Recognising Tissues in the Gas Exchange System
Cartilage
Cartilage micrograph
Cartilage – electron micrograph
- The cartilage in the trachea has a ‘glassy’ appearance due to its translucent protoplasm
- It contains no nerves or blood vessels
Ciliated epithelium
Ciliated epithelium – photomicrograph
Ciliated epithelium – electron micrograph
- Ciliated epithelial cells are distinctive due to their narrow cell bodies and hair-like cilia located along the apical layer
- The cilia are tiny projections which greatly increase the surface area of the cell
Goblet cells
Goblet cell – light micrograph
Goblet cells – electron micrograph
- Goblet cells can be found scattered among the ciliated epithelium of the trachea and bronchi
- They are distinctive in the epithelium due to their lack of cilia (although they still have some microvilli projecting outwards)
- The nucleus is found towards the basal (bottom) layer of the cell, with a large Golgi apparatus and mucus granules found towards the apical layer
Squamous epithelium
Squamous epithelium – light micrograph
Squamous epithelium – electron micrograph
- Squamous epithelium is made of thin, flat squamous cells
Smooth muscle
Smooth muscle – light micrograph
Smooth muscle – electron micrograph
- The cells of smooth muscle are tightly packed and are found beneath the ciliated epithelium
- Unlike skeletal muscles, they are not striated and so don’t show any cross stripes under a microscope
Capillaries
Capillary – photomicrograph
Capillary – electron micrograph
- Capillaries are distinctive from other blood cells due to their tiny diameter (~4 μm)
- Their walls consist of a single layer of epithelial cells
