Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling.

Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English

Date:: 1891

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling. Source: Wellcome Collection.

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$tricular contraction ilc) is feeble because the ventricle is imperfectly filled. The closures of the two valves, d and e, are relatively far apart, and one can hear distinctly a reduplicated second sound. The aortic valves close rapidly, because the aorta is imperfectly supplied with blood, while the more copious inflow of blood into the pulmonary artery causes its valves to close the heart beats rapidly and feebly— if the blood-pressure in the aorta and pulmonary artery be low, the signs of closure of the pulmonary valves maybe absent-as m curve L— taken from a girl suffering from nervous palpitation and morbus Basedowii. ^ ^ In very rare cases of insufficiency of the mitral valve, it has been observed that at certain times both ventricles contract simultaneously, as in a normal heart, but that this alternates with a condition where the right ventricle alone seems to contract. Curve M is such a curve obtained by Malbranc, who called this condition intermittent hemisystole The first curve (I ) is like a normal curve, during which the whole heart acted as usual. The curve II., how- ever is caused by the right side of the heart alone ; it wants the closure of the aortic valves d, and there was no pulse in the arteries. Owing to insufficiency of the tricuspid valve, the same person had a venous pulse with every cardiac impulse, so that the arterial and venous pulses first occurred together and then the venous pulse alone occurred. In these cases the mitral insufficiency leads to the right ventricle being over-distended, while the left is nearly empty so that the right side requires to contract more energetically than the left. It does not seem that the right ventricle alone contracts in these cases, but rather that the action of the left side is very feeble. 53. THE HEART-SOUNDS.—On listening over the region of the heart in a healthy man, either with the ear applied directly to the chest-wall {Harvey), or by means of a stethoscope (Laennec, 1819), we hear two characteristic sounds, the so-called heart-sounds. The two sounds are called first and second, and together they correspond to a single cardiac cycle. These sounds are separated by silences. [Fig. 59 shows the relation of the events occurring in the heart during a cardiac cycle to the sounds and silences.] 1. The first sound. 2. The first or short silence. 3. The second sound. 4. The second or long silence. [Relative Duration.—There is no absolute duration of each phase of a cardiac cycle, but we may take the average relative duration calculated from the measure- . nients of Gibson, in a case of fissure of the sternum, to be as follows:— — Auricular systole, . . • . •112 sec. Ventricular systole, . . • '368 ,, Ventricular diastole, . . • 578 Cardiac cycle, .... 1 '058 sec. Suppose we divide the cycle into tenths (Walshe), then 'the first sound will last ^V, the first silence ^q, the second sound ^% and the long silence of the entire period.] . The first sound [long or systolic] is twice as long as, Fig 59 somewhat duller, and one-third or one-fourth deeper, than the second sound; it is less sharply defined at first, Scheme of a cardjac eye e. synchronous with the systole of the ventricles. ^^JZ:r^t^ ^'= [short or diastolic^ is clearer, the heart, and the sharper, shorter, more sudden, and is one-third to one- outer, the relation of fourth higher in pitch; it is sharply defined and syn- the sounds and silences ^j^^.^^^^^ ^^^-^/i the closure of the semi-lunar valves. It to these events. ^^^^^^ ^^^^ beginning of ventricular diastole. The. sounds emitted during each cardiac cycle have been compared to the pronunciation of the syllables lülh, düpp. [If one hstens over the apex one hears the sounds like$