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The Esophagus, Stomach and Small Intestine

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1 The Esophagus, Stomach and Small Intestine

2 The Esophagus Gross anatomy – muscular tube
Begins as a continuation of the pharynx Joins the stomach inferior to the diaphragm Cardiac sphincter – closes lumen to prevent stomach acid from entering esophagus

3 The Esophagus Microscopic anatomy
Epithelium is stratified squamous epithelium When empty – mucosa and submucosa in longitudinal folds Mucous glands – primarily compound tubuloalveolar glands Muscularis externa Skeletal muscle first third of length Adventitia – most external layer

4 Microscopic Structure of the Esophagus
Figure 22.17a, b

5 1)Which layer of the digestive tract is responsible for the peristaltic waves that propel materials from one portion to another? A)submucosa B) serosa C)muscularis externa D) mucosa

6 The Stomach Site where food is churned into chyme
Secretion of pepsin begins protein digestion Functions under acidic conditions Food remains in stomach approximately 4 hours

7 The Stomach Figure 22.18a

8 Medial to both midclavicular lines and superior to the subcostal plane lies the A)pyloric sphincter. B) cecum. C)appendix. D) jejunum.

9 Another name for serosa is
A)adventitia. B) visceral peritoneum. C)serous gland. D) mucosa.

10 The Stomach Figure 22.18b

11 Microscopic Anatomy of the Stomach
Muscularis has three layers Circular and longitudinal layers and oblique layer Epithelium is simple columnar epithelium Mucosa dotted with gastric pits Gastric glands – deep to gastric pits

12 Microscopic Anatomy of the Stomach
Gastric glands of fundus and body Mucous neck cells Secrete a special mucus Parietal (oxyntic) cells Secrete hydrochloric acid and gastric intrinsic factor Chief (zymogenic) cells Secrete pepsinogen

13 2)Which of the following choices correctly pairs a type of cell in the stomach with its secretion?
A)chief cell; pepsinogen B)parietal cell; pepsinogen C)enteroendocrine; hydrochloric acid D)parietal cell; mucus

14 The Stomach – Microscopic Anatomy
Figure 22.19a–d

15 The Small Intestine – Gross Anatomy
Longest portion of the alimentary canal Site of most enzymatic digestion and absorption Three subdivisions Duodenum Jejunum Ileum

16 The Duodenum Receives digestive enzymes and bile
Main pancreatic duct and common bile duct enter duodenum Sphincters control entry of bile and pancreatic juices

17 The Duodenum and Related Organs
Controls flow of pancreatic and bile fluids into the duodenum Figure 22.20

18 What is the function of the hepatopancreatic sphincter?
A) It controls the entry of bile and pancreatic juices into the alimentary canal. B) It inhibits defecation in the upper alimentary canal while the anal sphincters do the same in the lower regions. C) As it contracts, it squeezes pancreatic secretions into the duodenum. D) It prevents the movement of bile into the gallbladder.

19 The Small Intestine – Microscopic Anatomy
Modifications for absorption Circular folds (plicae circulares) Transverse ridges of mucosa and submucosa Villi Finger-like projections of the mucosa Covered with simple columnar epithelium Microvilli Further increase surface area for absorption

20 Histology of the Intestinal Wall
Absorptive cells Uptake digested nutrients Goblet cells Secrete mucus that lubricates chyme Enteroendocrine cells Secrete hormones Intestinal crypts Epithelial cells secrete intestinal juice

21 The Small Intestine – Structural Features
Figure 22.21a–d

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