Physiology and Hygiene for Secondary Schools by Francis M. Walters;A.M.
page 50 of 527 (09%)
page 50 of 527 (09%)
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_tricuspid_ valve. It is suspended from a thin ring of connective tissue
which surrounds the opening, and its free margins extend into the ventricle (Fig. 16). It consists of three parts, as its name implies, which are thrown together in closing the opening. Joined to the free edges of this valve are many small, tendinous cords which connect at their lower ends with muscular pillars in the walls of the ventricle. These are known as the _chordæ tendineæ_, or heart tendons. Their purpose is to serve as _valve stops_, to prevent the valve from being thrown, by the force of the blood stream, back into the auricle. The _mitral_, or bicuspid, valve is suspended around the opening between the left auricle and the left ventricle, with the free margins extending into the ventricle. It is exactly similar in structure and arrangement to the tricuspid valve, except that it is stronger and is composed of two parts instead of three. [Fig. 16] Fig. 16â*Right side of heart* dissected to show cavities and valves. _B._ Right semilunar valve. The tricuspid valve and the chordæ tendineæ shown in the ventricle. The _right semilunar_ valve is situated around the opening of the right ventricle into the pulmonary artery. It consists of three pocket-shaped strips of connective tissue which hang loosely from the walls when there is no pressure from above; but upon receiving pressure, the pockets fill and project into the opening, closing it completely (Fig. 16). The _left semilunar_ valve is around the opening of the left ventricle into the |
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