GI Tract Flashcards
(232 cards)
1
Q
What is the life span of a chief cell?
A
about a year (long lifespan!)
2
Q
Where is the primary site for absorption and digestion in the GI tract?
A
small intestine
3
Q
Where would you find the parasympathetic motor nerve synapse in regards to the organ?
A
the ganglia are located very near the effector organ
4
Q
Why is lipid digestion so drawn out?
A
it stages the amount of lipid released into the blood at one time to prevent issues from mass amounts of fat being introduced into the bloodstream
5
Q
The production and secretion of urease ___ gastric pH and ___ acid production.
A
increases; increases
6
Q
What are the 5 different classes of gastric glands?
A
- mucus secreting cells
- acid secreting cells
- pepsin secreting cells
- enteroendocrine cells
- undifferentiated stem cells
7
Q
Food undergoes mechanical breakdown via muscle activity and chemical breakdown via gastric secretions to form ___.
A
chyme
8
Q
The ____ is a small, blind-ended sac that is distal to the ileocecal junction.
A
appendix
9
Q
Where would you find undifferentiated stem cells in gastric glands?
A
in the neck of the gland
10
Q
Which structure of the rectum contains longitudinal folds called anal columns?
A
anal canal
11
Q
How do you distinguish villi from plica circulares in section?
A
villi - core of lamina propria
plica - core of submucosa
12
Q
Are anal glands branched, straight, tubular glands?
A
YES - which secrete mucus
13
Q
What are the 5 phases of food breakdown?
A
ingestion fragmentation digestion absorption elimination
14
Q
The stomach completes ___ and initiates ___ during the first phases of digestion.
A
fragmentation; digestion
15
Q
What are APUD cells?
A
“amine precursor uptake and decarboxylation” cells
16
Q
____ stimulates the contraction of the gallbladder and the release of bile acids.
A
CCK
17
Q
__ cells secrete GIP, or gastric inhibitory peptide.
A
K
18
Q
____ are extracellular droplets for transport; ____ are intracellular droplets for transport.
A
Micelles; chylomicrons
19
Q
Epithelium of the villi is supported by the connective tissue ____ and contains capillaries and lymphatics for absorption of nutrients.
A
lamina propria
20
Q
Where would you find parasympathetic ganglia in the GI tract?
A
ganglia are located within the walls of the gut organ, within the submucosa and muscularis externa
21
Q
How often are enterocytes replaced?
A
every 3-5 days
22
Q
Peyer’s patches contain both __ and __ cells.
A
B; T
23
Q
How can someone decrease their risk of colon cancer?
A
- increasing fiber in diet
- decreases colon cancer
- by reducing transit time
- and increasing GI motility
24
Q
What are the pancreatic proteolytic enzymes secreted as?
A
inactive precursors (zymogens); so, trypsinogen and chymotrypsinogen to prevent autolysis
25
What is the more technical term for swallowing?
degluttination
26
___ and ___ promote the secretion of the exocrine pancreas.
Secretin; CCK
27
What is secreted by G cells?
gastrin
28
Where are actively dividing stem cells of the small intestine located at the base of?
crypts
29
What is the inner, third layer of muscle in the muscularis externa of the stomach?
inner oblique
30
APUD cells are sometimes referred to as ___ cells since they target cells in the local vicinity.
paracrine
31
What are M-cells responsible for in MALT tissues?
antigen sampling
| uptake of macromolecules
32
____ helps to produce and maintain an optimal pH for the very sensitive enzymes present in the small intestine.
Bicarbonate
33
___ and ___ amylases hydrolyze starch to disaccharides (sucrose, lactose, maltose, and isomaltose).
Salivary; pancreatic
34
What is the exit of the GI tract?
anus
35
Both the fundus and corpus of the stomach are ____ and almost non-discernible histologically.
glandular
36
What do the mucus secreting cells cover?
luminal surface and upper third of pit
37
In which mucosal layer might you find large numbers of lymphocytes and plasma cells?
within the lamina propria of the gut mucosa
38
What is one of the most common problems associated with the stomach?
peptic/gastric ulcers
39
Enterocytes produce various ____ for absorption of carbohydrates and amino acids.
carrier proteins
40
A cells secrete ___, which raises blood sugar.
glucagon
41
What are interspersed among the enterocytes and secrete mucus?
goblet cells
42
Where are plica circulares especially prominent?
in the jejunum
43
What are the clusters of parasympathetic ganglia within the submucosa called?
