Module 5: Development of the Digestive System, Heart, and Great Vessels Flashcards
1
Q
Embryonic folding of the gut tube
A
-ventral folding at anterior and posterior ends forms a closed tube
2
Q
Primary gut tube
A
-hollow cylinder of endodermal cells surrounded by mesoderm
3
Q
3 distinct regions of the gut tube
A
-foregut
-midgut
-hindgut
4
Q
Primitive foregut
A
-extends from oral cavity to initial part of duodenum
5
Q
Primitive midgut
A
-extends from mid-duodenum to initial 2/3 of transverse colon
6
Q
Primitive hindgut
A
-extends from distal 1/3 transverse colon to upper portion of anus
7
Q
Blood supply of primitive foregut
A
-celiac artery
8
Q
Blood supply of primitive midgut
A
-superior mesenteric artery
9
Q
Blood supply of primitive hindgut
A
-inferior mesenteric artery
10
Q
Mesentery
A
-double layer membrane formed by the fusion of the splanchnic mesoderm
11
Q
Dorsal mesentery
A
-composed of mesogastrium, mesoduodenum, mesentery proper, and mesocolon
12
Q
Ventral mesentery
A
-derived from the septum transversum and forms the falciform ligament of the liver and lesser omentum
13
Q
Steps of the development of the esophagus
A
-elongation
-occlusion
-recanalization
14
Q
Elongation of the esophagus
A
-after the trachea separates, esophagus continues to grow in length to keep up with overall growth
-also responsible for repositioning of stomach in abdomen
15
Q
Occlusion time period
A
-week 5
16
Q
Occlusion of esophagus
A
-proliferation of endoderm results in occlusion of esophagus
17
Q
Recanalization of esophagus time period
A
-week 9
18
Q
Recanalization of esophagus
A
-results in the formation of a hollow tube
19
Q
Parts of the stomach
A
-cardia
-fundus
-body
-pylorus
20
Q
Longitudinal rotation of the stomach
A
-rotates right 90 degrees about longitudinal axis
21
Q
Differential growth of stomach
A
-there is differential growth along one border of the stomach which causes it to elongate more rapidly than the other
-this produces the greater and lesser curvature
22
Q
Anteroposterior rotation of the stomach
A
-rotation about anteroposterior axis
-pylorus moves cranially and the cardia moves caudally
23
Q
Omental bursa
A
-created by rotation of the stomach that pulls the mesogastrium to the left
24
Q
What does the dorsal mesentery form
A
-forms the greater omentum and gastrosplenic and splenorenal ligaments
25
What does the ventral mesentery form
-forms the capsule and peritoneal coverings of the liver and ligaments of the liver
26
Ligaments of the liver
-lesser omentum
-triangular, coronary, and falciform
27
Development of liver and gallbladder steps
-hepatic diverticulum forms
-hepatic diverticulum divides
-hepatic duct forms
-hepatic duct outgrowth
-liver cords differentiate
-liver stroma forms
28
Hepatic diverticulum forms
-grows from distal end of foregut and penetrates the septum transversum
29
Hepatic diverticulum divides
-divides into a cranial part, which forms parachyma of liver, and caudal part which will later give rise to the gallbladder and cystic duct
30
Hepatic duct forms
-hepatic cells continue to penetrate septum transverum, and the connection between the diverticulum and foregut narrows, forming hepatic duct
31
Hepatic duct outgrowth
-from hepatic duct, outgrowth gives rise to gallbladder and cystic duct
-these then together form the bile duct
32
Liver cords differentiate
-epithelial liver cords differentiate into liver parenchyma and form the lining of the biliary
33
Liver stroma forms
-the connective tissue capsule of the liver is derived from the septum transversum
34
Development of the pancreas
-forms from 2 outgrowths of the gut tube endoderm
35
What are the outgrowths of the gut tube endoderm
-dorsal pancreatic bud
-ventral pancreatic bud
36
Dorsal pancreatic bud origin
-originates from the duodenum
37
Ventral pancreatic bud origin
-develops from the bile duct
38
Migration of the pancreas and duodenum
-ventral pancreatic migrates towards dorsal pancreatic bud, the proximal duodenum also rotates clockwise with pancreas
