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## The Flow of the Blood in the Heart ### Oxygen-poor blood coming from all parts of the body goes back to the right atrium of the heart through the vena cava. Contraction of the right atrium forces blood to move down the right ventricle. When the right ventricle contracts, blood moves toward the...

## The Flow of the Blood in the Heart ### Oxygen-poor blood coming from all parts of the body goes back to the right atrium of the heart through the vena cava. Contraction of the right atrium forces blood to move down the right ventricle. When the right ventricle contracts, blood moves toward the lungs, passing through the pulmonary artery. ### In the lungs, blood is oxygenated (pulmonary circulation). From the lungs, oxygenated blood goes to the left atrium by way of the pulmonary veins. When the left atrium contracts, blood moves to the left ventricle. Contraction of the left ventricle forces oxygen-rich blood to move to all parts of the body by way of the aorta (systemic circulation). ## Career in Focus Cardiologists are highly trained heart medical specialists who diagnose, assess and treat diseases of the heart and blood vessels and the different conditions that affect the cardiovascular system as a whole. They also know how these diseases and malfunctions progress and can be prevented. In the Philippines, becoming a cardiologist involves three steps: - First, you have to earn a bachelor’s degree in any appropriate life sciences as a pre-medicine course. - Second, you have to gain admission to a medical school to finish a four-year medical degree program; the final two years of which will involve internship in one or more hospitals. - Only upon completion of these four-year requirements that you will earn the degree Doctor of Medicine (MD). - Third, you have to pass the Medical Board Licensure Exam to be able to practice medicine in the Philippines. - Lastly, you have to undergo a residency for six or eight years to complete the clinical internal medicine training that specializes in cardiology. After these steps, you are now a heart specialist or a cardiologist. ## The capillaries are the smallest blood vessels that are just one-cell thick This is because the exchange of materials, such as gases and nutrients, can easily take place between the blood and the cells. The capillaries are located between the arterioles and venules. ## What do you think is the cause of the illness called "heart murmur?" The mitral valve is a valve that lets blood flow from the left atrium to the left ventricle. The mitral valve gets its name from its resemblance to the Pope's hat called MITRE. ## Take Note Another type of circulation taking place in living things is the open circulation. In an open circulatory system, blood does not pass through blood vessels. Instead, it is pumped by the heart into a space or cavity called hemocoel that surrounds the organs and then goes back to the heart by passing through small openings called ostia. In the hemocoel, blood mixes with the interstitial fluid (the fluid in-between cells), which is the reason blood is called hemolymph. Open circulation is common among insects.