Chapter 15 Gastrointestinal System Dr.LL Wang E-mail:wanglinlin@zju.edu.cn Rm 608,Block B,Research Building,School of Medicine,Zijingang Campus
Chapter 15 Gastrointestinal System Dr. LL Wang E-mail: wanglinlin@zju.edu.cn Rm 608, Block B, Research Building, School of Medicine, Zijingang Campus
Mouth,Pharynx,and Esophagus Mastication,or chewing,is the first step in the breakdown of complex foodstuffs and serves several functions as follows: .breaking large pieces into small pieces, resulting in a massive increase in surface area, which is where digestive enzymes work .softening of food and transformation into a size conducive to swallowing .lubrication of food by impregnating it with saliva
Mouth, Pharynx, and Esophagus Mastication, or chewing, is the first step in the breakdown of complex foodstuffs and serves several functions as follows: •breaking large pieces into small pieces, resulting in a massive increase in surface area, which is where digestive enzymes work •softening of food and transformation into a size conducive to swallowing •lubrication of food by impregnating it with saliva
Secretion of saliva Tongue Parotid gland The Salivary Glands ·Parotid gland ·Mandibular gland Sublingual gland Deep submandibular gland Superficial submandibular gland ·Sublingual gland Fleshandbones.com Davies et al:Human Physiology
The Salivary Glands • Parotid gland • Mandibular gland • Sublingual gland Secretion of saliva
Saliva Blood● 1000ml/d Transport Na,K.cr,HCO3 aminoacids pH6.0~7.0 alucose Composition of saliva Primary secretion Acinus」 -H0 production of cC plasma Amylase &mucus -Na,Cl,K+,HCO3 ucus synthesis -Mucus (containing a mucin) Duct- -Amylase,lysozyme,.. moditication of primary secretion (ionic) Hco3
• 1000 ml/d • pH 6.0~7.0 • Composition of saliva –H 2 O –Na +, Cl -, K +, HCO 3 - –Mucus (containing mucin) –Amylase, lysozyme, … Saliva
Physiological functions of saliva 。Lubrication:mucus ·Solubilizes dry food Oral hygiene:lysozyme Initiates starch digestion:amylase
Physiological functions of saliva • Lubrication: mucus • Solubilizes dry food • Oral hygiene: lysozyme • Initiates starch digestion: amylase
Swallowing
Swallowing
Com panles,Inc.Perml Ge20ghtomeMcragnGen8enienphesnpemisonequhediorepodocionordspley Hard palate Pharynx Epiglottis Glottis -Upper Trachea Esophagus (a) (6) The swallowing reflex is coordinated by the medulla oblongata, which stimulates the appropriate sequence of contraction and relaxation in the participating skeletal muscle,sphincters,and smooth muscle groups
The swallowing reflex is coordinated by the medulla oblongata, which stimulates the appropriate sequence of contraction and relaxation in the participating skeletal muscle, sphincters, and smooth muscle groups
Copyright The McGraw-Hill c Esophagus Diaphragm. Stomach The coordinated sequence of contraction and relaxation in the upper esophageal sphincter,the esophagus,and the lower esophageal sphincter is necessary to deliver swallowed food to the stomach
The coordinated sequence of contraction and relaxation in the upper esophageal sphincter, the esophagus, and the lower esophageal sphincter is necessary to deliver swallowed food to the stomach
Peristalsis Peristaltic waves Food Progressive wave of muscle contraction Esophaqus- Circular muscles contract Previous mouthful of food swallowed Heartburn Circular muscles relax (because the pain appears to be Sphincters located in the area of the heart) Stomach Gastroesophageal reflux
Heartburn (because the pain appears to be located in the area of the heart) Gastroesophageal reflux Peristaltic waves Progressive wave of muscle contraction
Digestion in the Stomach Duodenur Pancreas
Digestion in the Stomach