Name: Human Respiratory System
Uploaded: 2019-07-19
Duration: 4 min 39 s
Description: Fishes need gills for respiration, while frogs have skin as one of their respiratory organs. Check out this video for details about the respiratory organs in humans.

Question

Write an essay on the transport of oxygen and carbon dioxide by blood.

Accepted Answer

Oxygen is transported from the lungs to the tissues through the plasma and RBC of the blood. About $3$ percent of $O_{2}$ is carried through the blood plasma in a dissolved state and the rest is transported by the RBCs in the blood. Haemoglobin is a red coloured iron containing pigment present in the RBCs that can carry a maximum of four molecules of oxygen. Binding of oxygen with haemoglobin is dependent on the partial pressure of $O_{2}$ . At lungs, where the oxygen tension is high, oxygen binds to haemoglobin to form oxyhaemoglobin.

Carbon dioxide is transported in the blood in three ways:

As a hydrogen carbonate,

As carbamino compounds and

As dissolved in plasma.

About $5 - 7$ percent of all carbon dioxide is dissolved in the plasma. Carbon dioxide can bind to haemoglobin and about $10$ percent is transported in this mode. When carbon dioxide binds to haemoglobin in reversible manner as carbaminohaemoglobin is formed.

Third, about $85$ percent of carbon dioxide molecules are carried as part of the bicarbonate buffer system. Here, carbon dioxide diffuses into the erythrocytes. Carbonic anhydrase within erythrocytes quickly converts the carbon dioxide into carbonic acid. Carbonic acid dissociates into bicarbonate and hydrogen ions.
Since carbon dioxide is quickly converted into bicarbonate ions, this reaction causes the continued uptake of carbon dioxide into the blood. The bicarbonate ion is exported out of the red blood cell into the plasma in exchange for a chloride ion which is called the chloride shift. When the blood reaches the lungs, the bicarbonate ion is imported back into the red blood cell and produces the carbonic acid intermediate. This is then quickly which is converted back into carbon dioxide through the enzymatic action. The carbon dioxide produced is breathed through the lungs during exhalation.

Write an essay on the transport of oxygen and carbon dioxide by blood.

Important Questions on Breathing and Exchange of Gases

Learn and Prepare for any exam you want !