Development of the Digestive System (Lecture 2)

Questions and Answers

What forms the main pancreatic duct (of Wirsung)?

Only the ventral pancreatic duct

The distal part of the dorsal pancreatic duct and the entire ventral pancreatic duct (correct)

The entire dorsal pancreatic duct

The proximal part of the dorsal pancreatic duct

The ventral pancreatic bud comes to lie immediately below the bile duct.

False

What condition is caused when the right portion of the ventral pancreatic bud migrates normally while the left migrates in the opposite direction?

Annular pancreas

The accessory pancreatic duct is also known as the duct of __________.

Santorini Signup and view all the answers

Match the pancreatic structures with their descriptions:

Dorsal pancreatic bud = Lies in the dorsal mesentery Ventral pancreatic bud = Forms the uncinate process and part of the head Main pancreatic duct = Formed by the fusion of pancreatic ducts Accessory pancreatic duct = Usually remains as a small channel Signup and view all the answers

In what percentage of cases does the duct system fail to fuse, resulting in a double duct system?

10% Signup and view all the answers

Accessory pancreatic tissue only occurs at the distal end of the esophagus.

False Signup and view all the answers

What does the dorsal bud contribute to in the pancreas?

The remaining part of the pancreas excluding the uncinate process and inferior part of the head Signup and view all the answers

What is the main cause of gastroschisis?

Abnormal closure of the body wall around the connecting stalk Signup and view all the answers

Omphalocele is associated with a higher rate of chromosomal abnormalities than gastroschisis.

True Signup and view all the answers

What is the survival rate for infants born with gastroschisis?

Excellent Signup and view all the answers

What is the function of the urorectal septum?

To separate the allantois and hindgut Signup and view all the answers

Atresias and stenoses may occur anywhere along the __________.

intestine Signup and view all the answers

The cloacal membrane ruptures to create only the anal opening for the hindgut.

False Signup and view all the answers

Which of the following factors may cause intestinal atresias in the distal portion of the duodenum?

All of the above Signup and view all the answers

What is the estimated occurrence rate of gastroschisis in births?

1 in 10,000 Signup and view all the answers

What structure separates the endoderm and ectoderm in the cloaca?

cloacal membrane Signup and view all the answers

The junction between the endodermal and ectodermal regions of the anal canal is called the _____ line.

pectinate Signup and view all the answers

Match the following conditions with their descriptions:

Omphalocele = Associated with chromosomal abnormalities Gastroschisis = Abdominal contents protrude into amniotic cavity Volvulus = Twisting of the intestine leading to compromised blood supply Atresias = Blockages or narrowing in the intestine Signup and view all the answers

Which artery supplies the cranial part of the anal canal?

Superior rectal artery Signup and view all the answers

Which portion of the hindgut gives rise to the sigmoid colon?

Descending colon Signup and view all the answers

Rectourethral and rectovaginal fistulas occur in approximately 1 in 5,000 live births.

True Signup and view all the answers

When the anal membrane fails to breakdown, it results in _____ anus.

imperforate Signup and view all the answers

Match the following structures to their corresponding descriptions:

Cloacal membrane = Boundary between endoderm and ectoderm Inferior rectal arteries = Supply the caudal part of the anal canal Superior rectal artery = Supply the cranial part of the anal canal Urorectal septum = Separates allantois and hindgut Signup and view all the answers

What does the cephalic limb of the primary intestinal loop develop into?

Distal part of the duodenum, jejunum, and part of the ileum Signup and view all the answers

The primary intestinal loop rotates 360° clockwise during its development.

False Signup and view all the answers

What is omphalocele?

Herniation of abdominal viscera through an enlarged umbilical ring. Signup and view all the answers

The movement of the intestinal loops into the extraembryonic cavity is referred to as __________.

physiological herniation Signup and view all the answers

Match the following parts of the intestine with their respective development:

Cecum = Caudal limb of the primary intestinal loop Jejunum = Cephalic limb of the primary intestinal loop Appendix = Caudal limb of the primary intestinal loop Ileum = Both limbs of the primary intestinal loop Signup and view all the answers

During which week of development do the herniated intestinal loops begin to return to the abdominal cavity?

10th week Signup and view all the answers

The large intestine participates in the coiling phenomenon during its development.

False Signup and view all the answers

What causes omphalocele during fetal development?

Failure of the bowel to return to the body cavity from its physiological herniation. Signup and view all the answers

Study Notes

Pancreas Development

Formed from dorsal and ventral buds of endodermal lining of the duodenum.
Dorsal bud located in dorsal mesentery; ventral bud near the bile duct.
Duodenum rotation causes ventral bud to move behind the dorsal bud.
Ventral bud develops uncinate process and inferior part of the pancreas; dorsal forms the remainder.
Main pancreatic duct (Wirsung) results from the distal dorsal duct and entire ventral duct.
Accessory duct (Santorini) may persist from proximal dorsal duct; enters at minor papilla.
In about 10% of cases, duct systems do not fuse, leading to a double pancreatic duct system.

