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Frog Heart Model

Название Продукция: Frog Heart Model
модель: ZM042

Подробно о продукте: Frog Heart Model

AMPHIBIAN HEART
In the early stages of development amphibians breathe through gills.Later they breathe through lungs.when the gills often degenerate completely(e.g.,as in the flog.Rana esculenta).The frog also breathes through the skin.The amphibian heart has three chambers.Venous blood (and some arterial blood from the skin)flows to the right atrium(2)via two anterior and one posterior vena cava which unite to form the sinus uenosus(1).The fight atrium is separated by a septum from the left atrium(3)which receives pure arterial blood from the lungs via the pulmonary veins(4).Through the atrioventricular orifices the blood of both atriums flows into the common ventricle(5).which forces the blood towards the conus arteriosus(6).Membranous valves between the heart sections 1／2.2／5.3／5 and 5／6 control the direction of blood flow.Two branches of truncus arteriosus(7).one for each side of the body.arise from the conus arteriosus and each dividesinto three vessels: the pulmo-cutaneous artery(8).aorta(9).and common carotid artery f10).A complicated internal structure and contraction sequence prevents
the complete mixing of arterial and venous blood within the ventricle and eonus arteriosus, and provides arteries 8-10 with blood of differing oxygen concentrations.The carotid arteries(10) receive blood richest in oxygen and the pulmo—cutaneous arteries receive nearly pure venous blood.