Anatomy
Abdomen
Question 24 of 180
Which of the following is NOT an anatomical feature that prevents against gastric reflux:
Answer:
The lower oesophageal sphincter is not a distinct muscular structure composed of skeletal muscle like the upper oesophageal sphincter. The lower oesophageal sphincter is formed from a high-pressure zone of smooth muscle, located at the gastro-oesophageal junction.Oesophagus (Abdominal)
Anatomy / Abdomen / Gastrointestinal Tract
Last Updated: 7th June 2022
The abdominal oesophagus represents the short distal part (about 2 cm) of the oesophagus located in the abdominal cavity.
Emerging through the right crus of the diaphragm at the level of vertebra T10, it passes from the oesophageal hiatus to the cardiac orifice of the stomach just left of the midline at the level of vertebra T11.
Factors guarding against gastric reflux
Anatomical factors that help guard against gastric reflux include:
- The diaphragmatic pinchcock effect where at the oesophageal hiatus, diaphragmatic crural fibres exert pressure on the oesophageal wall and serve as an extrinsic sphincter
- The lower oesophageal sphincter which is a high-pressure zone of smooth muscle in the oesophageal wall maintained in a state of tonic contraction (except during swallowing, belching or vomiting)
- Intra-abdominal pressure which maintains the oesophagus in a state of collapse when empty
- The angle of His formed at the junction of the oesophagus and the gastric fundus, which together with the posterolateral position of the gastric fundus, minimises contact of gastric content with the gastro-oesophageal junction
- The gastric mucosal rosette-like folds formed at the gastro-oesophageal junction which compress against each other with increased intraabdominal pressure to prevent reflux
Abdominal Oesophagus. (Image modified by FRCEM Success. [CC BY-SA 3.0 , via Wikimedia Commons)
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
