BIO 241 1st Edition Lecture 19 Outline of Last Lecture I. Introduction to digestionII. Basic digestive processesIII. OrganizationIV. Tissue layers of the GI tractV. The peritoneum, Mouth (oral cavity)VI. TongueVII. Salivary glandsVIII. Saliva and salivationIX. Digestion in the mouthX. Swallowing (deglutition)Outline of Current Lecture II. EsophagusIII. Stomach gross anatomyIV. Stomach histologyV. Mechanical digestion in the stomachVI. Chemical digestionCurrent LectureII. The esophagus has smooth muscle that aids in the one-way direction of food flow. They contract superiorly first and move inferiorly. There is an upper and lower sphincter. The upper is by the epiglottis and marks the beginning of the esophagus from the pharynx. The lower sphincter marks the end of the esophagus. Sphincters are usually located where there is a distinct change in tissue. III. The stomach is located just under the left lung. This contains the pyloric sphincter which is the end of the stomach and beginning of intestine. The stomach folds into a C-shape. The area where the C is open is called the lesser curvature. The outer curved part of the C is called the greater curvature. Within the stomach, there are folds called rugae, which increase surface area which increases digestion. IV. The histology of the stomach is simple columnar epithelium, gastric glands, and the muscularis externa. Gastric glands are mucous cells, parietal cells (secretes hydrochloric acid, intrinsic factor, ghrelin), chief cells (pepsinogen, gastric lipase), enteroendocrine cells (gastrin and other factors), and regenerative stem cells. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.V. The mechanical digestion that occurs in the stomach are the regular gentle peristaltic waves and mixing waves that produce chyme. VI. The chemical digestion that occurs is the breakdown of pepsinogen into pepsin (pH 1-3), which dissociates into proteins and peptides. Gastric lipase, which is also acidic, helps with digestion in all people, while rennin is active in an infant stomach
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