deck_1667685 Flashcards

1
Q

What does the midgut give rise to?

A

o Small intestine, including most of the duodenum (post bile duct entry)o Caecum and appendixo Ascending colono Proximal 2/3rds of the transverse colon

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2
Q

How is the primary intestinal loop formed?

A

As a result of the rapid elongation of the midgut and the large size of the developing liver

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3
Q

Describe the midgut loop - What are its two parts, what is its axis and where does it connect?

A
  • Cranial and caudal limbs- Superior mesenteric artery at ais- Connected to vitelline duct
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4
Q

What does the cranial limb of the midgut loop become?

A

Distal duodenumJejunumProximal ileum

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5
Q

What does the caudal limb become?

A

Distal IleumCecumAppendix Ascending ColonProximal 2/3 transverse colon

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6
Q

What process occurs to make room for developing midgut?

A

Physiological herniation

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7
Q

What is physiological herniation?

A

Intestines herniate into the proximal umbilical cord

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8
Q

What is rotation of the midgut?

A

Midgut rotates in a counterclockwise direction until we get the shape of the normal Gi. 270* counterclockwise rotation

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9
Q

In what order do parts of the midgut return to the abdominal cavity?

A

Cranial limb return first, moving to left hand sideCecal bud returns last

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10
Q

What happens to the cecal bud once it has returned to the abdomen

A

Descends, moving caecum to right lower quadrant

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11
Q

Give two types of malrotation

A

Incomplete rotationReversed rotation

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12
Q

What does malrotation result in?

A

Gut hypermobility and volvulus

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13
Q

What is incomplete rotation?

A

Midgut makes only one 90* rotationResults in left sided colon

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14
Q

What is reversed rotation?

A

Midgut makes one 90* rotation clockwiseTransverse colon passes posterior to the duodenum

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15
Q

What is a volvulus?

A

A bowel obstruction where a loop of bowel abnormally twists in on itselfMore likely with hypermobile (malrotates) guts

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16
Q

What can volvulus lead to/

A

Strangulation and herniation

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17
Q

What does the hind gut give rise to?

A

o Distal 1/3 Transverse Colono Descending colono Rectumo Superior part of anal canalo Epithelium of the urinary bladder

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18
Q

What is the cloaca?

A

The end of the hind gut

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19
Q

What is the cloaca separated from the outside world by?

A

Cloacal membrane

20
Q

What happens at 6 weeks to the cloaca?

A

Partioning by the urorectal septum

21
Q

What does partioning by the urorectal septum create in the cloaca?

A

Urogenital sinusAnorectal sinus

22
Q

What are the two parts of the anal canal derived from?

A

Superior derived from hindgutInferior from ectoderm

23
Q

What is the line at which the two parts of the anal canal separate?

A

Pectinate line

24
Q

What is the Blood SupplyInnervationEpitheliaLymph Drainageabove the pectinate line

A

Blood Supply - IMAInnervation - S2-S4 PSEpithelia - ColumnarLymph Drainage - Internal iliac nodes

25
Q

What is the Blood SupplyInnervationEpitheliaLymph Drainagebelow the Pectinate line

A

Blood Supply - Pudendal AInnervation - S2-S4 Pudendal nerveEpithelia - Stratified squamous (non K)Lymph Drainage - Superficial inguinal nodes

26
Q

What is the only sensation possible aboe pectinate line?

A

Stretch

27
Q

What is the sensation possible below pectinate line and why?

A

Temperature, touch and pain due to somatic innervation from pudendal nerve

28
Q

What is the white line?

A

A portion of ectodermal anal canal which separates Non-K Strat squamous from K Strat Squamous

29
Q

What is meckel’s diverticulum?

A

Ileal diverticulum. Cul-de-sack as the result of failure of closure of vitelline duct

30
Q

What is the rule of 2’s for meckel’s diverticulum? (6)

A

o 2% of the population affectedo 2 feet from the ileocecal valveo 2 inches longo Usually detected in under 2’s Can be asymptomatico 2:1 Male:Female- 2 types of tissue, gastric or pancreatic

31
Q

What is a vitelline cyst?

A

Vitelline duct frorm fibrous strands at either end

32
Q

What is a vitelline fistula?

A

Direct communication between the umbilicus and intestinal tract. This results in faecal matter coming out of the umbilicus.

33
Q

What is atresia and stenosis of intestines?

A

Complete loss or narrowing of lumen

34
Q

Give two reasons for lumen atresia

A

Unsuccesful recanalisationVascular accidents due to a loss of blood supply and dead gut

35
Q

Where does most atresia occur?

A

Duodenum

36
Q

Where is loss of blood supply causing atresia most common?

A

Duodenum, but not the most common cause >Jejunum = Ileum > Colon

37
Q

What is most common cause of atresia in upper duodenum?

A

Failure of recanalisation

38
Q

What is most common cause of atresia in lower duodenum?

A

Vascular accident (malrotation and volvulus)

39
Q

What is pyloric stenosis?

A

Narrowing of pyloric sphincter resulting in projecile vomiting

40
Q

Give two defects of abdominal wall

A

GastroschisisOmphalocoele

41
Q

What is gastrochisis?

A

Failure of closure of abdominal wall during embryo folding leaving gut tube and its derivatives outside the body NO COVERING

42
Q

What is omphaocoele?

A

Persisence of physiological herniation Umbilical cord covered by reflection of the amnion COVERING PRESENT

43
Q

Give three hindgut abnormalities

A

Imperforate anus - Failure of anal membrane ruptureAnal agenesis - Failure of developmentHindgut fistula - Abnormal connection to bladder

44
Q

What five structures retain their mesentery?

A

o Jejunumo Ileumo Appendixo Transverse colono Sigmoid colon

45
Q

What four structures have fused mesenteries?

A

o Duodenumo Ascending colono Descending colono Rectum (no peritoneal covering in distal 1/3)