A textbook of human physiology / translated from [the] 6th German edition by W. Stirling.

  • Landois, Leonard
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of human physiology / translated from [the] 6th German edition by W. Stirling. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    126/980 page 74
    impure. II' a pathological cavity, filled with air, be so placed, and of such a form as to act as a resonator to the heart-sounds, they may assume a metallic character. The first and second sounds maybe reduplicated or [although duplication is a more accurate term {Barr)] doubled. The reduplication of the first sound is explained by the tension of the tricuspid and that of the mitral valves not occurring simultaneously. Sometimes in disease a sound is produced by a hypertrophied auricle producing an audible presystolic sound, i.e., a sound or murmur, preceding the first sound. [This has been questioned quite recently.] As the aortic and pulmonary valves do not close quite simultaneously, a reduplicated second sound is only an increase of a physiological condition. All conditions which cause the aortic valves to close rapidly (diminished amount of blood iu the left ventricle) and the pulmonary valves to close later (congestion of the right ventricle—both conditions together in mitral stenosis), favour the production of a reduplicated second sound. Cardiac Murmurs.—If irregularities occur in the valves, either in cases of stenosis or in insufficiency, so that the blood is subjected to vibratory oscillations and friction, then, instead of the heart-sounds, other sounds—murmurs or bruits—arise or accompany these. A combina- tion of these sounds is always accompanied by disturbances of the circulation. [These murmurs may be produced within the heart, when they are termed endocardial; or outside it, when they are called exocardial murmurs. But other murmurs are due to changes in the <|uality or amount of the blood, when they are spoken of as hsBmic murmurs. In the study of all murmurs, note their rhythm or exact relation to the normal sounds, their poi7it of maximum intensity, and t\iQ direction in ivhieh the mimmir is propagated.] It is rare that tumours or other deposits projecting into the ventricles cause murmiu-s, unless there be present at the same time lesions of the valves and disturbances of the circulation. The cardiac murmurs are always related to the systole or diastole, and usually the systolic are more accentuated and louder. Sometimes they are so loud that the thorax trembles under their irregular oscillations {fremitus, fremisse- ment cataire). In cases where diastolic murmurs are heard, there ai'e always anatomical changes in the cardiac mechanism. These are insufficiency of the arterial valves, or stenosis of the auriculo-ventricular orifice (usually the left). Systolic murmurs do not always necessitate a disturbance in the cardiac mechanism. They may occur on the left side, owing to insufficiency of the mitral valve, stenosis of the aorta, and in the calcification and dilatation of the ascending part of the aorta. These niTirmurs occur very much less frequently on the right side, and are due to insufficiency of the tricuspid and stenosis of the pulmonary orifice. Functional Murmiurs.—Systolic murmurs often occi;r without anj'valvular lesion, although they are always less loud, and are caused by abnormal vibrations of the valves or arterial walls. They occur most frequently at the orifice of the pulmonary artery [and are generally heard at the base], less frequently at the mitral, and still less frequently at the aortic or the tricuspid orifice. Anemia, general malnutrition, acute febrile affections, are the causes of these miu'murs. [Some of these are due to an altered condition of the blood, and are called hsemic, and others to defective cardiac muscular nutrition, and are called dynamic ( Walslie).] Sounds may also occur during a certain stage of inflammation of the pericardium (pericarditis) from the roughened surfaces of this membrane rubbing upon each other. Audible friction sounds are thus produced, and the vibration may even be perceptible to touch. [These are friction sounds,^' and quite distinct from sounds produced within the heart itself.] 55. DURATION OF THE MOVEMENTS OF THE HEART.—The heart con- tinues to beat for some time after it is cut out of the body. The movement lasts longer in cold-blooded animals (frog, turtle)—extending even to days—than in mammals. A rabbit's heart beats from 3 minutes up to 36 minutes after it is cut out of the body. The average of many experiments is about 11 minutes. [Waller and Reid recorded the ventricular contrac- ^^^^^^^^^^^^^^^^^^^^^ tions of a rabbit's heart 72 minutes after ^^^^^^^■i^^MBBBBBII^M its excision. Fig. 52 shows the prolonga- Fig. 52. ^^P^ the ventricular systole in an ex- Curves of excised rabbit's heart, 1, 6mins. after cised rabbit's heart, the movements being excision; 2, 10 mins.; 3, 20 mins.; 4, 70 recorded by a lever resting on the heart! mins. (after Waller and Reid). Panum found the last trace of contraction to occur in the right auricle (rabbit) 15 hours after death ; in a mouse's heart, 46 hours ; in a dog's, 96 hours. An excised frog's heart beats, at the longest, 21 days
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