GI I

Question 1

digestive system functions

Answer 1

• derive molecules from food necessary for maintenance, growth, and energy
• break down macromolecules into small molecules that are easily absorbed
• absorb water, vitamins, and minerals
• form a protective barrier between GI tract contents and inside of body

Question 2

four principle layers

Answer 2

• mucosa
• submucosa
• muscularis externa
• serosa or adventitia

Question 3

mucosa

Answer 3

• lining epithelium
• lamina propria
• muscularis mucosae
• functions are protection, absorption, and secretion

Question 4

submucosa

Answer 4

• dense irregular CT with vessels
• glands in esophagus and duodenum
• submucosal (meissner’s plexus)

Question 5

muscularis externa

Answer 5

• inner circular and outer longitudinal SM

- myenteric plexus

Question 6

serosa

Answer 6

-has mesothelium attached and is attached to organs, adventitia is just CT

Question 7

types of papillae in oral cavity

Answer 7

• filiform-no taste buds and small
• fungiform-few taste buds
• circumvallate- big and lots of taste buds
• foliate-kitty cats-many taste buds

Question 8

esophagus

Answer 8

10 in (25 cm) long muscular tube

• mucosa is stratified squamous
• esophageal cardiac glands at either end
• submucosa has esophageal glands proper
• muscularis externa- upper third is skeletal, middle is mixed skeletal and smooth, lower third is smooth
• adventitia above diaphragm and serosa below
• UES is circular skeletal muscle under voluntary and reflexic control
• LES is physiological thickened smooth muscle

Question 9

stomach

Answer 9

• 4 regions at gross level-cardia, fundus, body, and pylorus
• rugae are temporary longitudinal folds of mucosa and submucosa
• 3 histological regions- cardia, fundus/body, pylorus

Question 10

fundus mucosa

Answer 10

• has pit, isthmus, neck, and base

- there are surface mucous cells, mucous neck cells, parietal cells, chief cells

Question 11

cardiac glands

Answer 11

• short pits
• short coiled glands
• most glands produce mucous
• a few lysozyme and HCl producing cells

Question 12

gastric/fundic glands

Answer 12

• medium pits
• long straight glands
• four major cell types:
• mucous neck cells
• parietal (oxyntic)
• chief cells
• enteroendorcrine

Question 13

pyloric glands

Answer 13

• very long pits
• short slightly coiled glands
• mostly mucous cells with a few parietal cells
• enteroendocrine cells

Question 14

surface mucous cells

Answer 14

• form a secreting sheet on surface and in gastric pit

- secrete an alkaline, viscous mucous with a high bicarbonate content that protects the stomachs surface

Question 15

mucous neck cells

Answer 15

• secrete a soluble or mobile mucous

- occur in small groups or singly between parietal cells in the neck of gastric glands

Question 16

parietal cells

Answer 16

• secrete HCl and intrinsic factor
• large eosinphilic cells found in the middle and upper part of the gastric gland
• Ach, gastrin, histamine receptors stimulate acid secretion
• zantac and tagamet are histamine H2 receptor antagonists they also get intrinsic factor and can hurt B12 absorption
• prilosec hits H/K ATPase instead and doesn’t affect intrinsic factor

Question 17

chief cells

Answer 17

• typical serous cells
• synthesize and secrete pepsinogens and lipases
• found in the basal half of gastric glands

Question 18

enteroendocrine cells

Answer 18

• produce gastrin, somatostatin, and ghrelin
• occur singly or in groups of different varieties at the base of gastric glands
• endocrine and paracrine signaling