GI Physiology: First Aid & Ninja Nerd Because That Guy Sucks Flashcards
(232 cards)
1
Q
secreted by G cells in the antrum of stomach, duodenum
A
gastrin
2
Q
increases H+ secretion
A
gastrin
3
Q
increases the growth of gastric muscosa
A
gastrin
4
Q
increases gastric motility
A
gastrin
5
Q
upregulated by stomach distension/alkalinization, animo acids, peptides, vagal stimulation via GRP
A
gastrin
6
Q
down regulated by a pH less than 1.5
A
gastrin
7
Q
upregulated by chronic proton pump inhibitor use
A
gastrin
8
Q
secreted by D cells in pancreatic islet and GI mucosa
A
somatostatin
9
Q
decreases gastric acid and pepsinogen secretion
A
somatostatin
10
Q
decreases pancreatic and small intestine fluid secretion
A
somatostatin
11
Q
decreases gallbladder contraction
A
somatostatin
12
Q
decreases insulin and glucagon release
A
somatostatin
13
Q
upregulated by acid
A
somatostatin
14
Q
downregulated by vagal stimulation
A
somatostatin
15
Q
inhibits secretion of various hormones, encourages homeostasis
A
somatostatin
(somato-stasis)
16
Q
secreted by I cells in the duodenum and jejunum
A
cholecystokinin (CCK)
17
Q
increases pancreatic secretion
A
CCK
18
Q
increases gallbladder contraction
A
CCK
19
Q
decreases gastric empyting
A
CCK
20
Q
increases spinchter of Oddi relaxation
A
CCK
21
Q
upregulated by fatty acids, amino acids
A
CCK
22
Q
acts on neural muscarininc pathways to cause pancreatic secretion
A
CCK
23
Q
secreted by S cells in the duodenum
A
secretin
24
Q
increases pancreatic HCO3- secretion
A
secretin
25
decreases gastric acid secretion
secretin
26
increases bile secretion
secretin
27
upregulated by acid, fatty acids in lumen of duodenum
secretin
28
allows pancreatic enzymes to function by neutralizing the gastic acid in the duodenum via increased bicarb production
secretin
29
secreted by the small intestine
motilin
30
produces migrating motor complexes (MMCs)
secretin
31
upregulated in a fasting state
| 2
motilin
ghrelin*
| *don't think this has been discussed yet, FA pg 380
32
erythromycin can be used to stimulate peristalsis because it's a [...] receptor agonist
| not sure if he discussed this, but useful clinical correlation i think
motilin
| FA pg 380
33
increases smooth muscle relaxation and spinchter relaxation
NO and VIP
34
secreted from parasympathetic ganglia in spinchters, gallbladder, small intestine
VIP
35
increases intestinal water and electrolyte secretion
VIP
36
secreted by parietal cells of stomach
| 2
gastric acid
intrinsic factor
37
upregulated by histamine, gastrin, and vagal stimulation
| 2
gastric acid
intrinsic factor
38
downregulated by somatostatin, GIP, prostaglandin, and secretin
| 2
gastric acid and intrinsic factor
39
vitamin B12 binding protein
intrinsic factor
40
secreted by chief cells of stomach
pepsin
41
digests proteins
pepsin
42
upregulated by vagal stimulation (Ach), local acid
pepsin
43
pepsinogen is converted to pepsin in the presence of
H+
44
secreted by muscosal cells in the stomach, duodenum, salivary glands, and pancreas
and Brunner glands in the duodenum
bicarbonate
45
neutralizes acid
bicarb
46
upregulated by pancreatic and biliary secretion with secretin
bicarb
47
trapped in the mucus that covers the gastric epithelium
bicarb
48
autoimmune destruction of parietal cells can cause
chronic gastritis and pernicious anemia
(lack of gastric acid and intrinsic factor to bind B12)
## Footnote
FA pq 381
49
somatostatin analog used to treat acromegaly, carcinoid syndrome, VIPoma, and variceal bleeding
octreotide
| throwing it back to RC haha
## Footnote
FA pg 380
50
secreted by K cells in duodenum and jejunum
glucose dependent insulinotropic peptide
| GIP
51
exocrine: decreases gastric H+ concentration
endocrine: increases insulin release
glucose dependent insulinotropic peptide
| GIP
52
upregulated by fatty acids, amino acids, and oral glucose
glucose dependent insulinotropic peptide
| GIP
53
gastin increases acid production **primarily** through its effects on [...] cells, leading to histamine release
enterochromaffin like cells (ECL)
54
what layer of the alimentary canal contains the myenteric plexus?
muscularis externa
55
what layer of the alimentary canal contains the submucosal plexus?
submucosa
56
if a structure has serosa it is
| intra or retroperitoneal
intraperitoneal
57
if a structure has adventitia it is
| intra or retro peritoneal
retroperitoneal
58
for food to move down the gut, the circular muscles need to [...] and the longitudinal muscles need to [...]
| contract/relax
1. contract
2. relax
59
ascending fibers in the myenteric plexus work on the [...] side of the bolus to push it forward
| oral or aboral
oral
60
what neurotransmitters cause the circular muscles to contract
Ach
61
what neurotransmitters cause the longitudinal muscles to relax?
