GI, Topnotch Flashcards
1
Q
Basic layers of the GI tract
A
1) Mucosa 2) Submucosa 3) Muscularis 4) Serosa
2
Q
GI Mucosa: Layers
A
1) Epithelium 2) Lamina propria 3) Muscularis mucosa
3
Q
GI Mucosa: Layer with blood vessels
A
Lamina propria
4
Q
Layer of GIT: Contains glands and blood vessels
A
Submucosa
5
Q
GI Muscular layers
A
ICOL 1) Inner circular 2) Outer longitudinal
6
Q
GI Muscular layers: Decreases diameter
A
Inner circular
7
Q
GI Muscular layers: Shortens segment
A
Outer longitudinal
8
Q
GI layer: Layer deficient in esophagus
A
Serosa
9
Q
GI Submucosal plexus
A
Meissner’s plexus
10
Q
GI Myenteric plexus
A
Auerbach’s plexus
11
Q
GI Submucosal plexus, function
A
Secretion, absorption, contraction
12
Q
Esophagus: Strongest layer
A
Mucosa
13
Q
Small intestine: Strongest layer
A
Submucosa
14
Q
Stomach: Muscle layers
A
1) Inner oblique 2) Middle circular 3) Outer Longitudinal
15
Q
Myenteric plexus: Mainly excitatory except at (2)
A
1) Pyloric sphincter 2) Ileocecal valve
16
Q
PSY innvervation: Esophagus to upper large intestine
A
Vagus
17
Q
PSY innvervation: Lower large intestine to anus
A
Pelvic
18
Q
Gastrin: Source
A
G cells in antrum
19
Q
Gastrin: Inhibited by
A
1) H+ 2) Somatostatin
20
Q
Gastrin: Action
A
1) Increases H+ 2) Stimulates growth of gastric mucosa
21
Q
Gastrin: Location of receptors
A
1) Parietal cells 2) Enterochromaffin cells
22
Q
Secretin: Source
A
S cells in duodenum
23
Q
Secretin: Stimulus
A
1) H+ 2) Fatty acids
24
Q
Secretin: Action
A
1) Inc pancreatic bicarbonate 2) Inc biliary bicarbonate 3) Decrease effect of gastrin
25
Cholecystokinin: Source
I cells in duodenum and jejunum
26
Cholecystokinin: Stimulus
1) Monoglycerides and fatty acids 2) Peptides and amino acids
27
Cholecystokinin: Action
1) Gallbladder contraction 2) Sphincter of Oddi relaxation 3) Pancreatic enzyme and HCO3 secretion 4) Inc growth of exocrine pancreas and gallbladder 5) Inhibits gastric emptying
28
GIP: Source
K cells in duodenum
29
GIP: Stimulus
1) ORAL glucose 2) Fats 3) Amino acids
30
GIP: Action
1) Inc insulin secretion 2) Inhibits gastric emptying
31
Motilin: Source
M cells in duodenum and jejunum
32
Motilin: Stimulus
Fasting
33
Gastrin: Most potent stimuli
1) Phenylalanine 2) Tryptophan
34
GI hormones: Neurocrine from vagus to gastrin
GRP/bombesin
35
GI hormones: An incretin
1) GIP 2) GLP-1
36
GI hormones: Responsible for inter digestive myoelectric complex
Motilin
37
Pancreatic polypeptide: Secreted by pancreas in response to
CHO, CHON, and lipids
38
Pancreatic polypeptide: Inhibits
Pancreatic HCO3 and enzymes
39
Enteroglucagon: Stimulus
Hypoglycemia
40
GLP-1: Source
L cells
41
GLP-1: Action
Stimulates insulin secretion
42
Secreted by cells throughout GIT in response to H+
Somatostatin
43
Somatostatin: Action
Inhibits release of all GI hormones
44
Secreted by mast cells of gastric mucosa
Histamine
45
Histamine: Action
1) Inc H+ secretion 2) Potentiates gastrin action 3) Potentiates Ach action
46
GI neurotransmitters that cause smooth muscle contraction
1) Ach 2) Enkephalins/opiates 3) Substance P
47
Satiety center
Vuchog Ventromedial hypothalamus
48
Hunger center
Lamon Lateral hypothalamus
49
Sends signals to satiety/hunger centers
Arcuate nucleus
50
Release POMC
Anorexogenic neurons
51
Release Neuropeptide Y
Orexigenic neurons
52
Stimulates anorexigenic neurons and inhibits orexigenic neurons
Leptin
53
Inhibits anorexigenic neurons
Ghrelin
54
Inhibits Ghrelin
Peptide YY
55
