Valve (anatomy)

“ Each valve is equilateral, but the valves differ from one another in that one is larger and generally serves to attach the animal to rocks and other objects of support by a stalk or pedicle. Thus the larger valve is called the pedicle valve and the smaller, on account of its bearing the calcareous supports for the brachia or arms, the brachial valve. ”

“ Of course the heart will not work well if its valves are not tight any more than will an ordinary pump, so that persons suffering from this trouble cannot have as good a circulation as those whose valves have nothing the matter with them. It is true that in most cases of imperfect valve action there is a compensation in the form of an increase in the size and strength of the heart muscle, so that the circulation is maintained in spite of poor valve action by harder work on the part of the heart. ”

“ Valve linear, with rounded ends; axial area less than one-third the width of the valve, gradually widened in the middle to a transverse fascia; on each side of the central nodule is a lunate space; striæ divergent in the middle, convergent at the ends, 13 in 10 μ; terminal fissures very long, bayonet shaped. ”

“ It is evident that the hardest task is demanded from the spiral part of the valve, for it is that part which is first brought to bear upon the wood. This part also has a more solid structure and the denticles are much finer; it is moved by a muscle of considerable size; the power of this muscle is, moreover, sensibly increased by the fact of its being implanted upon the two middle parts of the valves, each of which can be considered as a long arm of a lever whose extremity passes over a space at least four times as large as the portion of the valve which, strictly speaking, does the work. ”

“ ACHNANTHES SUBSESSILIS KUETZ.
Valves linear-elliptical, rounded at the ends; upper valve with excentric pseudoraphe; striæ moniliform, puncta smaller than in A. brevipes.
Along the coast, in estuaries.
Pl. 16, Figs. 4, 5, 6.
The three species described above are named from the length of the stipe, but this varies considerably and is not of special significance.
ACHNANTHES INFLATA (KUETZ.) GRUN.
Valves more or less inflated in the middle, usually with the stauros of the lower valve asymmetrical and wider than in A. subsessilis, with which it agrees in size and markings. ”

“ The non-return valve is simply a mushroom or ball valve without handle, lifted off its seat by gas passing from underneath whenever the pressure of the gas exceeds the weight of the valve, but falling back on to its seat and closing the pipe when the pressure decreases or when pressure above is greater than that below. ”

“ A later valuable development in the history of valve systems is the enharmonic, invented by Messrs Besson & Co., in which they have perfected and simplified the principle of independent positions tried in the registre of the fifties. In the enharmonic valve system each position has its independent length of tubing theoretically accurate, which conies into play as the valves are depressed, and there is besides a tuning slide for the open notes. ”

“ Brachial valve moderately to deeply concave, usually following rather closely the inside curvature of the pedicle valve, leaving scarcely a sixteenth of an inch as the probable thickness of the animal. ”

“ Their workmanship is of the first order, and the valve is somewhat higher in price than ordinary mechanical valves. They have been in use on the apparatus for a year now and have invariably proved to be absolutely tight. They are easy to obtain and are much easier to manipulate and much less cumbersome than the mercury valves formerly used. ”

“ These valves are the tricuspid between the right auricle and right ventricle, the pulmonary semilunar valves between the right ventricle and the pulmonary artery, the mitral valve between the left auricle and the left ventricle, the aortic semilunar valves between the left ventricle and the aorta, and the valves which are scattered among the veins of the body. Of these by{76} far the most important are the valves in the heart: they do the chief work; those in the veins do little more than help. ”

“ When the chambers have attained their greatest state of expansion, the sides of the lower valve are forced upwards by the increased flow of the blood from the section below the valve, the lateral openings are closed, and the main current of the blood is projected through the two valves, as shewn in fig. ”

