. A text-book of human physiology . h,capillaries of the lower ex-tremity; ), capillaries of thehead and upper extremities;k, hepatic artery. Arterialblood, red; venous blood,blue; lymph vessels shownonly in outline. SECOXD SECTIOX THE MOVEMENTS OF THE HEART § 1. THE FORM CHANGES OF THEHEART IN SYSTOLE After opening the pericardium of a beatingheart it can be seen that the contraction beginsat the outlet of the great veins, which are heresurrounded by circular muscle fibers, and pro-ceeds thence onto the auricles. The two auricles contract simultaneously, andimmediately after the auricular sys
. A text-book of human physiology . h,capillaries of the lower ex-tremity; ), capillaries of thehead and upper extremities;k, hepatic artery. Arterialblood, red; venous blood,blue; lymph vessels shownonly in outline. SECOXD SECTIOX THE MOVEMENTS OF THE HEART § 1. THE FORM CHANGES OF THEHEART IN SYSTOLE After opening the pericardium of a beatingheart it can be seen that the contraction beginsat the outlet of the great veins, which are heresurrounded by circular muscle fibers, and pro-ceeds thence onto the auricles. The two auricles contract simultaneously, andimmediately after the auricular systole the ventricles contract, likewisesimultaneously. Xeither auricles nor ventricles completely empty themselvesbv their contractions. A. STRUCTURE OF THE VENTRICULAR WALL The arrangement of the muscular mass which forms the walls of the ven-tricles is verj- complicated. Our description here must be very brief. Of the two ventricles the left possesses a much stronger musculature than THE FORM CHANGES OF THE IN SYSTOLE 163. the right, a condition which conforms with the much heavier work to be doneby the former. In fact the outer wall of the right ventricle is formed for themost part of fibers which comefrom the left. To a certain ex-tent therefore the right ven-tricle may be looked upon asa cleft in the wall of the left,as shown in Fig. 51. With regard to the struc-ture of the ventricles the fol-lowing is worthy of mention:From the fibro-tendinous ringsat the base of the left ventricle,and from the muscular sides ofthe aorta superficial fibers passobliquely downward to the apexof the heart, enter for themost part the vertex of the leftventricle and double round intoits interior, to be insertedeither into the papillary mus-cles and chordte tcndineae, orinto the atrio-ventricular two layers thus formed are separated by a median layer, which, when isolated by a special methodof preparation, has the form of a muscular cone. It is connected also by manyfibers with
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
