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ppt on Digestive system akki

The document summarizes the structure and function of the digestive system. It is composed of the gastrointestinal tract, which extends from the mouth to the anus, as well as accessory organs that aid in digestion. The gastrointestinal tract contains two main layers - the mucosal layer that absorbs nutrients and the muscularis layer that propels food through peristalsis. Accessory organs include the teeth, tongue, salivary glands, liver, gallbladder and pancreas, which secrete enzymes and bile to break down food in the chemical digestion process.

Health & Medicine◦
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By – Mr ASHOK BISHNOI Lecturer
2 groups of organs composed of digestive system
 It is continuous tube that extends from the mouth to anus through the thoracic, abdominal & pelvic cavities. 1.Gastrointestinal tract/ Alimentary canal
◦ Mouth ◦ Pharynx ◦ Esophagus ◦ Stomach ◦ Small intestine ◦ Large intestine ◦ Rectum ◦ Anal canal ◦ Anus
 The length of GI tract is about 5-7 meters (16.5-23 ft) in a living person.  It is long in Cadaver about 7-9 meters (23- 29.5 ft)
Supply secretions contributing to the breakdown of food 2. Accessory digestive organs
◦ Teeth ◦ Lips ◦ Cheeks ◦ Tongue ◦ Salivary glands (3 pair) ◦ Gallbladder ◦ Liver ◦ Pancreas
 Teeth aid in the physical breakdown of food & tongue assist in chewing & swallowing.  The other accessory digestive organs never come in to direct contact with food.  They produce secretion in the chemical breakdown of food
1. Ingestion-Taking food in to mouth 2. Secretion- Relies of H2o,acid & enzymes in to lumen of GI tract. 3. Mixing & propulsion 4. Digestion- Mechanical breakdown of food by Mastication Chemical digestion by Enzymes 5. Absorption- Passage of digested product from the GI tract in to blood. 6. Defecation- The elimination of faeces from the GI tract Function of DS;-
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Structure of alimentary canal:-  The wall of GI tract from the lower oesophagus to the anal canal.  It has the “4” layers of tissue ◦ Mucosal layer ◦ Submucosal layer ◦ Muscularis layer ◦ Serosa layer 1.Gastrointestinal tract/ Alimentary canal
 It consist of Epithelium Tissue ◦ Stratified squamous (in mouth, esophagus & anus) ◦ Simple columnar in the rest Function:- ◦ Protection ◦ Secretion ◦ Absorbtion
 Loose connective tissue ◦ containing ,glands and lymphatic tissue  Meissner’s plexus  The secrete:- ◦ Saliva from salivary gland ◦ Gastric juice from gastric gland ◦ Intestinal juice from intestinal gland ◦ Pancreatic juice from pancreas ◦ Bile from liver
 Skeletal muscle = voluntary control ◦ in mouth, pharynx , upper esophagus and anus ◦ control over swallowing and defecation  Smooth muscle = involuntary control ◦ inner circular fibers & outer longitudinal fibers ◦ mixes, crushes & propels food along by peristalsis
4.Serosa:- • It is outer layer • Covers all organs and walls of cavities • Secretes a serous fluid • Consists of connective tissue .
 Peritoneum ◦ Cavity within the abdomen Formed by a ◦ Parietal layer- Which line the abdominal wall ◦ Visceral layer covers organs with in the abdomen & pelvic cavity  Peritoneal cavity ◦ potential space containing a bit of serous fluid
The path of food: oral cavity/teeth/salivary glands oropharynx/epiglottis oesophagus stomach small intestine: duodenum small intestine: ileum small intestine: jejunum large intestine: ascending colon large intestine: transverse colon large intestine: descending colon sigmoid colon rectum anus
21  It is the main window of G.I.tract  From mouth to pharynx is called oral cavity  Mouth or oral cavity is bounded by muscle & bone.  Lips- Orbicularis oris muscle  Cheeks – Buccinator muscle Mouth/Oral cavity:-
24 The vestibule :-is the space between gums & checks. The oral cavity:- It is the space contained within the upper and lower dental arches. Uvula:- Is a carved fold of muscle covered with mucus membrane hanging down from middle palate.
25 Teeth:-  Called “dentition” (like dentist)  Teeth live in sockets (alveoli) in the gum- covered margins of the mandible and maxilla  Chewing: raising and lowering the mandible and moving it from side to side while tongue positions food between teeth
26  Two sets 1. Temporary/Milk/Primary /deciduous teeth 1. “Baby” teeth 2. Start at 6 months 3. 20 are out by about 2 years 4. Fall out between 2-6 years 2. Permanent: 32 total 1. All but 3rd set of molars by end of adolescence 2. 3rd set = “wisdom teeth” 1. Variable 3. Some can be “impacted” (imbedded in bone)
27  Incisors: chisel-shaped for chopping off pieces  Canines: cone shaped to tear and pierce  Premolars (bicuspids) and  Molars - broad crowns with 4-5 rounded cusps for grinding incisor canine premolar molar Cusps are surface bumps
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29  Two main regions A. Crown (exposed) B. Root (in socket) C. Meet at neck  Enamel ◦ 99% calcium crystals ◦ Hardest substance in body  Dentin – bulk of the tooth (bone-like but harder than bone, with collagen and mineral)  Pulp cavity with vessels and nerves ◦ Root canal: the part of the pulp in the root A B C
30  Cementum – bone layer of tooth root ◦ Attaches tooth to periodontal ligament  Periodontal ligament ◦ Anchors tooth in boney socket of the jaw ◦ Continuous with gingiva (gums)  Cavities or caries - rot  Plaque – film of sugar, bacteria and debris A B C
31  Intrinsic salivary glands – within mucosa ◦ Secrete saliva all the time to keep mouth moist  Extrinsic salivary glands ◦ Paired (2 each)  Parotid  Submandibular  Sublingual ◦ External to mouth ◦ Ducts to mouth ◦ Secrete saliva only right before or during eating Saliva: mixture of water, ions, mucus, enzymes keep mouth moist dissolves food so can be tasted moistens food starts enzymatic digestion buffers acid antibacterial and antiviral
32  Parotids* - largest (think mumps) ◦ Facial nerve branch at risk during surgery here  Submandibular # - medial surface mandible  Sublingual + - under tongue; floor of mouth Compound = duct branches Tubo = tubes Alveolar = sacs * # +
33  Oropharynx and laryngopharynx ◦ Stratified squamous epithelium  Three constrictor muscles* ◦ Sequentially squeeze bolus of food into esophagus ◦ Are skeletal muscles  Voluntary action  Vagus nerve (X) ___oropharynx ___laryngopharynx * * *
ppt on Digestive system akki