The circulatory system of a human compared to that of a frog is different due to the number of chambers each contains. A frog’s heart has three chambers (two atria, and a single ventricle), whereas a human’s has four (two atria, and two ventricles). The atrium of a frog receives deoxygenated blood from the blood vessels that drain the various organs of the body. The left atrium receives oxygenated blood from the lungs and skin. Both atria empty into the single ventricle, which is divided into narrow chambers that reduce the mixing of the two bloods. The ventricle contracts, oxygenated blood from the left atrium is sent into the carotid arteries, thus taking blood to the head (and brain). Then, the deoxygenated blood from the right atrium is sent to the pulmocutaneous arteries, therefore taking blood to the skin and lungs where fresh oxygen can be picked up.
The systemic circulation of a human is a loop from the heart to the various parts of the body, which works in contrast to the pulmonary circulation. In the systemic circulation, arteries collect the oxygen-rich blood from the heart and transport it to the body tissues. In the process, oxygen from the blood is diffused into the body cells, and carbon dioxide from the cells is diffused in the blood. The pulmonary circulation, however, is a loop from the heart to the lungs. Here, deoxygenated blood from the heart is carried to the lungs and then oxygenated blood is returned to the heart. The oxygen-depleted blood leaves the heart through the two pulmonary arteries and moves into the lungs. In the lungs, respiration takes place in which the red blood cells release carbon dioxide and absorbs oxygen. Oxygenated blood from the lungs is then carried back to the heart with the help of pulmonary