Introduction
Analyzing the surrounded environment it can be concluded that the law of physics are the same for both non-organic and organic world, where in living organisms these laws are under the control of biological processes. Humans as the highest forms of those organic forms are studied by a number of scientific disciplines; however, a complete representation of the human phenomenon is incomplete without physics.
Every single part or system of the human body can be used to demonstrate a physical phenomena or a physical law. Taking the respiratory system of the human body it can be seen that the main processes involve the participation of air spaces and gases, and thus the laws of gas can be applicable to explain the processes of gas exchange and air flow. This paper analyzes the respiratory system, and the gas laws that can be applied in order to explain the main processes that occur in the system, particularly the air flow.
Definitions and Anatomy
Depending on the context in which the term respiratory is explained, the definition of respiration might vary. Accordingly, in the context physiology, respiration is “[a]n interchange of gases between an organism and its environment.” (Davies & Moores, 2003). Thus the respiratory system can be seen as an aggregate of organs, which perform the exchange of gases between the blood and the external environment.
On the cellular level, the respiration as a function implies “the processes by which cells utilize O2, produce CO2, and convert energy into useful forms.” (Wilhelm, Graaff, & Rhees, 2001). Under the general term “respiration” the processes that must happen include pulmonary ventilation, external respiration, transport of respiratory gases and internal respiration. (Marieb & Hoehn, 2007). Additionally, the functions of the respiratory system are not limited to the exchange of gases, where the system performs additional functions and tasks such as voice production, thermoregulation, protection form infection, the provision of transport for the air, abdominal compression and others. (Wilhelm, et al., 2001).
Functionally, the anatomy of the respiratory system includes “the nose and nasal cavity, pharynx, larynx, trachea, bronchi and their smaller branches, and the lungs, which contain the terminal air sacs, or alveoli.” (Marieb & Hoehn, 2007). In that regard, these parts can be divided into two zones: the respiratory zone, i.e. the zone where the gas exchanges, and the conducting zone, i.e. the transport or the passage ways through which the air reaches the gas exchange sites.
The Laws and Application
As the main aspect in the functioning of the respiratory system is related to gases, the laws applicable are the laws that govern gases’ behavior. One of the laws that can be applied to the respiratory system is Boyle’s Law. Boyle’s law outlines the relation between gases and their volumes, stating that the same amount of a confined gas will increase its volume if the pressure was increased, at a constant temperature. Thus, the sequence of processes can established through the following statements: a change in volume lead to change in pressure, a change in pressure lead to the flow of gases to equalize the pressure.
The application of the law can be seen through the process of inspiration, where the thoracic cavity’s volume increase due to the inspiratory muscles contract (diaphragm descends; rib cage rises), and thus the pressure inside thoracic cavity decreases. Accordingly, in order to equalize the pressure the air goes from the atmosphere flowing down to the cavity and down to the lungs. (Marieb & Hoehn, 2007). Similarly, expiration implies the same process, only in reverse order, where inspiratory muscles relax (diaphragm rises; rib cage descends), thoracic cavity volume decreases, lung passively recoil and thus intrapulmonary volume decreases and the air flows out of lungs into the atmosphere.
Using the same variables, i.e. volume, pressure and temperature, Charles’ law analyzes the relation between the volume and the temperature. The law states that, at a constant pressure, the same amount of gas will increase in volume with the increase in temperature. Charles law is not much applicable, due to somewhat constant temperature of the human body. Nevertheless, it can be seen that the air is warm when inhaled, which facilitates changing the volume, by helping to expand and inflate the lungs.
Another law that can be applied to the respiratory system is Dalton’s law, which analyzes the relation between the pressures of gases in a mixture, stating that the total pressure of a combination of gases is equal to the sum of separate pressures of each gas. (Ward, 2006). A notion that falls within Dalton’s law is the partial pressure, which is calculated as a fraction of the gas multiplying the fraction occupied by the gas related to the total pressure of the mixture.
The partial pressure is a determinant factor in diffusion, the movement of oxygen and carbon dioxide between atmosphere and lungs, blood, and blood cells; “it is only the difference in partial pressure that drives diffusion from one place to another…” (Davies & Moores, 2003). The Dalton law can be applied to the mixture of gases under consideration in the air, where the differences of the fraction and the pressure between Oxygen and Carbon dioxide respectively result in the following processes:
- Partial pressure gradient between inspired air and the alveolus, resulting in the diffusion of the oxygen into the alveoli, and carbon dioxide diffuses from the alveoli into air.
- A concentration gradient lead to that oxygen diffuses into blood from the alveoli, and carbon dioxide from the blood. (Swan, 2006).
Conclusion
It can be seen that the processes occurring in the respiratory system are based on physical laws, specifically gas laws. The control of the air flow is governed by Boyle’s law, where it explains not only the way the system functions, but also the biological rationale for all the processes occurring in the system. Other laws explain other processes in the respiratory system, such as Dalton’s law. It can be concluded that the law of physics can be extended to human’s body, where the applicability of such laws helps explaining the way the human body functions.
References
Davies, A., & Moores, C. (2003). The respiratory system (1st ed.). Edinburgh ; New York: Churchill Livingstone.
Marieb, E. N., & Hoehn, K. (2007). Human anatomy & physiology (7th ed.). San Francisco: Pearson Benjamin Cummings.
Swan, J. (2006). The Respiratory System. Class Videos. Web.
Ward, J. P. T. (2006). The respiratory system at a glance (2nd ed.). Malden, Mass. ; Oxford: Blackwell Pub.
Wilhelm, P. B., Graaff, K. M. V. D., & Rhees, R. W. (2001). Human anatomy and physiology: McGraw-Hill Professional.