Lecture 21: The Stomach and Pancreas

Question 1

what is the shape of the stomach?

Answer 1

J-shaped organ

Question 2

where is the stomach located?

Answer 2

base of the esophagus

Question 3

where does the esophagus pass through?

Answer 3

the diaphragm via the esophageal hiatus

Question 4

what does the lower esophageal sphincter do?

Answer 4

prevents reflux

Question 5

what are the main parts of the stomach?

Answer 5

• cardia
• fundus
• body
• pylorus

Question 6

what are curvatures?

Answer 6

attachment points for omentum

lesser omentum connects to lesser curvature
greater omentum connects to greater curvature

Question 7

what does the greater omentum have?

Answer 7

• lots of adipose
• immune cells

Question 8

Answer 8

Question 9

what is the muscularis modified for?

Answer 9

Motility

has 3 layers
- inner oblique
- middle circular
- outer longitudinal

Question 10

what does the inner surface of the stomach have?

Answer 10

Rugae
- temporary folds that allow for expansion of the stomach
- important for storage function

Question 11

what is the structure of rugae?

Answer 11

folded core of submucosa with overlying mucosa

Question 12

how is the mucosa of the stomach modified?

Answer 12

the mucosa has simple columnar epithelium
- in-folding increases surface area for secretion
- the glands are permanent

Question 13

why do we need glands?

Answer 13

we need acids and enzymes for digestion, mucus for protection, hormones for regulation

Question 14

what are the gastric glands and their secretions?

Answer 14

parietal cells - secrete acid and intrinsic factor
G cells - secrete hormones (gastrin)
Chief cells secrete pepsinogen (inactive precursor of pepsin)

Question 15

what is the structure of chief cells?

Answer 15

chief cells produce enzymes

• abundant rough endoplasmic reticulum
• apical zymogen granules (contain enzymes)
• basal nucleus

Question 16

what is the structure of parietal cells?

Answer 16

parietal cells produce acid

• pump ions (H+)
• abundant mitochondria
• central nucleus
• folded structure to increase surface area

Question 17

what regulates stomach function?

Answer 17

• endocrine control
• neural control

Question 18

how does endocrine control regulate the stomach?

Answer 18

• endocrine cells in the mucosa
• gastrin and ghrelin secreted in the bloodstream

Question 19

how does neural control regulate the stomach?

Answer 19

Enteric nervous system for local reflexes

Central nervous system modulates ENS for long neural reflexes

Question 20

what type of control does chyme need from the stomach to small intestine?

Answer 20

there needs to be a controlled release of chyme from stomach into the small intestine. this is done by the pyloric sphincter

Question 21

what happens to chyme after is enters the small intestine?

Answer 21

• it requires further digestion by enzymes
• protection from acidic chyme by mucus and neutralising acid

so mucus is provided by glands in the submucosa of the duodenum and enzymes and bicarbonate are provided by the pancreas

Question 22

what is the location of the pancreas?

Answer 22

• head in C-shaped duodenum
• head toward spleen
• posterior to the stomach
• duct into duodenal lumen

Question 23

where does the pancreas sit?

Answer 23

retroperitoneal

Question 24

where is the bile duct?

Answer 24

bile duct meets the pancreatic duct and the hepatopancreatic ampulla

Question 25

where is the duodenal papilla?

Answer 25

projects into the duodenal lumen

Question 26

what is the release of the pancreas controlled by?

Answer 26

hepatopancreatic sphincter

Question 27

Answer 27

Question 28

what is the endocrine function of the pancreas?

Answer 28

• pancreatic islet alpha cells secrete glucagon
• pancreatic islet beta cells secrete insulin

Question 29

what is the exocrine function of the pancreas?

Answer 29

• acinar cells secrete digestive enzymes
• duct cells secrete bicarbonate

Question 30

what is the structure and function of pancreatic acinar cells?

Answer 30

structure:
- apical zymogen granules
- basal nucleus
- abundant rough ER

function:
- secrete enzymes

(similar to chief cells of the stomach and salivary acinar cells)