. A text-book on physiology : for the use of schools and colleges : being an abridgment of the author's larger work on human physiology. Heart of the dugong. 118 COUESE OF THE BLOOD IN THE HEART. brane, pericardium, and in its interior is sheathed by theendocardium, an extension of the interior coat of thegreat blood-vessels. Though its movements are whollyinvoluntary, its muscular fibres are of the transverselystriated kind. They are about one third less in diame-ter than those of voluntary muscles generally, and are es-Fig. 4T. pecially characterized by their disposition toanastomose with on
. A text-book on physiology : for the use of schools and colleges : being an abridgment of the author's larger work on human physiology. Heart of the dugong. 118 COUESE OF THE BLOOD IN THE HEART. brane, pericardium, and in its interior is sheathed by theendocardium, an extension of the interior coat of thegreat blood-vessels. Though its movements are whollyinvoluntary, its muscular fibres are of the transverselystriated kind. They are about one third less in diame-ter than those of voluntary muscles generally, and are es-Fig. 4T. pecially characterized by their disposition toanastomose with oneanother, as represent-ed in Fig. 47. In the. ventricles the arrange- jj ment is such that the |||g| fibres of the external S3 and internal surfaces Muscular fibres of the heart. deCUSSate. The motions of the heart consist in the dilatations andcontractions of the muscular walls of its cavities. Thetwo auricles contract at the same moment, as do also thetwo ventricles, but the contractions of the auricles coin-cide with the dilatations of the ventricles. The course of the blood through the heart is venous blood, brought by the ascending and de-scending cavse, flows into the right auricle as it is dilat-ing, and for the moment pushes forward to the ventri-cle, but the auricle, being of less capacity than the ven-tricle, is filled to distention first; at this instant it con-tracts, forcing its contents past the tricuspid valve intothe ventricle, and fills it completely. The blood can notregurgitate into the veins to any extent while this isgoing on, because of the almost perfect closure of theirvalves. The right ventricle
Size: 2128px × 1174px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookautho, bookcentury1800, bookdecade1860, booksubjectphysiology