Meissner's plexus (submucosal plexus)
44
How would glucose, galactose, or fructose be absorbed in the small intestine?
through facilitated diffusion since these are all monosaccharides
45
What are the two primary types of actions performed by the muscularis externa?
segmentation and peristalsis
46
____ is secreted by S cells and inhibits gastric secretions and stimulates smooth muscle contractions.
Secretin
47
Where are surface mucus cells located?
at the surface of gastric glands
48
What is the result of ingestion accompanied by fragmentation of food?
a bolus
49
___ actions in the gut are local contractions only that mix food. They can occur both proximally and distally (both directions).
Segmentation
50
Is pancreatic lipase water soluble?
YES
51
What is the brush border coated with?
protective glycocalyx of disaccharides
52
What are the large numbers of commensal bacteria found in the large intestine called?
coliforms
53
What are the glands associated with the GI tract?
liver
pancreas
intestinal glands
54
What type of connective tissue does the submucosa contain? What is its role?
loose to dense connective tissue; supports mucosa and contains larger blood vessels, nerves, and lymphatics
55
____ project into the lumen of the small intestine and are dome-shaped.
Peyer's patches
56
What is the outer layer of the gut, containing a loose connective tissue layer and major nerves, vessels, and adipose tissue?
adventitia (serosa)
57
Can stem cells of the villi migrate up to replace any type of cell like stomach undifferentiated stem cells?
YES
58
Why is the term "peptic ulcer" preferred over "gastric ulcer?"
because the majority of these ulcers actually occur in the very first part of the duodenum
59
What is the most common sign of polyps?
rectal bleeding
60
How often are mucus secreting cells renewed?
every 3-5 or 4-7 days
61
How long is the small intestine in humans?
4-6 meters long
62
What would you find in the duodenum that is not present in the large intestine?
Brunner's glands
63
The smooth muscle of the gut is controlled by the ____ nervous system.
autonomic
64
Where are parietal cells most numerous?
in the middle third of the gastric gland
65
___ action propels food distally in one direction ONLY with rhythmic contractions.
Peristalsis
66
____ stimulation is excitatory to the gut; ____ stimulation is inhibitory to the gut.
Parasympathetic; sympathetic
67
What step is ESSENTIAL to maximize the actions of pancreatic lipase?
emulsification of fat
68
Are carbohydrates starches?
YES
69
Does absorption occur in the stomach?
NO - except for water, alcohol, and some drugs
70
What are the prominent longitudinal folds in the stomach called?
rugae
71
In the lower third of the esophagus, what type of muscle is the muscularis externa composed of?
smooth muscle only
72
What do goblet cells synthesize? What is its function?
mucinogen (>>mucus); lubricates and protects the epithelium
73
What secreted product helps delay gastric emptying?
GIP (gastric inhibitory peptide)
74
The liver, pancreas, and intestinal glands are all ____ of the GI tract.
embryological outgrowths
75
Where is mucinogen stored in goblet cells?
in membrane bound granules
76
____ coagulates milk proteins.
Rennin
77
What do surface mucus cells secrete?
thick insoluble mucus and bicarbonate ions
78
Enteroendocrine cells are what kind of cell? What do they do?
APUD cells; amine precursor uptake and decarboxylation
79
What are the 3 layers of mucosa?
epithelium
lamina propria
muscularis mucosae
80
What is the mesothelium?
the lining of the adventitia (simple squamous epithelium)
81
What bacteria are peptic ulcers associated with in chronic infections of the stomach?
Helicobacter pylori
82
What make up the epithelium of the villi?
enterocytes
83
Are the digested components of proteins and carbohydrates handled similarly in transport by the body?
YES - both transported to portal vein
84
Is the appendix active in adults?
NO - only in children
85
Panrcreatic secretions are highly ___. Why?
alkaline; high pH is due to high levels of bicarbonate
86
How do mucus secreting cells look on H+E staining?
clear
87
What is one of the cardinal features of Celiac disease?
malabsorption
88
What inhibits the secretion of gastrin?
somatostatin
89
What cells would you find in the mucosal epithelium of the small intestine but not in the epithelium of the large intestine?
paneth cells
90
The ___ of the stomach is surrounded by the smooth muscle cardiac sphnicter (GES) and contains predominantly mucus-secreting glands.
cardia
91
___ act as emulsifying agents for digestion of lipids, forming micelles.
Bile acids
92
What are the 3 overall functions of GI mucosa?
protection (barrier)
secretion
absorption
93
What is the purpose of microvilli? What are they the site of?
increase surface area for absorption; site of membrane digestion (at glycocalyx)
94
What is the basic process of carbohydrate breakdown?
primary starches >> disaccharides (sucrose, lactose, maltose, isomaltose) >> monosaccharides (glucose, galactose, fructose)
95
Where does the lymph eventually carry the chylomicrons to?
to the thoracic duct and eventually into general circulation
96
What are the two steps to digestion in the duodenum?
