DIGESTIVE SYSTEM STOMACHS Flashcards
(164 cards)
1
Q
What is the function of the stomach in the digestive system?
A
It is specialized for the enzymatic and hydrolytic breakdown of food into digestible nutrients.
2
Q
What feature of the stomach aids in mixing ingesta?
A
Its highly muscular wall.
3
Q
How many types of stomachs exist in domestic animals and what are they?
A
Two types: simple (glandular) and compound stomach.
4
Q
Which animals have a simple (glandular) stomach?
A
All domestic animals except ruminants.
5
Q
Which animals have a compound stomach?
A
Ruminants.
6
Q
What forms the gastric folds (plicae gastricae)?
A
The tunica mucosa and part of the tunica submucosa thrown into tortuous folds by small grooves.
7
Q
What are gastric pits and what do they lead to?
A
Small depressions in the mucosa into which gastric glands open.
8
Q
What kind of epithelium lines the stomach?
A
Simple columnar mucus-secreting cells.
9
Q
What is the function of the clear zones in the apical cytoplasm of the lining cells?
A
They indicate mucus secretion.
10
Q
What type of connective tissue is found in the lamina propria?
A
Loose connective tissue, scantly due to the presence of densely packed gastric glands.
11
Q
What is the lamina subglandularis and where is it found?
A
A distinct zone at the junction of lamina propria and lamina muscularis.
12
Q
What two layers make up the lamina subglandularis?
A
Stratum compactum (outer layer of DWFCT) and stratum granulosum (inner fibroblast layer).
13
Q
In which animals is the lamina subglandularis especially well developed?
A
Carnivores, occasionally equines.
14
Q
What is the protective function of the lamina subglandularis?
A
It protects the stomach from perforation by sharp objects.
15
Q
How many layers of smooth muscle can the tunica mucosa consist of?
A
2–4 layers.
16
Q
What is present in the tunica submucosa and what does it contain?
A
It is typical and contains Meissner’s plexus (nerve fibers and ganglion cells).
17
Q
What is found between the muscle layers of the tunica muscularis?
A
Myenteric plexus (Auerbach’s plexus).
18
Q
What is the outermost layer of the stomach wall?
A
Tunica serosa.
19
Q
Is the esophageal region glandular or non-glandular?
A
Nonglandular.
20
Q
What type of epithelium lines the esophageal region?
A
Stratified squamous epithelium (keratinized or non-keratinized).
21
Q
In which animals is the esophageal region limited?
A
Carnivores, humans, and swine.
22
Q
In which animals is the esophageal region extensive?
A
Ruminants.
23
Q
What are the subdivisions of the esophageal region in ruminants?
A
Rumen, reticulum, and omasum.
24
Q
What structure marks the beginning of the cardiac region in horses?
A
Margo plicatus.
25
What kind of glands are found in the cardiac region?
Cardiac glands – branched tubular coiled glands.
26
What are the parts of the cardiac glands?
Neck and body region.
27
How deep do cardiac glands extend into the tunica mucosa?
About half of the thickness.
28
What cell types line the neck and upper body of cardiac glands?
Cuboidal mucus-secreting cells.
29
What cells may be present in the canine cardiac gland?
Parietal cells.
30
What cells may be present in the porcine cardiac gland?
Chief cells.
31
What are argentaffin cells and where are they located?
Enteroendocrine cells located among lining cells that secrete hormones.
32
What is the function of argentaffin cells?
Secrete hormones that control secretory and muscular activities of GI organs.
33
Which stomach region has the thickest tunica mucosa?
Fundic region.
34
What type of glands are in the fundic region?
Fundic glands (aka gastric glands proper).
35
How much of the tunica mucosa do fundic glands occupy?
About 3/4 of the thickness.
36
What are the four parts of a fundic gland?
Base, body, neck, and isthmus.
37
What is the isthmus of the fundic gland?
The opening into the gastric pit, leading into the neck.
38
What is the terminal part of the fundic gland called?
Base or fundus (dilated and bent adenomere).
39
What are the 4 cell types found in fundic glands?
