conus arteriousus and sinus venosus

Answer 1

The conus arteriosus and sinus venosus are two structures found in the heart of certain animals.

The conus arteriosus is a section of the heart located between the ventricle and the main pulmonary artery. It is responsible for smooth blood flow from the ventricle to the pulmonary artery during ventricular contraction. In some animals, such as fish and amphibians, the conus arteriosus serves as a valve, preventing backflow of blood into the ventricle.

The sinus venosus, on the other hand, is a chamber located in the heart that receives deoxygenated blood from various veins before it enters the atrium. It serves as a pacemaker in some animals, controlling the heart rate and rhythm.

Both the conus arteriosus and sinus venosus are structures found in the hearts of lower vertebrates like fish and amphibians. In higher vertebrates, such as mammals, these structures have been modified or incorporated into other parts of the heart during evolution.