1. luminal digestion
| 2. membrane digestion
97
What constitutes erosion of the stomach?
when there is partial loss of the epithelial lining
98
What is the purpose of valves of Kerkring?
to increase surface area, slow down speed of food, and contain the submucosal core
99
When is the adventitia referred to as "serosa?"
when referring to it in regards to the abdominal cavity since the serosa = visceral peritoneum
100
What shape are gastric glands?
straight, tubular glands
101
____ cells secrete soluble mucus and are located at the upper third of the gastric pit.
Mucus neck
102
____ cells secrete a variety of peptide hormones in responses to local factors and control GI motility and gastric secretion.
Enteroendocrine
103
What are the 3 regions of the stomach?
cardia
fundus
pylorus
104
The small intestine is ___ in carnivores and ___ in herbivores.
shorter; longer
105
Can the adventitia merge with retroperitoneal tissue?
YES - this is why it may not be visible as a discreet layer
106
What is the junction called that separates the esophagus and the opening of the stomach?
gastroesophageal sphincter (at the gastroesophageal junction)
107
How much of our feces is our own sloughed epithelial cells?
a third
108
___ cells (epithelium) and ___ glands (submucosa) are found within the large intestine.
Goblet; colonic
109
The adventitia is continuous with the supporting ___ in the abdominal cavity.
mesentery
110
Which is grossly visible on the surfaces of mucosa? MALT or Peyer's patches?
Peyer's patches
111
How are proteins initially handled in the digestive tract?
they are initially denatured by HCl from parietal cells, then hydrolyzed by pepsin into polypeptide fragments
112
Rank the ileum, jejunum, and duodenum from shortest to longest.
duodenum >> jejunum >> ileum
113
Why do pepsin secreting cells stain purple?
they have large numbers of ribosomes
114
As ____ cells mature, they migrate up and down the gastric gland and differentiate into whatever cell type is needed.
undifferentiated stem
115
What are the larger clusters of ganglia called that are located between the circular and longitudinal muscle layers of the muscularis externa called?
Auerbach's plexus (myenteric plexus)
116
Is swallowing voluntary? Why or why not?
YES; it is voluntary because the upper third of the esophagus contains voluntary skeletal muscle
117
____ is located in the lamina propria ad submucosa of the small intestine, contains plasma cells, and secretes IgA.
MALT
118
What is the brush border (striated border)?
it is a highly folded structure modified into microvilli
119
What is the appendix?
it is a vestigial cecum
120
What does pepsin do?
hydrolyzes protein
121
What are the parts of the large intestine?
```
cecum
appendix
ascending colon
transverse colon
descending colon
rectum
```
122
In the duodenum, what do the pancreatic and biliary secretions do to fat?
emulsify it
123
What is the mucosa covered by?
a thick layer of mucus
124
Why are these proteolytic enzymes released as inactive precursors?
so the pancreas doesn't start digesting itself
125
Which gastric cells secrete insoluble mucus? Which secrete soluble mucus?
surface mucus cells; mucus neck cells
126
What happens after amino acids and monosaccharides are absorbed by enterocytes lining the villi?
they are transported across the epithelium, enter capillaries within the lamina propria and enter the portal vein to be stored in the liver
127
The ____ layer consists of inner circular muscle layers and outer longitudinal smooth muscle layers, with the fibers oriented at right angles from each other.
muscularis externa
128
What does H. pylori produce that raises gastric pH and acid production?
urease
129
Where are Brunner's glands located?
in the submucosa of the duodenum
130
I cells secrete ____, which stimulates pancreatic secretion and contraction of the ___.
cholecystekinin (CCK); gallbladder
131
How are lipids digested?
emulsified by actions of bile acids
132
What is secreted by D cells?
somatostatin
133
Where are chylomicrons transported to?
lacteals
134
What are intestinal villi lined by?
simple columnar epithelium
135
At what point of protein digestion can these components be absorbed by enterocytes via active transport by carrier proteins?
when they are digested into small peptides and amino acids
136
Which cells of the small intestine produce antibacterial proteins called defensins, as well as enzymes such as lysozyme?
paneth cells
137
Which anal sphincter is voluntary?
external anal sphincter
138
What are the intrinsic factors of the acid secreting cells necessary for?
this glycoprotein is necessary for the absorption of vitamin B12 from the ileum
139
Which cells of the gut do not require continuous replacement?
chief cells/peptic cells
140
What are the spaces called between villi?
crypts of Lieberkuhn
141
What is the diffuse lymphoid tissue scattered throughout the GI tract?
