Question

To go to the left side of the heart from the right the blood will have to cross
(a) Liver
(b) Lungs
(c) Kidney
(d) Brain

Answer 1

The circulatory system is the transportation of blood from the heart to the body and then back to the heart. The blood follows two pathways, one pathway is responsible for the oxygenated blood while the other is responsible for deoxygenated blood.

Complete answer
The circulatory system is responsible for the transportation of nutrients and gases to the body and waste products away from the body. It involves the chamber of the heart and the lungs.
In almost all mammals double circulation is seen, it has the following components:
-Systemic Circulation: The systemic circulation includes the circulation which helps in the distribution of oxygenated blood from the left ventricle of the heart to all the different body parts and the draining of deoxygenated blood from all the body parts into the right atrium of the heart. The oxygenated blood passes from the left ventricle to the aorta, from the aorta to the arteries. The arteries further branch into arterioles, capillaries, venules and these again unite to form veins of the whole body. Finally, two vena cava drains into the right atrium of the heart. Systemic circulation is also known as greater circulation or peripheral circulation as it supplies blood to a majority of body tissues.
-Pulmonary Circulation: It consists of the pathway of deoxygenated blood from the right ventricle to the lungs via the pulmonary artery and oxygenated blood from the lungs to the left atrium via the pulmonary vein.
-The systemic and pulmonary circulation together constitute the double circulation.

So, the correct answer is ‘Lungs’.

Note:
The valves open and close as the heart muscle contracts and relaxes, letting blood flow into the ventricles and atria at alternating times. The aortic valve and the mitral valve The aortic valve and the mitral valve are responsible for the blood flow into the left ventricle which is carried from the left atrium.