Chief cells, parietal cells, mucous neck cells, and enteroendocrine cells.
40
What shape are chief cells and where is their nucleus?
Pyramidal shape with a basally-positioned nucleus.
41
What do chief cells secrete?
Pepsinogen, lipase, and rennin (in young animals).
42
How does pepsinogen become active?
It is converted to pepsin by hydrochloric acid.
43
What is the function of rennin?
Converts casein into paracasein in milk for digestion in young animals.
44
What is the staining characteristic of parietal cells?
Bright acidophilic cytoplasm.
45
Where are parietal cells found in the gland?
Scattered from neck to base.
46
What do parietal cells secrete?
Hydrochloric acid and sometimes intrinsic factor (for Vit B12 absorption).
47
Where are mucous neck cells located?
In the neck of the gland, among parietal cells.
48
What shape and cytoplasm do mucous neck cells have?
Cuboidal or low columnar with pale-staining cytoplasm.
49
What is the function of the mucus they secrete?
Protects fundic glands from proteolytic and acid damage.
50
What is the potential differentiation ability of mucous neck cells?
They may become surface lining or glandular lining cells.
51
How are enteroendocrine cells identified histologically?
By silver staining (argyrophilic) or bichromate (enterochromaffin) staining.
52
What hormones do enteroendocrine cells produce?
Secretin, gastrin, cholecystokinin, gastric inhibitory peptide.
53
What is the function of secretin?
Stimulates the pancreas to release bicarbonate to neutralize acid.
54
What is the function of cholecystokinin (CCK)?
Stimulates the pancreas and gallbladder to secrete digestive enzymes and bile.
55
What cell group are enteroendocrine cells part of?
APUD cells (Amine Precursor Uptake and Decarboxylation).
56
How is the histology of the pyloric region compared to cardiac region?
Very similar.
57
How deep are gastric pits in the pyloric region compared to other stomach regions?
Deeper.
58
What type of glands are pyloric glands?
Short, simple or branched tubular glands.
59
How much of the tunica mucosa do pyloric glands occupy?
About 2/3 of its thickness.
60
What is the predominant cell type in the pyloric glands?
Mucus-secreting cells similar to those in the cardiac glands.
61
What is the pyloric sphincter and how is it formed?
A well-developed inner circular muscle layer at the gastro-duodenal junction.
62
What does the pyloric sphincter cause the submucosa and mucosa to form?
A protuberance called the pyloric torus.
63
In which animals is the pyloric torus very prominent?
Ruminants and pigs.
64
Are epithelial cells of the stomach replaced?
Yes, they are continually replaced.
65
How often are surface lining cells replaced?
Every 3 days.
66
How often are glandular cells replaced?
Every 5–7 days.
67
Where does mitotic activity occur in the stomach epithelium?
Only in the lining cells of the gastric pits.
68
What replaces exfoliated surface lining cells?
Cells from the gastric pits.
69
How are glandular cells replaced?
Undifferentiated cells from the isthmus migrate to the base of the gland.
70
Are chief cells rapidly replaced?
No, they are long-lived and replaced slowly.
71
How effective is stomach healing?
The stomach has excellent healing properties.
72
What are the four parts of the compound stomach in ruminants?
Rumen, reticulum, omasum, and abomasum.
73
Which parts of the ruminant stomach are non-glandular and which part is glandular?
The rumen, reticulum, and omasum are non-glandular; the abomasum is glandular.
74
What type of epithelium lines the non-glandular stomach of ruminants?
Stratified squamous keratinized epithelium.
75
What is the function of the forestomach (non-glandular parts) in ruminants?
It breaks down ingesta through mechanical and chemical processes, and absorbs metabolites through the epithelium.
76
What is the primary function of the rumen in ruminants?
Acts as a large fermentation vat where microorganisms break down ingested food and produce volatile fatty acids.
77
What characteristic structures project into the rumen lumen from the tunica mucosa?
Conical papillae.
78
What is the type of lining epithelium found in the rumen?
Stratified squamous keratinized epithelium.
79
Does the muscularis mucosae exist in the rumen?
No, it is absent.