MALT or GALT
142
___ stimulates gastric secretions.
Gastrin
143
____ are large numbers of highly convoluted, branched, tubuloalveolar submucosal glands.
Brunner's glands
144
____ digestion involves enzymes of the glycocalyx on the plasma membrane of enterocytes.
Membrane
145
What are the steps to lipid digestion?
- emulsification by bile acids
- broken down into monoglycerides and fatty acids by pancreatic lipase
- form extracellular micelles
- micelles absorbed by enterocytes
- micelles re-synthesized into triglycerides within cells
- form chylomicrons
- transported to lacteals
146
The mucosal ___ secretes and absorbs materials to have a variety of functions and is modified differently at each level of the GI tract.
epithelium
147
Does the large intestine have villi and plicae circulares?
NO
148
The mucosal ___ is the thin layer of smooth muscle that places a boundary between mucosa and submucosa.
muscularis mucosae
149
What is responsible for the formation of haustra (sacs) on the large intestine?
the outer longitudinal muscle layer in muscularis externa is reduced or incomplete and forms easily discernible longitudinal strips
150
What are the main functions of the duodenum?
neutralize gastric acid
neutralize pepsin
(do this with assistance of pancreas and gallbladder)
151
Contractions of smooth muscle is called ____, like what guides the bolus down the esophagus. Under what control is it under?
peristalsis; autonomic control
152
What does the secretion of gastrin stimulate?
the secretion of HCl and pepsin
153
Are there lacteals present in the lamina propria within the crypts of the large intestine?
NO
154
What are the proteolytic enzymes of pancreatic secretions?
trypsin
chymotrypsin
amylase
lipase
155
What are the 4 distinct layers of the GI tract?
mucosa
submucosa
muscularis externa
adventitia (serosa)
156
How many liters of watery gastric juice are secreted per day?
2 L
157
What constitutes a gastric ulcer?
when the damage extends BELOW the level of the basement membrane and there is associated bleeding
158
What portion of the stomach secretes acid, pepsin, and some mucus?
fundus
159
What prominent structures form the entrances to gastric glands in the stomach?
gastric pits OR foveolae
160
The mucosal ___ is the underlying connective tissue that contains lymphoid nodules, glands, blood vessels, and lymphatics.
lamina propria
161
____ digests lipids.
Lipase
162
What are the longitudinal strips on the large intestine called?
tenia coli
163
What does it mean when something is "pre-neoplastic?"
after repeated trauma, cells begin to become abnormal (can later develop into cancer if left unchecked)
164
When does the transition from mucosa to simple columnar epithelium to stratified squamous epithelium occur?
at the anal canal
165
What are some enzymes synthesized by enterocytes?
peptidases
peptide hydrolases
disaccharides
166
What does "aboral" mean?
to be moved away from the oral cavity
167
The external anal sphincter contains ___ muscle; the internal anal sphincter contains ___ muscle.
skeletal; smooth
168
What is the function of APUD cells (enteroendocrine cells) scattered throughout the small intestine?
regulate GI motility and secretion
169
In the middle third of the esophagus, what type of muscle is the muscularis externa composed of?
skeletal muscle and smooth muscle
170
In the ___, the resorption of water and elimination of waste occurs.
colon
171
Does the epithelium of the stomach/GI tract contain blood vessels?
NO
172
Where are chief cells located at in the gastric gland?
at the base of the gland in the bottom third
173
The ___ of the stomach contains primarily mucus- and gastrin-secreting glands and controls the outflow of the stomach.
pylorus
174
Colon cancers are called _____.
adenocarcinomas
175
What happens when the micelles are absorbed and re-synthesized within enterocytes?
they are coated with proteins and phospholipids to form intracellular chylomicrons
176
Are polyps generally asymptomatic?
YES
177
What tissue type does the appendix contain large amounts of?
MALT (active in children)
178
Anal columns are also called ___.
columns of Morgani
179
Which anal sphnicter is involuntary?
internal anal sphincter
180
Are Peyer's patches and MALT histologically identical?
YES
181
The ___ contains transverse rectal folds and large numbers of mucus glands.
rectum
182
What enzymes break down proteins into smaller peptide fragments?
