[Digestion] - Mastication and Mastication process

It is a sunny Monday here, and I am enjoying every bit of it. Today, I want to share with us something we are familiar with. Something we do every day, and is required for the nutrition process in the body. It is the first stage of digestion, which occurs in the mouth. I am talking about Chewing. I am sure you are familiar with it, as you cannot do without putting food through your mouth and chewing it, although some people do not chew food properly. In the post, I will be referring to it as Mastication, which is the medical word for the process of grinding food with our teeth and the entire process of chewing. Let me ask this very fast "Do you chew properly when eating, or do you just swallow as fast as you can?"

While I wait for you to answer that question, let me quickly answer this one; Why do we get tired after eating? Some researchers say that eating triggers Serotonin. It is said that when we eat, the body sends a signal to the brain which releases Serotonin and insulin. Where insulin regulates blood sugar levels as well as transporting glucose to the cells where it is converted to ATP. When insulin is produced, it will reduce the blood sugar level, thereby making people tired. Also, Serotonin is a hormone associated with stimulating the parasympathetic nervous system which is responsible for rest and digestion. Serotonin can cause drowsiness after a meal or the feeling of relaxation which leads to fatigue.

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Another research shows that the stomach produces acid during digestion making the blood basic, and since more energy is required for digestion, the blood flow to other parts of the body is reduced, leading to fatigue. Also, another study shows that this basic blood during digestion cannot stimulate the respiratory center of the medulla, thereby causing breathing to be slower, making people feel fatigued and tired.

If we are to do a run-through of the gastrointestinal tract, we will see that the mouth has the salivary gland, and in the esophagus, there is the upper esophageal Sphincter and the lower esophageal sphincter. Then to the stomach where the pyloric sphincter is found in the pylorus. After the stomach is the small intestine, then the large intestine, followed by the rectum and the anus. The Anus has two sphincters, the internal and external sphincter. The internal is involuntary, and the external is voluntary. That said, let's do mastication and mastication reflexes and processes.

During the process of mastication, GI motility and secretion can be done in two ways, either via nervous control or hormonal control. The salivary gland produces saliva which is under the nervous control. It is fast, to respond, and so produces saliva very fast. Digestion occurs in two ways, mechanical and chemical. Mechanical has to do with motility, while chemical has to do with the secretion of GI enzymes and GI hormones. in the mouth, the two processes occur. Which are mastication and Salivation. Salivation is chemical, while mastication is mechanical. Mastication is important in breaking down food to help reduce the surface area for enzymes to act upon them, as well as ease of swallowing. One importance of chewing/mastication is in the breaking down of cellulose in the cell wall of fruits and vegetables as the digestive gut doesn't secrete cellulase for digesting cellulose. There are four muscles of mastication, and they are the Masseter, the Temporalis, the Medial pterygoid, and the lateral pterygoid. The first three elevate the mandible but the lateral pterygoid is responsible for lowering the mandible, and they are all supplied by the V3 mandibular branch of the trigeminal nerve.

In case you are confused about the type of gland your salivary glands are, then let me help you out. There are two types of glands, the exocrine glands, and the endocrine glands. The exocrine glands are glands that possess ducts that transfer the enzymes from the duct to the nearby organ that needs it while endocrine glands do not possess ducts, they send the hormones to the blood directly which sends them to their needed locations. When it comes to digestion, the endocrine glands will secrete Gastrointestinal Hormones, while the exocrine glands will secrete gastrointestinal enzymes, and the salivary glands fall under the Exocrine glands, with 6 major salivary glands, with 3 on each side of the mouth but there are other numerous minor salivary glands.

If I were to run a full overview of the mouth and additions to the glands and explain food mastication in the mouth. When food goes into the mouth, it gets to the oral pharynx and then to the esophagus after passing through the esophageal sphincter, then to the stomach. Remember that the pharynx extends into three parts (the nasal pharynx to the nose, the oral pharynx to the mouth, and the laryngopharynx in the larynx).In the mouth, the mechanical process or motility in the mouth is known as mastication which is innervated by the mandibular branch of the trigeminal nerve (cranial nerve 5), while the chemical process of digesting food in the mouth is known as salivation. The saliva possesses ptyaline (amylase), and lipase. Ptyaline is responsible for carbohydrate digestion. The major salivary glands are the parotid gland, submandibular gland, and sublingual gland. During mastication, the food gets exposed to digestive enzymes in the saliva, and it is rolled to become a bolus which makes it easier to swallow. when the food leaves the mouth, it goes to the esophagus. The esophagus is divided into the upper, middle, and lower esophagus. The upper esophagus is made up of skeletal muscles, the middle esophagus is made up of both skeletal and smooth muscles, and the lower esophagus is made up of smooth muscles. The upper esophagus is the voluntary part of the esophagus where swallowing can be controlled but the lower esophagus is an autonomic part where swallowing cannot be controlled.

Conclusion

The mouth is a fundamental place for food digestion, and cannot be overlooked. While we have food in our mouth, the mouth performs both mechanical and chemical processes which help in the digestion of food. One final thing, you might be wondering which muscle is the strongest based on weight in the body, well the strogest muscle based on its weight is the masseter, which is one of the muscles responsible for mastication.