Physiology
Respiratory
In the control of breathing, which of the following statements is CORRECT:
Answer:
Voluntary control of breathing is mediated by motor neurones from the cortex contained in the pyramidal tracts, which bypass the pneumotaxic and medullary respiratory centres. The pneumotaxic centre in the pons receives input from the medullary respiratory centres, the hypothalamus and higher centres, not from peripheral receptors. The medulla contains dorsal and ventral respiratory groups that receive input from the chemoreceptors and lung receptors and drive the respiratory muscle motor neurones.Central Control of Respiration
Physiology / Respiratory / Control of Respiration
Last Updated: 11th April 2019
Control of breathing involves a central pattern generator that sets the basic rhythm and pattern of ventilation and controls the respiratory muscles. It is modulated by higher centres and feedback from central and peripheral chemoreceptors and peripheral mechanoreceptors.
Brainstem and Central Pattern Generator
The brainstem includes diffuse groups of respiratory neurones in the pons and medulla that act together as the central pattern generator.
The medulla contains dorsal and ventral respiratory groups that receive input from the chemoreceptors and lung receptors and drive the respiratory muscle motor neurones. The medullary respiratory groups also provide ascending input to, and receives descending input from the pneumotaxic centre in the pons.
The pneumotaxic centre receives input from the hypothalamus and higher centres, coordinates medullary homeostatic functions with factors such as emotion and temperature and affects the pattern of breathing.
Voluntary control of breathing is mediated by motor neurones from the cortex contained in the pyramidal tracts, which bypass the pneumotaxic and medullary respiratory centres.
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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 |