NO and VIP
62
the descending fibers work on the [...] side of the bolus to open and relax the next segment
| oral/aboral
aboral
63
what neurotransmitters relax the circular muscles?
NO and VIP
64
what neurotransmitters contract the longitudinal muscle fibers?
Ach
65
chemoreceptors are located in the [...] plexus
| submucosal or myenteric
submucosal
66
how to chemoreceptors stimulate blood vessels?
cause dilation, more blood flow, increased absorption of nutrients
67
how to chemoreceptors stimulate the glands in the submucosal plexus?
stimulates glands to secrete secretions into lumen to help digest food
68
foods rich in fatty acids and H+ stimulate the release os secretin. what 2 functions does secretin have?
1. stimulates hepatocytes to produce bile
2. stimulates duct cells in acini of pancreas to release bicarb to neutralize acid
69
food rich in protein stimulates the I cells to produce CCK. what are the 4 functions of CCK?
1. gall bladder contractions
2. potentiate secretins action on liver
3. stimulates pancreatic ductal cells to produce proteases, lipases, and amylase
4. relaxes spinchter of Oddi to allow more bile and pancreatic juices into duodenum
70
food rich in glucose activates K cells to procude GIP. what is the function of GIP?
stimulates pancreas to produce insulin, inhibiting gastric motility
71
how does the sympathetic nervous system effect the process of the GI tract?
overall: inhibits
decreases motility, blood flow, secretions, absorption
**however**, contracts spinchters
72
how does the parasympathetic nervous system effect the process of the GI tract?
overall, induces it
increases motility, secretions, and absorption
**however**, relaxes spinchters
73
GLP is secreted by what cells?
L cells in the ileum and large intestine
74
effects of GLP-1 on stomach
reduces gastric empyting, acid secretion, and motility
75
describe the vagovagal reflex
* chemoreceptor/stretch receptors transmist signal via afferent fibers to DNV of PNS
* stimulates DNV, sends signal via efferent fibers to activate submucosal and myenteric plexus
| parasympathetic response
76
the vagovagal reflex allows for [...] of the stomach
compensation
77
describe the entero-gastric reflex
* chemo/stretch receptors send signal to prevertebral ganglion (SNS)
* inhibits secretions, dilation, constriction of pyloric spinchter
| sympathetic response
78
the entero-gastric in an inhibitory reflex triggered by what 2 things?
* too much acid in intestines
* too much distension of stomach
79
describe the defecation reflex
* distension of colon activates chemo/stretch receptors, send signal to sacral plexus (S2-S4)
* sacral plexus sends signal to pelvic splanchinic nerves, which innervate the submucosal and myenteric plexus
* submucosal and myenteric plexus intiate peristaltic waves in descending colon, sigmoid, and rectum
80
list the layers of the alimentary canal
| 4
mucosa, submucosa, muscularis externa, serosa
81
where is the Auerbach plexus located?
| myenteric
muscularis externa
82
where is the Meissner's plexus found?
submucosa
83
ascending fibers cause the contraction of the [...] and the relaxation of the [...] to push food forward
| muscle types
1. circular muscles
2. longitudinal muscles
84
what receptor is the most powerful stimulator of the submucosal plexus?
chemoreceptors
85
what is the postganglionic cells bodies of the parasympathetic nervous system?
submucosal and myenteric plexus
86
which long reflex is activated when there is a high amount of acid in the intestines?
entero-gastric reflex
87
cells located in the antrum of the stomach
| 2
D cells
G cells
88
the vagus nerve can act directly on what cells in the stomach?
