Physiology
Gastrointestinal
Which of the following is NOT a function of the stomach:
Answer:
Iron absorption takes place in the duodenum and jejunum. The main functions of the stomach and pylorus are to:- Store food temporarily (as it can be ingested more rapidly than it can be digested)
- Chemically and mechanically digest food using acids, enzymes and churning movements
- Regulate the release of the resulting chyme into the small intestine
- Secrete intrinsic factor which is essential for absorption of vitamin B12
- Act as a pump to provide motility into the small intestine
Function of Stomach
Physiology / Gastrointestinal / Stomach
Last Updated: 26th July 2024
The stomach receives food and fluid from the oesophagus, mixes it with digestive juices to form chyme and releases its contents into the duodenum. The stomach acts as a reservoir for food as it is very distensible; when empty it has a volume of about 50 mL but it has capacity of up to 3 - 4 L.
There are two sphincters at each of the gastric orifices, the lower oesophageal sphincter protects the oesophagus from reflux of the gastric contents and the pyloric sphincter controls the flow of gastric contents into the duodenum.
Functions
The main functions of the stomach are to:
- Store food temporarily (as it can be ingested more rapidly than it can be digested)
- Chemically and mechanically digest food using acids, enzymes and churning movements
- Regulate the release of the resulting chyme into the small intestine
- Secrete intrinsic factor which is essential for absorption of vitamin B12
Gastric Cell Types
| Cell Type | Function |
|---|---|
| Parietal cell | Secretes HCl and intrinsic factor |
| Chief cell | Secretes pepsinogen |
| G cell | Secretes gastrin |
| Enterochromaffin-like cell | Secretes histamine |
| Surface mucous cell | Secretes mucus |
Gastric Cells. (Image by OpenStax College [CC BY 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 |