“ An irregular, round impression will be found at each end of the valve, near the hinge-margin. These show where the muscles are attached to move and close the valves, and hold them firmly together. The muscles run directly across from one valve to the other; and, to open a live mussel, it is necessary to pass a sharp blade between the valves, and cut through the muscles, before the valves will open. These muscles are called the adductor muscles and the scars or impressions on the valves are called the adductor muscular impressions. ”

“ Valves of the Lower Whorl.—These, seen externally, seem to belong to more than one whorl, but internally their basal margins stand on a level. They vary in number, as already stated, from 22 to 26. I have seen an individual with a valve more on one side than on the other. They are of unequal sizes, but they are rather variable in this respect: the largest are not above half the size of the upper latera: three or four pairs, together with the sub-rostrum (e) and sub-carina (c) , are always larger than the others: these two latter valves differ from the others only in being more concave. ”

“ Valves dissimilar, the upper valve with an excentric axial area, the lower with an excentric raphe.
ANORTHONEIS EXCENTRICA (DONK.) GRUN.
Valves orbicular, with radiating, punctate striæ, closer at the circumference, producing the appearance of a border. Axial area not reaching the ends. Frustules occur free on the sands of the sea-shore. ”

“ Both the intake and outflow valves are composed of stout but thin sheets of membrane, so that very little pressure is required to operate them. The weight of the blood that is accumulated in the auricles during the beat of the ventricle is more than sufficient to force the valve open and allow the blood to flow on through into the ventricle. In a heart that is beating seventy-two times a minute, there cannot be much time occupied either in filling or emptying. ”

“ A valve consists essentially of any simple hinged substance, arranged so that it may rise or fall, alternately opening and closing an aperture. A mere flap of leather, nailed on one edge, serves as a tolerably effective valve. At least one of the valves used by Ctesibius was a hinged piece of smooth metal. A piston fitted in a cylinder supplies suction when the lever is raised, and pressure when it is compressed, alternately opening the valve and closing the valve through which the water enters the tube. ”

“ The dorsal valve is uppermost.
In Lingula (Fig. 322) the muscular system is more complicated; in addition to the anterior (= anterior laterals) and posterior (= centrals) pairs of occlusors, there is a single divaricator (= umbonal) , whose contractions in conjunction with those of certain muscles in the body wall press forward the fluid in the body cavity, and thus force the valves of the shell apart; and there are three pairs of adjustor muscles. ”

“ The cavities for the males are not formed, as in S. ornatum, by the thickening of the internal surface of the valve round a defined space, but by the scutum being externally convex and internally concave down the middle, hollows being thus produced both for the lodgment of the males and for the attachment of the adductor muscle. These hollows are separated from each other by a slight transverse ridge. I do not know at which point of the margin of the valve, the orifice of the male is situated, but I presume close under the apex. ”

“ The method in which this animal fills its float is curious, it throws it back, and gradually lifts the lip of the valve out of water, until the valve stands vertical, it then closes the valve tightly round a globule of air, around which it folds, by means of the most complex and delicate machinery. ”

“ It is seldom, if ever, attached to other bodies. Shell more finely lamellated than that of the oyster, free or slightly adherent, sub-equilateral, very inequivalve; the lower valve very concave, with a summit more or less recurved like a hook; the upper valve much smaller, and formed like a lid; hinge without teeth; ligament inserted in an oblong arched cavity; one single muscular impression on each valve. ”

“ A valve larger than an automobile. The small, sixteen-inch valve on the side of the large valve is what we call a by-pass valve, and which, when opened, relieves the pressure, so that the large gate can be opened more easily. ”

“ In case the intake valve leaks, there will be a backward jet of blood from the ventricle into the auricle with every beat of the heart. This will cause a sort of hissing or murmur which can be heard with the stethoscope in connection with the first sound. If the outflow valve is the one that leaks, blood will squirt back into the ventricle from the aorta, while the ventricle is relaxing. ”