D cells and G cells
89
Ach binds to an M3 receptor on antral D cells, inhibiting the release of
somatostatin
| results in an increase of pepsin and HCl secretion
90
GRP released by the vagus nerve binds to receptors on the G cells to stimulate the release of
gastrin
| results in increase of pepsin and HCl secretion
91
gastrin binds to CCK2 receptors on parietal cells, resulting in
* increased intracellular Ca++
* stimulates proton pump, pushing H+ ions out into lumen and brings K+ in
| increases concentration of H+ in lumen
92
Ach binds to M3 receptors on parietal cells resulting in
* increased intracellular Ca++
* stimulates proton pumps
93
Histamine binds to the H2 receptor on parietal cells to stimulate
HCl secretion
94
prostaglandin binds to PGE2 receptors on parietal cells to inhibit
inhibits HCl production
95
somatostatin binds to SST receptors on parietal cells to inhibit
proton pumps
96
parietal cells are stimulated by
| 3
gastrin
Ach
histamine
| all end result in increased HCl
97
parietal cells are inhibited by
| 2
prostaglandin
somatostatin
| inhibit HCl production/proton pumps
98
chief cells are stimulated by
| 4
gastrin
histamin
Ach
secretin
| stimulate release of pepsinogen
99
stimulate enterochromaffin like cells (ECL)
| 2
Ach
gastrin
| stimulates release of histamin
100
inhibit ECLs
| 1
somatostatin
| inhibit release of histamine
101
the secretion of gastrin stops when the pH of gastric content is below
2
102
is released as a result of contact of acidic chyme with the duodenmal mucosa
secretin
103
stimulated by gastric distension and inhibited by presences of excess acid in pyloric antrum
gastrin
104
stimulates insulin secretion from pancreas
gastrin
105
the cephalic phase of gastric secretion is controlled by the [...] nerves
vagus
106
3 phases of gastric secretion
* cephalic (1/3 of secretions)
* gastric (2/3)
* intestinal (very little)
107
describe how contraction moves through the stomach
starts at cardia -> fundus -> antrum -> pylorus
108
what is it called when 25% of the chyme is pushed back into the corpus of the stomach to continue mixing?
retropulsion
109
secrete intrinsic factor important for absorbing vitamin B12
parietal cells
110
when high peptone concentration are sensed by duodenal G cells, the release gastrin into the blood to the parietal cells in the corpus, stimulating the release of
more H+ ions into lumen
| peptones are basic
111
endocrine secretions of the pancreas
insulin
glucagon
112
exocrine secretions of the pancreas
| general
* fluid: bicarb, H20, elctrolytes
* digestive enzymes
| secretions that aid in digestion
113
pancreatic cells that secrete enzymes, Na, Cl and some fluids
acinar
114
pancreatic cells that modify the fluid secreted by acinar cells, secrete bicarb, and add water to pancreatic juice
ductal cells
115
fluid secreted by the pancreas contains [...] to neutralize the acidic fluid from the stomach
bicarb
116
describe the flow rate of pancreatic fluid in a fasted state
low flow
* high Cl-
* low bicarb
117
describe the flow rate of pancreatic fluid in a fed state
high flow
* low Cl-
* high bicarb
118
the Na and K concentrations of pancreatic fluid are always
| isotonic, hypotonic, hypertonic
isotonic
| same as plasma
119
why is bicarb higher in high flow states?
* bicarb is secreted in the small ducts and reabsored in the large ducts
* reabsorption is ineffective at high flow rates
120
what hormone is the main stimulus for HCO3- release by the pancreas?
secretin
| released in response to increased H+ in duodenum
121
secreted by S cells in duodenum
secretin
122
major stimuli for release of pancreatic enzymes from acinar cells
CCK
| also Ach via vagovagal reflex
123
* local GI tract reflex circuit
* both afferent and efferent fibers found within the vagus nerve
vagovagal reflex
124
H+, amino acids, and fats in the duodenum activate the [...] reflex and stimulate pancreas to release enzymes
vagovagal
125
pancreatic enzyme that digests starch
a-amylase
126
hydrolyzes starch at a1-4 linkages
a-amylase
127
* secreted by the pancreas in the active form
* functional in small intestine
* elevated in acute pancreatitis
a-amylase
128
breaks down amylopectin and amylose
a-amylase
129
what is different about salivary amylase vs. pancreatic?
salivary amylase has an optimal pH of 6 and is inactivated in the stomach
130
only [...] are absorbed by the intestine
| carbohydrate form
monosaccarides
131
after amylase intital breaks down amylopectin and amylose, further digestion occurs at
intestinal brush border by oligosaccharide hydrolases
| maltase, sucrase, lastase, etc
132
rate limiting step of carbohydrate digestion
breakdown at the intestinal brush border
133
glucose
fructose
galactose
| are all...
