The Lower Oesophageal Sphincter

One of the body’s most under-rated sphincters…

BT_PO 1.107

Explain the:

  •   Physiology of swallowing
  •   Factors preventing reflux of gastric contents into the oesophagus
  •   Control of gastric motility and emptying
  •   Composition of gastric fluid
  •   Physiology of nausea and vomiting

General anaesthesia reduces lower oesophageal sphincter tone. TRUE/FALSE

Cricoid pressure reduces lower oesophageal sphincter tone. TRUE/FALSE

Suxamethonium reduces lower oesophageal sphincter tone. TRUE/FALSE

The lower oesophageal sphincter is a physiological sphincter, primarily due to the oblique gastro-oesophageal angle. TRUE/FALSE

Relaxation of the lower oesophageal sphincter after swallowing is neurally mediated. TRUE/FALSE



BT_PM 1.9

Describe the pharmacology of the following agents applicable to pain management, including:

  •   Opioids
  •   Tramadol
  •   Local anaesthetic agents (also refer to the Regional and local anaesthesia clinical fundamental)
  •   NSAIDs
  •   Paracetamol
  •   NMDA antagonists
  •   Anticonvulsants
  •   Antidepressants
  •   Corticosteroids
  •   Inhalational analgesics – nitrous oxide, methoxyflurane

Methoxyflurane has a risk of nephrotoxicity and hepatotoxicity TRUE/FALSE

Methoxyflurane can be used in paediatric practice TRUE/FALSE

Methoxyflurane is safe in patients with Malignant Hyperpyrexia. TRUE/FALSE

The “Penthrox” inhaler dispenses 2-4% methoxyflurane. TRUE/FALSE

A large proportion of the inhaled methoxyflurane that is taken up by the body is removed from the body by exhalation. TRUE/FALSE

Labour physiology and pharmacology

SB_OB 1.9 and SB_OB 1.8

Describe the influence of pregnancy on the pharmacokinetics and pharmacodynamics of drugs commonly used in anaesthesia and analgesia

Describe the anatomy and physiology of pain in labour and childbirth


Paracetamol is a category A drug in pregnancy, but care should still be taken in patients with pre-eclampsia. TRUE/FALSE

The addition of lipid-soluble opioids to lumbar epidurals allows a reduction of local anaesthetic concentration. TRUE/FALSE

Visceral pain receptors located in the lower uterine segment and cervix extend to the spinal segments of S2-S4. TRUE/FALSE

Oxygen consumption increases by 40% during the first stage of labour. TRUE/FALSE


Entonox side effects include maternal sedation. TRUE/FALSE.

Wednesday is always a good day for primary revision.

SS_OB 1.4 … again.

Describe the utero-placental circulation and the principles of placental physiology as related to placental gas exchange and regulation of placental blood flow.

The primary limitation to carbon dioxide transfer across the placenta is blood flow. TRUE/FALSE

Maternal-fetal exchange of most drugs and other substances occurs primarily by diffusion TRUE/FALSE

Foetal O 2 saturation does not exceed 40% even with 100% O 2 delivery to the mother. TRUE/FALSE

The placenta synthesises progesterone from cholesterol. TRUE/FALSE

O 2 delivery to the fetus is facilitated primarily because the fetal oxyhemoglobin dissociation curve is righ-shifted. TRUE/FALSE.

Obstetric Week

SS_OB 1.4

Describe the utero-placental circulation and the principles of placental physiology as related to placental gas exchange and regulation of placental blood flow.

Pregnant women have normal peripheral sympathetic nervous system activity. TRUE/FALSE

Uterine blood flow in the non pregnant state is 700mL/min. TRUE/FALSE

Increased maternal systemic resistance can lead to increased placental blood flow at term. TRUE/FALSE

A “normal” blood pressure reading in a supine (term) pregnant woman’s arm is a reliable indicator of uterine perfusion pressure. TRUE/FALSE

If there is no maternal hypotension then neuraxial blockade does not alter uterine blood flow. TRUE/FALSE

Obstetrics and the primary exam

SS_OB 1.1

Describe the physiological changes and their implications for anaesthesia that occur during pregnancy, labour and delivery, in particular the respiratory, cardiovascular, haematological and gastrointestinal changes.


Normal physiological changes begin in the first trimester of pregnancy. TRUE/FALSE

The largest increase in cardiac output in a pregnant woman occurs immediately after delivery. TRUE/FALSE

The closing capacity in normal pregnancy does not change. TRUE/FALSE

Gastrin is secreted by the placenta TRUE/FALSE

Progesterone from the gestational sac may cause changes in the renin-angiotensin-aldosterone system in the first trimester, promoting sodium absorption and water retention. TRUE/FALSE

Hats off to those of you who sit this exam pregnant!