“ There are also valves at the roots of the arteries that permit the [Pg 208] blood to go from the heart into the arteries, but not to return. There are no valves at the roots of the veins that enter the auricles, nothing to obstruct the flowing of the blood from them into the auricles. Thus the roots of the veins arise from the auricles, and the roots of the arteries from the ventricles. Do you understand this description, because it is the foundation of all that follows—understand what a valve is?"
"Yes, sir; the clapper in our pump-box is a valve ”

“ Constructed of a flexible material, and made in form, as nearly as may be, to the valves of the human body, they may be said to be automatic in their action, or self acting; upon the pump being actuated, the least motion of the pump ensuring a corresponding action of the valve, and the most rapid action of the pump, being equally responded to by the pulsation of the valves. ”

“ The valves of the left side of the heart, the aortic and mitral valves, are affected far more commonly than those of the right side. It is indeed comparatively rarely that the latter are attacked. In the process of healing of a damaged valve, scar tissue is formed which has a tendency to contract, so that in some cases the orifice of the valve becomes narrowed, and the resulting stenosis or narrowing gives rise to obstruction of the blood stream. ”

“ Ð Balance valve, a valve whose surfaces are so arranged that the fluid pressure tending to seat, and that tending to unseat the valve, are nearly in equilibrium; esp., a puppet valve which is made to operate easily by the admission of steam to both sides. ”

“ In the Richardson valve, the valve proper is a disk, and the extended surface is an annulus surrounding the disk, while, in the defendant's valve, the valve proper is an annulus, and the extended surface is a disk inside of the annulus. ”

“ A number of small valves and perforations in the partition sheet between the water and steam compartments, will remedy that hitherto very general annoyance of water rising to and through the valves, which is occasioned by pressure of steam upon the surface of the water, and when one large valve is opened, the pressure is partly removed from the water immediately under it, consequently the water rises through the valve. ”

“ COCCONEIS SCUTELLUM VAR. ORNATA GRUN.
Upper valve with linear axial area, and transverse and radiating punctate lines which end at the border in a double row of finer puncta; lower valve with much finer puncta, a lanceolate axial area and a loculiferous rim.
Atlantic City. Common.
Pl. 16, Figs. 27 and 28.
The forms along the coast vary infinitely both in size and appearance. The var. ornata is very abundant along the entire coast. In any gathering, valves are found with or without the rim which is frequently seen detached. The upper valve is sometimes without the double row of puncta. ”

“ Frustules single or in twos, usually broader than long, constricted near the margin. Valve with six to twelve internal projections forming with the outline of the constriction of the valve a polygonal figure within the circumference. Surface of the valve with radiating lines of puncta disappearing toward the centre, at which are numerous coarse puncta. ”

“ When it is desired to open the valve, force is applied to depress the valve-stem; this force compresses the spring, depresses the plunger, and opens the valve quickly, owing to the fact that the water can escape rapidly from the variable chamber, such rapid escape being due to the operation of the cup-leather, which now ceases to hug the plunger and acts as a valve, permitting the water to escape freely from the variable chamber. ”

“ Carapace semi-oval in outline, obliquely truncated be- hind. slightly mucronate in front. Dorsal line straight, somewhat shorter than the greatest length of the valves. Valves regularly convex, widest in the middle, length more than twice the greatest breadth. Lower and anterior mar- gins regularly curving to the lower posterior end of the valve, which is abruptly rounded, and from whence the margin is concave to the extremity of the hinge. ”

“ Although the same principle underlies all these methods, i.e. the lengthening of the main column of air by the addition of other lengths of tubing, the valve itself constitutes a radical difference, for, the adjustment of crooks demanding time and the use of both hands, they could only be effective for the purposes of changing the key and of rendering a multiplicity of instruments unnecessary. The action of the valve being as instantaneous as that of the key, the instrument to which it was applied was at once placed on a different basis ”

“ The oxygen flows from the tank through a reducing valve, which cuts down the pressure, and into a controlling valve whence it flows by a rubber tube to the face cap which fits tightly over the patient's nose and mouth. ”