02.2 Embryonic Development Flashcards Preview

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Flashcards in 02.2 Embryonic Development Deck (62)
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1
Q

What is the external lining of the gut derived from?

A

Splanchinic mesoderm

2
Q

What is a foregut derivative?

A
Oesophagus
Stomach
Pancreas
Liver
Gallbladder
Duodenum (proximal to bile duct entrance)
3
Q

What a re the derivatives of the midgut?

A
Duodenum (distal to the bile duct)
Jejunum
Ileum
Caecum 
Ascending colon
Proximal 2/3 of transverse colon
4
Q

What are the derivatives of the hind gut?

A
Distal 1/3 transverse colon
Descending colon
Sigmoid colon
Rectum
Upper anal canal
Internal lining of the bladder and urethra
5
Q

What supplies blood to the foregut?

A

Coeliac trunk

6
Q

What supplies blood to the midgut?

A

Superior mesenteric artery

7
Q

What supplies blood to the hind gut?

A

Inferior mesenteric artery

8
Q

Which organs of the GI tract have a mixed blood supply?

A

Duodenum
Pancreas

Both have both coeliac trunk and superior mesenteric artery blood supply.

9
Q

What is a mesentery?

A

Double layer of peritoneum suspending the gut tube from the abdominal wall

10
Q

What mesentery is present on the foregut, midgut and hindgut?

A

Dorsal mesentery

11
Q

What mesentery is only present on the foregut?

A

Ventral mesentery

12
Q

What forms the greater omentum?

A

Dorsal mesentery

13
Q

What forms the lesser omentum and what can therefore be conducted?

A

Ventral mesentery

The free edge can conduct the portal triad

14
Q

What does stomach rotation create?

A

Greater and lesser omenta

Repositions stomach so that greater curvature is inferior and left and the cardia and pylorus are away from the midline.

15
Q

What forms the barrier between the oesophagus and the trachea?

A

Tracheoesophageal septum

16
Q

What abnormalities can occur from the tracheoesophageal septum?

A

Proximal blind end oesophagus

Tracheoesophageal fistula

17
Q

What forms the liver?

A

The hepatic bud within the central mesentery

18
Q

What does the term secondarily retroperitoneal mean?

A

Began development in the peritoneum but excessive growth causes the mesentery to be lost through fusion at the posterior abdominal wall.

19
Q

What are the secondarily retroperitoneal structures of the foregut?

A

Duodenum (except cap)

Pancreas

20
Q

Why does the midgut run out of space in the abdomen?

A

Elongates very quickly

Liver is in the way

21
Q

What is the axis of the midgut loop?

A

Superior mesenteric artery

Vitelline duct

22
Q

After physiological herniation into the umbilical cord how does the midgut rotate?

A

270 degrees anti-clockwise

First turn during herniation
Cranial limb then returns first moving it to the left side
Caecum then descends

23
Q

What are common types of malrotations of the midgut and what do they result in?

A

Incomplete rotation - only makes one 90 degree rotation - left sided colon
Reversed rotation - makes one 90 degree rotation but clockwise - transverse colon is posterior to the duodenum

24
Q

What is a potential complication of midgut rotation defects?

A

Volvulus

25
Q

What is the internal lining of the gut formed from?

A

Endoderm

26
Q

What is the external lining of the gut derived from?

A

Splanchinic mesoderm

27
Q

What is a foregut derivative?

A
Oesophagus
Stomach
Pancreas
Liver
Gallbladder
Duodenum (proximal to bile duct entrance)
28
Q

What a re the derivatives of the midgut?

A
Duodenum (distal to the bile duct)
Jejunum
Ileum
Caecum 
Ascending colon
Proximal 2/3 of transverse colon
29
Q

What are the derivatives of the hind gut?

A
Distal 1/3 transverse colon
Descending colon
Sigmoid colon
Rectum
Upper anal canal
Internal lining of the bladder and urethra
30
Q

What supplies blood to the foregut?

A

Coeliac trunk

31
Q

What supplies blood to the midgut?

