. Public School Physiology and Temperance. e, and very lightness of textureis largely due to the pres-ence of air, which is neverentirely expelled, evenwhen we force out all wecan. Examined minutely,we find the lung to consistof lobules, closely connectedtogether, but yet quite dis-tinct from one lobule is formed ofone of the divisions of abronchial tube, with itsair-cells, and of the divisions of the pulmonary vessels. Ineach are also found nutritious vessels and nerves. There area large number of air-cells to one branch of a small bronchialtube. They cluster around
. Public School Physiology and Temperance. e, and very lightness of textureis largely due to the pres-ence of air, which is neverentirely expelled, evenwhen we force out all wecan. Examined minutely,we find the lung to consistof lobules, closely connectedtogether, but yet quite dis-tinct from one lobule is formed ofone of the divisions of abronchial tube, with itsair-cells, and of the divisions of the pulmonary vessels. Ineach are also found nutritious vessels and nerves. There area large number of air-cells to one branch of a small bronchialtube. They cluster around it like a bunch of grapes on astem. If the stem were hollow, and each grape an empty saccommunicating with it, to blow into the stem would give afair example of how the air fills up the air-cells every time wetake in a breath. Think how small these air-cells must be,when seventeen hundred of them cluster around one smalltube. Yet each cell is separated from the other by a fine,thin partition. In this delicate, thin wall is a dense network. j^^ DESCENDING?^ff AORTA V Fig. 29.—The Lungs and Heart,viewed in front. RESPIRATION. 93 of capillaries, and it is here the dark, impure blood, whilepassing through, parts with the carbonic acid, and in returnreceives from the air the required oxygen. As in the generalsystem, this network collects into larger vessels, and theblood, now changed to a bright red color, passes on throughthe pulmonary veins into the heart.
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishertoron, bookyear1893
