Select all that are true of epithelial tissue.

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The basal surface is usually exposed to internal body spaces.
The basal surface is usually exposed to internal body spaces.
They are almost completely composed of cells.
They are almost completely composed of cells.
Epithelia have a good blood supply. Epithelia have a good blood supply.
They allow for sensation and detection of the surrounding environment.
__They allow for sensation and detection of the surrounding environment.

The epithelial tissues or linings are the ones present in the internal ORGANS/SPACES that serve as their covering (pericardium, epimysium) or glandular tissues (trachea, kidneys). The basal surface comes before the basement membrane.

An example is the epidermis. It is made up of keratinized stratified squamous epithelium (wider than its height, almost scale-like) is a group of tightly-packed cells made to resist abrasions and protect from infections, coming from the external environment.

Another example is the digestive tract such as the small intestines. It is made up of simple columnar epithelium (taller than its width, like towers), sometimes with hair-like projections called cilia, which is responsible for the absorption of nutrients and protecting the gut from harmful pathogens.

Epithelial tissues don't have any blood supply. They get their nutrition through diffusion from the basement membrane, where blood vessels are abundant. You may observe this during minimal abrasions of the skin. Blood doesn't flow out easily when the abrasion is on the surface.

As for the case of ciliated epithelia, such as the upper respiratory tract, the hair-like projections can detect smell and taste, temperature, light touch or pain.

Additional notes:

In summary, epithelial tissues have the following functions:

Line the outer layers of the organs and vessels, and the inner layers of body cavities

They have 3 types and are also classified in layers.

Types of Epithelia:

According to layers: