The Digestive System PDF

THE DIGESTIVE SYSTEM  STRUCTURES OF THE DIGESTIVE SYSTEM ◦ The digestive system consists primarily of the gastrointestinal tract , which is also known as the GI tract (gastr/o means stomach, intestin means intestine, and -al means pertaining to). These organs work in cooperation w...

THE DIGESTIVE SYSTEM  STRUCTURES OF THE DIGESTIVE SYSTEM ◦ The digestive system consists primarily of the gastrointestinal tract , which is also known as the GI tract (gastr/o means stomach, intestin means intestine, and -al means pertaining to). These organs work in cooperation with accessory organs. ◦ The upper GI tract consists of the mouth, pharynx (throat), esophagus, and stomach. This transports food from the entry into the body until digestion begins in the stomach. STRUCTURES OF THE DIGESTIVE SYSTEM ◦The lower GI tract, which is sometimes referred to as the bowels, is made up of the small and large intestines plus the rectum and anus. Here digestion is completed, and waste material is prepared for expulsion from the body. ◦The accessory organs of the digestive system include the liver, gallbladder, and pancreas. The Oral Cavity ◦The major structures of the oral cavity, also known as the mouth, are the lips, hard and soft palates, salivary glands, tongue, teeth, and the periodontium The Lips ◦The lips, surround the opening to the oral cavity. ◦During eating, the lips, tongue, and cheeks hold the food in the mouth. ◦ The lips also have important roles in breathing, speaking, and the expression of emotions. ◦The Palate ◦The palate , which forms the roof of the mouth, consists of three major parts; 1- The hard palate is the anterior portion of the palate. This area is covered with specialized mucous membrane. ◦ Rugae are irregular ridges or folds in this mucous membrane. 2- The soft palate is the flexible posterior portion of the palate. During swallowing, it has the important role of closing off the nasal passage to prevent food and liquid from moving upward into the nasal cavity. 3- The uvula is the third part, and it hangs from the free edge of the soft palate. During swallowing, it moves upward with the soft palate. It also plays an important role in snoring and in the formation of some speech sounds. ◦ The Tongue ◦ The tongue is very strong, flexible, and muscular. ◦ The posterior portion of the tongue is attached to the floor of the mouth. ◦ The anterior end of the tongue moves freely and is flexible. ◦ It is the structure of the tongue that makes it so important for chewing, speaking, and swallowing. ◦The upper surface of the tongue has a tough protective covering and in some areas, small bumps known as papillae. These papillae contain taste buds, which are the sensory receptors for the sense of taste. ◦The Tongue ◦The sublingual surface of the tongue and the tissues that lie under the tongue are covered with delicate highly vascular tissues. ◦Sublingual means under the tongue. Highly vascular means containing many blood vessels. ◦The presence of this rich blood supply under the tongue makes it suitable for administering certain medications sublingually by placing them under the tongue, where they are quickly absorbed into the bloodstream. ◦The lingual frenum is a band of tissue that attaches the tongue to the floor of the mouth. ◦This frenum limits the motion of the tongue.  Tissues of the Oral Cavity ◦The term periodontium describes the structures that surround, support, and are attached to the teeth. ◦ This consists of the bone of the dental arches and the soft tissues that surround and support the teeth. ◦The gingiva, also known as masticatory mucosa or the gums, is the specialized mucous membrane that covers the bone of the dental arches and surrounds the neck of the teeth.  The Dental Arches ◦ The dental arches are the bony structures of the oral cavity. These arches hold the teeth firmly in position to facilitate chewing and speaking. ◦ The maxillary arch is commonly known as the upper jaw and consists of bones of the lower surface of the skull. This arch does not move. ◦ The mandibular arch, commonly know as the lower jaw, is a separate bone and is the only movable component part of the joint.  The Dental Arches ◦The temporomandibular commonly known as the TMJ, is formed at the back of the mouth where the maxillary and mandibular arches come together.  The Teeth ◦ The term dentition refers to the natural teeth arranged in the upper and lower jaws. Human dentition con- sists of four types of teeth These are the: ◦ Incisors and canines (also known as cuspids). These teeth are used for biting and tearing. ◦ Premolars, which are also known as bicuspids. ◦ and molars. premolar and molars are used for chewing and grinding. Primary and Permanent Dentition ◦ The primary dentition is also known as the deciduous dentition, or baby teeth. ◦These 20 teeth erupt during early childhood, are normally lost in late childhood, and are replaced by the permanent teeth. ◦The primary dentition consists of 8 incisors, 4 canines, and 8 molars, but no premolars. Primary and Permanent Dentition ◦ The permanent dentition consists of 32 teeth designed to last a lifetime. Of these teeth, 20 replace primary teeth and 12 erupt at the back of the mouth. ◦ The permanent dentition includes 8 incisors, 4 canines, 8 premolars, and 12 molars. ◦ The term occlusion, as used in dentistry, describes any contact between the chewing surfaces of the upper and lower teeth.  Structures and Tissues of the Teeth ◦ The crown is the portion of a tooth that is visible in the mouth. It is covered with enamel, which is the hardest substance in the body ◦ The roots of the tooth hold it securely in place within the dental arch. The roots are protected by cementum. This substance is hard, but it is not as strong as enamel. ◦ The cervix, also known as the neck of the tooth, is where the crown and root meet.  