O2 Transfer in Human Body


Course Instructor



O2 Transfer in Human Body

Oxygen (O2) is a significant element in the human body that plays a crucial role of sustaining life and enhancing metabolic process in human body. Despite life sustenance, oxygen helps in terminating destructive bacteria that human body does not need and leaves the important bacteria in human life safe. Chemical engineering treats human body as a chemical plant with air acting as both input and output to ensure smooth operation. There are also other input including food and water as well as other output such as feces and urine. In addition, complete circulation of oxygen requires pumping mechanism in the human body that involves two important organs, the heart, and the blood vessels. Chemical engineering treats circularly system as a chemical process that involves the heart as a pump while the blood vessels act as passageways for oxygen. Generally, chemical engineering uses mathematical equation to show a complete oxygen transportation process in the body. Moreover, chemical engineering involves two basic terms including convection and diffusion that helps in calculating oxygen transport in the human body. Convection is more common in the large blood vessels like arteries while diffusion is more likely to occur in the small blood vessels such as capillaries and veins.

The two main mathematical equations involved in determining oxygen transport are the overall flux that describes oxygen flow via pipes and Fick’s law that explains diffusion of fluid along a concentration gradient.

The overall flux

NA,z = YA ( NA,Z + NB,Z ) – DA,T∇c

Convection Diffusion

Fick’s law

JA,z = −DA,z∇c

Describing Oxygen Transport in Human Body

Oxygen moves in the human body in the breathing process through nose and mouth then goes via the lungs and dissolves in the water lining of alveoli. Oxygen then sticks to red blood cells while passing through the alveoli capillaries.

Circulatory System

Circulatory system plays a significant role in transporting various materials in the human body. Circulatory system ensures that nutrients, water and oxygen are transported to the body cells while transporting waste products produced by body cells such as carbon dioxide away from the body. The circulatory system acts as a highway with network throughout the human body and it involves the heart, and the blood vessel. The heart is responsible in pumping blood and maintaining blood flow in the whole of the body system while the blood vessels transport blood away from the heart to other parts of the blood. The whole of the circulatory system transports oxygen from outside the body into the blood stream and carries away waste from the blood cell, carbon dioxide to the outer part of the body.

The Blood Vessels

The blood vessels function as pathways in the human body through which the blood travels. Blood vessels include the arteries, veins, and capillaries that have distinct functions. The arteries carry blood away from the heart while the capillaries link arteries with veins as veins transports the blood back to the heart during blood circulation process. Initially, the heart usually pumps blood through the arteries (dorsal aorta) before arteries supply the blood to smaller arteries in ensuring that everybody cell receives oxygenated blood. Veins however receive blood from the capillaries after the blood has exchanged the two important gases, oxygen, and carbon dioxide and transports the waste rich blood back to the circulatory organs, lungs and the heart. Capillaries play a significant role of linking arteries with veins and further carry oxygenated blood to the other body parts thus enriching the tissues with oxygen. There are also thin capillary walls that provide a surface area for gaseous exchange by letting the red blood cells inside the capillaries to release oxygen to other surrounding tissues as the tissues release their waste products such as carbon dioxide that is absorbed in the red blood cells.

The Blood

The blood is a very significant substance in the human body system and in the circulatory system because it transports oxygen that is helpful in the life of the body tissues and helps in releasing carbon dioxide, which is harmful to the tissues. For a human being to be alive, the human tissues must receive oxygen, which is transported by the blood. Blood also carries very vital elements in the human body that include the red blood cells, water, oxygen, nutrients and waste products that provide life to the body cells. The blood transfers oxygen to the body tissues after taking it from the lungs and aids the tissues by carrying their waste, carbon dioxide from the tissues to the lungs.

