1. Biology
Histology of the respiratory system.
Trachea
Right Bronchus
Left Bronchus
Alveoli
Bronchus: Any of the major air passages of the lungs which diverge from the windpipe.
Alveoli: Small air sacs in the lungs.
The trachea and the Bronchi are very similar, however the bronchi are narrower than the
trachea.
Tissues present in the Trachea and BronchiThe wall of both the trachea and bronchi consists of cartilage, which is a flexible slightly
elastic connective tissue.
On the inside surface of the cartilage is a layer of:
- Glandular tissue
- Connective tissue
Often called the ‘loose tissue’
- Elastic fibres
- Smooth muscle
- Blood vessel
The inner lining is an epithelium layer that has two types of cell. Most of the cell have cilia.
Ciliated epithelium. Among the ciliated cells are goblet cells.

2. Trachea: The windpipe leading from the back of the mouth to the bronchi.
The cartilage in the Trachea is in the form of C-shaped rings that are connected by
ligaments, with a cilia-lined mucus membrane.
This structure helps push things out of the airway if something becomes blocked
inside.