The 3 parts of the mouth (and their functions)

The human body (and the rest of living beings) is an open system. In order to live, we require matter and energy, which we obtain from the environment. In addition to needing energy, we also release it in the form of heat, work, and matter, which comes as biological waste (feces) or fluids (saliva and sweat).

Depending on gender, age and physical activity, basal metabolic rate (BMR) and total energy expenditure (GET) vary between individuals, but a human being must ingest, on average, 2,500 kilocalories per day in order to be able to carry out their metabolic functions in a adequate. For this, we have the digestive system, a set of organs and tubes that allow us to ingest, digest and dispose of food products.

In order to understand the digestive functionality of the human being (and many other things), we must resort to the functional bases, "the beginning of the chain." Following this train of thought, today we tell you everything you need to know about the different parts of the mouth.

• Related article: "The 11 parts of the eye and their functions"

What is the mouth?

In animal anatomy, the mouth is defined as the opening through which animals ingest food and make vocal sounds. With this first sentence, we can already discern that the functionality of this opening is, at least, double: swallowing and phonation.

The most correct term to designate this set of structures is "oral cavity", and analogues of it exist in practically all animal taxa. From the proboscis of a butterfly to the fangs of a lion, the basic functionality remains: the eat food and, when possible, enable communication between individuals of the same species or groups different. In any case, if we get technical, the "mouth" or "oral cavity" is exclusive to vertebrates, since in all of them it is the first part of the digestive system.

The mouth in humans

The mouth in humans is the body opening through which food enters. It is located in the face and constitutes most of the stomatognathic apparatus, that is, the set of organs and tissues that allow us to perform the functions of eating, speaking, pronouncing, swallowing, smiling and many other things more.

Anyway, it should be noted that the functionality of the mouth in our species is much greater than that presented in other taxa of living beings. We tell you some of his work in the following lines.

1. Food processing

The mouth has a total of 32 teeth, specialized in tasks related to mechanical chewing of food. These are responsible for cutting up, grinding and mixing the food eaten with the saliva. Thanks to the movement of the jaw and the pressure of the teeth, the degradation of food occurs.

We cannot forget either that saliva is produced here. The salivary glands (the most important being the parotid, which produces 1.5 liters of this fluid per day) secrete this alkaline reaction fluid, which begins the digestion process as soon as the food enters the mouth. It is striking to know that saliva has lysozymes, substances responsible for the destruction of bacteria, thus protecting the oral cavity and teeth from pathogens.

2. Phonation

The production of sounds in humans occurs thanks to the respiratory system, the voice mechanism, the resonance mechanism and the articulating elements.

In the mouth there are structures included in the last 2 groups, since the oral cavity acts as a resonance mechanism and, in turn, contains articulating elements, such as mouth, teeth and lips.

• You may be interested in: "Human speech apparatus: what it is, parts and functions"

3. Aesthetics and communication

Mammals have a prodigious ability that enables us to communicate through body language: facial muscles. The mouth and the tissues associated with it allow us to make faces, gestures and transmit emotions and eigen states in multiple ways.

Did you know that 55% of human communication is based on body language? As much as we advance as a society, data like this reminds us that we are still animals.

The parts of the mouth, summarized

We have told you about the functionality of the mouth and, as you may have seen, it goes far beyond chewing. Without going any further, the incisors themselves (front teeth) have 80% communicative and aesthetic functionality and only 20% chewing. The mouth allows us to nourish ourselves, but also to communicate.

Next, we do a brief review of the most important parts of the mouth. Do not miss it.

1. Teeth

The teeth are hard structures that are aligned in the shape of an arch in the mouth, in the upper jaw and the lower jaw or mandible of the oral cavity. Infants have a total of 20 deciduous teeth, while adults have 32 permanent teeth.. Its morphology is based on the following keys:

• Tooth enamel: a tissue formed by hydroxyapatite, the hardest in the entire human body. It corresponds to the outermost part of the tooth.
• Dentin: mineralized and resistant tissue, but less than enamel. It is an intermediate tissue that accounts for most of the volume of the dental organ.
• Dental pulp: loose connective tissue that is surrounded by dentin.
• Periodont: the tissue that surrounds the tooth itself. Provides the necessary support for chewing to occur.