The red blood cells continuously run throughout the body by transferring oxygen to the body tissues and carrying carbon dioxide out of the tissues to the lungs. The red blood cells normally take oxygen from the lungs and releasing it by pressing its way through the body with the aid of capillaries. It is normally made up with a chemical known as hemoglobin, which is rich in iron that attracts oxygen to the red blood cells. Usually, as the blood moves through the lungs, oxygen molecules are attracted to the hemoglobin but as the blood goes through the tissues, it releases oxygen to the cells. Finally, after releasing oxygen to the body tissues, the oxygen-less hemoglobin combines with the tissues’ waste such as carbon dioxide and transports them away from the tissues back to the lungs. Nevertheless, plasma, a thick container that carries the red blood cells, usually occupies 55% of the blood capacity and it is composed of nutrients, waste products and the clotting protein.

Diffusivity: DA, B

Diffusion coefficient is a function that relies on the size and atomic component of the diffusing substances and the characteristics of the means. Tiny molecules easily go through biological system such as oxygen because they have higher diffusivity while bigger particles slowly pass through because they have lower diffusivity. Additionally, some medium with heavy or denser tissues experience little diffusion coefficient while less denser medium have higher diffusion coefficient.

Convection and Diffusion

Conviction had been earlier defined as the transfer of bulk material sandwiched between border surface and moving fluid while diffusion is the act of net motion of molecules in the path of lower concentration. Conviction is mainly evident in the larger blood vessels while diffusion mostly takes place in the small blood vessels. Nevertheless, looking at the overall flux equation based on conviction, what is normally considered is the rate at which oxygen flows because of flowing blood hence shown in the direction of the blood flow.

NA,z = CA + VA,z

By considering the conviction, the oxygen concentration within the blood vessels is regarded as constant as the small vessel oxygen moves out of the veins and to other neighboring tissues thus reducing the concentration. It is also worth noting that diffusion is quicker outside the capillary walls that normally have concentration profile. Additionally, convection usually occurs within the vessel whose concentration of dissolved oxygen presumed constant.

NA,z = YA ( NA,Z + NB,Z ) – DA,z∇c

Importantly, normally while the vessels reduces in diameter, convection’s dominance also reduces thus triggering a significant increase in diffusion.

Bio-hybrid Devices

Bio-hybrid devices is an artificial mechanism used in substituting tasks of damaged organs through amalgamation of cells with manmade constituents (polymer) so that they can discharge proteins that are regarded useful for the operation of particular organs. These devices further aid in defending organs from being damaged by the recipient immune system. Moreover, the devices may be explained as what enables the body to interchange and take the implant cells without denunciation from the immune system.

These devices may be helpful in averting various diseases such as diabetes. In the case of diabetes, especially amongst the genetically predisposed individuals, a device called artificial pancreas may remedy numerous challenges involving replacement of insulin that produces tissue in diabetic patients. Moreover, in the case of liver failure, the biohybrid artificial liver (BAL) which is an extracorporeal supportive device may represent a significant therapeutic strategy for people suffering from liver failure. The BAL system is composed of working liver cells that are aided by a synthetic cell culture substance and therefore serves as a link for the patients before a donor organ is provided or the liver is redeveloped.

Biohybrid consist of both intravascular and extravascular where intravascular are inserted within the large blood vessels while the cells are put outside the blood source. In the case of intravascular biohybrid device, oxygen moves from the capillaries to the tissues. On the other hand, there are extravascular biohybrid device that are put on the external part of the vascular section while the cells are condensed in tissue that is encircled with red blood cells. This provides a significant role of stimulating blood vessel growth hence permitting sufficient oxygen mass movement within the device.

Works Cited

Dorian, AI; 2009. The development of bio-articial organs. Medical Research Reviews 2009; 28(2):187-252-296

Jean Krudener, “circulatory system,” in Hillendale Health, web:02/25/2012 <http://hes.ucfsd.org/gclaypo/circulatorysys.html>

Lucy P , Hugye D, Vazeou P, Gentile T, Danne K,2010. Maintenance of narmoglycmia by biohybrid device. Science 2010; 254:1786-1784

Provost P ,2010, Application of CN79 hydrogel in Bioyhybrid encapsulation: mathematical model.

Transplant Proc 2010; 27:274493-3895