Structure and Function of Digestive Organs: Mouth, Oesophagus, Stomach, Intestines, Rectum, Anus-2

Organs of the Digestive Tract

A muscular tube that runs through the body, the digestive tract. The name "alimentary tract" for the digestive system comes from a Latin term that means "food." The gastrointestinal (GI) tract is the more frequent name for it. It consists of a number of parts.

• Mouth
• Pharynx
• Esophagus
• Stomach
• Small intestine:
  • Duodenum
  • Jejunum
  • Ileum
• Large intestine:
  • Caecum
  • Ascending colon
  • Transverse colon
  • Descending colon
  • Sigmoid colon
• Rectum and anal canal

The Mouth:

The tongue, hard and soft palates, and cheeks combine to form the mouth, also known as the oral cavity or buccal cavity. The lateral walls of the oral cavity are formed by the cheek. They are coated internally by a mucus membrane made of non-keratinized stratified squamous epithelium and tiny mucus-secreting glands, and outwardly by skin. Between the skin and mucous membrane of the cheeks on the lateral side are the buccinators muscle, masseter, and connective tissue. The lips mark the conclusion of the anterior cheekbone. The fleshy folds that round the mouth's aperture are known as the lips or labia. They have the orbicularis oris muscle and are coated internally by a mucous membrane and externally by skin. The anterior hard palate and the posterior soft palate make up the palate, which serves as the roof of the mouth. The maxilla and palatine bones combine to form the hard palate. The muscular soft palate curves downward from the back of the hard palate and merges with the side walls of the pharynx. The tongue, muscles, and soft tissues constitute the base.

 Functions of the mouth:

• The mouth performs three different digestive processes: ingestion, which is the act of receiving food.
• It gets food ready for digestion.

Tongue:

• One of the main speech organs, the tongue is a muscle organ found in the mouth that aids in chewing and swallowing food. It serves as the gustatory system's main organ of test. By the base of the hyoid bone and the frenulum, a fold of the mucous membrane covering, respectively, it is joined to the mouth floor. Bitter, sweet, sour, and salty taste sensations can be distinguished by the tongue's surface, which is covered in a number of specific structures called taste buds. The back of the tongue is sensitive to bitter, the tip of the tongue to sweet and salt, and the back half of each side of the tongue to sour taste.

Blood Supply of Tongue:

• The lingual branch of the external carotid artery provides the tongue with its primary arterial blood supply. Through the lingual vein, which connects to the internal jugular vein, the venous blood is expelled.

Tongue Nerve Supply:

• The chorda tympani [a branch of the face nerve (CN VII)] and lingual [a branch of the mandibular branch (V3) of the trigeminal nerve (CN V3)] supply the anterior oral and posterior pharyngeal portions of the tongue, respectively, for somatosesory perception and table perception.

Uvula:

• The uvula is a muscular fold that hangs downward from the center of the soft palate's free border and is covered in mucus. There are four mucus membrane arches that start at the top of the uvula. The two anterior folds are palatoglossal arches, while the two posterior folds, one on each side, are palatopharyngeal arches. The palatine tonsil, also known as a group of lymphoid tissue, is located on each side, in the space between the arches.

Teeth:

• The teeth are also located in the oral cavity. An adult with a full set of teeth has 32 teeth, compared to a child between the ages of 2 and 6 who has 20. The incisors, or cutting teeth, are located at the front of the oral cavity, while the molars, or larger grinding teeth, are located in the back. The teeth's primary use is to chew, chop, and ground food. The tooth sockets hold the teeth in place.

Deciduous teeth arrangement:

Permanent teeth arrangement:

Deciduous Teeth (Baby Teeth):

• At around 6 months of age, the baby or deciduous teeth start to erupt. The incisors are the first eight deciduous teeth to emerge from the gums. The molars and canines (eye teeth) emerge later. By the time a youngster is 2 or 2.5 years old, all 20 baby teeth have typically come in. The permanent teeth grow from buds that are present at birth within the jaw bones during the first two years of life. At the age of six, the first permanent tooth—the molar—emerges. Prior to the loss of the baby incisors, this permanent tooth erupts. Deciduous teeth require good care since decay and infection of nearby deciduous molars may travel to and affect growing permanent teeth.

Permanent Teeth (Adult Teeth):

• The second set of teeth that develop in a human being are permanent teeth, or adult teeth. The jawbones expand as a youngster develops, allowing room for more teeth. The infant incisors loosen and are replaced by permanent incisors after the molars erupt at the age of 6 years. The baby molars are then replaced by the bicuspids (premolars) of the permanent teeth, which come after the baby canines (cuspids) and before the permanent canines and canines. At the age of 12, the larger jawbones are now prepared for the eruption of second permanent molar teeth. The wisdom teeth may erupt in the late teens or after. In some situations, the third molars may need to be removed because the jaw is too small for them or there are other anomalies.

Time of teeth eruption:

Structure of the Teeth

• Each tooth has two primary components: a crown that extends past the gum line and a root that is anchored to the alveolar process of the jaw. Neck of tooth refers to the area where these pieces come together. Glossy white enamel that covers the crown is primarily made of calcium salts. It is the body's toughest material. Enamel that has been harmed or worn down by abrasion is not replaced. With time, enamel may deteriorate. Underneath the enamel of a tooth is the dentin, a living, cellular component that is similar to bone but harder. The central chamber of the tooth, known as the pulp cavity and filled with blood vessels, nerves, and connective tissue, is surrounded by dentin. This compartment is reached by blood vessels and nerves that extend into the root through tubular root canals.

Blood Supply of Teeth

• The branches of the maxillary arteries supply the majority of the arterial blood, and the internal jugular veins drain the venous blood.

Nerve Supply of Teeth

• Branch maxillary nerves supply the upper teeth, and mandibular nerves supply the lower teeth. Both are the trigeminal nerve's branches.

Digestive Activities in the Mouth: