Physiology
Gastrointestinal
Regarding mastication, which of the following statements is CORRECT:
Answer:
Mastication is the process of systematic mechanical breakdown of food in the mouth. Mastication breaks up large food particles, mixing them with salivary secretions and aiding subsequent digestion. At rest, saliva is predominantly produced by the submandibular gland (65%, with only 20% from the parotid gland), but when stimulated, saliva is increasingly produced by the parotid gland (50%, compared to only 30% from the submandibular gland). The parotid gland produces a more watery proteinaceous saliva, rich in electrolytes and enzymes with little mucus, compared to the submandibular gland.Mastication
Physiology / Gastrointestinal / Mouth and Oesophagus
Last Updated: 4th March 2019
Mastication is the process of systematic mechanical breakdown of food in the mouth. Mastication breaks up large food particles, mixing them with salivary secretions and aiding subsequent digestion. Certain foods require more chewing than others e.g. red meat or chicken compared to fish, eggs or rice in order to be fully digested and absorbed by the gastrointestinal tract.
Mastication involves the coordinated activity of the teeth, jaw muscles, temporomandibular joint, tongue and other structures such as the lips, palate and salivary glands.
During mastication, three main pairs of glands secrete saliva; the parotid, submandibular and sublingual glands.
At rest, saliva is predominantly produced by the submandibular gland (65%, with only 20% from the parotid gland), but when stimulated, saliva is increasingly produced by the parotid gland (50%, compared to only 30% from the submandibular gland). The parotid gland produces a more watery proteinaceous saliva, rich in electrolytes and enzymes with little mucus, compared to the submandibular gland.
Following mastication, the tongue propels the bolus of food along the palate towards the pharynx, initiating the swallowing reflex.
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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 |
