Chapter 26 - Digestive System - Mouth, Pharynx, Esophagus - Lecture Notes PDF

HHP:1100 HUMAN ANATOMY The Digestive System I: Overview and Mouth, Pharynx, Esophagus, and Stomach  HHP:1100 Lecture Overview Human Anatomy Overview of the Digestive System Oral Cavity Pharynx Esophagus Stomach 2  HHP:11...

HHP:1100 HUMAN ANATOMY The Digestive System I: Overview and Mouth, Pharynx, Esophagus, and Stomach  HHP:1100 Lecture Overview Human Anatomy Overview of the Digestive System Oral Cavity Pharynx Esophagus Stomach 2  HHP:1100 1. Overview of the Digestive System Human Anatomy Two categories of organs: 1. Gastrointestinal (GI) tract 2. Accessory digestive organs 3  1. Overview of the Digestive System HHP:1100 Human Anatomy GI Tract 1. GI tract is a continuous tube including: – Oral cavity – Pharynx – Esophagus – Stomach – Small intestine – Large intestine – Anal canal 4  1. Overview of the Digestive System HHP:1100 Human Anatomy Accessory Digestive Organs 2. Accessory digestive organs are connected to GI tract but not part of it – Teeth and tongue – Salivary glands – Liver – Gallbladder – Pancreas 5  1. Overview of the Digestive System HHP:1100 Human Anatomy Functions Ingestion Motility (peristalsis) Secretion Digestion (mechanical and chemical) Absorption Elimination of wastes 6  1. Overview of the Digestive System HHP:1100 Human Anatomy General Histology of GI Tract GI tract wall is composed of four tunics (layers) From deep to superficial they are: 1. Mucosa 2. Submucosa 3. Muscularis 4. Serosa 7  HHP:1100 2. Oral Cavity Human Anatomy Two regions of oral cavity 1. Vestibule 2. Oral cavity proper 8  2. Oral Cavity HHP:1100 Human Anatomy Palate Palate – Hard palate: anterior 2/3, palatine processes of maxillae bones and palatine bones – Soft palate: posterior 1/3, muscular Uvula extends posteriorly from soft palate, elevates during swallowing to close off posterior entrance to nasopharynx 9  2. Oral Cavity HHP:1100 Human Anatomy Tongue Primarily skeletal muscle lingual frenulum Papillae Functions: manipulates and mixes ingested materials, assists in swallowing 10  2. Oral Cavity HHP:1100 Human Anatomy Salivary Glands Salivary glands produce and secrete saliva into the oral cavity Saliva serves the following functions: – Moistens ingested materials to become a slick bolus – Moistens, cleanses, and lubricates oral cavity structures – Dissolves food so taste receptors on tongue can be stimulated Three pairs of extrinsic salivary glands make majority of the saliva: 1. Parotid glands 2. Submandibular glands 11 3. Sublingual glands  2. Oral Cavity HHP:1100 Human Anatomy Salivary Glands 1. Parotid salivary glands: secrete 25–30% of total saliva – Largest salivary glands – Located anterior and inferior to the ear – Parotid duct runs parallel to zygomatic arch, pierces buccinator muscle before opening into mouth near upper 2nd molar 12  2. Oral Cavity HHP:1100 Human Anatomy Salivary Glands 2. Submandibular salivary glands: produce 60–70% of total saliva – Inferior to body of mandible – Submandibular duct opens in the floor of the mouth next to lingual frenulum 13  2. Oral Cavity HHP:1100 Human Anatomy Salivary Glands 3. Sublingual salivary glands: contribute 3–5% of total saliva – Inferior to the tongue – Contain multiple, tiny sublingual ducts that open onto the inferior surface of oral cavity 14  2. Oral Cavity HHP:1100 Human Anatomy Teeth Collectively known as the dentition Crown – enamel Neck Root(s) Gingiva 15  2. Oral Cavity HHP:1100 Human Anatomy Teeth Dentin Pulp cavity Root canal 16  2. Oral Cavity HHP:1100 Human Anatomy Teeth Teeth have several surfaces: – Mesial surface – Distal surface – Buccal surface – Labial surface – Lingual surface – Occlusal surface 17  2. Oral Cavity HHP:1100 Human Anatomy Teeth Two sets of teeth typically erupt in a lifetime: – 20 deciduous teeth (milk teeth) erupt between 6–30 months – 32 permanent teeth replace the deciduous teeth 18  2. Oral Cavity HHP:1100 Human Anatomy Teeth Permanent teeth types: – Incisors: most anterior, shaped like chisels for slicing – Canines: posterolateral to incisors, pointed for puncturing and tearing – Premolars: posterolateral to canines, have flat crowns with ridges (cusps) for crushing and grinding – Molars: thickest and most posterior teeth, also adapted for crushing and grinding Each quadrant has 2 incisors, 1 canine, 2 premolars, and 3 molars 19 – Wisdom tooth is 3rd molar  HHP:1100 3. Pharynx Human Anatomy Oropharynx and laryngopharynx are shared by respiratory and digestive systems Food is routed into esophagus by closure of the epiglottis during swallowing 20  HHP:1100 4. Esophagus Human Anatomy Esophagus (~10” long) conducts ingested materials from pharynx to stomach Passes through opening in diaphragm (esophageal hiatus) just before it connects to stomach Transitions from skeletal muscle (voluntary control of swallowing) superiorly to smooth muscle inferiorly 21  HHP:1100 4. Esophagus Human Anatomy Superior esophageal/ pharyngoesophageal sphincter – Closes during inhalation preventing air entry Inferior esophageal/ gastroesophageal/cardiac sphincter – Prevents materials from regurgitating from stomach 22  4. Esophagus HHP:1100 Human Anatomy Peristalsis Rhythmic contraction of digestive tubes Begins in esophagus, continues through the entire GI tract, pushing the bolus along Controlled voluntarily in top 1/3 of esophagus, slightly voluntarily in middle 1/3, then completely involuntary 23  5. Stomach HHP:1100 Human Anatomy Overview Stomach is located in upper left quadrant of abdominal cavity Function: mechanical and chemical digestion of the bolus – Bolus processed into chyme 24  HHP:1100 Learning Outcomes Human Anatomy You Should Be Able To … 1. list and identify the organs that compose the gastrointestinal (GI) tract 2. explain the differences between the gastrointestinal (GI) tract and the accessory digestive organs 3. describe the major functions of the digestive system 4. identify the four GI tract tunics: mucosa, submucosa, muscularis, and serosa/adventitia 5. identify and describe the location and function of the visceral peritoneum and parietal peritoneum, and the peritoneal cavity 25  HHP:1100 Learning Outcomes Human Anatomy You Should Be Able To … 6. identify and describe the boundaries of the oral cavity 7. compare and contrast the composition and functions of the hard palate and soft palate 8. identify the uvula and state its function 9. compare and contrast the number, function, and first general appearance of deciduous teeth versus permanent teeth 10. describe the locations of the major salivary glands: parotid, submandibular, and sublingual salivary glands 11. identify and describe the regions of the pharynx with respect to 26 passage of air and/or food  HHP:1100 Learning Outcomes Human Anatomy You Should Be Able To … 12. describe the location of the esophagus relative to other body structures 13. define “peristalsis” and explain how it occurs along the esophagus, differentiating voluntary contractions (skeletal muscle) and involuntary contractions (smooth muscle) 27