```
pancreatic enzymes
(trypsin)
(chymotrypsin)
(elastase)
(carboxypeptidase)
```
183
What do Brunner's glands secrete, unique to the duodenum?
mucus and zymogens
184
Where do the pancreatic duct and bile duct empty into?
the duodenum at the major duodenal papilla
185
____ mucus cells secrete thick, insoluble mucus and bicarbonate ions.
Surface
186
HCl, pepsinogen (precursor to pepsin), gastrin, rennin, and lipase are all constituents of ____.
gastric juice
187
What type of epithelium is the esophagus lined by?
stratified squamous nonkeratinized epithelium
188
What are some alternative names for pepsin secreting cells?
chief cells
peptic cells
zymogenic cells
189
How are dead cells shed from the villi?
cells migrate up the villus, mature, and then are shed from the tips
190
Where are paneth cells found?
at the base of crypts of Lieberkuhn
191
What forms from the actions of pancreatic lipase to break down monoglycerides and fatty acids?
extracellular micelles
192
In the small intestine, what is the mucosal surface made up of?
villi that contain a core of lamina propria
193
Which portions of the small intestine accomplish primary absorption of nutrients?
jejunum and ileum
194
Is vomiting involuntary?
YES
195
What are some examples of secretory products in the GI tract? What portion of the mucosa secretes these products?
```
digestive enzymes
hormones
mucus
antibodies;
mucosal epithelium
```
196
What are the three stages of protein digestion?
- denatured by HCl
- hydrolyzed by pepsin
- further hydrolyzed by pancreatic enzymes
197
How is an H. pylori infection treated?
"triple therapy" consisting of 2 long-term antibiotics and a proton pump inhibitor
198
How are monosaccharides absorbed?
by facilitated diffusion
199
How is pepsinogen converted to pepsin?
by the action of HCl
200
Trypsin is activated by ____; trypsin then activates ___.
enterokinase; chymotrypsin
201
Within the anal canal, where do the anal glands extend into?
the submucosa and muscularis externa
202
What are the valve-like rings or folds called in the small intestine?
plica circulares (valves of Kerkring)
203
What results from the occasional enlargement and irritation of submucosal veins?
hemorrhoids
204
What are the primary starches?
polysaccharides
oligosaccharides
disaccharides
205
____ are benign adenomas/masses in the wall of the colon that protrude into the lumen.
Polyps
206
In the upper third of the esophagus, what type of muscle is the muscularis externa composed of?
voluntary skeletal muscle
207
S cells secrete ___, which stimulates release of ___ from the pancreas.
secretin; bicarbonate
208
What are chylomicrons?
drops of triglycerides coated with proteins and phospholipids
209
What are our primary sources of lipids to be digested?
triglycerides from diet
210
____ are blind-ended lymph vessels within the lamina propria of villi.
Lacteals
211
The epithelium of MALT tissues contains ___, which are squamoid enterocytes modified for antigen sampling and macromolecule uptake.
M-cells (microfold cells)
212
What does chyme from the stomach stimulate the release of?
stimulates the release of 2 hormones from APUD cells - secretin and CCK
213
Does MALT in the large intestine form grossly visible patches?
NO
214
What are two alternative names for acid secreting cells?
parietal cells
| oxyntic cells
215
Which glands are unique to the duodenum?
Brunner's glands
216
What are parietal and chief cells controlled by?
autonomic nervous system and hormones from endocrine cells in the region of the pylorus
217
What area of the stomach is the glandular portion?
fundus
218
What are the primary functions of the colon?
water and electrolyte resorption (also produces some mucus for waste elimination)
219
____ is the inactive precursor to pepsin.
Pepsinogen
220
The mucosal folds in the colon contain a core of ____. How is this different than the cores of plicae circulares?
lamina propria; plicae circulares contain cores of submucosa, NOT lamina propria
221
Repeated damage to the esophagus can lead to ____, which is a pre-neoplastic condition.
Barrett's
222
Why does increasing fiber intake decrease the risk of colon cancer?
because fiber promotes GI motility, decreasing the time that carcinogens may rest against the walls of the colon and cause neoplastic cells to form
223
What cells secrete pepsin?
chief cells/peptic cells
224
How often is the entire epithelial lining of the small intestine replaced?
every 3-5 days
225
What is the technical term for heartburn, that results from the regurgitation of stomach acid into the distal portion of the esophagus from the cardia of the stomach?
pyrosis
226
What do chief cells secrete?
pepsinogen
227
Starch is broken down into what?
disaccharides
228
Which disease causes villus blunting and atrophy, leading to malabsorption and weight loss due to gluten intolerance?
Celiac disease (gluten enteropathy)
229
What do parietal cells secrete?
HCl and intrinsic factor
230
Where are foveolae located?
in the body of the stomach
231
What would we refer to our single-chambered stomach as, especially in the veterinary world?
monogastric
232
____ digestion involves the mixing of chyme with pancreatic enzymes for molecular breakdown.
Luminal
