Organs of The Digestive System

• The vestibule is the space which is contained externally by the lips and cheeks, and internally by gums and teeth.
• The palate, tongue, and teeth constitute the oral cavity.
• The digestive system consists of three main parts: the mouth; the

  gastrointestinal tract; and the accessory organs.
• A sensory receptor is a nerve ending that senses changes in light, temperature, pressure, and other stimuli.
• The palate is the oral cavity’s upper boundary.
• Towards the front of the palate is the hard palate and to the back is the soft palate.
• The structure that dangles from the posterior area of the soft palate is known as the uvula.
• The muscular organ connected to the bottom of the oral cavity is the tongue.
• The papillae are responsible for the rough surface of the tongue. They also contain taste buds which sense different tastes.
• A complete permanent set of teeth numbers is 32.
• The four different types of teeth are incisors, canines, premolars, and molars.
• Incisors are found at the front portion of the mouth. They have sharp ends to cut food into smaller pieces easily.
• Canines are located immediately after the incisors. They are also sharp and pointed teeth meant for tearing food.
• Premolars have a flat surface. These teeth are responsible for tearing and crushing.
• Molars are the largest teeth, and they also have flat surfaces. They are meant for chewing, grinding, and crushing.
• The organ which connects the mouth to the esophagus is the pharynx.
• The upper portion, also known as the nasopharynx, serves as a passage of air. Its middle section is also known as the oropharynx, while the lowest section is the laryngopharynx.
• The epiglottis is found in the throat behind the tongue. This structure is primarily made up of cartilage and serves to prevent the entry of food and water into the respiratory tract.
• The portion that follows the mouth is the gastrointestinal tract.
• The long muscular tube where food travels from the mouth to the stomach is called the esophagus.
• The upper portion of the esophagus is kept closed by its sphincter. A sphincter is a muscle which contracts to close an opening.
• The inner walls of the stomach have folds known as rugae.
• The stomach has three sections: the cardia, the fundus, and the pylorus.
• The beginning of the cardia, after the esophagus, is the cardiac sphincter. The end of the pylorus is the pyloric sphincter. These sphincters serve to prevent the backflow of food.
• The small intestine is a 20 feet-long tube where the process of digestion ends.
• The duodenum is the shortest and widest part of the small intestine. This is where chyme mixes with the substances secreted by the liver and pancreas. The middle part, jejunum, is the site of nutrient absorption. Nutrients are further absorbed in the ileum.
• Chyme is partially digested food entering the intestine coming from the stomach.
• The large intestine is the region where vitamins and water are absorbed. The large intestine is also responsible for converting the chyme into feces.
• The portion where feces is transported to be stored before being eliminated from the body is called the colon.
• The last portion of the large intestine which connects the colon to the anus is the rectum.
• Feces produced in the colon is stored in the rectum before defecation. Defecation is the process of eliminating feces from the body. The walls of the rectum absorb the remaining water from the feces.
• The last portion of the gastrointestinal tract is the anus. It is a very short tube which serves as the opening for the feces. It also has folds known as anal columns. These columns help the anus in controlling the disposal of feces.
• The role of salivary glands is to secrete saliva into the oral cavity.
• The parotid glands produce saliva and are found anterior to the ears. The submandibular gland is found in the submandibular fossa, which is a depression under the mandible. The sublingual glands are located under the tongue, on the floor of the mouth.
• The liver is the second largest organ. It is a triangular-shaped organ located below the diaphragm. Its main role is the production of bile.
• The gallbladder stores and holds the bile until it is needed for lipid digestion in the duodenum.
• The pancreas secretes pancreatic juices which are essential in breaking down proteins, fats, and carbohydrates in food.