The oral cavity, the anatomy of which will be discussed in our article, is a "border" organ between the environment and the internal environment of a person. It creates a serious barrier to microorganisms, providing the initial stage of digestion and the appearance of sounds.
Oral cavity: anatomy in ontogeny
In the course of human embryonic development, the oral cavity begins to develop already on the 12th day. Visually, it is a protrusion of the ectoderm, which is located between the cardiac protrusion and the brain bladder. During this period, it is called the fossa, or oral cavity.
Language develops at 4-5 weeks of ontogeny. Together with the chewing muscles, it is the result of a modification of the gill arches. Further development of the oral cavity, the anatomy of which is much more complicated, allows the fetus to taste the amniotic fluid. This is the environment he is in. In the 7th week, taste buds appear on the tongue. By the beginning of the second month of the development of the embryo, the formation of the sky is completed.
Features of the mucosashells
The anatomy of the oral cavity (the photo shows its structure) is represented by the following components: lips, tongue, cheeks, teeth, gums, salivary gland ducts, palate and tonsils.
An important role in ensuring its functions is played by the mucous membrane formed by stratified squamous epithelial tissue. Beneath it are the basement membrane and the submucosal layer. A characteristic feature of the oral epithelium is a high ability to regenerate, which is carried out due to its germ layer, as well as resistance to the negative effects of infections and environmental irritants.
Actually, the mucous membrane is formed by connective tissue cells. It is in it that the nerve endings, capillary and lymphatic vessels are located. The mucosa itself has specialized cellular structures that perform the most important functions. These include macrophages, mast and plasma cells. They provide phagocytosis of foreign particles, regulation of blood vessel permeability, synthesis of immunoglobulins.
There are various types of receptors in the oral mucosa. These include pain, tactile and temperature. But the mucous does not perceive the taste. This function is performed by the muscular organ of the oral cavity - the tongue.
As a result, we can say that the mucous membrane of the human oral cavity provides protective, sensitive and plastic functions.
Language
The anatomy of the human oral cavity also provides the formation of taste sensations. They occur whenthe action of various chemicals on specialized receptors. Agree, the perception of taste is purely individual. But scientists distinguish between its main varieties. These include sour, bitter, sweet, and s alty.
Taste receptors are called chemoreceptors. They are located in the taste buds, each of which is sometimes connected to the mouth opening. Despite the general plan of the building, they are all specialized. So, receptors that perceive sweet are concentrated at the tip of the tongue, sour at the edges, and bitter at the root. More extensive is the area capable of perceiving s alty taste. It is located at the tip and along the edges. The tongue is also involved in making sounds, wetting, mixing and swallowing food.
Anatomy of the mouth and teeth
Mechanical processing of food is carried out with the help of teeth. Normally, there are 32 of them. In the holes of each of the jaws there are 4 incisors, 2 canines, 4 small and 6 large molars. All of them are specialized. So, with the help of incisors and fangs, food is bitten off, and with the help of the molars, it is already crushed to a mushy state.
According to the features of the external structure in the tooth, the root, neck and crown are distinguished. The latter is its visible part and is located above the gum. The tissue that covers the crown is called enamel. It is considered the hardest in the human body. The neck is formed by a less durable substance - cement. The connective tissue that fills the cavity of the tooth is the pulp. It contains nerve fiberslymphatic and blood vessels. Therefore, it is due to the pulp that nutrition and growth of teeth occur.
How do these oral structures form? The laying of teeth occurs even in the embryonic period. But they appear 6 months after the birth of the child. There are 20 of them in total. They are dairy, up to 10 years being replaced by permanent ones. The last to grow are wisdom teeth, which appear by the age of 25. For humans, they are an atavism, since they have lost their meaning in the course of evolution.
Receptors
Scientists say that there are about 2,000 taste buds in the mouth. They get irritated in response to food. The signals that are formed in this case are sent along the nerve fibers through the intermediate to a specialized section of the cerebral cortex. This is where the sense of taste is formed.
For all people it is really individual. Taste is determined by the threshold of sensitivity. It is not the same for different chemicals. This indicator is highest for bitter, low for sour. But s alty and sweet people perceive the same way.
Chemical food processing
The anatomy of the oral cavity and pharynx is such that they are also a kind of reservoir for the primary breakdown of food. Directly the food, its image or even the smell stimulates the secretion of saliva. This happens with the help of glands, the ducts of which open into the oral cavity. Saliva breaks downcomplex carbohydrates into simple ones, neutralization of microorganisms, moisturizing and enveloping the food bolus. Then, with the help of the tongue, it is pushed to the pharynx, moving into the esophagus and stomach.
Composition of saliva
By physical properties, saliva is a colorless liquid of mucous consistency. More than 98% of its content is water. The breakdown of complex sugars is provided by saliva enzymes - m altase, amylase and lysozyme. The latter substance also performs a protective function, neutralizing pathogens and healing wounds in the oral cavity.
Saliva also contains a mucus called mucin. It provides hydration and enveloping of food. Thus, it is the oral cavity that performs both mechanical and chemical processing of food. The anatomy of this part of the digestive system is completely interconnected with the functions it performs.
How salivation occurs
The process of salivation occurs reflexively. For its "launch" it is necessary to irritate the receptors of the oral mucosa. As a result, nerve impulses arise, which are subsequently sent to the center of salivation of the medulla oblongata. Such a process is unconditioned reflex.
But if we just imagine a sour lemon or a fragrant cake, saliva will immediately begin to flow into the mouth. Such stimuli are conditional.
So, the oral cavity, the anatomy of which was considered inour article, performs the following functions:
- determining the quality and taste of food;
- mechanical and chemical processing of food;
- protecting the body from pathogens, low-quality products;
- formation of a food bolus;
- break down complex carbohydrates into simple ones.
