How is oxygen and carbon dioxide transported in human beings?

Oxygen and carbon dioxide are transported in the human body through the circulatory system, primarily using the blood as the carrier. The main components involved in the transport of these gases are red blood cells and the respiratory pigment hemoglobin. Here’s how the transport of oxygen and carbon dioxide occurs:

Transport of Oxygen:

1. Breathing: Oxygen is inhaled into the lungs during the process of breathing.

2. Exchange in the Lungs: In the lungs, oxygen diffuses across the thin walls of the alveoli (air sacs) into the bloodstream. This is facilitated by the concentration gradient, with higher oxygen levels in the alveoli and lower levels in the blood.

3. Binding to Hemoglobin: Oxygen binds to hemoglobin, a protein found in red blood cells. Each hemoglobin molecule can bind up to four oxygen molecules.

4. Formation of Oxyhemoglobin: When oxygen binds to hemoglobin, it forms oxyhemoglobin. Oxyhemoglobin is a bright red color.

5. Transport in Blood: The oxygen-rich blood is pumped by the heart through the arteries to various tissues and organs.

6. Release of Oxygen: In the capillaries of tissues, oxyhemoglobin releases oxygen to the cells where it is needed for cellular respiration.

Transport of Carbon Dioxide:

1. Cellular Respiration: Cells produce carbon dioxide as a byproduct of cellular respiration.

2. Diffusion into Blood: Carbon dioxide diffuses from the cells into the bloodstream, creating a concentration gradient.

3. Transport in Blood: Carbon dioxide is transported in three main ways:

» As dissolved carbon dioxide (around 7%)
» Bound to hemoglobin (around 23%) in the form of carbaminohemoglobin.
» As bicarbonate ions (around 70%) formed when carbon dioxide reacts with water in the red blood cells.

4. Transport to Lungs: The blood, now carrying carbon dioxide, is pumped back to the lungs through the veins.

5. Exchange in the Lungs: In the lungs, carbon dioxide is exchanged for oxygen. Oxygen binds to hemoglobin, and carbon dioxide is released from hemoglobin.

6. Exhalation: Carbon dioxide is then exhaled from the lungs.

This cycle of oxygen uptake in the lungs, transport to tissues, and release of oxygen to cells, along with the reverse process for carbon dioxide, is essential for cellular respiration and maintaining the body’s overall functioning. The transport of these gases is a dynamic and precisely regulated process to meet the metabolic needs of the body’s cells.