Outlines of a new system of physiology / by Louis Mackall.

  • Mackall, Louis, 1801-1876.
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of a new system of physiology / by Louis Mackall. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    I thrown out so as to form valves, which, when extended, close up the passage, and thus limit the quantity of blood going into the ventricle at one time. In addition to this arrangement, bundles of muscular fibres stand out from the sides of the ventricles, and terminating in tendons are inserted into the tips or free edges of the valves ; and by their extension assist materially in closing the passage—the bundles of muscular fibres are called Column® Carneae, and their tendons Chordae tendineae. (26.) The arteries have the same arrangement of fibres about their walls, and their entrance is guarded simply by valves. (27.) The Capillaries are minute vessels receiving the blood from the Arteries and have the same size throughout; their action is not understood, but it is said the flow of blood in them is constant and equable, and not in jets as in the arteries ; they communicate freely with one another and have no valves. (28.) The blood passes from the Capillaries into the veins, and flows in them also in a constant and equable course. The veins have valves projecting at irregular intervals from their walls, which are in- tended, no doubt, to prevent excessive accumulations of blood in any part of its course. (29.) A supply of blood having been collected from the veins of the system, generally, into the right auricle of the Heart, is received into the right ventricle; which is dilated for the purpose by the action of its fibres. Having received its due quantity, any further supply is cut off by the action of its valves. It is next received by the Pulmo- nary Artery and conveyed to the Lungs; here it undergoes a striking change, but similar in its nature to what has been taking place all along, that is, it gives off a portion of its life to, and receives a portion in its stead from, the. Atmosphere. By this change the blood is again prepared to enter on its course ; it is received by the Pulmonary vein, and conveyed to the left auricle of the Heart. The left ventricle re- ceives it from the left auricle, and has its supply limited by valves, Columnae Carneae, and Chordae tendineae, as in the right ventricle. The arteries of the general system then receive it from the left ventri- cle, the supply limited again by the valves at the entrance, and convey it to the Capillaries, which, in their turn convey it to the veins of the general system, whence it was first derived. (30.) The veins coming from some of the abdominal viscera, unite into one large trunk which enters the liver. This vein, called the Vena Portarum, takes on an action similar to that of the arteries, that is, it is actively dilated, and to enable it to do this, it is surrounded throughout its course by a loose cellular structure called the Capsule of Glisson. (31.) The Blood in its course, is continually giving off and receiv- ing life, as in the first stage of nutrition, and as the nutritious matter become vitalized and passed into another set of vessels, the Lacteals, so a portion of the blood in its passage through the arteries becoming more vitalized passes into a set of vessels peculiar to the glands and forms the secretions.