Human Physiology Focusing on Heart and Lungs

Both the respiratory and cardiovascular systems are essential for the maintenance of life in the human body. The respiratory system is primarily responsible for gas exchange, as oxygen is taken in via the mouth or nose, eventually being expelled as carbon dioxide. The circulatory, or cardiovascular, system is responsible for circulating blood through the body. The respiratory and cardiovascular systems work together by delivering oxygen and essential nutrients to all the cells of the body.
The basic process of the respiratory system from initial respiration through gas exchange begins when a person takes a breath. Air enters through the mouth or nose, travels down the throat area’s pharynx, larynx, and trachea, and from there to the bronchial tubes (bronchi). The trachea itself splits to form the upper region of the left and right bronchial tubes (“Gas Exchange”). Each of the two primary bronchial tubes is then further divided into secondary, tertiary, and even smaller bronchi called bronchioles, each of which leads to the lungs and the alveoli.
The alveoli are the heart and soul of the respiratory system because this is where gas exchange primarily takes place. Located within the lungs, these “tiny air sacs” that inflate during the intake of oxygen (“Gas Exchange”). Naturally, the alveoli deflate during exhalation. All the alveoli are surrounded by capillaries, the site of intersection between the respiratory and circulatory systems. The capillaries and the alveoli share a wall or membrane, and this is where the alveoli transmit the inhaled oxygen to the bloodstream and where the they receive the unneeded carbon dioxide gas back so that it can be exhaled. The respiratory system can be described by its three main functions: ventilation (the movement of air), diffusion (the gas exchange), and perfusion (at which point the cardiovascular system takes over). The cardiovascular system is what carries the oxygen acquired during gas exchange to all the cells of the body.
The cardiovascular system centers on its primary organ, the heart. Essentially a pumping organ, the heart is what sends blood throughout the system of blood vessels to all the organs, tissues, and cells of the body. Blood enters the heart first through the right atrium and left atrium. The left atrium receives the oxygenated blood newly received from the lungs, carried from the alveoli through the pulmonary veins. This blood can then be carried through the arteries, veins, and capillaries throughout the body. Other important veins that connect the heart with the blood vessels that send blood throughout the entire body include the aorta, the vena cava, and the pulmonary trunk.
The right atrium receives the un-oxygenated blood from the heart, allowing it to flow into the right ventricle. Likewise, the left atrium sends blood into the left ventricle. Both the right and left ventricles are divided from their respective atria by a valve. The valve on the right side is called the tricuspid valve, and on the left side, the mitral valve. Both the tricuspid valve and the mitral valve prevent blood from flowing the wrong way. Whenever the ventricles are full with blood, the valves close so the heart can function optimally.
During the circulation of blood throughout the body, there are two main loops: the pulmonary circulation loop and the systemic circulation loop (“Cardiovascular System,” n.d.). These two loops are conducted on each side of the heart. The pulmonary loop involves the right atrium and right ventricle and takes the un-oxygenated blood from the heart to the lungs. From there, the blood acquires new oxygen from the alveoli. The systematic circulation loop takes place on the left side of the heart by taking the blood that has already circulated through the body and which contains waste products, and systematically circulating it to the right side of the heart. Thus, the process or circulation becomes a seamlessly integrated whole.






References

“Cardiovascular System,” (n.d.). Retrieved online: http://www.innerbody.com/image/cardov.html
“Gas Exchange.” Biology. Retrieved online: http://www.passmyexams.co.uk/GCSE/biology/gas-exchange.html
Lechtzin, N. (n.d.). Exchanging oxygen and carbon dioxide. Merck Manuals. Retrieved online: http://www.merckmanuals.com/home/lung-and-airway-disorders/biology-of-the-lungs-and-airways/exchanging-oxygen-and-carbon-dioxide