Oxygen is essential to the survival of all body cells. The supply of oxygen to those cells is maintained via the circulatory system. The circulatory system is an integral part of the cardiovascular system which is maintained by the heart, blood vessels and blood. The three main subtypes of circulatory systems that occur in humans are the systemic circulation, pulmonary circulation and coronary circulation. All the three types of circulation are dependent on one another to maintain the supply of oxygen to and removal of carbon dioxide from the body tissues.
Pulmonary circulation serves as the link between the respiratory system and the cardiovascular system. This is simply because deoxygenated blood that is being transported from the body is pumped by heart to the lungs for oxygenation (Farabee, 2010). The red blood cells that are already deprived of oxygen use their haemoglobin to collect oxygen within the lungs. This is then transported to the heart for further pumping to the other parts of the body. Oxygenation of depleted red blood cells occurs as a result of the hypoxia condition of the blood (Stein, 2006).
The gaseous exchange which occurs within the alveoli is responsible for the elimination of the carbon dioxide which is a waste product and collection of oxygen from the inspired air. This whole process involves gaseous diffusion which is influenced by concentration gradient of the two gases (Farabee, 2010). Oxygen which is highly concentrated within the alveolus diffuses into the red blood cells while carbon dioxide which is highly concentrated within the red blood cells simultaneously diffuses out.
The alveoli are made up of squamous epithelial cells that are thin to allow simple diffusion of oxygen from the alveoli to the network of vessels that surrounds the alveoli (Farabee, 2010). This is simply because of the concentration gradient between the two sides. During the process of diffusion, oxygen is being exchanged for carbon dioxide to balance the changes in body system. When oxygenated blood gets to the tissues of the body, the waste product of cellular respiration which is needed are being produced in large quantities. This is simply because of the availability of the oxygen to perform the cellular respiration needed for body functions. The metabolically active cells produce carbon dioxide in high quantity, hence creating a concentration gradient for diffusion to occur for effective gaseous exchange. The carbon dioxide simply changes into bicarbonate within blood for easier removal from the body. Once the bicarbonate gets to the lung, it is being converted back into carbon dioxide for excretion out of the body.
Heart which is the body main machine that pumps blood to all parts of the body also needs oxygen and nutrient to maintain its continuous function. To achieve this goal, the coronary circulation helps provide what is needed by the myocardium. The coronary arteries come in different types and shapes which help supply oxygen to myocardium. The major coronary arteries are the Left Main Coronary Artery and Right Main Coronary Artery (Klabunde, 2007).
The left main coronary artery divides into two other main branches that are left anterior descending artery and circumflex branches. The other major branch is right main coronary artery. There are several other types of coronary arteries which include the left marginal artery, right marginal artery, and posterior descending artery. These arteries supply different parts of myocardium. They have their origin from the aorta which transports oxygenated blood. The origin is beyond the semilunar valves.
Blood enters the coronary arteries during the diastole (Klabunde, 2007). This is because it is during this period that there is an increased in the aortic pressure which automatically forces blood into those coronary arteries. When blood enters into those arteries, the myocardium will be supplied the required oxygen. This oxygen supply is in exchange for carbon dioxide (deoxygenated blood). Deoxygenated blood from myocardium is drained into different smaller coronary veins that converge together to form coronary venous sinus (Klabunde, 2007). The content of the venous sinus will then be emptied into the right ventricle. Oxygen consumption by the myocardium is usually very high compared to the other tissues of the body. The need is usually what determines the coronary flow.
The important notes in this discussion are that respiratory and cardiovascular systems are interdependent. Concentration gradient creates an essential factor in gaseous exchange. Coronary vessels perform the major function of coronary circulation which help provides oxygen to the heart musculature.
References
Farabee, M.J. (2010). The respiratory system.
Retrieved 21 May, 2012 from http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookrespsys.html
Klabunde, R.E. (2007). Coronary Anatomy and Blood Flow. Cardiovascular physiology concepts.
Retrieved 21 May, 2012 from http://www.cvphysiology.com/Blood%20Flow/BF001.htm
Stein C., (2006). Circulatory System. Biology.
Retrieved 21 May, 2012 from http://biology.clc.uc.edu/courses/bio105/circulat.htm
