A text-book of physiology - for medical students and physicians (1916) (14747322226)

Identifier: textbookofphysio1916howe (find matches)

Title: A text-book of physiology : for medical students and physicians

Year: 1916 (1910s)

Authors: Howell, William H. (William Henry), 1860-1945

Subjects: Physiology Medicine

Publisher: Philadelphia and London : W. B. Saunders Company

Contributing Library: Yale University, Cushing/Whitney Medical Library

Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library

Text Appearing Before Image:

although a slightly highertemperature may be withstoodunder special conditions. At theother extreme the mammalianheart ceases to beat when thetemperature falls as low as 17° to18° C. The rate of the heart beat maybe influenced also by many sub-stances added to the blood. Theinfluence of atropin and muscarinhas already been alluded to, butchanges also in the normal con-stituents of the blood may have similar effects. An increased out-put of epinephrin from the adrenal glands, such as may result fromemotional excitement (p. 621), will modify the heart beat eitherdirectly or through the cardio-inhibitory center of the medulla,and distinct variations in the reaction or the inorganic constituents * Martin, Croonian Lecture, Philosophical Transactions, Royal Society,London, 174, 663, 1883; also Collected Physiological Papers, p. 40, 1895. t Martin and Applegarth, Studies from the Biological Laboratory, JohnsHopkins University, 4, 275, 1890; also Collected Physiological Papers,p. 97, 1895.

Text Appearing After Image:

Fig. 247.—To show the effect oftemperature on the rate and force 01the heart beat. Contractions of theterrapins ventricle at different tem-peratures. Kymograph moving atthe same speed. At 30° the rate is>still increasing, but the extent of con-traction has passed its optimum. THE EATE OF THE HEART BEAT. 601 of the blood may also affect the rhythm of the heart. Addition ofpotassium salts in excess will stop the heart beat entirely, bringingabout the condition of potassium inhibition, but such conditionsare, for the most part, exceptional or experimental. In the usual ft sir&Hr /.( ,a 1 3 k 1 « t> \: S-.. -~ \ s Ifiztiszezi?6/ a siutt SO &0 so \ v \ \ \ \ / / / / / f * / ■m /<y tS It ssa (S -:? ^ ^ \ \\ l/r ^ 1 : i * i i S C N 5 ; t ; ! « , : • < Sfry -^ ^ •? i < * N 1 * I ! i 0 , 5- I , 3.9 3 m - o-t-« a °~C d »ogg»«— a u-^ 3 eg - O 0 a a **-< ^ o s s £ « b .a o a •&£.§ 8 5 2 * mc S o) £-j0/43 a K3 5 % &l

ein Lehrbuch der Physiologie für Medizinstudenten und Ärzte 1916 Kymographen Buchillustrationen Physiologie Medizin Lehrbuch Medizin Biologie Bilder aus dem Internetarchiv

1916

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