monosaccharides
134
hydrolyzes 1 and 3 bonds of triglycerides into fatty acids and monoglycerides
pancreatic lipase
135
pancreatic enzymes for fat digestion
| 3
colipase
lipase
phospholipase
136
assists pancreatic lipase
colipase
137
* secreted as inactive pro-phospholipase A2
* activated by trypsin
phospholipase A2
138
pancreatic enzymes that aid in protein digestion
| 4 big ones
* trypsin
* chymotrypsin
* elastase
* carboxypeptidases
139
pancreatic enzymes that aid in protein digestion are all secreted as
zymogens
| inactive proenzymes
140
trypsin is secreted as inactive trypsinogen and activated by [...]
enterokinase
| brush border enzyme
141
once activated by enterokinase, [...] activates all other protein enzymes
trypsin
142
when pancreatic secretion is blocked, auto-activation of trypsin leads to auto-digestion of pancreatic enzymes causing
| clinical correlate
acute pancreatitis
| increased amylase and lipase
143
* found in the gastric glands
* secrete HCl (gastric acid)
parietal cells
144
* maintains very low pH in stomach
* provides protection against infectious agents
* denatures proteins for breakdown/absorption
gastric acid
145
stomach cells are protected from gastric acid by
mucous and bicarb secreted by neck cells
146
hormone from G cells in antrum of stomach
gastrin
147
binds to CCKb receptor on parietal cells to trigger them to release HCl
gastrin
148
activates ECL cells which produce histamine to stimulate parietal cells to release more HCl
gastrin
149
activates G cells to produce gastrin via binding on M3 receptors
Ach
| from vagus
150
the vagus can release [...] to stimulate G cells to produce gastrin
GRP
151
3 stimuli for acid procdution
1. direct gastrin
2. indirect gastrin (histamine mediated)
3. vagus nerve (Ach and GRP)
152
* muscarinic blocker
* blunts parietal cells stimulation by Ach
* but does not block GRP so not great for acid control
atropine
153
* necessary for B12 absorption
* released by parietal cells
intrinsic factor
154
block H+ secretion by parietal cells
proton pump inhibitors
| omeprazole, pantoprazole
155
H+ that is pumped out of parietal cells is formed from what enzyme?
carbonic anhydrase
156
H+ formed by carbonic anhydrase causes HCO3- to be pumped out of the cell. The increased serum HCO3- after meals if referred to as the
alkaline tide
157
how does vomiting cause metabolic alkalosis?
* increased production of HCl
* more HCO3- is generated during the production of HCl
| hypochloremia as well
158
a low urinary chloride indicates
vomiting
| loss of Cl- in gastric secretions
159
stimulate secretion of HCl by parietal cells
| 3
Ach
gastrin
histamine
160
inhibit secretion of H+ by parietal cells
| 2
somatostatin
prostaglandins
161
work via Gq proteins with IP3/Ca second messenger system
| 2
Ach
Gastrin
162
work via Gs/i and cAMP second messenger system
histamine, somatostatin, PGs
163
Gq proteins
| 2
Ach
Gastrin
164
Gs/i proteins
| 3
histamin
prostaglandins
somatostatin
165
H2 blockers
* cimetidine
* ranitidine
* fomotidine
* nizatidine
| decrease HCl production
166
PGE1 analog that blunts acid production
misoprostol
167
released by chief cells to digest proteins
pepsin
168
chief cells release pepsinogen, it is activated to pepsin by
H+
169
works best at a pH of 1-3
pepsin
170
what stimulates the release of pepsin?
vagus nerve
171
* major hormone that stimulates acid secretion in stomach
* produced by antral G cells
gastrin
172
gastrin is secreted into the [...] vein blood and takes physiologic action on [...] cells
portal vein
parietal
173
found in glands of lamina propria in the mucosa layer in **antrum**
| cell type
G cells
174
found in glands of lamina propria in the mucosa layer in **body**
| cells type
parietal cells
175
stimulates H+ secretion by parietal cells
gastrin
176
effects of gastrin
| 3
* stimulates H+ secretion by parietal cells
* stimulates growth of gastric mucosa
* increases gastric motility
| gets stomach ready for digestion
177
gastrin stimulates [...] cells to release histamine, which stimulates parietal cell
ECLs
178
parietal cell receptors
| 3
* histamine (most important)
* gastrin
* Ach (vagus)
179
most important way by which HCl secretion is stimulated
indirect gastrin pathway
gastrin -> ECL -> histamine -> parietal cells
180
stimuli for increased gastrin secretion
| 4
* stomach distension
* alkalinazation
* amino acids
* vagal stimulation (GRP)
181
gastrin secretion is inhibited by
* low pH
* somatostatin
182
atropine does not block [...] mediated gastrin release
GRP
183
phenylalanine and tryptophan are potent stimuli for [...] release
gastrin
184
* tumors that occur in duodenum or pancreas
* cause excessive acid secretion
* cause hypertrophy/hyperplasia of mucosa
| clinical correlate
gastrinoma
| gastrin secreting tumors
185
* abdominal pain that improves with food
* chronic diarrhea
* ulcers in distal duodenum refractory to PPI therapy
* heartburn
| clinical correlate
zollinger-ellison syndrome
from gastrinoma
186
* extremely high gastrin levels
* increased gastrin after secretin administration
| would indicated what disease?