39
Union of the pancreas and duodenum
-ventral bud fuses with dorsal bud and becomes the uncinate process
40
What does dorsal pancreatic bud make up
-main body of pancreas
41
Steps of the development of the midgut
-elongation
-herniation and rotation
-retraction
42
When does elongation of the midgut occur
-week 5
43
What structure is formed by the elongation of the midgut
-primary intestinal loop
44
2 limbs of the midgut
-cephalic (cranial) limb
-caudal limb
45
Vitelline duct
-how the loop communicates with the yolk sac
46
Umbilical herniation of the midgut
-while looping continues, abdomen becomes too small for intestines and several intestinal loops are forced into the umbilical cord
47
Rotation of midgut
-intestinal loop rotates 90 degrees and axis of rotation is relative to the superior mesenteric artery
48
Retraction of the midgut
-intestinal loop returns into abdominal cavity later once there is space
-this loop is the small intestine
49
What does not participate in intestinal looping
-large intestine
50
Midgut volvulus
-improper rotation of small intestine
-rotates around axis of its own mesentery
51
Midgut volvulus symptoms
-improper flow of digestion
-intestinal blockages
-blocking of intestinal circulation
52
Hindgut derivatives
-caudal half of transverse colon
-descending colon
-rectum
-superior part of anal canal
53
Steps of hindgut development
-cloaca
-urorectal septum
-perineal body
-anal pit
54
Cloaca
-shared end of the hindgut and urogenital tract
-common chamber that intestinal, urinary, and genital tract opens into
55
Urorectal septum
-migrates to cloacal membrane, and separates hindgut from urinary system
56
Urogenital sinus
-forms the bladder and urethra
57
Perineal body
-between urogenital and anal membranes, where the anal canal begins to develop
58
Anal pit formation
-ectoderm invaginates cloaca
-establishes continuity of the anal canal and rectum
59
What is the proximal 2/3 anal canal derived from
-endoderm
60
What is the distal 1/3 of anal canal derived from
-ectoderm
61
Imperforate anus
-normal anal opening is absent at birth
-results from abnormal development of urorectal septum
62
Enteric nervous system parts
-myenteric plexus
-submucosal plexus
63
Myenteric plexus location
-located between inner circular and outer longitudinal muscle layers
64
Submucosal plexus location
-situated within submucosa layer
65
What is the enteric nervous system derived from
-autonomic nervous system
66
What are ENS neurons derived from
-derived from neural crest cells
67
Function of the enteric nervous system
-functions with smooth muscle cells and mucosal villi to control absorption and secretion of GI system, including small and large intestines
68
Formation of the heart tube steps
-progenitor cells
-migration
-heart field
69
When does formation of the heart tube begin
-week 3
70
What are progenitor cells derived from
-intraembryonic mesoderm and cranial 1/3 of primitive streak
71
Migration of progenitor cells
-leave primitive streak and become localized on either side of primitive streak
72
Heart field
-progenitor cells form a U shaped tube around notochord
-these merge to form endocardial tube
73
Longitudinal heart tube folding
-starts in front of oropharyngeal membrane
-ends up in the thorax
74
Lateral heart tube folding
-allows for endocardial tubes to fuse
-forming heart tube
75
Components of the heart tube
-bulbis cordis
-sinus venosus
76
Components of bulbis cordis
-truncus arteriosus
-conus cordis
-primitive ventricle
-primitive atrium
77
Truncus arteriosus
-outflow tracts of aorta and pulmonary arteries
78
Conus cordis
-outflow tracts of both right and left ventricles
79
Primitive ventricle
-trabeculated walls of the ventricles
80
Primitive atrium
-later divides into left and right atrium
-connected to sinus venosus
81
Sinus venosus
-derives from and is connected to venous system
82
Cardiac looping
-when heart grows it is restricted by the septum transversum and pericardium and must bend
