Session 3- Saliva + Mid Gut Development

Question 1

What is the composition of Saliva?

Answer 1

Water
Potassium + bicarbonate
Mucins (lubrication)
Amylase
Lingual lipase
Immune proteins (IgA, lysozyme, lactoferrin)

Question 2

What is the main driver of saliva production?

Answer 2

Parasympathetic

Question 3

Describe the stages of swallowing?

Answer 3

Oral Preparatory phase- A voluntary phase that pushes food bolus towards the pharynx

Pharyngeal phase- A short involuntary phase. Soft palate seals off the nasopharynx, pharyngeal constrictors move the bolus down. Suprahyoids elevate the larynx closing the epiglottis. The vocal cords adduct briefly ceasing breathing. The upper oesophageal sphincter opens.

Oesophageal phase- An involuntary phase closing the upper oesophageal sphincter. Peristalsis moved the bolus down the oesophagus.

Question 4

What nerves are involved in control of gag and swallowing reflex?

Answer 4

Mechanoreceptors - Glossopharyngeal nerve - Medulla - Vagus nerve - Pharyngeal Constrictors

Question 5

At what week of embryonic development does the midgut herniate into the umbillicus, and when does it return?

Answer 5

In week 6 it herniates and returns on week 10.

Question 6

What is an Omphalocoele?

Answer 6

A herniation from the umbilicus in babies where midgut structures are visible under a peritoneal covering. Mortality is high due to other developmental abnormalities.

Question 7

What is gastroschisis?

Answer 7

Failure of the abdominal wall to form anteriorly due to incomplete lateral folding in development. This presents as midgut structures herniating from the umbilicus not covered by peritoneum which may effect gut development.

Question 8

The vitelline duct is between the midgut and yolk sac in development, describe some abnormalities if the duct does not regress?

Answer 8

Vitelline cyst

Vitelline fistula- Can result in fecal matter coming out the umbilicus

Vitelline diverticulum- Rule of Two
2% population effected, located 2 feet proximal to oleo-caecal valve, Detected in under 2s, 2 times more common in men

Question 9

You are looking at an Anus diagram 😆 what is the name of the line separating the 2 parts? What is the pain description above and below these 2 lines?

Answer 9

Pectinate Line

Pain below the line is localised as it is somatic derived
Pain above is more vague