GI 2 Flashcards
1
Q
Surface mucous cells
A
- protection
2
Q
Mucous neck cells
A
- protection
- replace cells in lumen after desquamation
3
Q
Parietal cells
A
- HCl and intrinsic factor
4
Q
Chief cells
A
- Pepsinogen and gastric lipase
5
Q
Endocrine cells
A
- Somatostatin and gastrin
6
Q
Mucus
A
- lubricates/protects gastric mucosa from decrease pH
7
Q
HCl
A
- digests food
- kills bacteria
- converts pepsinogens to pepsins
8
Q
Intrinsic factor
A
- only indispensable gastric secretion required for VitB12 absorption
- binds to B12 primarily in duodenum
9
Q
Pepsinogens
A
- cleaved to pepsins by the acidic environment
10
Q
Gastrin
A
- stimulates gastric motility and HCl secretion
- decreases gastric emptying
11
Q
Somatostatin
A
- inhibits HCl secretion
12
Q
Histamine
A
- stimulates HCl secretion
13
Q
R protein
A
- protects vitamin B12 from degradation
- high affinity for B12 in acidic environment
- cleaved by trypsin in duodenum and intrinsic factor takes over
14
Q
Gherlin
A
- hormone when fasting
- acts on hypothalamus to stimulate hunger
- opposes the satiety effects of leptin and peptide YY
15
Q
Enterochromaffin (ECL) cells
A
- release histamine
- stimulates HCl secretion
16
Q
D cells (endocrine)
A
- releases somatostatin
- inhibits gastrin and HCl release
17
Q
G (endocrine) cells
A
- releases gastrin
- stimulate parietal cells to release HCl
18
Q
Stimulate secretion of Gastric HCl
A
- PNS
- Ach
- gastrin
- histamine
(*chief cell - pepsinogen production stimulated by vagus, gastrin)
19
Q
Inhibit secretion of Gastric HCl
A
- Secretin (G cells)
- Somatostatin (Parietal, G cells)
- GIP (parietal cells)
- Peptide YY (indirect)
- Prostaglandins (ECL, G cells)
20
Q
3 Phases of Gastric Secretion
A
- Cephalic “anticipation”
- Gastric
- Intestinal
21
Q
Cephalic phase
A
- anticipation
- chemo and mechanoreceptors on tongue and buccal canal, nasal mucosa
- vagal effects –> gastrin, acid, enzymes
22
Q
Gastric phase
A
- food in stomach
- vagal effects –> gastrin, acid, enzymes, pH changes
- intestinal –> highly acidic chyme enters duodenum
- composition of chyme important –> feedback to HCl secretion and decrease gastric emptying
23
Q
Intestinal phase
A
- intestinal mucosal secretions (mucus, hormomes, enzymes) and secretions from pancreas, liver, and indirectly - gallbladder (travels down hepatic duct through sphincter of Oddi) to enter duodenum
24
Q
Crypt cells
A
- Have CFTR which secretes Cl- into lumen of gut
- Na+ and H20 follow
- stimulated by secretin
25
Paneth cells
- small intestinal mucosa
| - host defense, secreting Zn and lysozymes that attack bacteria
26
Goblet cells
- small intestinal mucosa
| - secrete mucus
27
Endocrine cells of small intestine
- secrete gastrin, CCK, secretin, GIP, motilin, serotonin
28
Brunner's Glands
- small intestinal mucosa (duodenum before Sphincter of Oddi)
- secrete thick mucus and proteases
- stimulated by secretin
- vagus --> inhibited by SNS
29
What is the source of enterokinase?
- cells in duodenum
30
What are the endocrine functions of the pancreas?
- secrete insulin, glucagon, and somatostatin which affects gastric secretion and motility in addition to their other systemic effects
31
What are the exocrine functions of the pancreas?
- enzyme secretions
| - electrolyte secretions
32
Pancreatic acinar cells
- located outside
| - produce enzymes
33
Pancreatic centroacinar cells
- located innermost cells
| - secrete and electrolyte solution rich in HCO3-
