Running head: CASE STUDY QUESTION 2 1
Case Study Question 2: Cardiorespiratory System
Kanani Jackson
Liberty University
EXSC 510 Advanced Exercise Physiology
Dr. Kilian
CASE STUDY QUESTION 2 2
Case Study Question 2: Cardiorespiratory System
The three major biochemical cycles that govern aerobic respiration by catabolizing one
molecule of glucose can be estimated by identifying a chemical reaction inside a cell that was
maintained under laboratory conditions. During these laboratory conditions one glucose
molecule when an organism is grown in a glucose-containing medium. The organism of the cell
utilized is glucose and it converts it into pyruvate (Powers et al., 2021). It is then converted into
acetyl co by enzyme, pyruvate d, hydrogenous of PDH, and this acetyl co enters another cycle
called the TCA cycle. After the TCA cycle; two high-energy compounds, the FADH2 and NADH
further enter the electron transport chain to produce carbon dioxide, water, and also ATP (Powers
et al., 2021). This can be grown by a controlled medium under laboratory conditions, so in vitro
conditions, it can easily demonstrate the catabolism of glucose to ATP by process of glycolysis
TCA cycle and also electron transport chain, oxidative phosphor relation.
When it comes to glycolysis, the tricarboxylic acid cycle (also known as TCA or Kerb’s
cycle), and oxidative phosphorylation there are the main energy factors that utilize the human
body to produce ATP or Adenosine 5′-triphosphate. Glycolysis and the TCA cycle are linked by
the linking reaction catalyzed by the pyruvate dehydrogenase complex. Pyretic acid produced at
the end of glycolysis is transported to the matrix of mitochondria, where it undergoes oxidative
decarboxylation to produce acetyl CoA. Acetyl CoA enters the TCA cycle (Powers et al., 2021).
Glycolysis starts with one molecule of glucose and ends with two pyruvate (pyruvic acid)
molecules, a total of four ATP molecules, and two molecules of NADH. Fermentation starts after
glycolysis, replacing the citric acid cycle and oxidative phosphorylation. During glycolysis, only
two ATP molecules are produced. NADH is then oxidized to transform the pyruvate made in
glycolysis into lactic acid.
CASE STUDY QUESTION 2 3
The citric acid cycle captures the energy stored in the chemical bonds of processed
glucose in a step-by-step process, trapping it in the form of high-energy intermediate molecules.
The trapped energy from the citric acid cycle is then passed on to oxidative phosphorylation,
where it is converted to a usable form of cellular energy, ATP (Powers et al., 2021). We can then
use that energy to move and breathe. Not only that but make our hearts beat, and think among
other things. Electron shuttles accept the energy released by stepwise rearrangements and the
subtraction of carbons in the form of electrons. They are small organic molecules, such as NAD.
FADH transports high-energy electrons to where they need to be by gaining electrons (through
“reduction”) and losing electrons (through “oxidation”). The electrons transported by electron
shuttles will later be used to generate ATP (Powers et al., 2021).
Finally, as far as why it may be better to utilize free fatty acids as a raw source of fuel
versus carbohydrates and why it is the body’s preference not to use protein as a source of fuel
unless it has to be done so; there are a few factors why. From a nutritional perspective, fats are
used for energy only after they are broken down into their fatty acids whereas carbohydrates are
used for more instantaneous energy or glucose. One triglyceride molecule yields three fatty acid
molecules with as many as 16 or more carbons in each one (Powers et al., 2021). Therefore, fat
molecules yield more energy than carbohydrates and are an important source of energy for the
human body. More energy is liberated when a greater number of electrons around carbon atoms
in fatty acids are shifted to oxygen, rather than when the same process occurs to carbohydrates
(Powers et al., 2021). Now if we want to change the direction to proteins, protein is not a quick
or efficient source of fuel, and since it cannot be stored, any protein consumed that doesn’t get
used immediately is converted into fat or storage. Fat has more than twice as many calories as
CASE STUDY QUESTION 2 4
carbohydrates and proteins. In more simple terms, one would have to eat twice as many
carbohydrates or proteins as fat for the same number of calories.
Overall, ATP or adenosine triphosphate is synthesized by the cell through respiration.
When there is no oxygen, respiration occurs in the following steps: Glycolysis, Kreb’s Cycle,
and Cytochrome System. In addition to that, fatty acids as a raw source of fuel are better to
utilize than carbohydrates because fats contain 2.25 times the calories per gram than protein or
carbohydrates. Fats contain 9 grams per gram while protein and carbohydrates contain 4 calories
per gram (Powers et al., 2021). Continuing and topping it off, the main type of fat we consume is
triglycerides. Triglycerides are more suited for energy storage. Once they have been broken
down during digestion, they are shipped out to cells through the bloodstream, therefore the
human body would prefer fatty acids over carbohydrates and protein based on how much energy
one is receiving.
Kanani Jackson
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