Ebook Textbook of histology a practical guide (2nd edition): Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Textbook of histology a practical guide (2nd edition): Part 2
Ebook Textbook of histology a practical guide (2nd edition): Part 2
12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2ssociated with it. The main function of the digestive system is to digest the ingested food and absorb the nutrients.ORAL CAVITYGeneral Features•The oral cavity is the first part of the digestive system where the food is broken into small pieces by teeth, moistened and lubricated by saliva. Saliva i Ebook Textbook of histology a practical guide (2nd edition): Part 2s secreted by three pairs of major salivary glands and minor salivary glands present in the oral mucosa. The digestive enzyme, amylase, present in theEbook Textbook of histology a practical guide (2nd edition): Part 2
saliva initiates carbohydrate digestion in the oral cavity. The saliva has got bactericidal action also.•The oral cavity consists of two parts, namel12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2ternally. The oral cavity proper is the large space limited anteriorly and laterally by the dental arches and superiorly by the palate. It contains the tongue which arises from the floor.•The oral cavity is lined by moist oral mucous membrane or oral mucosa which is continuous with the dry skin at t Ebook Textbook of histology a practical guide (2nd edition): Part 2he mucocutaneous junction of the lips.Structure of Oral Mucosa•The oral mucosa is made of covering epithelium (stratified squamous epithelium) and theEbook Textbook of histology a practical guide (2nd edition): Part 2
underlying connective tissue (lamina propria). It has no muscularis mucosa.•The deeper part of the lamina propria that contains major blood vessels, 12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2 they are found in, e.g. labial glands in the lip, buccal glands in the cheek, palatine glands in the palate and lingual gland* in the tongue.•Sebaceous glands are occasionally seen in the lamina propria of oral mucosa. They appear as pale yellow spots called Fordyce’s spots. Presence of sebaceous g Ebook Textbook of histology a practical guide (2nd edition): Part 2lands in the ora) mucosa may be due to retention of parts of skin ectoderm when oral ectoderm invaginates to form the lining of oral cavity.•The oralEbook Textbook of histology a practical guide (2nd edition): Part 2
mucosa shows considerable structural variation in different regions of the oral cavity. Based on the function, it can be divided into three main types12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2bjected to mechanical trauma during mastication of food, e.g. gingiva and mucosa over hard palate.•It is firm and immobile and attached to the periosteum of the underlying bone forming mucoperiosteum.•The stratified squamous epithelium of masticatory mucosa is moderately thick and frequently paraker Ebook Textbook of histology a practical guide (2nd edition): Part 2atinized (parakera-tinization is otherwise called incomplete keratinization, where the superficial partly keratinized cells retain their shrunken212 TEbook Textbook of histology a practical guide (2nd edition): Part 2
extbook of Histology and a Practical Guidepyknotic nuclei and other remnants of organelles, refer to Plate 2.11:1b). Its basal surface is indented by 12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2g. For the same reason, injection of local anaesthetics into these areas are difficult, often painful as is any swelling arising from inflammation.Lining Mucosa•Lining mucosa is soft and pliable. It covers the inner surface of lips, cheeks, soft palate, floor of the mouth and ventral surface of tong Ebook Textbook of histology a practical guide (2nd edition): Part 2ue.•The epithelium of lining mucosa is thicker than that of masticatory mucosa and is nonkeratinized. Its basal surface is largely smooth and occasionEbook Textbook of histology a practical guide (2nd edition): Part 2
ally indented with slender connective tissue papillae.•The lamina propria is thick, made up of irregularly arranged collagen and elastic fibres. The s12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2being stretched, except over the undersurface of the tongue where the mucosa is firmly bound to the underlying muscle.•Since the mucosa is soft and flexible, surgical incisions gape and frequently require sutures for closure. Injection into this region is easy because dispersion of fluid occurs read Ebook Textbook of histology a practical guide (2nd edition): Part 2ily in the loose connective tissue; similarly infection also spreads rapidly.Specialized Mucosa•Specialized mucosa is found on the dorsum of the tonguEbook Textbook of histology a practical guide (2nd edition): Part 2
e. Though it is functionally a masticatory mucosa, it has been classified as specialized mucosa because of the presence of taste buds in it. The detai12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2 tongue.LIPS•The upper and lower lips are fleshy mucocutaneous flaps forming the boundaries of the oral fissure.•Each lip is covered externally by dry hairy skin and internally by wet mucous membrane, enclosing in the middle, circularly arranged skeletal muscle, orbicularis oris.•Oral orifice is one Ebook Textbook of histology a practical guide (2nd edition): Part 2 of the regions of the mucocutaneous junctions of the body where the skin becomes continuous with the mucous membrane. This junction shows a transitioEbook Textbook of histology a practical guide (2nd edition): Part 2
n of keratinized epidermis of skin to nonkeratinized epithelium of labial mucosa. This transitory zone is called red line or vermilion border of the l12 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands as Ebook Textbook of histology a practical guide (2nd edition): Part 2ns large labial glands (predominantly mucous) (Box 12.1).GINGIVA•Gingiva is formed of masticatory oral mucosa located around the neck of the tooth and is commonly called gum. It is paler than the alveolar mucosa. Ebook Textbook of histology a practical guide (2nd edition): Part 212 DIGESTIVE SYSTEMIntroductionThe digestive system consists OÍ oral cavity and a hollow tubular gastrointestinal tract (GIT) plus digestive glands asGọi ngay
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