The functions of the
respiratory system are the exchange of water and oxygen, to control body fluid
and heat, and to control pH levels. But the most significant contribution the
respiratory system has for the human body is the allowance for cellular respiration
to occur, as this process provides the energy the cells of the body need. To
allow cellular respiration to occur, the respiratory and cardiovascular systems
work in collaboration to transport gases, which are used or disposed of. The
concentration of these gases is maintained in order to ensure homeostasis.
The respiratory and cardiovascular
systems ensure that cellular respiration occurs by exchanging gases at the
alveoli. The air is made up of multiple gases, including oxygen and carbon
dioxide. These gases are measured by their partial pressure, or the amount of concentration
of a gas measured in mm/Hg. P02, or the partial pressure of oxygen, is around
21% while PCO2, or the partial pressure of carbon dioxide, is less than 1%.
Upon inhalation, oxygen enters the alveoli after passing the lungs, bronchi,
and bronchioles. At this point, P02 is 104 mm/Hg while PCO2 is 40 mm/Hg (fig.
1). The oxygen passes the pulmonary capillaries to red blood cells, where they
attach to hemoglobin. Hemoglobin can carry up to four oxygen molecules,
allowing many gas molecules to form oxyhemoglobin. Next, the oxyhemoglobin
travel to the body cells that need it, through the bloodstream (fig. 1). As
this occurs, carbon dioxide is picked up, which is not good as it upsets the
balance of pH in the bloodstream. Chemoreceptors monitor the pH levels of blood
and report it to the medulla oblongata and pons, which then change how fast and
deep breathing should be by controlling the diaphragm and intercostal muscles
(fig. 2). On the other hand, carbon dioxide enters the alveoli and is exhaled.
In the tissue cells, PO2 is 40 mm/Hg while PCO2 is 45 mm/Hg because cellular
respiration is producing carbon dioxide at a fast rate (fig. 1). Due to this,
the concentration of oxygen is low because it is being consumed by cellular
the largest priority of the body is getting carbon dioxide out of the body so
that blood pH levels are not tipped. The pH of blood has to be around 7.35 to
7.45, otherwise fatal consequences will follow. What happens to the waste gas
known as carbon dioxide? 93% of carbon dioxide diffuse into red blood cells,
23% combine with hemoglobin to form carbaminohemoglobin, 70% are converted to
bicarbonate ions by carbonic acid, and 7% dissolve into blood plasma. Diffusion
occurs in 0.25 seconds, as it reaches equilibrium quickly. . As
carbominohemoglobin reaches the lungs, the carbon dioxide and hemoglobin
separate, allowing the carbon dioxide to leave the body.
respiratory and cardiovascular systems contribute to the maintenance of
homeostasis through the bicarbonate buffer system. Carbonic acid allows
cellular respiration and the transportation of gases to occur, and is important
to pH levels because it can stabilize blood pH levels. During the process of
carbonic acid when carbon dioxide is converted into bicarbonate ions, hydrogen
ions are also produced. Hydrogen is one problem the body has to get rid of,
because it can change the pH levels of blood. One way the body gets rid of
hydrogen is by binding it with hemoglobin to create a buffer. A buffer ensures that the pH levels in a given chemical
equation vary as little as possible. This guarantees that blood, for example,
is not damaged by high acids or basic levels of concentration in pH.
respiratory and cardiovascular systems maintain homeostasis by allowing
cellular respiration to occur and ensuring that carbon dioxide and hydrogen are
able to exit the body.