Question

The blood leaving the tissues becomes richer in:
A. $CO_{2}$
B. $H_{2}O$
C. Hb
D. $O_{2}$

Answer 1

Hint: Blood transports different substances like gases, namely oxygen and carbon dioxide, among the lungs and rest of the body. It conveys nutrients from the digestive tract and accumulation sites to the rest of the body. Waste products for detoxification or removal from the liver and kidneys are done with the help of blood.

Complete answer: Oxygen saturation is extra in the blood exuding out from the lungs to the heart. When deoxygenated blood reaches to lungs by the pulmonary artery it collects oxygen from inspired air and becomes oxygenated. The oxygenated blood comes back to the heart by pulmonary veins.
Water and hemoglobin concentration is roughly similar in tissues as well as in the lungs part.
The blood that leaves the tissues of the body becomes rich in carbon dioxide. Oxygenated blood is transported from the heart to the lungs by the main artery (aorta). As this blood flows into the capillaries of the organs of the body, the cells of the body are given oxygen. Carbon dioxide emitted during respiration reaches the blood at the same time. Deoxygenated blood (carrying carbon dioxide leaves tissues and enters the vena cava from where they are transported for oxygenation to the lungs again).
So, the correct answer is “Option A”.

Note:
The ultimate aim of the cardiorespiratory system is to supply tissue cells with oxygen and to eliminate the carbon dioxide that they create. Blood is transported through the body by the arteries and veins. In capillaries, oxygen is transferred through the hemoglobin solution within red cells, then through the cell membrane and the plasma of the blood. Both convection and diffusion (free and facilitated) may be necessary because cells and plasma are in motion.