83
Cardiac looping movements
-primitive atria moves posteriorly
-bulbus cordis and right primitive ventricle come to lie between primitive right and left atria
84
Why is the primitive heart different from the adult heart
-resembles it, but primitive heart is still one continuous tube
85
Interatrial septum
-separate right and left atria
86
Interventricular septum
-separate right and left ventricles
87
Formation of interatrial septum steps
-septum primum
-ostium secondum
-septum secundum
88
Septum primum
-cells from the roof of common atria grow caudally
-grows towards endocardial cushion but does not fuse
89
Ostium secundum
-when septum fuses with the endocardial cushion this second opening is created
90
Septum secundum
-second septum forms from roof of atria
-common atria is now divided into left and right atrium
91
Formen ovale
-oval shaped window that allows blood to pass between the atria
92
What is the foramen ovale covered by
-thin valve-like membranous flap from septum primum
93
First step of foramen ovale formation
-fetus receives oxygenated blood from the placenta via the umbilical vein, oxygenated blood enters the right atrium
94
Second step of foramen ovale formation
-since blood is already oxygenated, it does not need to be pumped to the lungs
95
Third step of foramen ovale formation
-foramen ovale allows blood to bypass the pulmonary circulation by shunting blood from right atrium to left atrium
96
Where does blood move from left atrium
-blood moves into left ventricle, and then through aorta to the rest of the body
97
Patent foremen ovale
-incomplete fusion of septum secundum and septum primum
-has been associated with increased risk of adverse events including strokes
-most are asymptomatic and do not require treatment
98
Embryonic arteries
-aortic sac
-ventral aorta
-aortic arches
-dorsal aorta
99
Aortic sac
-sits cranial to truncus arteriosus
100
Ventral aorta
-aortic sac branches into 2 horns, right and left ventral aorta
101
Aortic arches
-6 arteries branch off each ventral aorta, and wrap around the pharynx
102
What do aortic arches follow the pattern of
-pharyngeal arches
103
Dorsal aorta
-connects with the aortic arches and connect back with aortic sac
104
How many aortic arches are there
-6
105
Aortic arches 1, 2 and 5
-all regress
106
Arch 3 parts
-dorsal aortae
-ventral aortae
107
Arch 3 dorsal aortae
-forms the internal carotid arteries and common carotid arteries
108
Arch 3 ventral aortae
-external carotid arteries
109
Arch 4 parts
-right ventral aorta
-left ventral aorta
110
Arch 4 right ventral aorta
-forms right subclavian artery
111
Arch 4 left ventral aorta
-aortic arch
112
Arch 6
-forms right and left pulmonary arteries
-also forms ductus arteriosus which forms the ligamentum arteriosus at birth
113
Ductus arteriosus general function
-directs the flow of blood in the fetus
114
Ductus arteriosus prenatal function
-instead of entering underdeveloped lungs through pulmonary arteries, blood passes through the ductus arteriosus and enters aorta at aortic arch
115
Ductus arteriosus postnatal function
-lungs are now developed and blood must travel through pulmonary arteries
116
What is formed when the ductus arteriosus obliterates
-ligamentum arteriosum
-separates the pulmonary and systemic circulation
117
Patent ductus arteriosus
-condition where ductus arteriosus does not fully close and there is still a connection between pulmonary and systemic circulation
-small openings may be asymptomatic
-larger openings are closed with ligation
118
When do embryonic veins develop
-week 4
119
Embryonic veins
-vitelline veins
-umbilical veins
-cardinal veins
120
Vitelline veins function
-drain the yolk sac
121
Umbilical veins function
-come from chorionic villi and carry oxygenated blood to embryo
122
Cardinal veins function
-drain the body of the embryo
123
Vein remodelling
-left veins tend to regress while right veins enlarge and give rise to great veins
