Question

1. Why might the heart be referred to as a double pump?

2. There are four valves in the heart. Name each valve, list its location, and give its function.

3. List the features that were labeled on the heart image so that they trace the path of the blood as it travels into and out of the heart (include the lungs in the pathway).

Answer 1

1) Mammalian heart is four chambered, consisting of two auricles and two ventricles. The right side receives deoxygenated blood from the body via superior and inferior vena cava and pumps it to the lungs for oxygenation while the left side of the heart receives oxygenated blood from lungs via pulmonary veins which is then pumped to the rest of the body. Therefore, heart acts as double pump.

2) Heart valves prevent back flow of blood within the heart. The atrioventricular valves (AV) lies between the atria and ventricles are - tricuspid valve, seperates right atria and right ventricle and bicuspid valve, seperates left atria and left ventricle. The semilunar valves (SL) are the aortic valve, at the entrance to the aorta and the pulmonary valve at the entrance to the pulmonary trunk.

3) In pulmonary circulation, blood is circulated to lungs for oxygenation of deoxygenated blood. Oxygenated blood is then returned to left atrium from lungs through pulmonary vein. The deoxygenated is collected by superior vena cava, inferior vena cava and coronary sinus which drain it into right auricle/atrium. Superior vena cava brings deoxygenated blood from the head and upper region of the body. The inferior vena cava brings deoxygenated blood from the lower region of the body. Blood exits right atrium through the tricuspid valve to the right ventricle. Right ventricle pumps blood through the pulmonary valve into pulmonary trunk. Pulmonary trunk branches into pulmonary artery which carries deoxygenated blood to the lungs for oxygenation.

In systemic circulation, oxygenated blood is circulated in the body, providing oxygen and nutrients to organs and tissues; also collects blood rich in carbon dioxide. Pulmonary vein brings the oxygenated blood from lungs and fills the left atrium which pressurizes the bicuspid valve to open releasing the blood from left atrium to left ventricle.

During contraction, left ventricle pumps oxygenated blood through aortic valve into aorta which distributes it though out the body (except lungs) through the network of arteries and capillaries. The used blood or deoxygenated blood is then returned to right atrium through veins.