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Fig.14.16 Open circulatory system of cockroach, (a) The heart with alary muscle and dorsal diaphragm,
(b) T.S of cockroach through thorax showing various sinuses.
Vertebrate blood circulatory system
The components of vertebrate blood vascular system are typical of a circulatory system-blood,
heart, blood vessels (arteries, capillaries and veins). All vertebrates have closed circulatory system
In addition there is lymphatic system which also aids in transportation.
Heart pumps the blood to different parts of the body via aorta and arteries Arteries break into fine
blood vessels, the capillaries. These join to form veins which bring blood back to the heart. The
capillaries are sites where exchange of materials between blood and body tissues takes place.
Evolution of vertebrate heart
The heart of fishes have sinus venosus, an atrium, a ventricle, and bulbus arteriosus or conus
arteriosus. Sinus venosus receives deoxygenated blood from the body,and then blood is passed
to atrium, which on contraction passes it to ventricle. ventricle has thick muscular wall. When
the muscles of ventricle contract, they push the blood via conus arteriosus or bulbous arteriosus
(proximal swollen portion of ventral aorta).
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