Video Transcript
Which of the following will
decrease a person’s blood glucose level? (A) Jogging five kilometers, (B)
eating a large meal, (C) drinking an isotonic sports drink, or (D) snacking on bread
and sweets.
This question asks us about blood
glucose levels. Blood glucose levels describe the
amount of free glucose in the bloodstream, which is regulated by the pancreas. Glucose is the main source of
energy for cells. It is broken down during cellular
respiration. This process requires oxygen and
releases carbon dioxide and water as waste products. During respiration, the energy held
in the bonds of glucose is released and transferred to a molecule called ATP.
ATP is often referred to as the
energy currency of cells. The energy stored in ATP can be
used in reactions in the cell. Metabolically active cells which
utilize more energy will therefore require more ATP. For instance, liver cells use a lot
of ATP because they are highly active carrying out detoxification. Muscle cells also require a lot of
energy, especially when exercising. Metabolically active cells will
take in glucose from the blood for use in respiration, therefore lowering blood
glucose levels.
Thankfully, the pancreas can
counteract low blood glucose levels by releasing a hormone called glucagon. This stimulates the breakdown of
glycogen, the storage form of glucose, releasing glucose molecules into the
blood. It also stimulates the production
of glucose from other molecules, for example, amino acids.
Another way to raise blood glucose
levels is to ingest food high in carbohydrates. Too much glucose in the blood can
also be damaging. So the pancreas secretes another
hormone called insulin when blood glucose levels are too high. Insulin causes cells to take up
glucose and stimulates the liver to begin building glycogen, storing excess
glucose.
Now that we have reviewed how
glucose levels can fluctuate based on activity and hormones, let’s have another look
at our question. We are asked “Which of the
following will decrease a person’s blood glucose level?” We know that blood glucose levels
will decrease when the body’s cells require more energy. So the correct answer is (A),
jogging five kilometers.