen) and pumps it to the lungs.The left side of the heart (left atrium and left ventricle) receives oxygenated blood (blood rich in oxygen) from the lungs and pumps it throughout the body.
Right Atrium
The right atrium receives systemic venous blood from the superior vena cava,which drains the upper portion of the body,and from the inferior vena cava,which drains the lower portion.The coronary sinus is an additional opening into the right atrium that receives venous blood from the myocardium of the heart itself.

英语翻译The interior of the heart is divided into four chambers:upper right and left atria and lower right and left ventricles.The atria contract and empty simultaneously into the ventricles,which also contract in unison.The walls of the atria ar
内部的心脏分为四个商会：上左,右心房和较低的左,右心室.心房合同和空洞的同时进入脑室,其中也异口同声地合同.墙壁上心房,加强与latticelike pestinate肌肉.收缩,这些修改心脏肌肉弹出的血液从心房到心室.每个心房有一耳形,可扩展的附庸称为耳廓.心房脱离对方所薄,肌肉间隔隔;心室脱离对方所厚,肌肉间隔.房室阀（房室瓣膜）的谎言之间的心房和心室,半月阀设在基地的两个大型船只离开的心.心脏瓣膜保持一个双向流动的血液.
槽洼地表面上的心脏,表明分区之间的分庭和还包含心脏船只供应的血液,肌肉壁的心脏.最突出的沟槽是冠状动脉沟认为,围绕着心脏和马克之间的分工心房和心室.分区之间的左,右心室,是指由两个（前,后）间沟.
下面的讨论表明,序列中,血液流经心房,心室,和阀门.这是很重要的要请记住,右侧的心脏（右心房和右心室）收到deoxygenated血液（血低,在氧）和水泵它的肺部.左边的心脏（左心房和左心室）收到含氧血（血液丰富的氧）由肺部和水泵,它的整个身体.
右心房
右心房接受系统性的静脉血由上腔静脉,排水渠上的部分尸体,并从下腔静脉,排水渠较低的部分.冠状窦是一项额外的开放进入右心房接收静脉血由心肌心脏本身.