Physiology
Gastrointestinal
Intrinsic factor is vital for gastrointestinal absorption of which of the following:
Answer:
Intrinsic factor is produced by parietal cells, and is essential for vitamin B12 absorption. Intrinsic factor binds to vitamin B12, allowing it to escape degradation in the stomach and intestine and to be safely transported to the terminal ileum where it is absorbed.Gastric Juice
Physiology / Gastrointestinal / Stomach
Last Updated: 18th April 2019
The average adult produces 2 - 3 L of gastric fluid every 24 hours.
Gastric fluid contains:
- Mucus
- Hydrochloric acid (HCl)
- Digestive enzymes
- pepsinogen
- gastric lipase
- Intrinsic factor
Mucus
Mucus is secreted by surface mucous cells. The alkaline, mucin-rich fluid forms a water-insoluble gel that adheres to the surface of the stomach lumen and plays an important role in protection of the stomach against its acid contents and autodigestion by pepsin. In addition, local mediators, such as prostaglandins, are released when the mucosa is irritated, and these increase the thickness of the mucus layer and stimulate the production of bicarbonate which neutralises acid.
Hydrochloric Acid
Hydrochloric acid is secreted by gastric parietal cells.
Digestive Enzymes
Proteins in food are broken down into polypeptides in the stomach by enzymes called pepsins. Pepsin is secreted in the form of its inactive precursor, pepsinogen, from chief cells in the gastric mucosa, and is converted to its active form by the acid environment in the stomach.
Gastric lipase is of little physiological importance except in pancreatic insufficiency.
Intrinsic Factor
Intrinsic factor is produced by parietal cells, and is essential for vitamin B12 absorption. Intrinsic factor binds to vitamin B12, allowing it to escape degradation in the stomach and intestine and to be safely transported to the terminal ileum where it is absorbed.
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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 |
