The Mouth
The Mouth
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Figure 1 - Diagram with Labels of an Open Mouth
The mouth is the entrance to the digestive system and is split into the vestibule and oral cavity, the part between the cheeks and teeth and the part behind the teeth respectively. The roof of the mouth is further split into a hard (front) and soft (back) palate.
The tongue is known as a muscular hydrostat, a complex muscular structure used to arrange things. On the tongue are thousands of taste buds as well as papillae bumps to give a rough texture for friction.
The gums, also known as gingiva, are the first barrier against infection as it seals the teeth to the alveolar bone.
There are three frenulums, a fold of mucus membrane for anchoring, in the mouth. Two of them are to anchor the lips to the gingiva and one to anchor the tongue to the floor of the mouth.
Lastly, a teardrop tissue at the back of the soft palate known as the uvula serves a protective function. It is able to prevent foods from entering the nasopharynx as well as producing the gag reflex.
Figure 2: Cross-section of a Tooth
As mentioned before, the gingiva seals the tooth to the alveolar bone. The small depression in the seal is known as the gingival sulcus. The hard outer layer called enamel is made of calcium phosphate. Below it is a sensitive tissue called dentin and a soft inner structure called pulp where blood vessels and nerves run.
Figure 3: Highlighted Areas of Types of Teeth
The teeth are responsible for mechanical digestion, more specifically, they have the ability for mastication. The teeth are split into the incisors (cutting food), canines (biting and tearing), premolars (chewing and grinding), and molars (chewing).
Figure 4: Diagram of the Salivary Glands
Chemical digestion already begins in the mouth. Just at the sight or smell of food, the mouth and throat secretes saliva. Saliva can assist in carbohydrate and fat digestion, moisten the mouth, as well as reduce infections. The saliva has a composition of amylase and lingual lipase which starts beginning to breakdown large polymers - polysaccharides and triglycerides respectively.
There are 3 types of saliva secreted by different glands.
Parotid gland - Serous saliva, a watery secretion rich with enzymes.
Sublingual gland - Mucus saliva, a viscous secretion with large amounts of mucus.
Submandibular gland - Mixed saliva, a secretion with both mucus and enzymes.
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