Question

Blood circulation in human is
A) Single and open
B) Double and open
C) Double and close
D) Single and close

Answer 1

Hint: The blood circulation is carried by pulmonary circulation and systemic circulation with the help of arteries, veins and capillaries. In the pulmonary circulation, the deoxygenated blood is converted into oxygenated blood by the lungs and in the systemic circulation, the oxygenated blood is supplied to the body.

Complete answer:
Blood circulation in humans is double circulation as it involves two circulations, first are the pulmonary circulation and the second one is the systemic circulation. In the pulmonary circulation, the deoxygenated blood is taken by the venules and veins to the right atrium and are carried by the pulmonary artery from the right ventricle to the lungs.

The systemic circulation starts from the left atrium which is supplied with the oxygenated blood by the pulmonary vein and it goes to the aorta, arteries and arterioles to the whole body by the left ventricle. The arterioles, venules and capillaries are interlinked all over the body for circulation.

i) Single circulation: In this only one cycle of circulation takes place. Fish comprises this type of circulation, in which the blood is carried from the heart to the gills and then it is provided to the whole body.
ii) Open circulation: The primitive organisms have this kind of circulation that is invertebrates (molluscs and arthropods), in this, the blood is not conducted by blood vessels rather haemolymph (fluid flowing in the system) directly baths the organs. There is no capillary system in this circulation.
iii) Closed circulation: this is found in humans and most vertebrates. In this, the blood is circulated by blood vessels that are closed. The capillary system is present

Therefore, humans have double and close blood circulation. So, option (C) is correct.

Note: The blood consists of plasma in a major amount as well as the cells in fewer amounts. The cells are Red blood cells, white blood cells and platelets. RBC helps to carry oxygen all over the body whereas the WBC helps in immunity.