Anatomy
Thorax
Regarding the tracheobronchial tree, which of the following statements is CORRECT:
Answer:
The trachea bifurcates into the right and left main bronchi at the level of vertebra T4/T5. The right bronchus is wider, shorter and runs more vertically than the left bronchus. The lobar bronchi each supply a lobe. The respiratory bronchioles participate in gas exchange.Tracheobronchial Tree
Anatomy / Thorax / Pleura and Lungs
Last Updated: 28th January 2019
The trachea bifurcates into a left and right main bronchus at the level of vertebra T4/T5. At the bifurcation of the main bronchi, a ridge of cartilage called the carina runs anteroposteriorly between the openings of the two bronchi.
Each main bronchus enters the root of a lung and passes through the hilum into the lung itself. The right main bronchus is wider and takes a more vertical course through the root and hilum than the left main bronchus, therefore inhaled foreign bodies are more likely to lodge on the right than the left.
The main bronchus divides into lobar bronchi (secondary bronchi) which each supply a lobe. The lobar bronchi further divided into segmental bronchi (tertiary bronchi) which supply bronchopulmonary segments (the functional unit of the lung).
Within each bronchopulmonary segment, the segmental bronchi give rise to multiple generations of divisions and ultimately to bronchioles (in order, conducting bronchioles, terminal bronchioles, respiratory bronchioles). The respiratory bronchioles continue as alveolar ducts and sacs, the walls of which form alveoli.
![By LadyofHats [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/01/Lung-lobe2.png)
Tracheobronchial Tree. (Image by LadyofHats [Public domain], 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 |