80
What type of connective tissue condenses in the deep region of the rumen's lamina propria-submucosa?
Collagen, elastic, and reticular fibers.
81
What layer in the rumen can be mistaken for muscularis mucosae?
The dense connective tissue layer similar to the stratum compactum of the lamina subglandularis.
82
Are lymphatic nodules or glands present in the rumen?
No, the rumen is devoid of lymphatic nodules and glands.
83
What makes the mucosa of the reticulum distinct from that of the rumen?
It has numerous anastomotic folds arranged in a honeycomb pattern.
84
What is the structure of the primary, secondary, and tertiary folds in the reticulum?
Primary folds divide the mucosa into compartments, which are further divided by shorter folds. The surface between folds has conical papillae.
85
What unique feature is found at the tip of the primary folds in the reticulum?
An isolated mass of smooth muscle from the muscularis mucosae.
86
Are tunica submucosa, muscularis, and serosa present in the reticulum?
Yes, and they are typical in structure.
87
What papillae types characterize the omasum?
Numerous foliate (leaf-like) primary papillae and smaller papillae.
88
What smooth muscle arrangement is found in the omasum?
A double layer of smooth muscle in the lamina muscularis mucosae that follows the contour of the papillae and unraised surface, with another muscle layer interdigitated with the muscularis layer.
89
Is the inner smooth muscle of the omasum continuous with any other layer?
Yes, it is continuous with the inner layer of the tunica muscularis.
90
What kind of stomach is the abomasum classified as?
Glandular stomach.
91
What other structure is the abomasum histologically similar to?
The simple or monogastric (glandular) stomach.
92
What is the primary function of the stomach?
The stomach is responsible for enzymatic and hydrolytic breakdown of food into digestible nutrients.
93
How does the muscular wall of the stomach aid digestion?
It helps mix the ingesta (ingested food).
94
How many types of stomachs exist in domestic animals?
Two types: simple (glandular) and compound stomach.
95
Which animals have a compound stomach?
Ruminants.
96
Which animals have a simple or glandular stomach?
All domestic animals except ruminants.
97
What folds are formed by the mucosa and submucosa in the stomach?
Plicae gastricae (gastric folds).
98
What structures open into the gastric pits?
Gastric glands.
99
What type of epithelium lines the stomach?
Simple columnar mucus-secreting cells.
100
What special zones are visible in the apical cytoplasm of stomach epithelial cells?
Clear zones.
101
What does the lamina propria of the stomach contain?
Loose connective tissue and extensive gastric glands.
102
What is the lamina subglandularis?
A distinct zone at the junction of lamina propria and lamina muscularis.
103
What are the two layers of the lamina subglandularis?
Stratum compactum (outer) and stratum granulosum (inner).
104
In which animals is the lamina subglandularis well-developed?
Carnivores; occasionally in equines.
105
What is the protective function of the lamina subglandularis?
It may protect the stomach from perforation by sharp objects.
106
How many layers of smooth muscle does the t. mucosae have?
2-4 layers.
107
What is found in the submucosa of the stomach?
Submucosal (Meissner’s) plexus.
108
Where is the myenteric (Auerbach’s) plexus located?
Between the inner and outer layers of the muscularis.
109
What type of tissue is the tunica serosa?
Typical serosa (simple squamous epithelium with underlying connective tissue).
110
What type of epithelium lines the esophageal region?
Stratified squamous (keratinized or non-keratinized).
111
Which animals have a limited esophageal region?
Carnivores, humans, and swine.
112
Which animals have an extensive esophageal region?
Ruminants.
113
What are the subdivisions of the esophageal region in ruminants?
Rumen, reticulum, and omasum.
114
What marks the beginning of the cardiac region in horses?
Margo plicatus.
115
What glands are present in the cardiac region?
Cardiac glands.
116
What type are cardiac glands?
Branched, tubular, and coiled.
117
How deep are the cardiac glands relative to the t. mucosa?
About half the thickness.
118
What cells line the neck and upper body of cardiac glands?
Cuboidal mucus-secreting cells.
119
What cells line the remainder of the cardiac glands?
