Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

(LUSUMA) Gastro-intestinal System > S2-3) Development of the Gut > Flashcards

S2-3) Development of the Gut Flashcards

1
Q

In the 4th week, the embryo folds.

Describe the result of its lateral folding

A

Lateral:

  • Creates ventral body wall
  • Primitive gut becomes tubular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In the 4th week, the embryo folds.

Describe the result of its craniocaudal folding

A

Craniocaudal:

  • Creates cranial & caudal pockets from yolk sac endoderm
  • Beginning primitive gut development
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the gut tube?

A
  • The gut tube is an endoderm-lined tube
  • It runs the length of the body and opens at the umbilicus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe some features found on the primitive gut tube

A
  • Blind pouches at the head and tail ends
  • Splanchnic mesoderm covering
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Identify and describe the divisions of the gut tube

A
  • Foregut and hindgut begin as blind diverticula
  • Midgut has an opening at first and is continuous with the yolk sac
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Identify the derivatives of the foregut

A
  • Oesophagus
  • Stomach
  • Pancreas, liver & gall bladder
  • Duodenum (proximal to entrance of bile duct)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Identify the derivatives of the midgut

A
  • Duodenum (distal to entrance of bile duct)
  • Jejunum
  • Ileum
  • Cecum
  • Ascending colon
  • Proximal 2/3 transverse colon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Identify the derivatives of the hindgut

A
  • Distal 1/3 transverse colon
  • Descending colon
  • Sigmoid colon
  • Rectum
  • Upper anal canal
  • Internal lining of bladder & urethra
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Explain how the embryonic divisions have implications for blood supply in the adult

A
  • Arterial supply reflects embryonic development
  • Each embryonic segment receives blood supply from a distinct branch of the abdominal aorta
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The structures that develop close to the junction between foregut and midgut will have mixed blood supply.

Relate this to the duodenum

A

- Proximal to entry of bile duct: gastroduodenal artery & superior pancreaticoduodenal artery (CT)

- Distal to entry of bile duct: inferior pancreaticoduodenal artery (SMA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The structures that develop close to the junction between foregut and midgut will have mixed blood supply.

Relate this to the head of the pancreas

A
  • Superior pancreaticoduodenal artery (CT)
  • Inferior pancreaticoduodenal artery (SMA)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the formation of the intraembryonic coelom

A
  • Formed as the embryo folds
  • Begins as one large cavity
  • Later subdivided by the future diaphragm into abdominal and thoracic cavities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain the specialisation of intraembryonic coelom and its membrane

A
  • One membrane lining the whole intraembryonic cavity
  • Specialises as the cavities specialise:

I. Pericardium

II. Pleural membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are mesenteries and why are they needed?

A
  • Mesenteries are a double layer of peritoneum suspending the gut tube from the abdominal wall
  • Purpose:

I. Allow a conduit for blood and nerve supply

II. Allow mobility where needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How are mesenteries formed?

A

The new primitive gut is suspended within the intraembryonic coelom:

  • Splanchnic mesoderm surrounds new gut
  • Mesentery formed from a condensation of this mesoderm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where are the mesenteries?

A
  • Dorsal mesentery suspends the entire gut tube from the dorsal body wall
  • Ventral mesentery is only in the region of the foregut
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Explain the contribution of the dorsal and ventral mesenteries to the lesser and greater sacs of the peritoneal cavity

A

Dorsal and ventral mesenteries divide the cavity into left and right sacs (in foregut only):

  • The left sac contributes to the greater sac
  • The right sac becomes the lesser sac
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are omenta?

A

Omenta are specialised regions of peritoneum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the formation of the greater omentum

A
  • Formed from the dorsal mesentery
  • First structure seen when the abdominal cavity is opened anteriorly
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the formation of the lesser omentum

A
  • Formed from the ventral mesentery
  • Free edge conducts the portal triad
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is meant by the term peritoneal reflection?

A

A change in direction:

  • From parietal peritoneum to mesentery
  • From mesentery to visceral peritoneum, etc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What influences the position of the greater and lesser sacs?

A

Rotation of the stomach during development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Structures that are not suspended within the abdominal cavity are retroperitoneal.

What does this mean?

A

Retroperitoneal structures were never in the peritoneal cavity & never had a mesentery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is meant by the term secondarily retroperitoneal?

A

Secondarily retroperitoneal structures are structures which developed intraperitoneally whose mesentery was lost to fusion with posterior abdominal wall parietal peritoneum due to massive expansion of GI tract during development

25
Q

Identify some secondarily retroperitoneal structures of the foregut

A
  • Duodenum
  • Pancreas
26
Q

Describe the location of the foregut

A

Extends from the lung bud to the liver bud

27
Q

What happens in the 4th week of development in relation to the foregut?

A

A respiratory diverticulum forms in the ventral wall of the foregut at the junction with the pharyngeal gut:

  • Respiratory primordium (ventrally)
  • Oesophagus (dorsally)
28
Q

A variety of oesophageal abnormalities occur as a consequence of abnormal positioning of the tracheoesophageal septum.