Pancreatic Abnormalities

Annular pancreas can occur when portions of the ventral bud migrate abnormally, constricting the duodenum.
Accessory pancreatic tissue can be present from the distal esophagus to the primary intestinal loop, often found in stomach mucosa or Meckel's diverticulum.

Midgut Development

Rapid elongation leads to formation of primary intestinal loop connected to yolk sac via vitelline duct.
Cephalic limb develops the distal duodenum, jejunum, and part of the ileum.
Caudal limb gives rise to lower ileum, cecum, appendix, ascending colon, and proximal transverse colon.

Physiological Herniation

Intestinal loops herniate into umbilical cord cavity during sixth week due to rapid growth.

Midgut Rotation

Intestinal loop rotates 270° counterclockwise around the superior mesenteric artery.
During the tenth week, herniated loops begin returning to the abdominal cavity, creating coiled loops of small intestine and displacing the cecum to the lower right abdomen.

Anomalies

Omphalocele: Herniation of viscera through enlarged umbilical ring, covered by amnion; occurs in 2.5/10,000 births, associated with high mortality and severe malformations.
Gastroschisis: Herniation of contents through body wall without covering, occurring at right umbilicus; seen in 1/10,000 births, better survival outcomes compared to omphalocele.
Volvulus: Rotation resulting in compromised blood supply, potentially leading to fetal death.

Gut Rotation Defects

Abnormal rotation causing left-sided colon; can lead to volvulus.
Reversed rotation allows transverse colon to pass behind duodenum.
Duplications or cysts may result from gut parenchyma proliferations.

Gut Atresias and Stenoses

Can occur along the intestine; most commonly in duodenum.
Caused by failure of recanalization in upper duodenum and vascular accidents below that site.
Associated conditions include malrotation, volvulus, gastroschisis, and omphalocele.

Hindgut Development

Develops into the distal transverse colon, descending colon, sigmoid, rectum, and upper anal canal.
The cloaca serves as the entry point, divided by the urorectal septum into urogenital and hindgut openings.
The cloacal membrane ruptures by the seventh week, creating anal and urogenital openings.

Hindgut Abnormalities

Rectourethral and rectovaginal fistulas: Result from cloacal formation issues; may occur in 1/5,000 live births.
Rectoanal atresias: May present as fibrous remnants or segment loss due to vascular accidents.
Imperforate anus: Caused by failure of the anal membrane to break down.

Additional Notes

The superior rectal artery supplies the cranial anal canal, while the inferior rectal arteries supply the caudal anal canal.
The pectinate line differentiates the transition point between ectodermal and endodermal regions in the anal canal.

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Description

This quiz explores the development of the digestive system, focusing particularly on the pancreas and its formation from the buds originating from the endodermal lining of the duodenum. Understand key anatomical changes and the role of the dorsal and ventral pancreatic buds in the digestive system's development.

Development of the Digestive System (Lecture 2)

Questions and Answers

What forms the main pancreatic duct (of Wirsung)?

The ventral pancreatic bud comes to lie immediately below the bile duct.

What condition is caused when the right portion of the ventral pancreatic bud migrates normally while the left migrates in the opposite direction?

The accessory pancreatic duct is also known as the duct of __________.

Match the pancreatic structures with their descriptions:

In what percentage of cases does the duct system fail to fuse, resulting in a double duct system?

Accessory pancreatic tissue only occurs at the distal end of the esophagus.

What does the dorsal bud contribute to in the pancreas?

What is the main cause of gastroschisis?

Omphalocele is associated with a higher rate of chromosomal abnormalities than gastroschisis.

What is the survival rate for infants born with gastroschisis?

What is the function of the urorectal septum?

Atresias and stenoses may occur anywhere along the __________.

The cloacal membrane ruptures to create only the anal opening for the hindgut.

Which of the following factors may cause intestinal atresias in the distal portion of the duodenum?

What is the estimated occurrence rate of gastroschisis in births?

What structure separates the endoderm and ectoderm in the cloaca?

The junction between the endodermal and ectodermal regions of the anal canal is called the _____ line.

Match the following conditions with their descriptions:

Which artery supplies the cranial part of the anal canal?

Which portion of the hindgut gives rise to the sigmoid colon?

Rectourethral and rectovaginal fistulas occur in approximately 1 in 5,000 live births.

When the anal membrane fails to breakdown, it results in _____ anus.

Match the following structures to their corresponding descriptions:

What does the cephalic limb of the primary intestinal loop develop into?

The primary intestinal loop rotates 360° clockwise during its development.

What is omphalocele?

The movement of the intestinal loops into the extraembryonic cavity is referred to as __________.

Match the following parts of the intestine with their respective development:

During which week of development do the herniated intestinal loops begin to return to the abdominal cavity?

The large intestine participates in the coiling phenomenon during its development.

What causes omphalocele during fetal development?

Study Notes

Pancreas Development

Pancreatic Abnormalities

Midgut Development

Physiological Herniation

Midgut Rotation

Anomalies

Gut Rotation Defects

Gut Atresias and Stenoses

Hindgut Development

Hindgut Abnormalities

Additional Notes

Studying That Suits You

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