Swallowing!

by Afrina Ariff

A X-Ray view of a person drinking and swallowing

Hello again! Today we're gonna talk about swallowing! (minds out of the gutter please!)

Swallowing, or in its fancy scientific term, Deglutition (dee-glu-ti-shun) is a process that comes after chewing food into a swallow-able thing, called a Bolus. It's a process that has to occur in order for the food to reach its next destination for the next phase of Digestion, in the stomach. 

There are 3 main parts to this process which are;

1. Buccal Phase

2. Pharyngeal Phase

3. Esophageal Phase

What are these weird words Afrina?! Didn't you promise to cut out the Medical jargon?!

Indeed I did, and indeed I shall!

1. Buccal (book-al) Phase

Buccal, which is Latin for Cheek simply means that the first phase happens in the cheeks, on more specifically, happens in the oral cavity.

• The soft palate, a structure located at the back of the throat, is raised and seals off the Nasopharynx (a structure that directs the air breathed in through the nose and later directs it into the lungs). 

Here's something that you may or may not have experienced; 

ever had someone make you laugh while you were drinking and had it splattering out through your nostrils? Well, that's because soft palate had no time to shut off your nasopharynx, allowing the liquid to travel up the nasopharynx and out through your nostrils. Beautiful! Moving on...

• The Bolus is pushed against the hard palate by the tongue, shaping it into a near-spherical shape.
• The Bolus, now round-ish in shape, is now able to move down into the oropharynx, pushed by the tongue.

2. Pharyngeal (fareen-gee-al) Phase

The pharyngeal phase is movement of the Bolus towards the Esophagus from the oral cavity. 

But first, the entry of the Bolus into the oropharynx stimulates a bunch of nerves which triggers the Swallowing Reflex; the larynx moves up, the epiglottis shuts off the trachea (a passageway for air) to prevent food/water from entering the lungs. Breathing ceases for a while.

3. Esophageal (ay-so-fa-gee-al) Phase

Peristaltic waves (pulsation of the muscle walls of the Esophagus and the rest of the Digestive system) pushes the Bolus down into the stomach where it enters through the gastroesophageal sphincter (gastro-eso-fa-gee-al sfink-tur).

Once the Bolus enters the stomach, further Mechanical digesting will occur and a new type of phase begins... and you will find out in the next post!

This has been Afrina, and now you know the phases of Swallowing! Now go forth young Padawan, chew and swallow to your heart's desire!

REFERENCES

1.    Tortora, Gerard J., et al, “Organization, Support and Movement, and Control Systems of the Human Body 13^th Edition”, John Wiley & Sons (Asia) Pte. Ltd., 2011.