A

Superior mesenteric artery

32
Q

What supplies blood to the hind gut?

A

Inferior mesenteric artery

33
Q

Which organs of the GI tract have a mixed blood supply?

A

Duodenum
Pancreas

Both have both coeliac trunk and superior mesenteric artery blood supply.

34
Q

What is a mesentery?

A

Double layer of peritoneum suspending the gut tube from the abdominal wall

35
Q

What mesentery is present on the foregut, midgut and hindgut?

A

Dorsal mesentery

36
Q

What mesentery is only present on the foregut?

A

Ventral mesentery

37
Q

What forms the greater omentum?

A

Dorsal mesentery

38
Q

What forms the lesser omentum and what can therefore be conducted?

A

Ventral mesentery

The free edge can conduct the portal triad

39
Q

What does stomach rotation create?

A

Greater and lesser omenta

Repositions stomach so that greater curvature is inferior and left and the cardia and pylorus are away from the midline.

40
Q

What forms the barrier between the oesophagus and the trachea?

A

Tracheoesophageal septum

41
Q

What abnormalities can occur from the tracheoesophageal septum?

A

Proximal blind end oesophagus

Tracheoesophageal fistula

42
Q

What forms the liver?

A

The hepatic bud within the central mesentery

43
Q

What does the term secondarily retroperitoneal mean?

A

Began development in the peritoneum but excessive growth causes the mesentery to be lost through fusion at the posterior abdominal wall.

44
Q

What are the secondarily retroperitoneal structures of the foregut?

A

Duodenum (except cap)

Pancreas

45
Q

Why does the midgut run out of space in the abdomen?

A

Elongates very quickly

Liver is in the way

46
Q

What is the axis of the midgut loop?

A

Superior mesenteric artery

Vitelline duct

47
Q

After physiological herniation into the umbilical cord how does the midgut rotate?

A

270 degrees anti-clockwise

First turn during herniation
Cranial limb then returns first moving it to the left side
Caecum then descends

48
Q

What are common types of malrotations of the midgut and what do they result in?

A

Incomplete rotation - only makes one 90 degree rotation - left sided colon
Reversed rotation - makes one 90 degree rotation but clockwise - transverse colon is posterior to the duodenum

49
Q

What is a potential complication of midgut rotation defects?

A

Volvulus

50
Q

What is the internal lining of the gut formed from?

A

Endoderm

51
Q

What is the difference between a vitelline cyst and a vitelline fistula?

A

Vitelline cyst is a pocket where the vitilline duct used to be that does not open up onto the umbilicus or the midgut
Vitelline fistula is a fully patent vitelline duct where the midgut can communicate with the umbillicus

52
Q

Other that a vitelline cyst or fistula what other abnormality can occur due the the remnants of the vitelline duct?

A

Meckel’s diverticulum

53
Q

Where is the most likely place for recanalisation to fail?

A

Duodenum

54
Q

What can happen if recanalisation of the GI tract is unsuccessful?

A

Atresia

Stenosis

55
Q

Why is pyloric stenosis not an example of recanalisation failure?

A

Actually due to pyloric sphincter hypertrophy

56
Q

What is gastroschisis?

A

Failure of closure of the abdominal wall during folding of the embryo. This leaves the gut tube and derivatives outside the body cavity.

57
Q

What is omphalocoele/exomphalos?

A

Persistence of physiological herniation

This is different to an umbilical hernia as there is no skin covering

58
Q

What is the pectinate line?

A

The line that splits the histologically different upper and lower anal canal

59
Q

What is the difference between the epithelia above and below the pectinate line?

A

Above - columnar epithelium

Below - stratified squamous epithelium

60
Q

What is the difference in blood supply above and below the pectinate line?

A

Above - IMA

Below - Pudenal artery

61
Q

What is the difference in nervous supply above and below the pectinate line?

A

Above - parasympathetic pelvic nerve

Below - pudenal nerve

62
Q

What are potential hindgut abnormalities?

A

Imperforate anus
Hindgut fistulae (eg rectum to bladder)
Anorectal agenesis