PPT showed by Clinical medicine Dept ,class 6 group 3

Group leader of medical English subject: 郭涵 Group members : 陶训勋 李丝丝 陈银妹 任芹 刘璐 戴晓峰 马强 龚宇 蒋凯南 沈海林 刘成

Section B Readings

Passage One The Cardiovascular System

Main contents:

Structure of the cardiovascular system

Primary functions of its organs

Associated medical terms

subdivision n. 细分；分支

arteriole n. 小动脉

aorta n. 主动脉

platelike adj. 盘状的

carbon dioxide n. 二氧化碳

bloodstream n. 血流

lining n. 内层

venule n. 小静脉

valve n. 瓣膜

myocardium n. 心肌

endocardium n. 心内膜

epicardium n. 心外膜

pericardium n. 心包

atrium 【复】 atria n. 心房

ventricle n. 心室

interventricular adj. （心）室间的

septum n. 隔

interatrial adj. （心）房间的

tunic n. 层

innermost adj. 最里层的

endothelium n. 内皮

The cardiovascular system is made up of the heart and blood vessels. The heart is situated between the lungs with its apex directed toward the left. The thick muscle layer of the heart wall is the myocardium ,which is lined on the inside with a thin endocarium and is covered on the outside with a thin epicardium. The heart is contained with a fibrous sac, the pericardium.

the upper receiving chambers of the heart are the atria. The lower pumping chambers are the ventricles. The interventricular septum separates the two ventricles; the interatrial septum divides the two atria.

There are three major types of blood vessels, i.e. ,arteries, veins ,and capillaries. Arteries lead blood from the heart. These blood vessels have the thickest walls because they receive the pumping drive from the ventricles of the heart. These are three coat (tunics) which resemble the three tissue layers of the heart. These are :1)the innermost membrane of endothelium ,which forms a smooth surface over which the blood may easily move;2)the second, more bulky layer, which is made of involuntary muscle combined with elastic connective tissue; and 3)an outer tunic ,which is made of a supporting connective tissue. The largest artery ,the aorta, is about 1 inch in diameter and has the thickest wall.

The smallest subdivisions of arterioles ,have thinner walls in which there is very little connective tissue but relatively more muscle. These smaller branches of the arteries carry blood to the tiniest of blood vessels, the capillaries.

Capillaries have walls that are only one epithelial cell thick. The capillary walls are transparent and are made of smooth platelike cells that continue from the lining of the arteries. The walls are so thin that they can allow passage of oxygen and nutrients out of the bloodstream and into the tissue fluid surrounding the cells. At the same time, waste products such as carbon dioxide and water pass out of the cells and into the thin-walled capillaries. The capillary boundaries are the most important center of activity of the entire circulatory system.

Veins are thinner-walled than arteries. They conduct waste-filled blood toward the heart from the tissues. Veins have little elastic tissue and less connective tissue than arteries. The smallest vein ,called venule, are formed by the union of capillaries. Their walls are only slightly thicker than those of the capillaries. As the veins become larger ,the walls become thicker. However, veins have much thinner walls than those of comparable arteries. Although there are three layers of material in the walls of the larger veins, as in the artery walls ,the middle tunic is relatively thin in vein walls . Therefore, veins are easily collapsed, and slight pressure by a tumor or some other mass may interfere with the return blood flow. Most veins are equipped with one-way valves that permit the blood to flow in only one direction. They are most numerous in the veins of the extremities.

The heart pumps blood through two circuits . The right side of the heart pumps blood to the lungs to be oxygenated through pulmonary circuit. Pulmonary vessels include the pulmonary artery and its branches , and the veins that drain the lung capillaries. The pulmonary arteries carry blood low in oxygen from the right ventricle, while the pulmonary veins carry blood high in oxygen from the lungs into the left atrium. This circuit concerns itself with eliminating carbon dioxide from the blood and replenishing its supply of oxygen. The left side of the heart pumps blood to the remainder of the body through the systemic circuit. This circuit is concerned with supplying food and oxygen to all the tissues of the body and carrying away waste materials from the tissues for disposal.

Blood returning from tissues other than the lungs enters the heart by way of the venae cavae : the superior vena cava and the inferior vena cava. The venae cavae empty into the right atrium. When the atria contract, blood in the right atrium is forced through the tricuspid valve( 三 尖 瓣 ） into the right ventricle. When the ventricle contracts, blood in the right ventricle is forced through the pulmonary semilunar valve （ 肺 动 脉 瓣 ） into the pulmonary artery; at the same time ,the tricuspid valve close to prevent the backward flow of blood into the atrium. Blood that enters the pulmonary artery is carried to the lungs. There it undergoes oxygenation, a process in which carbon dioxide (a waste product of cellular metabolism) is exchanged for oxygen from the environment.

Two circuit :

Pulmonary circuit

Systemic circuit

Oxygenated blood returns to the heart by way of pulmonary veins, which empty into the left atrium. Atrium contraction force blood from the left atrium through the mitral valve, also called bicuspid valve( 二 尖瓣） , into the left ventricles. When the ventricles contract ,blood in the left ventricle is forced through the aortic semilunar valve （主动脉瓣） into the aortic, the body’s largest artery, for distribution to the tissues. The aortic is one continuous tube divided into the following regions :1 ） the ascending aorta （升主动脉） ,which is near the heart and inside the pericardial sac; 2) the aortic arch （主动脉弓） , which curves from the right to the left, and also extends backward; 3) the thoracic aorta （ 胸 主 动 脉 ） ,which lies just in front of the vertebral column behind the heart and in the space behind the pleura; and 4) the abdominal aorta （ 腹 主 动 脉 ） , which is the longest section of the aorta, spanning the abdominal cavity.

翻译：腹主动脉——主动脉的最长部分，横跨腹腔。

正常心脏血管解剖：心瓣膜与血流方向:

WISE 拍摄星云图酷似心脏 仿佛还有血液流动

据美国《连线》杂志报道，近期美国宇航局“广域红外探测器” (Wide-Field Infrared Survey Explorer ，简称WISE) 拍摄到一张神奇星云图片，两个相邻的星云外形都酷似心脏，星云内部仿佛还有红色的血液在流动。　　 　　 5 月 24 日，加州大学洛杉矶分校的天文学家奈德 · 赖特 (Ned Wright) 在参加美国天文学会 (American Astronomical Society) 的一次会议时向外公布了这张照片。赖特表示：“这两个星云，其中一个酷似情人节心形心脏，而另一个则类似于人体心脏，十分神奇。”据悉，这两个星云位于仙后座星系，距离地球约有 6000 光年的距离。

There are two phases of the heartbeat: diastole (relaxation)

and systole (contraction). This diastole-systole cardiac cycle

(relaxation-filling, then contraction-pumping) lasts about 0.9 second

and occurs between 70 and 80 times per minute. That is to say ,the

ventricles pump blood into the arteries regularly about 70 to 80

times a minute. The force of ventricular contraction starts a wave of

increased pressure which begins at the heart and travels along the

arteries. This wave is called the pulse. It can be felt in the arteries

that are relatively close to the surface, particularly if the vessel can

be pressed down against a bone. At the wrist the radial artery

passes over the bone on the thumb side of the forearm, and the

pulse is most commonly obtained here. Other vessels sometimes

used of obtaining the pulse include the carotid artery in the neck

and the dorsalis of the top of the foot.

That’s all for our presentation.

Thanks for listening !