The interrelationship of the heart and lungs

The interrelationship of the heart and lungs

The interrelationship between the cardiovascular and respiratory systems.

The respiratory system works in conjunction with the circulatory system to supply all the cells and tissues of the body with oxygen and to remove carbon dioxide.

This involves four separate processes.

a) Breathing (pulmonary ventilation)

b) The exchange of gasses between the lungs and the blood (pulmonary diffusion).

c) Transportation of oxygen and carbon dioxide via the blood

d) Exchange of gases between the capillary blood and the tissues of the body.

A +B are referred to as external respiration.

C + D are known as the internal respiration. Both external and internal respiration are linked to the circulatory system

There are two blood circulations in the body.

The pulmonary circulation, from the right ventricle of the heart, and from the lungs to the left atrium of the heart, is shown on the far right.

The systemic circulation, from the left ventricle of the heart and from the lungs to the right atrium of the heart is shown of the left.

The right side of the heart pumps blood around the pulmonary system to be oxygenated and the left side of the heart pumps the oxygenated blood to all parts of the body, and deoxygenated blood back to the right atrium of the heart via the systemic system.

Blood high in oxygen is shown in red and blood low in oxygen is shown in blue.

Let us now look at this in more detail, especially at the point of gas exchange.

The pulmonary artery brings deoxygenated blood from the heart’s right pump, this divides into two branches, one for each lung. Just as the bronchial tree divides into ever smaller branches (alveoli) the artery divides many times into arterioles until the vessels become capillaries. A whole network of these pulmonary capillaries surrounds each alveolus. Blood flows steadily bringing carbon dioxide for disposal and collecting oxygen for dispersal.

The interface where gas exchange takes place is very thin indeed. Each alveolus has a wall that is only one cell thick, likewise the walls of the capillaries are also only one cell thick. The distance between air and blood is about one thousandth of a millimeter. (1)

Oxygen travels in the blood via the red blood cells, these travel in single file through the pulmonary capillaries. Red blood cells are packed with haemoglobin, the blood’s red pigment, this acts as a magnet for the oxygen.

As oxygen latches on to the haemoglobin, it is converted to oxyhaemoglobin, which is a much bright redder colour, this way the blood is transformed from its dark red-blue de-oxygenated state.

To complete the gas exchange, carbon dioxide leaves the blood through the capillary and alveolar walls.

The pulmonary capillaries reconnect to become larger and larger vessels called the pulmonary veins and these return blood to the heart.

Ref 1 / The Human Body /page 78

Bibliography
Yoga Training notes (April-May 1999)

Anatomy colouring workbook by I.Edward Alcamo, Ph.D. (Random House 1997)

The Human Body (Marshall books 1998)

Bibliography Yoga Training notes (April-May 1999)

Bibliography
Yoga Training notes (April-May 1999)