The figures given below show diagrammatic cross sections of three kinds of blood vessels. Mention two structural differences between A and B.

The human circulatory system consists of the heart, blood vessels, and blood. The heart pumps the blood in the respective blood vessels through which, it reaches the body organs to supply oxygen and nutrients and collects the carbon dioxide and nitrogenous wastes. The given diagram represents the three types of blood vessels: artery as 'A', vein as 'B', and capillary as 'C'. Characteristics Arteries Veins Structure The arteries have a thick muscular wall and narrow lumen. The veins have a thin muscular wall and wide lumen. Characteristics Arteries Veins Semilunar valves These do not have semilunar valves as the blood flow under great pressure and does not backflow into the ventricles. These have semilunar valves as to prevent the backflow of blood.

The figures given below show diagrammatic cross sections of three kinds of blood vessels. Name the kinds of blood that flow through A and through B respectively.

The human circulatory system consists of the heart, blood vessels, and blood. The heart pumps the blood in the respective blood vessels through which, it reaches the body organs to supply oxygen and nutrients and collects the carbon dioxide and nitrogenous wastes. The given diagram represents the three types of blood vessels: artery as 'A', vein as 'B', and capillary as 'C'. Arteries: The oxygenated blood is received by the lungs through the pulmonary veins into the left atrium. The blood then reaches the left ventricle. The main artery called the aorta arises from the left ventricle of the heart and transport the oxygenated blood to the body organs through the respective arteries such as the hepatic artery to the alimentary canal and liver, renal artery to kidneys. It can be concluded that except for the pulmonary artery, all the arteries carry oxygenated blood from the left ventricle to the body organs. Veins: The deoxygenated blood is received from the body organs through the main vein called the superior and inferior vena cava and is transported to the right atrium. The blood then reaches the right ventricle and transported to the lungs through the pulmonary artery. It can be concluded that except the pulmonary vein, all the veins carry deoxygenated blood.

The figures given below show diagrammatic cross sections of three kinds of blood vessels. In which one of the above given vessels exchange of gases actually take place?

The given diagram represents the three types of blood vessels: artery as 'A', vein as 'B', and capillary as 'C'. The arteries carry oxygenated blood and the veins carry deoxygenated blood. The arteries are progressively branched into arterioles and the veins are progressively united and form the venules. The capillaries are the thinnest blood vessels that are connected with the arteries and veins and reach each body cell. It has a single layer of squamous epithelial cells called the endothelium through which the gases and the substances can be easily diffused. The capillaries act as the site for the exchange of gases and substances with the cells.