. The human body and health : an elementary text-book of essential anatomy, applied physiology and practical hygiene for schools . the heart, caused by the muscle being changedto fat, is likely to affect fleshy persons, and is especiallyprevalent among beer drinkers. A most serious affection of the heart is the inability ofthe valves to prevent the blood from flowing backward. Disease of the valves oftenresults from rheumatism,scarlet fever, and diph-theria. The medicinesmuch advertised to cureheart ailments are of nouse, and should never betaken by those wl*o wantto live. A physicianshould be
. The human body and health : an elementary text-book of essential anatomy, applied physiology and practical hygiene for schools . the heart, caused by the muscle being changedto fat, is likely to affect fleshy persons, and is especiallyprevalent among beer drinkers. A most serious affection of the heart is the inability ofthe valves to prevent the blood from flowing backward. Disease of the valves oftenresults from rheumatism,scarlet fever, and diph-theria. The medicinesmuch advertised to cureheart ailments are of nouse, and should never betaken by those wl*o wantto live. A physicianshould be consulted. Thevery rapid and irregularbeating of the heart isspoken of as palpitationof the heart. It is fre-quently caused by somedigestive trouble in thestomach. The Arteries. — Thevessels carrying the bloodaway from the heart arethe arteries. Prior to theseventeenth century they were thought to conduct air,hence the name. They are empty after death, and theblood is found in the heart and veins. The walls of thearteries are much thicker and more elastic than those ofthe veins, They are made of elastic fibers, other con-. FiG. 82. — Microscope arranged to seethe blood circulating in the tail of atadpole. THE CAPILLARIES 121 nective tissue, involimtaiy muscle cells, and a layer offlat epithelial cells within. The chief artery of the trunk is the aorta, which leadsfrom tlie left ventricle, and at once forms an arch to passbehind the heart down through the body cavity in frontof the backbone. Itgives off more thanthirty branches to thetrunk and the internalorgans. In the lowerpart of the abdominalcavity it divides intoa right iliac and a leftiliac to supply the legswith blood. From thearch of the aorta threebranches are given offto supply the arms,neck, and head. Thelarge artery on eitherside of the windpipe is the carotid^ taking blood to thehead and brain. The pulmonary artery is a large vessel leading fromthe right ventricle to the lungs. This is the only arterytransporti
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