Stratified squamous epithelial tissue:
Stratified squamous epithelium is a type of epithelial tissue composed of multiple layers of flattened cells, forming a strong, protective barrier on the body's surface.
Key characteristics:
- Multiple layers: Unlike simple squamous epithelium with only one cell layer, stratified squamous epithelium has several layers, providing increased protection.
- Flattened cells: The cells are flattened and tightly packed, resembling scales, offering a barrier against friction and external damage.
- Keratinization (optional): In some types of stratified squamous epithelium, the outermost layers undergo keratinization, a process where cells die and fill with keratin, a tough protein, for additional protection. This is seen in the outermost layer of the skin (epidermis).
Functions:
- Protection:
The primary function is to protect underlying tissues from:
- Physical damage: The multiple layers and flattened cells form a strong barrier against friction, abrasion, and other physical stresses.
- Chemical insults: The tight junctions between cells help prevent harmful substances from entering the body.
- Pathogens: The barrier hinders the entry of microorganisms like bacteria and viruses.
- Waterproofing:
In some locations, like the skin, the stratified squamous epithelium helps prevent excessive water loss from the body.
Locations:
- Epidermis (outermost layer of skin):
Keratinized stratified squamous epithelium provides the primary protection for the body's surface.
- Oral cavity (lining):
Non-keratinized stratified squamous epithelium lines the inside of the mouth, withstanding friction from chewing and speaking.
- Esophagus:
Non-keratinized stratified squamous epithelium lines the esophagus, allowing food passage while protecting underlying tissues.
- Vagina:
Non-keratinized stratified squamous epithelium lines the vagina, providing protection during intercourse and childbirth.
Overall, stratified squamous epithelium plays a crucial role in safeguarding the body from various external threats, making it a vital component of the integumentary and other systems.
