CARDIORESPIRATORY SYSTEM
Case Study Essay Question: Cardiorespiratory System.
The human body is capable of performing many complex processes at the cellular level
that so many of us are not aware of. Everything that we do, whether it is the most simplest
movement such as standing up from a sitting position, all the way to high-intensity training, our
body needs energy in order to function properly. If our bodies are not supplied with the proper
amount of energy, the task we are trying to perform will be very difficult to accomplish. The
human body consists of three major biological energy systems that are constantly ebbing and
flowing depending on the type of activity we are doing. In this paper, I will go in depth about
what each biological energy system is and when the body is utilizing it in comparison to both
short and long distance runners.
Our bodies are supplied with energy through a molecule called adenosine triphosphate,
also known as ATP. ATP however, is not only responsible for being an immediate source of
energy for the body, it is also needed for other bodily functions such as brain function and
nervous system function. The first energy system in which ATP is readily available is called the
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phosaphagen system. This is the fastest system, in which ATP is accessible for the first ten to
fifteen seconds of any activity. This system is mainly utilized during high-intensity training and
exercise that last for a short period of time. A great example of athlete who would be utilizing
this system and this system only would be a short distance sprinter in a 100m race finishing at
about 10 seconds flat. During this phase, creatine phosphate will suddenly rise to help supply the
body with ATP for those first few seconds of intense activity before the other energy systems
start to take place. This system does not require oxygen during energy transfer, therefore it is an
anaerobic energy system.
Once the initial momentum passes, the second biological energy system that kicks in is
the glycolysis system. This is considered the intermediate phase as it typically takes place
roughly at about forty-five seconds of activity and can last up two minutes in duration, before the
final system comes into play. This phase uses glucose as its primary substrate in order to gain the
ATP it needs for energy trasnfer. Glucose is the breakdown of carbohydrates that is either
glycogen stored in the muscles already or from glucose delivered in the blood. Either of these
sources then resynthesize ATP, giving the body what it needs to properly function and complete a
successful workout. The type of athlete that would be utilizing this system would be a runner
entering in a 800m race, typically finishing at about two minutes flat. However in order for this
runner to have reached the glycolysis phase, they had to have undergone the phosaphagen system
as well. Once that individual passes the initial jumpstart of activity, in this case running, the
body’s demand for energy and oxygen will increase, therefore leading into the next energy
system.
The last and final energy system of the human body is the oxidative phosphorylation
system or the aerobic system in other terms. This system is the bodies primary source of ATP at
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both rest and during low-intensity activity that lasts for a longer period of time. It uses both
carbohydrates and fats as its subtrates and will continue to supply the body with ATP needed for
the duration of the workout. This is an important for trainers, athletes and even non-athletes to
know because fueling our bodies with the right kinds of food before any form of activity,
whether it is running, hiking, walking, swimming, etc., will ensure proper function of this
system. We need to fuel our bodies with a good source of carbohydrates prior, so that our body is
able to break it down and turn it into the energy our bodies need. This system is utilized more so
in a long distance runner who enters in a 10km race, finishing at about roughly thirty minutes.
Being that this runner has now reached a time frame that caused them to surpass the
glycolysis phase, that individual has undergone all three bioenergetic systems. This athlete
predominately uses the oxidative system because the individual is exercising at an intensity
where pyruvate, which is the end result of glycolysis, was shuttled into the mitochondria to
undergo the Krebs Cycle, which lead to further oxidation. Being that the end result of glycolysis
is pyruvate, this system can end in one of two ways. Pyruvate will either be converted into
lactate where ATP will resynthesize at a faster rate in a short amount of time, also known as
anaerobic glycolysis, or pyruvate will be shuttled into the mitochondria to undergo the Krebs
Cycle in which ATP will resynthesize at a slower rate over a longer period of time, known as
aerobic glycolysis. Aerobic glycosis occurs when an individual's activity level is long enough in
duration but also low enough in intensity, as the body will need more energy due to the body’s
increase in demand for oxygen. The “shuttling” of hydrogens across the mitochondrial membrane
requires a specific transport system process. This transport system is located within the
mitochondrial membrane and transfers NADH-released hydrogens from the cytosol into the
mitochondria, where they can enter the electron transport chain (Powers & Howley, 2018). This
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process is also when the body will progress into the oxidative phosphorylation phase as the
activity remains steady and ongoing . The oxidative system then gives the body the ATP needed
to last through the duration of his/her workout.
To sum it up, when taking into account the different runners and which energy system
they utilized the most; the person who sprinted 100m only went through the phosphagen system,
the 800m runner went through both the phosphagen and glycolysis system and lastly, the 10km
runner went through the phosphagen system, aerobic glycolysis system and the oxidative
phosphorylation system.
References
Powers, S. K., & Howell, E. T. (2018). Exercise physiology: Theory and
application of fitness and performance. (10th ed.). McGraw Hill Education.
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