GI contraction: Due to sub threshold slow waves
Tonic
56
Tonic contractions are seen in
GI sphincters
57
GI contraction: Due to spike potentials
Phasic
58
Slow waves vs spike potentials: True action potential
Spike potentials
59
Slow waves are generated by this intrinsic GI pacemaker
Interstitial cells of Cajal
60
Slow waves: Slowest frequency at
Stomach
61
Slow waves: Fastest frequency at
Small intestines
62
Slow waves: Depolarization due to __ influx
Na
63
Spike potentials: Depolarization due to __ influx
Ca
64
Spike potentials: Threshold
-40mV
65
Most common stimulus for GI peristalsis
Distention of gut
66
Reflex: Muscles upstream contract, muscles downstream exhibit receptive relaxation
Myenteric reflex
67
Cannon's law of the gut
Peristalsis always proceeds in the oral-aboral direction
68
Effectual peristalsis requires
An active myenteric plexus
69
T/F: Chewing can be involuntary
T
70
Swallowing center
Medulla
71
Phases of swallowing
1) Oral phase 2) Pharyngeal phase 3) Esophageal phase
72
Phases of swallowing: Oral phase is triggered by presence of food at
Pharynx
73
Phases of swallowing: T/F Oral phase is voluntary
T
74
Phases of swallowing: Relaxation of UES
Pharyngeal phase
75
Phases of swallowing: Prevents aspiration
Pharyngeal phase
76
Phases of swallowing: Closes UES
Esophageal phase
77
Esophageal peristaltic contraction: Creates pressure behind bolus of food
Primary
78
Esophageal peristaltic contraction: Clears oesophagus of remaining food
Secondary
79
Esophageal peristaltic contraction: Accelerated by gravity
Primary
80
Esophageal peristaltic contraction: Relaxation of LES is mediated by
Vagus nerve using VIP
81
Stomach: 2 functional divisions
1) Orad stomach: Upper 2/3 2) Caudad: Lower 1/3 + antrum
82
Stomach: Capacity once fully relaxed
0.8-1.5L
83
Stomach, functional divisions: Thin-walled
Orad
84
Stomach, functional divisions: Thick-walled
Caudad
85
Receptive relaxation of orad stomach is mediated by
Vagus nerve using Ach
86
Increases distensibility of orad stomach
CCK
87
Caudad stomach: Frequency of contraction
3-5x per minute
88
Caudad stomach: Frequency of additional contractions
Every 90 minutes
89
Caudad stomach: Additional contractions mediated by
Motilin
90
Size required to enter duodenum
Less than 1 mm3
91
Inhibitors of gastric emptying
1) CCK 2) H+ in duodenum
92
Small intestinal motility: Back-and-forth movement with no net forward motion
Segmentation contraction
93
Small intestinal motility: Propels chyme towards large intestine
Peristaltic contraction
94
Large intestine: Saclike segments due to segmental contractions
Haustra
95
Proximal colon is for
Absorption
96
Distal colon is for
Storage
97
Mass movements in the LI: Frequency
1-3x a day
98
Mass movements in the LI: Segments
Transverse colon to sigmoid colon
99
T/F Circular and longitudinal muscles are reciprocally innervated such that when 1 is contracted, the other is relaxed
T
100
Segmental vs peristaltic contraction: Haustra
Segmental
101
Stimulus for internal anal sphincter relaxation
Rectal contents
102
Reflex whereby rectal contents cause internal anal sphincter relaxation
Rectosphincteric reflex
103
Urge to defecate is felt once rectum is ___ filled
25%
104
Combustible material from feces
Methane
105
Gastroileal reflex
Food in stomach increases peristalsis in the ileum and relaxation of ileocecal sphincter
106
Gastrocolic reflex
Food in the stomach increases peristalsis in the colon and frequency of mass movements