Structures and Tissues of the Teeth ◦ Dentin makes up the bulk of the tooth. The portion that is above the gum line is covered with enamel. The root area is covered with cementum. ◦ The pulp cavity is the area within the crown and roots of the tooth that is surrounded by the dentin to protect the delicate pulp of the tooth. In the roots, the pulp continues in the space known as the root canals. ◦ The pulp itself consists of a rich supply of blood vessels and nerves that provide nutrients and innervation to the tooth.  Saliva and Salivary Glands ◦Saliva is a colorless liquid that maintains the moisture in the mouth. ◦It helps maintain the health of the teeth, and it begins the digestive process by lubricating food during chewing and swallowing.  Saliva and Salivary Glands ◦ The three pairs of salivary glands secrete saliva that is carried by ducts into the mouth ◦ The parotid glands are located on the face, slightly in front of each ear. The ducts for these glands are on the inside of the cheek near the upper molars. ◦ The sublingual glands and their ducts are located on the floor of the mouth under the tongue. ◦ The submandibular glands and their ducts are located on the floor of the mouth near the mandible.  MEDICAL SPECIALTIES RELATED TO THE DIGESTIVE SYSTEM ◦An oral or maxillofacial surgeon specializes in surgery of the face and jaws to correct deformities, treat diseases, and repair injuries. ◦An orthodontist is a dental specialist who prevents or corrects malocclusion of the teeth and related facial structures (orth means straight or normal, odont means the teeth, and -ist means specialist). ◦A periodontist is a dental specialist who prevents or treats disorders of the tissues surrounding the teeth (peri- means surrounding, odont means the teeth, and -ist means specialist). PATHOLOGY OF THE DIGESTIVE SYSTEM Tissues of the Oral Cavity ◦Aphthous ulcers , also known as mouth ulcers, are gray-white pits with a red border in the soft tissues lining the mouth. Although the exact cause is unknown, the appearance of these very common sores is associated with stress, certain foods, or fever. ◦An ulcer is an open lesion of the skin or mucous membrane resulting in tissue loss around the edges  PATHOLOGY OF THE DIGESTIVE SYSTEM Tissues of the Oral Cavity ◦ Leukoplakia is an abnormal white precancerous lesion (sore) that develops on the tongue or the inside of the cheek (leuk/o means white, and -plakia means plaque). ◦ These lesions develop in response to chronic irritation in the mouth such as constant rubbing against a broken tooth  PATHOLOGY OF THE DIGESTIVE SYSTEM Tissues of the Oral Cavity ◦ Stomatitis is an inflammation of the mucosa of the mouth (stomat means mouth or oral cavity, and -itis means inflammation). ◦ Stomatomycosis is any disease of the mouth due to a fungus (stomat/o means mouth or oral cavity, myc means fungus, and -osis means abnormal condition or disease). ◦ Oral thrush is a type of stomatomycosis that develops when the fungus Candida albicans grows out of control. The symptoms are creamy white lesions on the tongue or inner cheeks. This condition occurs most often in infants, older adults with weakened immune systems, or individuals who have been taking  PATHOLOGY OF THE DIGESTIVE SYSTEM Tissues of the Oral Cavity ◦ The term trismus describes any restriction to the opening of the mouth caused by trauma, surgery, or radiation associated with the treatment of oral cancer. This condition causes difficulty in speaking and affects the patient’s nutrition due to impaired ability to chew and swallow.  PATHOLOGY OF THE DIGESTIVE SYSTEM Tissues of the Oral Cavity ◦Xerostomia, also known as dry mouth: is the lack of adequate saliva due to diminished secretions by the salivary glands. ◦This condition can be due to medications or radiation of the salivary glands, and can cause discomfort, difficulty in swallowing, changes in the taste of food, and dental decay. PATHOLOGY OF THE DIGESTIVE SYSTEM Tissues of the Oral Cavity ◦Cleft Lip and Cleft Palate ◦A cleft lip: also known as a harelip, is a birth defect in which there is a deep groove of the lip running upward to the nose as a result of the failure of this portion of the lip to close during prenatal development. PATHOLOGY OF THE DIGESTIVE SYSTEM Tissues of the Oral Cavity ◦A cleft palate: ◦ is the failure of the palate to close during the early development of the fetus. ◦This opening can involve the upper lip, hard palate, and/or soft palate. If not corrected, this opening between the nose and mouth makes it difficult for the child to eat and speak.  Dental Diseases and Conditions ◦ Bruxism: is the involuntary grinding or clenching of the teeth that usually occurs during sleep and is associated with tension or stress. Bruxism wears away tooth structure, damages periodontal tissues, and injures the temporomandibular joint. ◦ Dental caries, also known as tooth decay or a cavity: ◦ is an infectious disease caused by bacteria that destroy the enamel and dentin of the tooth. If the decay process is not arrested, the pulp can be exposed and become infected. ◦Dental plaque, which is a major cause of dental caries and periodontal disease, forms as soft deposits in sheltered areas near the gums and between the teeth. ◦ Dental plaque consists of bacteria and bacterial by-products. In contrast, the plaque associated with heart conditions consists of deposits of cholesterol that form within blood vessels.  Dental Diseases and Conditions ◦Edentulous means without teeth. ◦This term describes the situation after the natural permanent teeth have been lost.  Dental Diseases and Conditions ◦ Malocclusion is any deviation from the normal positioning of the upper teeth against the lower teeth. Malocclusion  Periodontal Disease ◦Gingivitis: is the earliest stage of periodontal disease, and the inflammation affects only the gingiva. ◦Periodontal disease, also known as periodontitis, is an inflammation of the tissues that surround and support the teeth usually involves the alveolar bone. Thank you