deck_1369783 Flashcards

1
Q

When does embryonic folding occur?

A

Fourth week

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2
Q

What make the gut tube become tubular?

A

Lateral folding

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3
Q

What does cranial folding achieve?

A

Creates the cranial and the caudal blind pockets (these are derived from the endoderm which covers the yolk sac)

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4
Q

Describe the primitive gut tube after folding

A

It is suspended inside the future abdominal and thoracic cavity by a double layer of splanchnic mesoderm.

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5
Q

What are the gut divisions in the embryo?

A

Foregut, mid gut and hindgut

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6
Q

Why are the gut divisions important?

A

Help to allow for the organisation of blood supply and the lymphatic system in the adult

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7
Q

When does the development of the primitive gut tube begin?

A

In the third week

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8
Q

Give two features of the primitive gut tube

A
  1. Runs from the stomatodeum to proctodeum with a single opening in the umbilicus (midgut region which is continuous with the yolk sac)2. Internal lining is endoderm and external lining is splanchnic mesoderm
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9
Q

What does lateral folding achieve?

A

Creates the ventral body wall and allows for the primitive gut tube to become tubular

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10
Q

What will you find in the embryo after craniocaudal folding?

A

Primitive gut tube has formedThe vague shape of the embryo in the mesodermA connection where the umbilicus is Blind end diverticulum at both the head and tail end

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11
Q

What are the adult derivatives of the foregut?

A

OesophagusStomachPancreasLiverGall BladderDuodenum (proximal to the entrance of the bile duct)

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12
Q

What are the adult derivative of the midgut?

A

Duodenum(distaltoentranceofbileduct)JejunumIleumCecumAscendingcolonProximal two thirds of the transverse colon

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13
Q

What are the adult derivatives of the hindgut?

A

Distalthird of the transversecolonDescending colonSigmoidcolonRectumUpperanalcanalInternalliningofbladder&urethra

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14
Q

What is the blood supply to the foregut?GIve a distinguishing factor of it.

A

Celiac trunk– branches off into 3 main vessels very quickly

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15
Q

What is the blood supply to the midgut?

A

Superior mesenteric artery

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16
Q

What is the blood supply to the hindgut?

A

Inferior mesenteric artery

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17
Q

Where are the exceptions to the blood supply?

A

At area where structures are close to the junctions between the foregut and midgut, there is a mixed blood supply e.g. duodenum and pancreas

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18
Q

Describe the blood supply to the duodenum

A

Proximal to the entry of the bile duct, the supply is from the celiac trunkDistal to the entry of the bile dict, the supply is from the superior mesenteric artery

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19
Q

Describe the blood supply to the pancreas

A

The head of the pancreas gets its supply from the celiac trunk (superior pancreaticoduodenal artery) as well as the superior mesenteric artery (inferior pancreaticoduodenal artery)

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20
Q

What is the intraembryonic coelem?

A

It is the primordium of all the body cavities, but it starts of as a single, large cavity inside the embryo.

21
Q

What divides the intraembryonic coelem into the separate cavities and what are those cavities?

A

The future diaphragm divides the intraembryonic coelem into the abdominal and thoracic cavities.

22
Q

What is the function of the peritoneum?

A

It wraps around abdominal cavity and invests the viscera (protects it)

23
Q

What does the peritoneal cavity contain?

A

It is a potential space, should not contain anything except a small amount of serous fluid

24
Q

What function does the peritoneum have in the embryo?Why is this important?

A

A double layer of peritoneum suspends the gut tube from the abdominal wall. Allows somewhere for blood to travel through, a nerve supply and allows mobility when it is needed (peristalsis)

25
Q

What are the mesenteries?What are they derived from?

A

Double layer of peritoneum which suspends the gut tube from the abdominal wall. The mesentery is formed from a condensation of the splanchnic mesoderm which surround the gut tube

26
Q

What are the differences between the dorsal and ventral mesenteries?

A

Dorsal mesentery – suspends the entires gut tube from the dorsal body wall Ventral mesentery – is only found the the region of the foregut in addition to the dorsal mesentery

27
Q

What do the dorsal and ventral mesenteries do?

