Difference Between Circulatory and Respiratory System

The human circulatory and respiratory systems are closely related systems which have evolved to do interrelated function in the body. Hence, smooth functioning of these two systems are vital for the survival of humans. Though these systems have interrelated functions, their physiology and other functions vary widely.

What is Circulatory System?

The human circulatory system mainly consisting of a muscular heart, which is acting as a pump, and a network of blood vessels. In addition, lymphatic system is sometimes referred to a supplementary system of the circulatory system. The main function of the circulatory system is to transport blood throughout the body that nourishes cells, remove their metabolic waste products and destroy pathogenic substances which cause disease in the human body. Blood is the transporting media and is composed of mainly blood cells (red blood cells and white blood cells) and blood plasma. The network of blood vessels is composed of arteries, veins and capillaries that carry the blood inside them. Since, all the blood is circulating within blood vessels, the human circulatory system is known as closed system. The human circulatory system has two systems, (a) pulmonary system connecting the lungs and heart, and (b) systemic system connecting every other tissue and organ with heart.

What is Respiratory System?

The human respiratory system is composed of two portions, (a) conducting portion, which includes the nose, pharynx, larynx, trachea and bronchi, and (b) respiratory portion, which includes the bronchioles, alveolar ducts, alveolar sacs, and alveoli. The respiratory portion is found within the unique structures called lungs. The two lungs are found within the thoracic cage above diaphragm. The main function of the respiratory system is the exchange of gasses (oxygen and carbon dioxide) between environment and body. Alveoli are the main sites where gas exchange is taken place. The walls of alveoli together with tiny blood capillaries compose the respiratory surface. Due to the concentration gradients, oxygen from the inhaled air diffuses into blood, while carbon dioxide from the blood diffuses into alveoli sacs through the respiratory surfaces. The diffused carbon dioxide is then forced out of the lungs by the movement of the diaphragm muscles.

What is the difference between Circulatory and Respiratory System?

• Circulatory system is composed of the heart, blood, blood vessels, lymph and lymph nodes, whereas respiratory system is composed of nose, pharynx, larynx, trachea, bronchi, bronchioles, alveolar ducts, alveolar sacs, and alveoli.

• The requirement of oxygen and carbon dioxide is fulfilled by the respiratory system, whereas the transportation of substances throughout the body tissues via blood is done by the circulatory system.

• Unlike the respiratory system, circulatory system has a network of blood vessels.

• The main organ of the circulatory system is the heart, whereas that of respiratory system is lung.

• Respiratory system helps to produce voice, but circulatory system does not.


Further Reading:

  1. Difference Between Circulatory System and Lymphatic System
  2. Difference Between Open Circulatory System and Closed Circulatory System
  3. Difference Between Ventilation and Respiration