The Respiratory System and Generation of ATP

Humans are aerobic creatures so we require oxygen to produce the energy we need to exist. In order to acquire it, humans resort to the respiratory system, which involves the use of lungs to draw air into the body. The average person breathes 12-20 times per minute to attain enough oxygen. This essay will be going over why we require oxygen, the pressure involved in breathing, the advantages and disadvantages of our respiratory system in comparison to alternatives as well as how it relates to the economic factor.

The human body specifically requires ATP (adenosine triphosphate) to function. An active cell uses approximately 2 million ATP per second, meaning that each day the body has to generate large amounts of ATP in order to meet the requirements of the cells. The process of creating this energy begins by obtaining glucose from the food we consume and putting it through several chemical reactions to remove its electrons. These electrons are moved to a series of proteins within a specialized organelle named the mitochondria, where they serve as the electron transport chain and continue to move from one protein to another. Oxygen is an electronegative chemical and therefore steals electrons from the chain, thus, keeping the flow going. These proteins pump hydrogen ions to another section of the mitochondria, where they pass through a specific protein called the ATP synthase, which produces ATP. In the absence of oxygen, this procedure cannot occur and as a result, this energy cannot be created. All of the body’s functions rely on this process to continue to work so if a person’s oxygen supply is continually cut off, it will eventually lead to death.

The human body solves the problem of acquiring oxygen through the use of the respiratory system. Breathing occurs when the muscles surrounding the lungs relax or contract in order to alter the volume of air within the bronchi and bronchioles. Inspiration (inhalation) takes place when the inspiratory muscles contract. This makes the thoracic cavity increase and thereafter when the external intercostal muscles contract, the ribs and sternum are raised. The combination of both these sets of muscles contracting, makes the lungs expand, increasing the volume of the internal air passages. The pressure within the lungs then decreases, in accordance with Boyle’s law, which states that when the volume of an area, in this case, the lungs, increases then the corresponding pressure must decrease if the temperature remains constant. The relationship stated in the law can be represented by the formula: P 1V 1 = P 2V2. As a result of the lowered pressure, air rushes in, since gases move from areas of high pressure to low pressure. Expiration (exhalation) takes place when the same muscles relax and the elastic fibers within the lung tissue respond by bringing the lungs back to their original volume. Following Boyle’s law, the pressure increases so that it is higher than that of the outside and the air rushes out.

Other animals obtain their oxygen in slightly different ways rather than using the respiratory system present in humans. Fish, for example, utilize gills in order to procure the oxygen they need to survive. Their gills take in dissolved oxygen from the water and replace it with carbon dioxide. Within the gills, there are rows of lamellae that absorb oxygen as water passes through them. Insects such as grasshoppers transport and exchange gases through a system of smaller tubes known as the tracheae. Another animal such as the grasshopper contains spiracles within its skin, through which the oxygen diffuses. From there it is transported to the rest of the body so that energy can be produced.

There are many benefits to our respiratory system in comparison to alternatives, however there also some disadvantages. One advantage of the method used by mammals is that they possess a circulatory system, meaning that the oxygen can be transported to every cell in the body. As a result of this, the size of mammals isn’t limited and regardless of their size, there will always be a capillary delivering oxygen to each cell. The use of lungs diminishes water loss and allows mammals such as us to live in a variety of territories, unlike fish, which are restricted to water and sometimes one particular region. Due to the large ratio of surface area to volume of the lungs, meaning that more oxygen can diffuse at one time, which increases the efficiency of the procedure.

In addition to these advantages, there are also multiple disadvantages to using this particular system. For example, this system does not work underwater, which restricts the period of time a person can remain underwater before coming up for air, whereas fish have no such restrictions. Another disadvantage is that the air flow is tidal, which means that not all the air can be removed the lungs and some of it remains, mixing with the new air. This is a problem which a grasshopper doe not possess due to its spiracles. The surface of the gas exchange system is warm and is therefore particularly vulnerable to diseases. As well as that, chronic diseases such as asthma can restrict the amount of air we can inspire and lead to difficulty breathing, an issue which the respiratory systems present in other creatures do not face.

Breathing relates to the environmental factor because breathing requires ATP to be able to take place and the production of ATP requires glucose from the food we eat, which leaves a large carbon footprint. The work of breathing makes up for about 5% of the energy usage in the body, so in order to generate enough ATP for breathing as well as the rest of the body’s functions, sufficient food must be consumed. The production, consumption, and disposal of this food, from which the glucose is extracted, all have a significantly large impact on the environment. A substantial section of the daily food ingested by the average person was produced on a farm, through the use of pesticides. Pesticides negatively influence wildlife and the quality of water as well as many other aspects of the environment. In addition to that, the production of most sources of food has a large carbon footprint due to climate change emissions, water use, and several other factors. Studies show that the production of merely 100g of beef can generate up to 105kg of greenhouse gases.

In conclusion, acquiring sufficient oxygen is vital to existing. Without ATP the body will cease to function and eventually result in death. Fortunately, we have evolved a system of breathing which prevents this from happening when going about our daily lives. This problem has been completely solved and no further steps need to be taken in the future to solve this problem.