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Digestive System Development Flashcards
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Digestive System Development Flashcards
Digestive System Development Flashcards
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1
Question
What marks the posterior limit of the pharynx?
Answer
The region of narrowing where the trachea becomes confluent with the gut tract.
2
Question
What does the original endodermal lining of the primitive gut give rise to in the esophagus?
Answer
The epithelial lining of the esophagus and its glands.
3
Question
What happens to the human esophageal epithelium during the seventh and eighth embryonic weeks?
Answer
It proliferates and nearly occludes the lumen.
4
Question
From what are the connective tissue and muscle coats of the esophagus derived?
Answer
Mesenchymal cells which gradually become concentrated about the original epithelial tube.
5
Question
How is the region of the primitive gut destined to become the stomach marked?
Answer
By a dilation.
6
Question
In young embryos, which border of the stomach faces ventrally?
Answer
The concave border.
7
Question
Define 'concomitantly'.
Answer
At the same time.
8
Question
How many degrees does the stomach rotate down the line of the esophagus?
Answer
Approximately 90 degrees.
9
Question
What happens to the dorsal and ventral borders of the stomach during rotation?
Answer
Dorsal convex border becomes left, ventral concave border faces right.
10
Question
In what direction does the pyloric caudal end of the stomach tip?
Answer
Cranially.
11
Question
The dorsal mesogastrium forms what pouch-like structure?
Answer
Omental bursa.
12
Question
What two organs are embedded in the dorsal mesogastrium?
Answer
Tail of the pancreas and the spleen.
13
Question
What organ does the primitive ventral mesentery enclose?
Answer
Massive liver.
14
Question
What are the first structures to appear during histogenesis of the human gastric mucosa?
Answer
Folds (rugae) and the first gastric pits.
15
Question
When do hydrochloric acid and pepsin become present in the gastric contents?
Answer
Near term.
16
Question
What shape does the primitive gut form as it extends into the belly stalk?
Answer
Hairpin-shaped loop.
17
Question
The attachment of the yolk stalk is cephalic to what point of transition?
Answer
Transition from small to large intestine.
18
Question
What kind of twist initiates positional changes in the primary U-shaped bend of the gut?
Answer
Counterclockwise twist.
19
Question
What is the immediate result of the twist in the gut loop during intestinal development?
Answer
The initial twist of the gut loop brings the cephalic limb posterior to the caudal limb, establishing the positional relations of the large and small intestines.
20
Question
What adult structure can be recognized in the crossing segment of the caudal limb of the gut loop?
Answer
The transverse colon.
21
Question
What happens to the portion of the cephalic limb destined to become the jejunum and ileum after the primary twist?
Answer
It increases in length and becomes freely coiled.
22
Question
When does the protruding part of the intestinal loop move back into the abdominal cavity?
Answer
Around the tenth week of human development.
23
Question
During retraction, which part of the intestine tends to slip into the abdominal cavity ahead of other parts?
Answer
The small intestine.
24
Question
What are the three major phases of histogenesis of the intestinal epithelium according to Colony 1983?
Answer
1) Epithelial proliferation and morphogenesis. 2) Cellular differentiation. 3) Physiological maturation of epithelial cells.
25
Question
When does the intestinal epithelium begin a phase of rapid proliferation?
Answer
Early in the second month (6 to 7 weeks).
26
Question
How is the continuity of the intestinal lumen restored after being temporarily occluded by exuberant epithelial growth?
Answer
Usually restored by the end of the second month.
27
Question
What structures greatly increase the absorptive surface of the intestine?
Answer
Minute fingerlike intestinal villi.
28
Question
Where does mitosis occur in the intestinal epithelium?
Answer
Epithelial cells in the intestinal crypts.
29
Question
How long does it take for daughter cells of crypt cells to migrate up the villi and shed from the tips?
Answer
Over 3 to 4 days.
30
Question
When does the period of differentiation of specific epithelial cell types begin?
Answer
At the time when villi form.