gastrinoma
187
elevated [...] levels are a typical finding of pernicious anemia
gastrin
188
* hormone for gallbladder contraction
* stimulates secretion of pancreatic enzymes
CCK
189
released by I cells in the duodenum and jejunum
CCK
190
how does CCK stimulate pancreatic enzyme secretion?
* CCK receptors in vagus nerves
* CCK stimulates vagus -> Ach -> pancreas
191
* relaxes spinchter of Oddi
* inhibits gastric empyting
CCK
192
major stimuli for CCK release
| 3
* fatty acids
* monoglycerides
* amino acids
| not triglycerides
193
hormone to raise pH in small intestine
secretin
194
released by S cells of duodenum
secretin
195
released in response to H+ in duodenum and fatty acids in duodenum
secretin
196
increases HCO3- secretion by pancreatic duct cells
secretin
| neutralizes gastric acid, allows pancretic enzymes to function
197
inhibits gastic H+ secretion by inhibiting gastrin release
secretin
198
increases bile production
secretin
199
* promotes pancreatic flow
* water secreted with bicarb and flushes pancreatic enzymes into intestines
secretin
200
inhibits most GI hormones
somatostatin
201
released by D cells throughout GI tract
somatostatin
202
major stimuli for somatostatin release
low pH
203
major inhibitor for somatostatin release
vagus nerve
| thinking about eating decreases somatostatin to prepare digestive tract
204
how does somatostatin regulate digestion/acid secretion
| describe both fed and fasted states
fed: food in stomach -> decreases somatostatin -> hormones are released
fasted: acid in stomach -> increases somatostatin -> hormones inhibited
205
analog of somatostain used in upper GI varices bleeding
octreotide
| reduces splanchnic blood flow
206
used to treat carcinoid syndrome,
acromegaly,
gastrinoma
octreotide
207
* stimulates insulin release from pancreas
* blunts H+ secretion
GIP
208
released by K cells of duodenum/jejunum
GIP
209
what stimulates the release of GIP?
| 3
glucose
fatty acids
amino acids
| **only hormone released in response to fats, protein, and carbs**
210
why is oral glucose metabolized faster than IV glucose?
IV glucose does not stimulate GIP release
211
* synthesized in neurons
* released in response to action potential onto target cells
VIP
212
* causes relaxation of the smooth muscle
* raises pH
* inhibits gastric H+ secretion
VIP
| similar to secretin
213
how does VIP raise pH?
stimulates pancreatic HCO3- secretion
214
important for relaxation of lower esophageal spinchter
VIP
215
* watery diarrhea (tea colored, odorless)
* hypokalemia
* achlorhydria
| clinical correlate
VIPoma
| WDHA syndome
216
rare VIP secreting tumors in pancreatic islet cells
VIPoma
217
* adult 30-50 years old
* long standing watery diarrhea without blood or pus
* no response to diet change
* high pH in stomach on EGD
* elevated VIP on serum testing
| clinical correlate
VIPoma
218
* released by cells in stomach, intestines, and colon
* promotes motility in fasting state
motilin
219
highest levels of motilin are found
| fed/fasted state
between meals
| fasted
220
binds motilin receptors and used to treat gastroparesis
erythromycin
221
secreted in antrum
gastrin
222
secreted in duodenum and jejunum
| 3
CCK
secretin
GIP
223
secreted throughout GI tract
| 3
motilin
VIP
somatostatin
224
major player in cephalic phase of digestion
vagus nerve
225
stimulated by thought, sight, and smell of food
vagus
226
in the cephalic phase, the vagus nerve primarily stimulates
acid secretion by triggering gastrin release
227
major player in gastric phase
stomach
228
how does the stomach trigger acid secretion in the gastric phase?
gastric distension, increased gastric pH and amino acids trigger gastrin release
229
major player in intestinal phase of digestion
small intestine
230
how does the small intestine trigger CCK, secretin, and GIP release in the intestinal phase?
presence of fatty acids, amino acids, and H+ trigger this release
231
what does CCK do during the intestinal phase?
| 3
* gallbladder contraction
* release of pancreatic enzymes
* relax spinchter of Oddi
232
what does secretin do during the intestinal phase?
| 2
* release bicarb
* inhibit H+ secretion