2. The walls of the mouth

The mouth can be considered a room in communication with the outside that has 5 walls. The anterior wall is made up of the lips, the muscular gateway to the digestive system. These muscle tissues are also essential for communication, both oral and gestural, and for the demonstration of affection and the strengthening of bonds in the human species (and other animals).

Beyond the most visual area of ​​the mouth, humans have 2 side walls (cheeks), one lower (the floor of the mouth and tongue), an upper (palate) and a posterior (isthmus), which communicates the mouth proper with the pharynx.

3. The oral flora

You weren't expecting this last point, were you? As has been shown on multiple occasions in recent years, without the bacteria in our body we are nothing. For this reason, we must dedicate these last lines to those microbial agents that make life easier for us and that, unfortunately, sometimes complicate it in an excessive way.

As much as the term "flora" is used, the most appropriate thing is that we talk about microbiota or microbiome, since this term refers to the set of colonies of microorganisms that live as commensals or symbionts in any tissue of our body, in this case, the oral cavity. The word "flora" is used to facilitate communication and dissemination, but a bacterium has nothing to do with the kingdom Plantae, so its use is wrong.

The human mouth is one of the most colonized parts of the body (along with the intestine), since it is in continuous contact with the outside. Hundreds of species of bacteria, viruses and fungi live here. Ecological balance is self-maintaining in healthy individuals, but immunosuppressive conditions and other events can turn these commensal microbes into a health problem. Unfortunately, it is not by chance that many HIV patients detect their infection due to a secondary disease in the mouth.

Among the more than 700 species that live in our oral cavity, the genera stand out Streptococcus (soft tissues, saliva and tongue), Actinomyces (supragingival and infragingival level) or Veillonella parvula Y Neisseria, detectable in all oral tissue. Apart from these commensal microorganisms, which do not cause any kind of harm, there are other bacteria that compromise the health of the oral system: Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) are usually the main suspects in periodontal diseases.

Resume

We have covered a lot of ground without pause but without haste, but we have left many peculiarities of the mouth in the inkwell. Talking about such a utilitarian cavity (eating, digesting, expressing, speaking and tasting, among other things) is a real challenge, since each of the fronts it covers would serve for the writing of a book by itself only.

The central idea of ​​this space, if one can be extracted, is the following: it is not correct to conceive of the organs and structures of our body as “watertight mechanisms”. Surely, no matter how much you think you know a structure, you will be surprised with thousands of accessory functionalities that it presents if you investigate enough. In the human body, the maximization of resources prevails, so it is difficult to find structures that "only serve one thing." The mouth is a clear example of this.

Bibliographic references:

• Berner, J. E., Will, P., Loubies, R., & Vidal, P. (2017). Physical examination of the oral cavity. Ibero-Latin-American Cutaneous Medicine, 44 (3), 167-170.
• Cruz Quintana, S. M., Díaz Sjostrom, P., Arias Socarrás, D., & Mazón Baldeón, G. M. (2017). Microbiota of the ecosystems of the oral cavity. Cuban Journal of Stomatology, 54 (1), 84-99.
• Guijarro, J. B., Moreno, M. G., & Iruela, I. R. ORAL PATHOLOGY.
• Ovallos, C. D. D., & Cespedes, J. C. S. (2015). ANATOMICAL PARTICULARITIES OF THE ORAL CAVITY IN USERS WITH SPECIFIC CHARACTERISTICS. Scientific Journal of Phonic Signs, 1 (3), 101-113.
• Sologuren, N. (2009). Anatomy of the airway. Rev chil anest, 38, 78-83.