Columnar mucus-secreting cells.
120
What additional cells may be present in canine cardiac glands?
Parietal cells.
121
What additional cells may be present in porcine cardiac glands?
Chief cells.
122
What are argentaffin cells and where are they found?
Enteroendocrine cells between lining cells; they secrete hormones for GI regulation.
123
Which region has the thickest t. mucosa?
Fundic region.
124
What glands are characteristic of the fundic region?
Fundic or gastric glands proper.
125
How much of the t. mucosa do fundic glands occupy?
About 3/4.
126
How much of the t. mucosa do gastric pits occupy in the fundic region?
About 1/4.
127
How many parts does the fundic gland have?
Four: isthmus, neck, body, base (fundus).
128
What are the four main cell types in the fundic glands?
Chief (zymogen) cells, parietal (oxyntic) cells, mucous neck cells, and enteroendocrine cells.
129
What shape are chief cells?
Pyramidal with basally-positioned nuclei.
130
What gives chief cells a basophilic appearance?
Abundant rough ER and free ribosomes.
131
What enzymes do chief cells secrete?
Pepsinogen, lipase, and rennin.
132
What is the active form of pepsinogen?
Pepsin (activated by HCl).
133
What is the function of rennin and in which animals is it found?
Present in young animals; converts casein into paracasein.
134
How are parietal cells identified histologically?
Bright acidophilic cytoplasm.
135
What is the shape and location of parietal cells?
Large, spheroidal or pyramidal, scattered from neck to base.
136
What do parietal cells secrete?
Hydrochloric acid and possibly intrinsic factor.
137
What is the function of intrinsic factor?
Absorption of Vitamin B12 (extrinsic factor).
138
Do carnivores need intrinsic factor for Vitamin B12 absorption?
Not necessarily.
139
Where are mucous neck cells found?
In the neck of the gland, among parietal cells.
140
What type of secretion do they produce?
Less viscous mucus than surface lining cells.
141
What is a possible function of mucous neck cells' secretion?
Protect fundic gland from proteolytic/hydrolytic damage.
142
What can mucous neck cells differentiate into?
Surface lining or glandular lining cells.
143
What stains are used to identify enteroendocrine cells?
Silver stain (argyrophilic) or bichromate (enterochromaffin).
144
What hormones are secreted by enteroendocrine cells?
Gastrin, secretin, cholecystokinin, gastric inhibitory peptides.
145
What is the function of secretin?
Stimulates pancreas to secrete bicarbonate.
146
What is the function of cholecystokinin?
Stimulates pancreas and gallbladder to secrete enzymes and bile.
147
What group do enteroendocrine cells belong to?
APUD (amine precursor uptake and decarboxylation) cells.
148
Where are transitional cells occasionally found?
In the isthmus of the fundic gland.
149
What might transitional cells be responsible for?
Replacement of lining and glandular cells.
150
How do pyloric glands compare histologically to cardiac glands?
They are similar.
151
How deep are the gastric pits in the pyloric region?
Deeper than in other regions.
152
What type are pyloric glands?
Short, simple or branched tubular glands.
153
What portion of the t. mucosa do pyloric glands occupy?
About 2/3.
154
What is the predominant cell type in the pyloric glands?
Mucus-secreting cells (like those in cardiac region).
155
What muscular feature is prominent in the pyloric region?
Pyloric sphincter (inner circular layer of t. muscularis).
156
What structure does the pyloric sphincter form by causing a bulge in mucosa and submucosa?
Pyloric torus.
157
In which species is the pyloric torus prominent?
Ruminants and pigs.
158
How often are surface lining cells replaced?
Every 3 days.
159
How often are glandular cells replaced?
Every 5-7 days.
160
Where does mitotic activity occur in the stomach epithelium?
In the lining cells of the gastric pits.
161
What replaces exfoliated surface cells?
Cells from gastric pits.
162
How are glandular cells replaced?
By undifferentiated cells from the isthmus migrating toward the gland base.
163
Are chief cells replaced quickly?
No, they are long-lived and replaced slowly.
164
How effective is the stomach's healing ability?
Excellent.