107
Gastrocolic reflex is mediated by (3)
1) PSY nervous system 2) CCK 3) Gastrin
108
Reverse peristalsis that results in vomiting begins from what segment of the GIT
Small intestines
109
Vomiting center
Medulla (area postrema)
110
Send inputs to the vomiting center
1) Chemoreceptor trigger zone 2) Vestibular system 3) Back of throat 4) GIT
111
Average daily amount: Saliva
1L
112
Average daily amount: Gastric secretion
1.5L
113
Average daily amount: Pancreatic secretion
1L
114
Average daily amount: Bile
1L
115
Average daily amount: SI secretion
1.8L
116
Average daily amount: Brunner gland secretion
200mL
117
Average daily amount: LI secretion
200mL
118
Average daily amount: Total GIT secretion
6.7L
119
pH: Saliva
6-7
120
pH: Gastric secretion
1-3.5
121
pH: Pancreatic secretion
8-8.3
122
pH: Bile
7.8
123
Submucosal duodenal glands
Brunner's glands
124
Salivary enzyme: Initial digestion of starch
Ptyalin (α-amylase)
125
Salivary enzyme: Initial digestion of lipids
Lingual lipase
126
T/F Lingual lipase is secreted in the saliva in its activated form
F
127
Phases of salivary secretion
1) Cephalic 2) Buccal 3) Esophageal 4) Gastric
128
Steps in formation of saliva
1) Primary secretion 2) Modification
129
Formation of saliva: Cells responsible for primary secretion
Acinar
130
Formation of saliva: Cells responsible for modification
Ductal
131
Formation of saliva: Primary secretion vs modification, secretion of isotonic saliva
Primary secretion
132
Formation of saliva: Steps in modification
1) Reabsorption of Na and Cl 2) Secretion of K and HCO3
133
Principal glands of salivation
1) Parotid 2) Submandibular 3) Sublingual
134
Serous vs mucinous: Ptyalin
Serous
135
Serous vs mucinous: Parotid gland
Serous
136
Serous vs mucinous: Submandibular gland
Mixed
137
Serous vs mucinous: Sublingual gland
Mixed
138
Increases vs decreases salivation: PSY nervous system
Increases
139
Increases vs decreases salivation: SY nervous system
Decreases
140
PSY vs SY: Saliva high in electrolytes but low in proteins
PSY
141
PSY vs SY: Saliva viscid and rich
SY
142
Initial vs final saliva: High in Na and Cl
Initial
143
Initial vs final saliva: High in HCO3 and K
Final
144
Formation of saliva: Hormone involved in reabsorption of Na by the ductal cells
Aldosterone
145
High vs low flow rate (saliva): High in Na, Cl, HCO3; Low K
High
146
High vs low flow rate (saliva): Low in Na, Cl, HCO3; High K
Low
147
Serous vs mucinous: Buccal glands
Mucinous
148
Initial vs final saliva: Na and Cl content less than in plasma
Initial and final
149
Initial vs final saliva: K and HCO3 higher than in plasma
Final
150
Components of gastric secretion (3)
1) HCl and pepsinogen 2) IF 3) Mucus
151
GIT segment: Vitamin B12 absorption
Ileum
152
Cell type-location: Parietal cells
Body
153
Cell type-location: Chief cells
Body
154
Cell type-location: G cells
Antrum
155
Cell type-location: Mucous cells
Antrum
156
Cell-secretion: Parietal cells
1) HCl 2) IF
157
Cell-secretion: Chief cells
Pepsinogen
158
Cell-secretion: G cells
Gastrin
159
Cell-secretion: Mucous cells
Mucus
160
Gland-location: Oxyntic glands
Body
161
Gland-location: Pyloric glands
Antrum
162
Gland-cells: Oxyntic glands
1) Mucus neck cells 2) Parietal cells 3) Chief cells
163
Gland-cells: Pyloric glands
1) G cells 2) Mucus cells
164
Cell-secretion: Mucus cells and mucus neck cells
1) Mucus 2) HCO3
165
Cell-secretion: Enterochromaffin cells
Serotonin
166
Cell-secretion: Enterochromaffin-like cells