Identify two

A
29
Q

Which mesentery do the liver and biliary system (foregut-derived glands) develop from?

A

Ventral mesentery

30
Q

Describe which mesentery is responsible for the development of different areas of the pancreas (foregut-derived gland)

A
  • Ventral mesentery: uncinate process and inferior head
  • Dorsal mesentery: superior head, neck, body & tail
31
Q

Explain why the duodenum is regarded as a secondarily retroperitoneal structure?

A
  • Its shape is determined by rotation of the stomach
  • Rotation of the stomach pushes duodenum to right, then against posterior abdominal wall
32
Q

Describe the formation of the primary intestinal loop

A

The midgut elongates enormously then makes a loop that:

  • Has the SMA as its axis
  • Is connected to the yolk sac by the vitelline duct
  • Has cranial & caudal limbs
33
Q

How does physiological herniation occur?

A
  • Primary intestinal loop elongates rapidly and liver also grows rapidly
  • Abdominal cavity is too small to accommodate both & intestines herniate into the umbilical cord
34
Q

What immediately follows the rotation of the gut?

A

The descent of the caecal bud

35
Q

How does incomplete rotation occur and what is the result?

A
  • Midgut loop makes only one 90° rotation
  • Result: left-sided colon
36
Q

How does reverse rotation occur and what is the result?

A
  • Midgut loop makes one 90° rotation clockwise
  • Result: transverse colon passes posterior to the duodenum
37
Q

Most complications arising from midgut defects occur in the neonatal period.

Identify two of them

A
  • Strangulation
  • Ischaemia
38
Q

The vitelline duct can persist resulting in a number of different abnormalities.

Identify 3 of these

A
  • Vitelline cyst
  • Vitelline fistula
  • Meckel’s diverticulum
39
Q

How does a vitelline cyst form?

A

Vitelline cyst – vitelline duct forms fibrous strands

40
Q

Describe the features of a vitelline fistula

A

Vitelline fistula – direct communication between the umbilicus & intestinal tract

41
Q

Meckel’s diverticulum is the most common GI anomaly.

Describe the incidence of its occurrence

A
  • Affects 2% population
  • Usually detected in under 2s
42
Q

In some gut structures, cell growth becomes so rapid that the lumen is partially or completely obliterated.

Identify three of these

A
  • Oesophagus
  • Bile duct
  • Small intestine
43
Q

What does recanalisation do?

A

Recanalisation occurs to restore the lumen of gut structures

44
Q

What happens if recanalisation is wholly or partially unsuccessful?

A
  • Atresia: lumen obliterated
  • Stenosis: lumen narrowed
45
Q

What is the most common location for atresia and stenoses?

A

Duodenum

46
Q

What is pyloric stenosis?

A
  • Pyloric stenosis is hypertrophy of the circular muscle in the region of the pyloric sphincter
  • It is not a recanalisation failure
47
Q

What is gastroschisis?

A
  • Gastroschisis is the failure of closure of the abdominal wall during folding of the embryo
  • Gut tube & derivatives are outside the body cavitiy
48
Q

What is omphalocoele?

A

Omphalocoele is the persistence of physiological herniation

49
Q

How does the omphalocoele differ from an umbilical hernia?

A

Umbilical hernias have the covering of skin and subcutaneous tissue

50
Q

How is the anal canal divided?

A

The anal canal is divided by the pectinate line into histologically distinct superior and inferior parts

51
Q

What is the proctodeum?

A

The proctodeum is the junction between two embryonic germ layers (anal pit)

52
Q

Above the pectinate line, describe the following:

  • Blood supply
  • Innervation
  • Epithelium
  • Lymphatic drainage
A
  • Blood supply: IMA
  • Innervation: S2-4 pelvic parasympathetics
  • Epithelium: columnar
  • Lymphatic drainage: internal iliac nodes
53
Q

Below the pectinate line, describe the following:

  • Blood supply
  • Innervation
  • Epithelium
  • Lymphatic drainage
A
  • Blood supply: pudendal artery
  • Innervation: S2-4 pudendal nerve
  • Epithelium: stratified epithelium
  • Lymphatic drainage: superficial inguinal nodes
54
Q

What is the significance of the contribution of two embryonic tissues to the anal canal?

A
  • Above the pectinate line: stretch sensation
  • Below the pectinate line: temperature, touch and pain sensations
55
Q

Describe the nature of visceral pain?

A

Visceral pain is poorly localised

56
Q

Identify the regions of visceral pain and its origins

A
  • Foregut & its derivatives – epigastrium
  • Midgut – periumbilical
  • Hindgut – suprapubic
57
Q

Identify 3 different hindgut abnormalities

A
  • Imperforate anus
  • Anal / anorectal agenesis
  • Hindgut fistulae
58
Q

Identify the 5 structures which retain the mesenteries

A
  • Jejunum
  • Ileum
  • Appendix
  • Transverse colon
  • Sigmoid colon
59
Q

Identify 4 structures of the midgut/hindgut with fused mesenteries

A
  • Duodenum
  • Ascending colon
  • Descending colon
  • Rectum

(LUSUMA) Gastro-intestinal System (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions