GIT

2 1st edition 2026-2027 GIT Definition : » of a congenital congenital aganglionic megacolon occurs as a result defect in colonic innervation » Ε characterized by : enormous dilatation Ε and sometimes the entire colon. hypertrophy of the upper part of the rectum, sigmoid Pathogenesis: » embryogenesis. crest cells that migrate into the bowel wall during The enteric neuronal plexus develops from neural » migration of neural crest cells is disrupted. Hirschsprung disease results when the normal » the It occurs due to absence of ganglion cells of both Meissner submucosal plexus and the Auerbach myenteric plexus (aganglionosis) of a colonic segment. » Ε This will lead to: failure of peristaltic movement Ε functional obstruction of the aganglionic segment Ε dilatation of segment proximal to obstruction. Clinical picture: » Ε Hirschsprung's disease is presented by : distention. neonatal failure to pass meconium or abdominal Complications: » Ε There is risk of enterocolitis Ε fluid and electrolyte disturbances Ε perforation and peritonitis Megacolon Acquired Congenital (Hirschsprung disease) Congenital Megacolon (Hirschsprung disease) الـ picture Clinical( هنشوف إيه عىل الطفل؟(: مرض الـ Hirschsprung بيبان من أول لحظة بعد الوالدة وبيمتاز بعالمتني � ن أساسيتني � ن : :)Neonatal failure to pass meconium( الميكونيوم نزول في فشل � الطبييع ي إن الطفل أول ما يتولد يزنز ل أول feces ليه )الميكونيوم( يفي أول 24 لـ 48 ساعة.طفل الـ Hirschsprung مش بيعرف يزنز له نتيجة االنسداد الوظييف ي اليلي اتكلمنا عنه. انتفاخ بطن شديد )distention Abdominal): بما إن القولون مقفول والفضالت والغازات محبوسة ومش عارفة تخرج، بطن البييب � ي . بتفضل تتنفخ وتكربر بشكل ملحوظ جدًاً الـ Complications( المخاطر والمضاعفات(: لو الحالة متلحقتش وتشخصت بدري، بنبىقى خايفني � ن جدًاً من 3 كوارث بالرت ر : تيب التهاب األمعاء والقولون )Enterocolitis): ركود الفضالت والربر از لفرت ر ة طويلة ورا السدة بيبىقى بيئة ممتازة لنمو البكترير يا، فبيحصل التهاب حاد وميكرويب �ي يفي جدار األمعاء والقولون، وده من أخطر المضاعفات اليلي ممكن تدخل الطفل يفي تسمم يفي الدم. :)Fluid and electrolyte disturbances( واألمالح السوائل لخبطة بسبب االنسداد وااللتهاب، الجسم بيفقد قدرته عىل امتصاص السوائل بشكل طبييع ي ، والطفل وممكن يدخل يفي جفاف شديد ولخبطة يفي أمالح الدم )زي الصوديوم والبوتاسيوم(. :)Perforation and peritonitis( ني انفجار القولون والتهاب الغشاء ال� ب يتو� دي المحطة األخرير ة والمرعبة؛ الجزء المتضخم )segment Proximal )بيفضل يتنفخ ويتنفخ من كرت ر الضغط لحد ما الجدار بتاعه ينفجر )Perforation)، فكل محتويات القولون تخرج لتجويف البطن وتعمل التهاب بريتويني حاد )Peritonitis)، . ودي حالة طوارئ جراحية قصوى إلنقاذ حياة الطفل فكرة الDisease يع� ني إيه disease Hirschsprung؟ ده عيب خليقي )Congenital )بيحصل فيه مشكلة يفي األعصاب اليلي .)Defect in colonic innervation( القولون بتغذي المشكلة ف� ي ن ؟ القولون بيبىقى فيه جزء "أقرع" معندوش خاليا عصبية )Aganglionic)، ودي بنسميها )segment Aganglionic). وبما إن الجزء ده مفيش فيه أعصاب، فـ مش بيتحرك )مفيش Peristalsis)، فـ بيعمل انسداد .)Functional obstruction( ليه بيحصل تضخم )Megacolon)؟ األكل والfeces بييجوا يمشوا يفي القولون عادي، لحد ما يوصلوا للجزء الـ "أقرع" )الـ Aganglionic )ويقفوا.. فالجزء اليلي قبله )الـ segment Proximal )يتجمع فيه ال feces، فـ يحصل له تضخم واسع جدًاً وتضخم يفي جدار العضالت )& dilatation Enormous .)hypertrophy الPathogenesis( قصة المرض من البداية( الطبييع ي بيحصل إيه؟ وإحنا لسه أجنة يفي بطن أمنا )Embryogenesis)، فيه خاليا اسمها )cells crest Neural )بتسافر وتهاجر لحد ما توصل لجدار األمعاء عشان تعمل لنا شبكة األعصاب الداخلية بتاعة الجهاز الهضيم ي اليلي .)Enteric neuronal plexus( بنسميها الخلل ف� ي ن ؟ مرض الـ Hirschsprung ! بيحصل لما السفرية دي باختصار تبوظ رحلة هجرة الـ cells crest Neural بتتقطع أو بتتحبس )Disrupted)، . فمبتوصلش آلخر القولون النتيجة عىل مستوى األنسجة: )Aganglionosis )يفي . جزء من القولون الغياب ده بيرض ر ب شبكتني � ن بما إن الخاليا موصلتش، فـ بيحصل غياب تام للخاليا العصبية : أعصاب مهمني � ن جدًاً Meissner submucosal plexus Auerbach myenteric plexus المحصلة )السلسلة اليلي بتبوظ الدنيا(: الحتة اليلي مفيهاش شبكات األعصاب دي )segment Aganglionic ) ً بتموت فيها الحركة الدودية تمامًا )peristaltic of Failure movement)، فتقف كأنها انسداد )obstruction Functional).. ونتيجة لكده، األكل يتجمع ويفضل ينفخ يفي الحتة السليمة اليلي قبلها .)Dilatation of segment proximal to obstruction( بالظبطGIT 1 1st edition Chapter 1 Introduction The Digestive System It consists of the following components: 1. The Oral cavity: Ē lips Ē cheeks Ē tongue Ē palate Ē pharynx Ē teeth 2. Gastro-intestinal tract (GIT): Ē Esophagus Ē Stomach : • cardiac region • fundus • body region • pyloric region Ē Small intestine : • duodenum • jejunum • ileum Ē Large intestine: • colon • appendix • rectum • anal canal 3. Associated glands: Ē Salivary glands • minor • major Ē Pancreas Ē Liver and gall bladder Functions of the digestive system: 1. Breaking food substances into small particles & transport them into different areas of the digestive system. 2. Secretion of the necessary enzymes for digestion. 3. Digestion of the food particles. 4. Absorption of the digestive products. 5. Excretion of unwanted substances from the body.GIT 2 1st edition Chapter 1 ANATOMY OF THE ORAL CAVITY The mouth cavity extends from: Ē the lips to the oropharyngeal isthmus. Ē It is composed of 2 main parts: 1. Vestibule Ē lies between the lips and the cheeks externally and the gums and the teeth internally. Ē The parotid duct opens at a papilla opposite the upper 2nd molar tooth. 2. Mouth cavity proper: Lies within the gums and the teeth. Roof: Is formed by: Ē The hard palate anteriorly Ē The soft palate posteriorly. Floor: Is formed by: Ē The anterior 2/3 of the tongue Ē The reflection of the mucous membrane from the tongue to the gums Sublingual region: shows the following structures: Ē Frenulum of the tongue: it connects the undersurface of the tongue to the floor of the mouth. Ē Sublingual papilla: it lies on each side of the frenulum and the submandibular duct opens in its top. Ē Sublingual fold: it is an oval fold lateral to the papilla for sublingual salivary gland Sensory innervation of the mouth: Roof: • greater palatine • nasopalatine nerves. Floor: • lingual nerve for general sensation • chorda tympani for taste sensation. Cheek: • buccal nerveGIT 3 1st edition Chapter 1 The Palate It forms the roof of the mouth and floor of the nasal cavity. it is divided into: Ē Hard palate (anterior 2/3). Ē Soft palate (posterior 1/3). 1. Hard Palate: Formed by: • The palatine process of the maxillae • The horizontal plates of the palatine bone. 2. Soft Palate Ē A mobile fold attached to the posterior border of hard palate Ē It is formed of • palatine aponeurosis and • muscles. Ē Its free border shows a median conical projection (uvula). Ē From the base of the uvula, two mucosal folds extend laterally and downwards on each side: • Palato-glossal arch anteriorly • Palato-pharyngeal arch posteriorly Palatine aponeurosis: Ē A fibrous sheath, attached to posterior border of hard palate and receives the insertion of palatine muscles Ē It is the expanded tendon of the tensor palatini.GIT 4 1st edition Chapter 1 Muscles of the soft palate: Muscle Nerve supply Action Tensor veli palatine Nerve to medial pterygoid Tighten the soft palate Levator veli palatine Pharyngeal plexus Elevates the soft palate Palatoglossus Pulls the root of the tongue upwards Palatopharyngeus Elevates the wall of the pharynx Musculus uvulae Elevates the uvulaGIT 5 1st edition Chapter 1 Blood supply of the palate Arteries • Greater palatine artery • Lesser palatine artery • Sphenopalatine artery • Ascending palatine artery  from facial artery • Ascending pharyngeal artery Veins Drain into: • Pharyngeal venous plexuses • pterygoid venous plexuses Lymphatic drainage of the palate Drains into: • Deep cervical lymph nodes • Retropharyngeal lymph nodes Nerve supply of the palate Motor: Ē All the muscles of the soft palate are supplied by the cranial part of the accessory nerve through the pharyngeal plexus. Ē EXCEPT the tensor palati which is supplied by the mandibular nerve. Sensory: • Glossopharyngeal nerve • Greater palatine nerve • Middle palatine nerve • Lesser palatine nerve • Sphenopalatine nerve From maxillary arteryGIT 6 1st edition Chapter 1 HISTOLOGY OF THE ORAL CAVITY Ē All parts of the oral cavity and gastrointestinal