Histamine
167
Chief cells are aka
Zymogen cells
168
Main gastric glands
Oxyntic glands
169
Progenitor of epithelial cells and glands of the stomach
Mucus neck cells
170
Parietal cells vs chief cells: Acidophilic
Parietal cells
171
Parietal cells vs chief cells: Basophilic
Chief cells
172
Transport mechanism: Secretion of H into gastric lumen
H-K ATPase
173
3 substances that stimulate gastric HCl secretion
1) Histamine 2) Acetylcholine 3) Gastrin
174
Gastric HCl secretion, stimulus: Paracrine
Histamine
175
Gastric HCl secretion, stimulus: Neurocrine
Ach
176
Gastric HCl secretion, stimulus: GI hormone
Gastrin
177
Parietal cell receptor: Histamine
H2
178
Parietal cell receptor: Ach
M3
179
Parietal cell receptor: Gastrin
CCKB
180
Inhibitors of gastric HCl secretion (3)
1) Somatostatin 2) pH
181
Somatostatin analog
Octerotide
182
Inhibitors of gastric HCl secretion, drug classes
1) H2-blocker 2) Anti-muscarinic 3) PPI
183
Inhibitors of gastric HCl secretion: H2 blocker
Ranitidine
184
Inhibitors of gastric HCl secretion: Anti-muscarinic
Atropine
185
Inhibitors of gastric HCl secretion: PPI
Omeprazole
186
Phases of HCl secretion
1) Cephalic 2) Gastric 3) Intestinal
187
Phases of HCl secretion: Responsible for majority of acid secretion
Gastric phase (60%)
188
Phases of HCl secretion: Least contributor to acid secretion
Intestinal phase (10%)
189
Stimuli for acid secretion: Intestinal phase
1) Amino acids 2) Peptides
190
Substances that protect mucosa from HCl and pepsin (3)
1) Mucin 2) HCO3 3) PG
191
Protective factors against PUD (3)
1) Mucosal blood flow 2) PG 3) Growth factors
192
Pancreatic secretion: High vs low volume
High
193
Pancreatic secretion: High vs low HCO3
High
194
Pancreatic secretion: Hypertonic vs isotonic vs hypotonic
Isotonic
195
Pancreatic secretion: Higher vs lower Na and K content than plasma
Equal
196
Pancreatic secretion: High vs low Cl
Low
197
Pancreatic secretion: Contents (4)
1) Pancreatic amylase 2) Lipase 3) Protease 4) Tryspin inhibitor
198
Pancreatic secretion: Phases
1) Cephalic 2) Gastric 3) Intestinal
199
Pancreatic secretion: Stimuli (3)
1) Secretin 2) CCK 3) Ach (PSY)
200
Pancreatic secretion, stimulus: Acts on ductal cells
Secretin
201
Pancreatic secretion, stimulus: Acts on ductal and acinar cells
1) CCK 2) Ach
202
Pancreatic secretion, stimulus-receptor: CCK
CCKA
203
Pancreatic secretion, stimulus-receptor: Ach
Muscarinic
204
Pancreatic secretion, stimulus: Potentiates effect of secretin in increasing HCO3
1) CCK 2) Ach
205
Sources of digestive enzymes: Carbohydrates
1) Saliva 2) Pancreas 3) Intestinal mucosa
206
Sources of digestive enzymes: Proteins
1) Stomach 2) Pancreas 3) Intestinal mucosa
207
Sources of digestive enzymes: Lipids
1) Saliva 2) Pancreas
208
Digestive enzyme for carbohydrates: Saliva
Amylase
209
Digestive enzyme for carbohydrates: Pancreas
Amylase
210
Digestive enzyme for carbohydrates: Intestinal mucosa (5)
1) Sucrase 2) Maltase 3) Lactase 4) Trehalase 5) α-dextrinase
211
Digestive enzyme for proteins: Stomach
Pepsin
212
Digestive enzyme for proteins: Pancreas (4)
1) Trypsin 2) Chymotrypsin 3) Carboxypeptidase 4) Elastase
213
Digestive enzyme for proteins: Intestinal mucosa (3)
1) Amino-oligopeptidase 2) Dipeptidase 3) Enterokinase
214
Digestive enzyme for lipids: Saliva
Lingual lipase
215
Digestive enzyme for lipids: Pancreas
1) Lipase-colipase 2) Phospholipase A2 3) Cholesterol ester hydrolase
216
