第二十四章心血管系統(tǒng)的發(fā)生

1、第二十四章 心血管系統(tǒng)的發(fā)生（Development of the cardiovascular system）一、 原始心血管系統(tǒng)的建立二、1、原始血細(xì)胞與胚外血管：2胚內(nèi)血管：胚內(nèi)間充質(zhì)Capi. Capi.網(wǎng)+胚外Capi.網(wǎng) 原始血管系統(tǒng)3、胚胎早期血管：成對二 、development of heart 1. Development of primitive heartThe heart primordium forms in a houseshoe-shaed region of the splanchnopleuric mesoderm at the cranial end of

2、 the germ disc called the cardiogenic region. In response to signals form the underling endoderm, angioblastic（成血管細(xì)胞） cords on this region coalesce to form a pair of lateral endocardial tubes. The cephalic（頭的） and lateral folding of the embryo during the early fourth week causes these tubes to be br

3、ought together along the midline in the future thoracic region, where they fuse to form a single primitive heart tube.(fig 7-1)2. The heart tube folds and loops to establish the spatial relationship of the future heart chambers(心臟外形建立)Starting at the in flow end, these are the left and right horns o

4、f the sinus venosus(靜脈竇), the primitive atrium(心房), the ventricle(心室), and the bulbus cordis(心球). Fig 7-9 and7-103.心臟內(nèi)部分隔(1)房室管分隔第四周末：背腹心內(nèi)膜墊（endocardialcushion）(2) 原始心房分隔第房間隔 septum primum：鐮狀 心內(nèi)膜墊第房間隔 septum secudum: 卵圓孔foramen ovale意義：出生前：血液心內(nèi)分流卵圓孔 左右心房相通 右房壓力>左房右房血卵圓孔第房間孔左房左房血右房出生后：肺循環(huán)左房壓力>右

5、房卵圓孔關(guān)閉心房完全分隔(3)原始心室分隔室間隔肌部：心室底壁 肌性隔膜心內(nèi)膜墊室間隔膜部(4)主動脈干與心球分隔 三. 胎兒血循環(huán)及出生后改變(一)胎兒血循環(huán)特點：臍V1 含A血1. A含：混合血2.2.肝內(nèi)靜脈導(dǎo)管存在臍V血 V導(dǎo)管 直入下腔V3.卵圓孔和房間孔：心內(nèi)血液分流作用下腔靜脈 右心房 卵圓孔4動脈導(dǎo)管存在：肺A血 A導(dǎo)管 降主A （二）出生后血循環(huán)改變四心血管系統(tǒng)常見畸形1 房間隔缺損 atrial septal defect（ASD）23 室間隔缺損 ventricular septal defect43動脈導(dǎo)管未閉:原因：A導(dǎo)管壁肌肉收縮無力4法洛四聯(lián)癥(tetrology

6、 of Fallot):5.Dextrocardia.(右位心)6.Acardia.無心畸形Surprisingly complete development of the human fetus may occur in the absence of a heart動脈干分隔不均主A肺A隔偏位肺動脈狹窄主動脈騎跨室間隔缺損右心室肥大SummaryThe heart primordium forms in a houseshoe-shaed region of the splanchnopleuric mesoderm at the cranial end of the germ disc c

7、alled the cardiogenic region. In response to signals form the underling endoderm, angioblastic（成血管細(xì)胞） cords on this region coalesce to form a pair of lateral endocardial tubes. The cephalic（頭的） and lateral folding of the embryo during the early fourth week causes these tubes to be brought together a

8、long the midline in the future thoracic region, where they fuse to form a single primitive heart tube.Between weeks 5 and 8, the primitive heart tube undergoes a process of looping , remodeling, and septation that transforms its single lumen into the four chambers of the definitive heart, thus layin

9、g down the basis for the separation of pulmonary and systemic circulations birth.Initially, the primitive heart tube develops a series of expansions and shallow sulci（溝） that subdivide it into primordial heart chambers. Starting at the in flow end, these are the left and right horns of the sinus ven

10、osus, the primitive atrium, the ventricle, and the bulbus（球） cordis. The inferior end of the bulbus cordis then differentiates onto the right ventricle, whereas the primitive ventricle gives rise to most of the left ventricle. The supereior end of the bulbus cordis( the conotruncus) will form the co

11、nus cordis and the truncus arteriosus, which split to become outflow regions of both ventricles(the ascending aorta and the pulmonary trunk).Venous blood initially enters the sinus horns through paired, symmetrical common cardinal veins. As described in chapter8, however, changes in the venous syste

12、m rapidly shift the entire systemic venous return to the right so that all the blood from the body and umbilicus enters the future right atrium through the developing superior and inferior venae cavae. The left sinus horn becomes the coronary sinus, which drains the myocardium. A process of intussus

13、ception incorporates the right sinus horn and the ostia of the venae cavae into the posterior wall of the future right atrium, displacing the original right half of the atrium s it forms the right auricle. Meanwhile, the future left atrium sprouts a pulmonary vein, the trunk of which is subsequently

14、 incorporated by intussusception to form most of the definitive left atrium. In the fifth and sixth weeks, a pair of septa, the septum primum and the septum secundum, grow to separate the right and left atria. These septa are perforated by a staggered pair of foramina that allow right-to left shunti

15、ng of blood throughout gestation. The bicuspid(mitral) and tricuspid atrioventricular valves also develop during the fifth and sixth weeks,. Meanwhile, the heart undergoes a remodeling that brings the future atria and ventricles into correct alignment and also aligns both ventricles with their respe

16、ctive outflow tracts. The base of the bulbus cordis expands to enlarge the right ventricle, and during the sixth week a muscular ventricular septum partially separates the ventricles. Finally, furing the seventh and eighth weeks, the outflow tract of the heart- the conotruncus- undddergose a process

17、 of septation and division that converts it into the separate, helically arranged ascending aorta and pulmonary trunk during this process swellings within the truncus arteriosus give rise to the semilunar vales of the aorta and pulmonary trunk. The conotruncal septa also grow into the ventricles to complete ven