A

Divide the foregut region into left and right sacs. The left sac forms the greater sac and the right sac forms the lesser sac

28
Q

What are the greater and lesser omenta?

A

Are specialised regions of peritoneum which surround the abdominal organs

29
Q

Describe the greater omenta

A

First structure you see when you open the abdominal cavity– formed from dorsal mesentery

30
Q

Describe the lesser omenta

A

– formed from ventral mesentery and the free edges conduct the portal triad

31
Q

What is the portal triad?

A

Arrangement in the liver of proper hepatic artery, hepatic portal vein, common bile duct, lymphatic vessels and branches of the vagus nerve found in hepatic lobules

32
Q

How are the greater and lesser omenta formed?

A

By rotation of the stomach– rotates around its longitudinal axis to form the greater and lesser curvature– rotates around the anteroposterior axis to move the cardia and pylorus horizontally which pushes the greater curvature inferiorly

33
Q

Describe what has happened at the end of stomach rotation

A
  1. Vagus nerves are put anteriorly and posteriorly to the stomach (instead of left and right)2. Shifts cardia and pylorus from the midline (stomach lies obliquely)3. Pushes the lesser sac behind the stomach 4. Creates the greater omentum5. Changes the positions of the dorsal and ventral mesenteries
34
Q

What is a peritoneal reflection?Where are the main reflections?

A

A point at which the peritoneal membrane changes its direction1. From parietal peritoneum to mesentery2. From mesentery to visceral peritoneum

35
Q

What happens if the organ does not have a mesentery?

A

The organs are known as retroperitoneal – were never suspended in the peritoneal cavity so never had a mesentery

36
Q

What is secondarily retroperitoneal?

A

– A structure thatdeveloped intraperitoneally whose mesentery waslost to fusion withthe posterior abdominal wallparietal peritoneum due to massiveexpansionofGItractduring development. Form fusion fascia against the posterior abdominal wall. – duodenum (except duodenal cap) and pancreas are secondary retroperitoneal structures

37
Q

What is the transoesophageal septum?

A

A septum which divides the trachea and oesophagus which develop together

38
Q

How common are oesophageal abnormalities?

A

Occur in 1 in 3000 live births

39
Q

Give some examples of oesophageal abnormalities

A

Proximal blind end oesophagous, tracheoesophageal fistula (infant cannot feed)

40
Q

How is the stomach formed from its gut derivative?

A

A dilation occurs in the distal foregut in the middle of week four which indicates the stomach primordium.The dorsal border grows faster and to a bigger size than the ventral border which becomes the lesser curvature.

41
Q

What glands are derived from the foregut?

A

Liver and duodenum

42
Q

Describe the features of the liver and what it is derived from

A

Develops from a hepatic gland within the ventral mesenteryOccupies a large proportion of the abdomen during development

43
Q

What is the falciform ligament?

A

Attaches liver to the anterior abdominal wall

44
Q

What is the bare area of the liver?

A

Where the liver attaches to the diaphragm

45
Q

Describe the development of the duodenum

A

It develops from caudal foregut and cranial midgutGrows rapidly, forming a C shaped loop when the stomach rotates. In week 5-6, lumen is obliterated and it is recanalised at the end of the embryonic period– Rotation of the stomach pushes duodenum to right then agains the posterior wall so it is secondarily retroperitoneal

46
Q

What is physiological umbilical herniation and why does it occur?

A

Due to the rapid growth and expansion of the liver, the abdominal cavity becomes too small to contain all the loops of the intestine so they enter the extra embryonic cavity in the umbilical cord at during the sixth week

47
Q

What is the inguinal canal?

A

A cavity which the gonads descend down in order to reach their site in the adult body. This cavity tends to close within a year after birth

48
Q

Why can hernias occur?

A

Intestinal loops may descend into the scrotum, meaning that the cavity cannot close. There is also a weak spot in the fascia of the posterior wall of the inguinal canal (transversalis fascia) leading to direct inguinal hernias

49
Q

When do indirect hernias occur?

A

They occur when the abdominal contents push through the deep inguinal ring (failure of closure of the processus vaginalis)