Session 3

Question 1

The mid gut is connected to the yolk sac at its

Answer 1

Midpoint

Question 2

What happens to the midgut in week 6

Answer 2

Grows faster than abdominal cavity
Protrudes through abdominal wall and tiny umbilical cord (physical herniation)

Question 3

The herniated midgut forms a

Answer 3

Loop with the superior mesenteric artery within the umbilical cord

Question 4

What do distal and proximal parts of herniated midgut loop form

Answer 4

Distal- caecal bulge
proximal- convoluted

Question 5

Explain mid gut loops rotation

Answer 5

Rotates whilst in umbilical cord- returns to abdomen around week 10

3 x 90 degree rotations

Abnormal rotations are fairly common

Question 6

What may happen if an abnormally large opening between the abdominal cavity and the umbilical cord persists

Answer 6

An umbilical hernia may be present

Question 7

What is Meckel’s diverticulum

Answer 7

Persistent yolk sac remnant in the midgut

Question 8

The hindgut forms what

Answer 8

Distal part of transverse colon through to superior portion of anal canal

Question 9

Where does the hindgut end at first

Answer 9

Cloacal membrane- separates it from proctodaeum

Question 10

What happens when the cloacal membrane ruptures

Answer 10

The hindgut is connected to the exterior, the anal canal therefore has dual origin

Question 11

Initially the developing intestines have

Answer 11

No lumen- canalisation occurs in weeks 6-8

Question 12

What happens if canalisation fails

Answer 12

Partial or full obstruction. Recanalisation occurs in oesophagus, bile duct and SI

Question 13

What is pyloric stenosis

Answer 13

Hypertrophy of pyloric sphincter

Not recanalisation failure

Causes projectile vomiting in infants

Question 14

What is Gastroschisis

Answer 14

Failure of closure of the abdominal wall following folding of embryo- gut tube and derivatives outside body cavity

Question 15

What is Omphalocoele

Answer 15

Persistence of the physiological herniation of midgut

Question 16

Anal canal is divided into

Answer 16

Superior and inferior parts by the pectinate line

Differ with regards to vasculature, nerve supply, lymphatic drainage and histological features

Question 17

What is the cloaca

Answer 17

Region at end of hindgut
Divides into anterior urogenital sinus and posterior anorectal canal

Question 18

What makes up saliva

Answer 18

Primarily water
Oral hygiene- IgA, lysozymes and lactoferrin
Digestion- amylase and lingual lipase

Question 19

What is the word for reduced flow of saliva in oral cavity

Answer 19

Xerostomia

Question 20

What are the 3 paired salivary glands

Answer 20

Parotid, submandibular, sublingual

Question 21

Primary regulator of saliva production

Answer 21

Autonomic system- particularly parasympathetic

Question 22

What results in dry mouth

Answer 22

Anything that reduces parasympathetic innervation

Question 23

3 phases to swallowing

Answer 23

Oral, pharyngeal and oesophageal

Question 24

Describe Oral phase

Answer 24

Voluntary- bolus pushed back into pharyngeal wall

Question 25

Describe pharyngeal phase

Answer 25

Involuntary- bolus moves from oral cavity to beginning of oesophagus

Question 26

Nasal cavity is protected by

Answer 26

Elevation of the soft palate

Question 27

Respiratory tract is protected by

Answer 27

Elevation of the larynx (which closes epiglottis) and adduction of the vocal cords

Question 28

Describe the oesophageal phase

Answer 28

Involuntary- closure of upper oesophageal sphincter (to prevent reflux), rapid peristaltic movement of oesophagus

Question 29

Sensory component of swallow reflex

Answer 29

Glossopharyngeal nerve CNIX

Question 30

What innervates most of the muscles involved in swallow reflex

Answer 30

vagus nerve CNV

Question 31

What moves the bolus from the posterior aspect of the oral cavity to the oesophagus

Answer 31

Pharyngeal constrictor muscles

Question 32

What is difficulty swallowing

Answer 32

Dysphagia- can have neural cause or a physical obstructive cause

Question 33

Landmark at start of midgut

Answer 33

Where common bile duct and major pancreatic duct enter duodenum

Question 34

What happens in mal rotation

Answer 34

Only 1 90 degree rotation Left sided colon

Question 35

What happens in reversed rotation

Answer 35

1 90 degree rotation clockwise Transverse colon behind SI

Question 36

3 Vitelline duct abnormalities

Answer 36

Cyst, fistula or Meckel’s diverticulum (Should regress at week 7)

Question 37

Meckel’s diverticulum rule of 2s

Answer 37

2% of population 2 feet proximal to ileo-caecal valve Detected in under twos 2:1 ratio M:F

Question 38

Recanalisation failure often affects the

Answer 38

Duodenum

Question 39

What makes up hind gut

Answer 39

Distal 1/3 transverse colon, descending colon, sigmoid colon, rectum, superior anal canal, bladder epithelia

Question 40

What happens to urorectal septum in 4th-7th week

Answer 40

Divides into mesoderm and divides cloaca Urogenital sinus and anorectal canal formed

Question 41

Above pectinate line

Answer 41

Non keratinised above Chemical injury or stretch = vague pain Gut blood supply

Question 42

Below pectinate line

Answer 42

Keratinised below Localised pain Systemic blood supply

Question 43

Hindgut abnormalities

Answer 43

Imperforate anus, anorectal agenesis, fistulae

Question 44

What is imperforate anus

Answer 44

No anal hole

Question 45

Anorectal agenesis

Answer 45

Anus doesnt form due to problems with blood supply

Question 46

What is fistulae

Answer 46

Abnormal connection between 2 hollow epithelial lined cavities

Question 47

Functions of saliva

Answer 47

Phonation, mastication, oral health, digestion, immune surveillance, solvent for tasty molecules, way of transmitting disease

Question 48

Sympathetic activation on salivary glands

Answer 48

Stimulates secretion of small amounts of saliva, but also causes vasoconstriction

Question 49

What nerve supplies the sublingual and submandibular glands

Answer 49

Facial nerve VII

Question 50

Which nerve supplies the carotid gland

Answer 50

IX

Question 51

Which muscles elevate larynx

Answer 51

Suprahyoids

Question 52

How can babies breathe and swallow at the same time

Answer 52

-Epiglottis sits higher in relation to soft palette -Airway and food way separate -Don’t close vocal cords when swallowing -Same reason babies can’t talk

Question 53

Neural control of swallowing and gag reflex

Answer 53

Mechanoreceptors Glossopharyngeal nerve Medulla Vagus nerve Pharyngeal constrictors

Question 54

Narrowings of oesophagus

Answer 54

Junction with pharynx Crossed by arch of aorta Compressed by left main bronchus Oesophageal hiatus

Question 55

How is Gastro-oesophageal reflux prevented

Answer 55

Functional sphincter Diaphragm Intra-abdominal oesophagus flap valve Mucosal rosette at cardia Acute angle of entry of oesophagus

Question 56

What is function of a flap valve

Answer 56

Intra-abdominal oesophagus which gets compressed when intra-abdominal pressure rises