tract (GIT) are lined by a wet epithelial membrane protected by mucus. Ē This membrane is known as mucous membrane or mucosa. Ē This membrane is formed of an epithelium with a layer of connective tissue called lamina propria. Ē The epithelial lining of the oral cavity is stratified squamous epithelium either non-keratinized or keratinized according to its location. Non-keratinized on the: • The Ventral surface of the tongue • The floor of the mouth • The mucosal (inner) surface of the lips • The mucosal (inner) surface of the cheeks Keratinized or partially keratinized over: • The gingiva (gums) • hard palate • most of the dorsum of the tongue ↠ which need more protection during eating.GIT 7 1st edition Chapter 1 The Lips They are formed mainly of : Ē striated muscle (orbicularis oris) and have three surfaces: 1. The outer surface Ē is skin stratified squamous keratinized epithelium with: • hair follicles • sweat and sebaceous glands in the dermis. 2. The inner surface Ē is mucous membrane, lined with stratified squamous non-keratinized epithelium with • mucus-secreting (labial) glands in the lamina propria. 3. The red (lip) margin Ē is a transition zone between keratinized and non-keratinized epithelium. Ē The lamina propria is rich in blood vessels that cause redness of the lip margin. Ē It has neither hair follicles nor glands. The Cheeks Ē They are formed of: skeletal muscle (buccinator). Ē They are covered on: The outer side: by skin and subcutaneous C.T from inside: by a mucous membrane with: • minor salivary glands (buccal glands) lying deep in their lamina propria. GIT 8 1st edition Chapter 1 Palate Ē It is the roof of the mouth consists of two parts: 1. The hard palate Ē Forms the anterior two thirds of the palate. Ē It is lined with mucous membrane formed of keratinized stratified squamous epithelium and lamina propria resting directly on the maxillary and palatine bones. 2. The soft palate Ē Forms the posterior one third. Ē It is formed of: core of skeletal muscle covered with mucous membrane formed of: • Non-keratinized stratified squamous epithelium and lamina propria. • Numerous mucous glands are present in a connective tissue layer between the mucous membrane and the muscle core. MASTICATION Functions of mastication: 1. It crushes the food and facilitates its mixture with saliva. 2. It acts as a stimulant for salivary secretion. 3. It reduces the mechanical irritation of gastrointestinal mucosa by large particles of food. 4. It helps swallowing by mixing food particles with saliva & formation of a bolus that can be easily swallowed. Definition  It is the process of breakdown of large food particles into small pieces. The uvula  It is a conical downward extension of the soft palate and is formed of a core of skeletal muscle covered by typical oral mucous membrane.GIT 9 1st edition Chapter 1 GIT 1st eddition Chapter 1 DISEASES OF THE ORAL CAVITY Ulcers of the tongue: Tumours of the oral cavity: 1. Benign tumors: A variety of benign tumours are seen e.g: Type of Ulcer Cause / Site Appearance & Characteristics Dental ulcer It is related to irregular rough tooth (traumatic contact ulcer). • It is a shallow ulcer • at the edge of the tongue • near a sharp tooth. Dyspeptic ulcers • Pathogenesis is not clear. • Occurs in cases of dyspepsia. It is small, superficial, painful, multiple. Tuberculous ulcer Caused by coughed sputum in cases of open pulmonary tuberculosis. It develops at the tip of the tongue, and it has undermined edges. Malignant ulcer Common in the anterior two thirds. The edges are everted, with necrotic floor and indurated base. 6 Granular cell tumour Ē This is a rare tumour arising from the tongue Ē its importance lies in the fact that it may be mistaken for carcinoma of the tongue. Ē It is composed of large cells with indistinct cell borders, small central nucleus and esinophilic granular cytoplasm. 7 Adenoma Ē arises from minor salivary glands. 8 Lymphangioma Ē May cause macroglossia and macrochelia Ē can interfere with swallowing and may easy bleed. 3 Fibroma 1 Squamous cell papilloma 4 Leiomyoma 2 Cavernous haemangioma 5 Lipoma