Anatomy
Thorax
The trachea is lined with which type of epithelium:
Answer:
The trachea and bronchi are lined by ciliated pseudostratified columnar epithelium.The trachea arises at the lower border of the cricoid cartilage in the neck, as a continuation of the larynx. It extends from vertebral level C6 to T4/T5 at which point it bifurcates into the right and left main bronchi (at the level of the sternal angle).
Trachea. (Image by Blausen.com staff. “Blausen gallery 2014”. Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. (Own work) [CC BY 3.0 , via Wikimedia Commons)
The trachea is formed anteriorly by 15 - 20 C-shaped rings of hyaline cartilage which mechanically hold the airway open whilst allowing it flexibility. The trachealis muscle connects the ends of the incomplete rings and forms the posterior wall of the trachea. The trachealis muscle is able to constrict the trachea, allowing air to be expelled with more force e.g. during coughing.
The trachea and bronchi are lined by ciliated pseudostratified columnar epithelium, interspersed by mucus-producing goblet cells. This mucous membrane functions as the mucociliary escalator, trapping particles in sticky mucus and sweeping it along the airway.
Relations
The trachea descends anterior to the oesophagus and inclines slightly to the right.
In the thorax, anteriorly it is related to:
- the thymic remnants
- the left brachiocephalic vein
- the aortic arch
- the brachiocephalic trunk
- the left common carotid artery
- the deep cardiac plexus.
Laterally it is related to:
- the pleura, the right vagus nerve and the brachiocephalic trunk on the right
- the left recurrent laryngeal nerve, the aortic arch and the left common carotid and subclavian vessels on the left.
Relations of the Trachea. (Image by ZooFari [CC BY-SA 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 |
