Breakthrough Junior Challenge 2019 – The Human Digestive System

Breakthrough Junior Challenge 2019 – The Human Digestive System


I’ll be proposing a way we can break down
food faster for energy. All living things eat, including us humans. It’s habitual, enjoyable, and necessary. We need lipids to store long-term energy,
proteins to build muscle, and carbohydrates for immediate energy. But it takes a long time before we can actually
do anything with the food we because breaking it down requires so much energy. Although it’d be pretty cool to see an entire
chicken nugget swim through the bloodstream casually, it’s not possible. Our food is way too big to be absorbed and
it can’t directly be used. Sorry. This brings us to the digestive system. Our model includes eight organs: the mouth,
the oesophagus, the stomach, the liver, the pancreas, the small intestine, and the large
intestine. The journey starts here in the mouth where
the digestion of larger carbohydrates or starch such as bread, potatoes, and rice occurs. A biological substance called an enzyme is
used to speed up the process of digestion by lowering the amount of energy required
to break down the foods. In this case, the salivary glands in your
mouth secrete amylase in order to break down starch into maltose. Partially digested food in your mouth known
as “bolus” then travels down the oesophagus through a process called peristalsis where
muscles contract and relax in order to push the food down. Once bolus moves towards the stomach, the
brain then signals for a release in gastric juice to break down proteins. The low acidity of gastric juice is favoured
by pepsin, which is an enzyme that breaks down polypeptides or proteins into smaller
chains of peptides also known as dipeptides. After an amount of time, these dipeptides
then break down into amino acids, which are then able to be absorbed by the body. Yay! Fun fact because gastric juice is so acidic,
it also breaks down pathogens, which are harmful organisms to the body and are responsible
for making you sick. So really, the 5-second rule does not apply. Your food is still contaminated after falling
on the ground. It’s just your stomach doing you a favour
🙂 After the stomach, the remaining bolus then travels to the small intestine to be
fully digested and then absorbed into the bloodstream to finally be carried to other
regions of the body. Remember maltose? Well, maltose is not able to be absorbed right
away because it’s still too big. Therefore, we need additional enzymes, maltase
and dextrinase, to break down maltose into glucose. Now it can be absorbed. Lipids can be broken down by lipase, which
is another enzyme secreted by the pancreas, as well as bile, which is an emulsifier from
the liver that helps break down lipids into smaller pieces since they’re not water-soluble. The breakdown of lipids results in fatty acids,
typically three, and glycerol. Other enzymes known as endopeptidases such
as trypsin and chymotrypsin also exist in the small intestine to help break down short
peptides into amino acids. The small intestine has specific structures
known as villi on the epithelium, which is the outermost layer of the small intestine
and on the villi, there are microvilli, which are like strands of hair. These structures exist in the small intestine
to increase the rate of absorption by having a larger surface area, a thin membrane and
capillaries that are close to the surface, as well as having a lacteal which helps absorb
fatty acids and glycerol away from the small intestine. Any waste then leaves the body via the large
intestine as poop. You know what? Just take my bank account. And that, my friends, is how you make a pitch
😉

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