Basic types and properties of epithelial tissue at the microscopic level

Lumen

The inner inside open space of a hollow organ/cavity or structure like intestines, blood vessels, or stomach

• pic: also on the white surface that is outside of all the purple (its zoomed in)

Apical surface

Top or exposed side of epithelial cells & it faces outside of the body (skin) or the inside space of an organ (intestines)

• specialized for absorption, secretion and protecting underlying tissues

Apical surface: Microvilli

Extend from the surface of the certain cells particularly in the small intestine and increases the surface area of the cell, allowing for more efficient absorption of nutrients

Apical surface: Cilia

Extends from the apical surface and moves substances along the surface of the tissue

Basal surface

is attached to the basement membrane

Simple squamous epithelium

1 layer squished, reduces friction, controls vessel permeability, and performs absorption and secretion

location: portions of kidney tubules which are thin sections of nephron loops

Simple cuboidal epithelium

It has limited protection, secretion, and absorption. 1 layer, cube shaped

locations: glands; thyroid gland, portions of kidney tubules

Simple columnar epithelium

1 layer and column shaped, it protects, secretion, absorption. TALL cells

locations: lining of stomach, gallbladder, etc

Pseudostratified columnar epithelium

Protects, secretion, and moves mucus with cilia

Location: lining of nasal cavity, trachea, and bronchi

Stratified squamous epithelium: Keratinized

It contains keratin and is a protein that provides strength and waterproofing, acts as a protective barrier for underlying tissues from mechanical stress, dehydration, and microbial invasion/infection

location: epidermis of the skin, oral cavity-surface of tongue, and palms hands and sole of feet

Stratified squamous epithelium: non-Keratinized

many layers and squished, it provides physical protection against abrasion, pathogens, and chemical attack and lacks keratin

• locations: surface of skin; lining of mouth, throat, esophagus, rectum, anus, vagina

Transitional epithelium

It allows organs to stretch and expand when needed and returns to its normal shape, it protects underlying tissues from urine’s effects

Location: urinary system: lining of bladder

Goblet cell

Specialized epithelial cells that secrete mucins, which are key components of mucus, unicellular glands, protecting and lubricating the epithelial surfaces.

Location: in the respiratory and gastrointestinal tracts