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In 1852 H.F. Stannius experimented on the heart. By tying a ligature as a constriction between the sinus venosus and the atrium in the frog and also one around the atrioventricular groove, Stannius was able to demonstrate that the muscle tissues of the atria and ventricles have independent and spontaneous rhythms.
Diagram of the frog heart preparation used by Loewi. Vagus nerve stimulation slows heart rate while accelerator (sympathetic) nerve stimulation speeds up heart rate. Vagusstoff (literally translated from German as "Vagus Substance") refers to the substance released by stimulation of the vagus nerve which causes a reduction in the heart rate.
In 1852, H. F. Stannius used a frog's heart in a procedure called a Stannius ligature to demonstrate the ventricle and atria beat independently of each other and at different rates. [224] The African clawed frog or platanna (Xenopus laevis) was first widely used in laboratories in pregnancy tests in the first half of the 20th century.
The next time you declare that you are “freezing to death,” spare a thought for the wood frog who gets so cold in winter that its heart stops beating – but it does not die. Once the spring ...
A lymph heart is an organ which pumps lymph in lungfishes, amphibians, reptiles, and flightless birds back into the circulatory system. [ 1 ] [ 2 ] In some amphibian species, lymph hearts are in pairs, and may number as many as 200 in one animal the size of a worm , while newts and salamanders have as many as 16 to 23 pairs of lymph hearts.
Ringer's solution is named after Sydney Ringer, who in 1882–1885 determined that a solution perfusing a frog's heart must contain sodium, potassium and calcium salts in a definite proportion if the heart is to be kept beating for long.
The early bulbus cordis is formed by the fifth week of development. [4] The truncus arteriosus is derived from it later. [2]The adjacent walls of the bulbus cordis and ventricle approximate, fuse, and finally disappear, and the bulbus cordis now communicates freely with the right ventricle, while the junction of the bulbus with the truncus arteriosus is brought directly ventral to and applied ...
In order to relate the work of the heart to skeletal muscle mechanics, Frank observed changes in diastolic pressure with varying volumes of the frog ventricle. His data was analyzed on a pressure-volume diagram, which resulted in his description of peak isovolumic pressure and its effects on ventricular volume.