Most common component of bile
Water
217
Active component of bile
Bile salts
218
Component of bile responsible for fat emulsification, absorption, and removal from body
Bile salts
219
Components of bile (6)
1) Water 2) Bile salts 3) Bilirubin 4) Cholesterol 5) Phospholipids 6) Electrolytes
220
Amount of bile in gallbladder
30-60 mL
221
T/F Liver bile = gallbladder bile
F
222
Most abundant substance secreted in bile (solute)
Bile salts
223
Bile salts accounts for \_\_\_% of solutes in bile
50`
224
Precursor of bile salts
Cholesterol
225
Primary bile acids (2)
1) Cholic acid 2) Chenodeoxycholic acid
226
Secondary bile acids (2)
1) Deoxycholic acid 2) Lithocholic acid
227
Site of synthesis: Primary bile acids
Liver
228
Site of synthesis: Secondary bile acids
Intesines (bacteria)
229
Site of synthesis: Bile salts
Liver
230
Enzyme for synthesis: Primary bile acids
7α-hydroxylase
231
Enzyme for synthesis: Secondary bile acids
7α-dehydroxylase
232
Direct precursor: Primary bile acids
Cholesterol
233
Direct precursor: Secondary bile acids
Primary bile acids
234
Direct precursor: Bile salts
Secondary bile acids
235
Process by which secondary bile acids are converted into bile salts
Conjugation
236
Bile is concentrated in what organ
Gallbladder
237
Substances that cause GB contraction
1) CCK 2) Ach (PSY)
238
Most potent stimulus for sphincter of Oddi relaxation
CCK
239
T/F Bile is released in PULSATILE spurts
T
240
% bile salts recirculated back to the liver
94%
241
Where bile salts are reabsorbed for recirculation
Terminal ileum
242
Transporter responsible for reabsorption of bile salts in the terminal ileum
Na-bile contransporter
243
Substance that causes secretion of ions and water into bile before being reabsorbed in the gallbladder (concentration)
Secretin
244
Hyper- vs iso- vs hypotonic: Saliva
Hypotonic
245
Factors that increase secretion: Saliva
1) PSY (prominent) 2) SY
246
Factors that increase secretion: Pepsinogen and IF
PSY
247
Factors that decrease secretion: Saliva
1) Sleep 2) Dehydration 3) Atropine
248
Increase vs decrease gastric secretion: Chyme in duodenum
Decrease
249
Factors that decrease secretion: Bile
Ileal resection
250
GI surface area for absorption
250 m2
251
Only form of carbohydrates absorbed in the GIT
Monosaccharides
252
Starch is digested by ptyalin to form
1) α-dextrins 2) Maltose 3) Maltotriose
253
Enzyme that digests maltotriose to form glucose
Sucrase
254
Trehalose \> trehalase =
Glucose
255
Lactose \> lactase =
Glucose + galactose
256
Sucrose \> sucrase =
Glucose + fructose
257
Transporter: Glucose and galactose from lumen to intestinal cell
SGLT-1
258
Transporter: Fructose from lumen to intestinal cell
GLUT-5
259
Transporter: Glucose, galactose, and fructose from intestinal cell to bloodstream
GLUT-2 (and GLUT-5)
260
Passive vs active: SGLT-1
Active (secondary active)
261
Passive vs active: GLUT-2
Passive uniport
262
Passive vs active: GLUT-5
Passive uniport
263
Form of protein absorbed from the GIT
1) Amino acids 2) Dipeptides 3) Tripeptides
264
Transporter: Tripeptides and dipeptides
H-dependent cotransport
265
Transporter: Amino acids
Na-aa cotransport
266
Activator of pepsinogen
Low pH
267
Activators of trypsinogen (2)
1) Trypsin (activates itself) 2) Enterokinase from intestinal brush border)
268
Enzymes activated by trypsin
1) Trypsinogen 2) Chymotrypsinogen 3) Proelastase 4) Procarboxypeptidase A 5) Procarboxypeptidase B
269
Optimum pH for pepsin activity
1-3
270
