Hey everyone! I’m back again, to bug you with….
THE ALIMENTARY CANAL PT. 2!!!
As I was saying- today we’ll be focusing on the first three components of the Alimentary Canal. These are- the oesophagus, the mouth and the stomach. Oesophagus can also be spelt as esophagus, but I prefer oesophagus becuase it’s more wacky to write/say/pronounce.
Well, let’s get to it…
Food enters the mouth via ingestion. Here, two things occur- mechanical and chemical digestion! The food is physically broken down by your teeth- in a process known as mastication.
Mastication is a form of physical digestion- meaning that the food isn’t changed chemically. However, in your saliva, there’s an enzyme called amylase. Amylase has an important job of breaking down starch to the sweet, simple sugar maltose.
Once the food has been completely chewed, it travels down the oesophagus in a mushy ball thingy called a bolus.
The oesophagus is a long tube through which food travels down to reach the stomach. It’s approximately 25 centimeters long, which is about two-thirds the size of a bowling pin!
The food doesn’t just fall down the oesophagus and plop into your stomach- it travels downward slowly. The muscles in the oesophagus contract and relax periodically in a motion called peristalsis, pushing the food downwards! The sphincter muscles at the end of the oesophagus open up- much like a gate- to let food in.
What’s J-shaped, full of a scarily destructive acid, and made entirely of muscle? The stomach! [I mean, duh.]
The stomach is an organ which plays a crucial role in digestion. Over here, our bolus is converted to a more liquidy, more digested chyme. The stomach contains a very corrosive acid called hydrochloric acid [HCl]. This acid has two purposes- to provide an acidic environment for the enzyme, pepsin, to work, and to kill any ingested pathogens.
There’s an enzyme called pepsin that functions best at an acidic pH pf 2. Hydrochloric acid provides a great environment for it to work, speeding up the process of digestion. Pepsin converts proteins to polypeptides, which’ll be further broken down later.
All food contains bacteria, viruses, and a whole bunch of microscopic things that basically want you dead, or ill. They [obviously] pose a ginormous threat to the body. However, in an environment so severely acidic, these pathogens are killed off, leaving you safe!
We’re done for today, guys. Thanks for reading! Any question? Drop them in the comment section, and I’ll answer them ASAP!