Answer:
The circulatory and respiratory systems interact to transport carbon dioxide to the lungs, where it is expelled from the body.
Explanation:
Carbon dioxide produced by the cells and tissues during cellular respiration is removed from the body through the interaction of the circulatory and respiratory system. The medium of transport of carbon dioxide is the blood which carries to the lungs, where it is expelled from the body in ordernto maintain homeostasis in the body.
Carbon dioxide molecules are transported in the blood from body tissues to the lungs in three ways:
1. Dissolution directly into the blood - due to its greater solubility in blood than oxygen, carbon dioxide is dissolved in blood plasma. On reaching the lungs, it leaves the blood by diffusion and is then expelled out of the body.
2. Binding to hemoglobin - carbon dioxide binds reversibly with haemoglobin in the red blood cells to form a molecule called carbaminohemoglobin. When it reaches the lungs, the carbon dioxide freely dissociate from the hemoglobin and is expelled from the body.
3. Carried as a bicarbonate ion - the majority of carbon dioxide molecules are carried as part of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the red blood cells. The enzyme carbonic anhydrase within the red blood cells quickly converts the carbon dioxide into carbonic acid (H2CO3) which then dissociates into bicarbonate and hydrogen ions. The bicarbonate ions leaves the red blood cells in exchange for chloride ions in the plasma. The bicarbonate ions then travel in plasma to the lungs, where they enter the red blood cells again. It combines with hydrogen ions from the haemoglobin to form carbonic acid. Carbonic anhydrase breaks carbonic acid down into water and carbon dioxide which is then expelled from the lungs.
