In its most basic terms the pulmonary circulation system is the movement of the blood from the heart, to the lungs and back to the heart. It is a simple transfer to help eliminate the waste (carbon dioxide) in the blood out through the lungs. It then fills the blood with oxygen (the nutrient) and takes it back to the heart.
The heart is located in about the center of the chest cavity. It is covered by the pericardium. The pericardium is a protective membrane designed to prevent damage to the heart. It is a lining.
Lets take a look at the pulmonary circulation system based on the center of activity, the heart. Blood travels through a series of arteries, veins, and capillaries delivers blood and nutrients to all the vital organs and tissues of the body. When the blood is depleted it arrives back into the heart through the right atrium.
The blood then flows through a valve made up of three flaps called the tricuspid valve. The valve is designed so the blood can only flow in one direction.When the ventricle contracts the tricuspid valve is closed and it forces open the pulmonary valve. The blood flows through the pulmonary valve and into the pulmonary artery. That artery immediately branches off into the left and right lungs.
The lungs are elastic and spongy organs used to breathe. The right lung has three lobes and the left has two. Air travels in from the mouth and nostrils down the windpipe and then goes into the left and right bronchial tubes to enter the lungs. These large tubes break into smaller tubes that are referred to as bronchioles. Eventually they break down to the smallest air sacs that are called alveoli. It is these small air sacs that the oxygen is collected and then moves into the bed through the capillary beds.
Respiration is the term uses to describe how the cells of the body use the oxygen to create energy and how they exhale carbon dioxide, which is the waste product of building the energy. The capillary beds release the carbon dioxide and take in fresh oxygen.
The venules then drain the capillary beds and two pulmonary veins carry the oxygen rich blood into the left atrium of the heart.
The heart can then pump the oxygen filled blood out to feed the body.
This is the map that the blood travels through the pulmonary circulation system.
When people practice the basics of CPR (cardio-pulmonary resuscitation) when the heart and breathing stops this is the system that they are attempting to keep going on a manual system until the heartbeat resumes. It helps to save the life of many. It keeps the blood moving through the system on a limited basis.