Human beings, as well as animals, have blood flowing throughout their bodies. Now, how does the blood circulate, getting from the brain to the farthest part and back again? Well, this method in transporting blood within the body is known as the circulatory system, which consists of a complex highway of vessels with the primary purpose of moving blood that contains oxygen and other nutrients.
There are two types of circulatory system, namely the open circulatory system and the closed circulatory system, with the latter having more of particular interest to us knowing that it is the type that we, humans, have. Unlike the former, the latter is more controlled and structured, with the blood always flowing inside vessels that can be found throughout our entire body, making up its plumbing circuit that is also broken down into three different kinds of vessels—arteries, capillaries and veins—that transport blood throughout the body. The circulation works with the arteries being responsible for moving blood away from the heart and to the tissues. When blood reaches the tissues, it is contained inside the capillaries, which are the very tiny vessels that are found inside thin walls, which are responsible for allowing the waste and gas exchange to occur between the tissues and the blood. From here, the blood then leaves the capillaries and flows into the veins that are tubes that carry blood back to the heart.
While it is an essential system in the body, the closed circulatory system is often assessed against the open circulatory system in terms of efficiency in helping our body function. To get a good idea about this matter, let us take a look at its pros and cons.
List of Pros of Closed Circulatory System
1. It is efficient in delivering oxygen throughout an organism.
This type of system offers great ability for oxygen delivery. As you can see, it involves the ultra filtration of the blood, pulmonary circulation and the systemic circulation. The deoxygenated blood is transported from heart to the lungs to be oxygenated, which is known as pulmonary circulation. The oxygenated blood is then transported to the rest of the organs, which is known as systemic circulation. After the blood reaches the tissues through the capillaries, it is then returned back to the heart through the veins, with the blood pressure in the venous system being lower compared with that in the arterial system.
2. It provides more power in the form of pressure.
Compared to the open circulatory system, the closed circulatory system operates with much higher blood pressure, though it is said to be more efficient considering that it uses much less blood for even faster and higher levels of distribution. And since the blood containing oxygen might reach the body’s extremities in a much faster rate than with an open circulatory system, human beings, as well as other organisms with the closed system, can metabolize much faster, which means faster movements, digestion and waste elimination. Aside from this, it also allows for better and efficient distribution of antibodies, making immune responses much stronger and making the body more powerful to fight off infections. Furthermore, the system and the pulmonary circulation process maintain their pressure, respectively.
3. It has a lymphatic system that works separately.
In this system, the lymphatic system is working separately. Here, the blood is responsible for transporting gases (oxygen and carbon dioxide), cells that defend the body and chemical substances (hormones, salts and nutrients); regulating the electrolyte and fluid balance, acid and base balance, and body temperature; and protecting the body from infection and from loss of blood by means of clotting. Meanwhile, the lymph system is responsible for cleansing the cellular environment; offering a pathway for absorbing fats and fat-soluble vitamins into the blood stream; returning tissue fluids and proteins to the blood; and defending the body against illnesses.
List of Cons of Closed Circulatory System
1. It is more complex than the open circulatory system.
As already implied, humans, vertebrates and larger, more active animals have a closed circulatory system. Compared to the open circulatory system, the closed circulatory system is quite more complex that includes two major processes—the above-mentioned pulmonary and systemic circulation. While pulmonary circulation transports deoxygenated blood through the lungs to get oxygen, systemic circulation distributes this oxygenated blood throughout your body. And to direct this blood to every organ and tissue, it uses a network of arteries and veins.
As opposed to bathing all tissues and organs with blood as what happens in the open circulatory system, the closed circulatory system works with the blood remaining in the vessels and transported to all extremities of the body at high pressures and rapid rate. As you can see, the open circulatory system is simpler, where the heart pumps blood into open cavities, with blood vessels carrying the blood at a low pressure throughout the body, and then bathes all organs and tissues with blood. Also, it does not use major veins and arteries to increase blood pressure and efficiently direct distribution. Organisms with an open circulatory system, such as spiders, insects, mollusks and prawns, typically have lots of blood, yet they have low blood pressure.
2. It requires more energy for blood distribution.
Compared to the open circulatory system, the closed circulation system requires more energy for distribution of blood. That is why it is said to be naturally designed for animals having a fast metabolism and larger bodies. This is also true considering the fact that oxygenated blood needs a lot of networks to travel to the extremities of the body.
A lot of organisms on this planet need a circulatory system in order to distribute nutrients throughout their body in an efficient matter and survive. Now it is important to consider that the two types of circulatory systems have their own sets of advantages and disadvantages. Although the closed circulatory system allows for quicker distribution and is more advanced, it is not suited for all species. It actually boils down to where it is most efficient.