pH at which pepsin is inactivated
\>5.0
271
Optimum pH at which lipase is activated
7.5-8
272
T/F Pepsin is essential for protein digestion
F
273
T/F Trypsin is essential for protein digestion
T
274
Site of lingual lipase activation
Stomach
275
Site of gastric lipase activation
Stomach
276
Site of pancreatic lipase activation
Small intestine
277
Form of fat absorbed from intestinal lumen to intestinal cell
Micelle
278
Form of fat absorbed from intestinal cell to lacteals
Chylomicrons
279
Enzyme for digestion: TAG
Lingual, gastric, and pancreatic lipase
280
Enzyme for digestion: Cholesterol ester
Cholesterol ester hydrolase
281
Enzyme for digestion: Phospholipid
Phospholipase A2
282
Triglyceride \> lipase
Monoglyceride + 2 FA
283
Cholesterol ester + cholesterol ester hydrolase
Cholesterol + FA
284
Phospholipid + phospholipase A2
Lysolecithin + FA
285
Monoglyceride is made of
1 glycerol + 1 FA
286
Cholesterol ester is made of
Cholesterol + FFA
287
TG is made of
MG + FFA
288
Phospholipid is made of
Lysophospholipid + FFA
289
Chylomicron is absorbed from intestinal cell through what transport mechanism
Exocytosis
290
Mechanism by which micelles are absorbed from intestinal lumen to intestinal cell
Passive diffusion
291
Form of fat that does not need to be processed by SER in the intestinal cell form absorption into lacteals, instead are directly absorbed
Short- and medium-chain fatty acids
292
Inactivate pancreatic lipase
Bile salts
293
Coenzyme secreted by pancreas to prevent inactivation of pancreatic lipase by bile salts
Colipase from procolipase
294
Enzyme: Procolipase \> lipase
Trypsin
295
Only product of TG metabolism that is not hydrophobic
???
296
Components of TAG
1) Glycerol 2) 3 FAs
297
GIT: Main site for water absorption
LI
298
GIT: Potassium absorption
SI
299
GIT: Potassium secretion
LI
300
GIT: Primary ion secreted in intestinal lumen
Cl-
301
GIT: Needed for absorption of Ca
1,25-dihydroxycholecalciferol
302
GIT: Needed for iron absorption
Vitamin C
303
GIT: Vitamins whose metabolism involves normal colonic flora
K, B1, B2, B12
304
Substances absorbed in ileum
1) Vitamin B12 2) Bile salts
305
GI transport mechanism of water-soluble vitamins
Na-dependent cotransport
306
GI transport mechanism: Calcium
Vitamin D-dependent Ca-binding protein
307
GI transport mechanism: Iron, intestinal cell
Apoferritin
308
GI transport mechanism: Iron, bloodstream
Transferrin
309
% body weight: Liver
2
310
% cardiac output: Liver
25
311
Phase I vs Phase 2 metabolism: CYP450 enzymes
Phase I
312
Bilirubin metabolism
313
Functional unit of liver
Lobule
314
Liver lobule: Shape
Hexagonal
315
Liver lobule: Center
Central vein (hepatic vein)
316
Liver lobule: Borders
Portal triad
317
Liver lobule, zone: Periportal
Zone 1
318
Liver lobule, zone: Midzonal
Zone 2
319
Liver lobule, zone: Centrilobular
Zone 3
320
Liver can regenerate up to \_\_\_% of lost mass
70
321
Condition for optimal liver regeneration
Must not be accompanied by viral infection or inflammation
322
Liver macrophage
Kupffer cells
323
T/F Kupffer cells are extremely effective in blood cleansing that less than 1% of bacteria make it to the systemic circulation
T
324
Special liver cells: Found in space of Disse
Ito cells
325
Special liver cells: Found in liver sinusoids
Kupffer cells
326
Special liver cells: Vitamin A storage
Ito cells
327
Special liver cells: APC
Kupffer cells
328
Water-soluble vitamins
B and C
329
Fat-soluble vitamins
ADEK
