Question

Humans have an open circulatory system
A. Tue
B. False

Answer 1

Hint: In case of an open circulatory system, the blood is not bounded in blood vessels, rather it is pumped into a cavity known as a hemocoel. The blood in an open circulatory system is known as hemolymph as it mixes with the interstitial fluid in the hemocoel.

Complete answer: All vertebrates including human beings, have a closed type of circulatory system. This type of circulatory system differs both in the structure and function from an open type circulatory system that is present in insects and other arthropods. In a closed circulatory system, the blood is enclosed in the blood vessels, namely, arteries, veins, capillaries, or directly in the heart. Whereas in an open circulatory system, the blood, known as hemolymph, flows freely in body cavities known as a hemocoel. All internal tissues and organs are directly bathed in the blood. The closed type of circulation is basically of two types:
1. Pulmonary Circulation: The pulmonary circulation is a part of the closed circulatory system that carries the deoxygenated blood to the lungs from the right ventricle of the heart, and then brings back the oxygenated blood from the lungs to the left atrium and ventricle of the heart.
2. Systemic Circulation: Systemic circulation is a part of the closed circulatory system that carries the oxygenated blood in the tissues of the body through the arteries and the capillaries from the left ventricle of the heart. The deoxygenated blood is then returned to the right atrium of the heart from the tissue capillaries through a network of veins.
Hence, the correct answer is option B.

Additional Information: The closed circulatory system in humans also includes the lymphatic system that circulates lymph. The passing of lymph through the circulatory network takes more time than in the circulation of the blood. Lymph is basically recycled and filtered blood plasma from the interstitial fluid and is returned again to the lymphatic system.

Note: Vasculogenesis marks the beginning of the development of the circulatory system in an embryo. The human arteries and veins network develop from various parts of the embryo. The arterial network develops from the aortic arches, while the venous system develops from three bilateral veins during 4th to 8th week of embryogenesis. The foetal circulation starts within the 8th week of the development of the circulatory system.