what is the noncellular layer that attaches epithelial tissue to other layers?

Characteristics of Epithelial Tissue

The homo body consists of four types of tissue: epithelial, connective, muscular, and nervous. Epithelial tissue covers the body, lines all cavities, and composes the glands.

Learning Objectives

Describe the primary functions and characteristics of epithelial tissue

Key Takeaways

Cardinal Points

• Epithelial tissue is composed of cells laid together in sheets with the cells tightly continued to one another. Epithelial layers are avascular, but innervated.
• Epithelial cells have two surfaces that differ in both construction and function.
• Glands, such as exocrine and endocrine, are composed of epithelial tissue and classified based on how their secretions are released.

Key Terms

• epithelium: A membranous tissue composed of one or more layers of cells that form the covering of most internal and external surfaces of the trunk and its organs.
• avascular: Lacking blood vessels.
• vascular: Containing blood vessels.

Functions of the Epithelium

Epithelia tissue forms boundaries between different environments, and nearly all substances must pass through the epithelium. In its part as an interface tissue, epithelium accomplishes many functions, including:

1. Protection for the underlying tissues from radiation, desiccation, toxins, and physical trauma.
2. Absorption of substances in the digestive tract lining with distinct modifications.
3. Regulation and excretion of chemicals between the underlying tissues and the trunk cavity.
4. The secretion of hormones into the claret vascular system. The secretion of sweat, mucus, enzymes, and other products that are delivered past ducts come from the glandular epithelium.
5. The detection of sensation.

Characteristics of Epithelial Layers

Epithelial tissue is composed of cells laid out in sheets with strong cell-to-cell attachments. These protein connections hold the cells together to form a tightly connected layer that is avascular but innervated in nature.

The epithelial cells are nourished by substances diffusing from blood vessels in the underlying connective tissue. I side of the epithelial jail cell is oriented towards the surface of the tissue, torso cavity, or external environment and the other surface is joined to a basement membrane. The basement layer is non-cellular in nature and helps to cement the epithelial tissue to the underlying structures.

Types of Epithelial Tissue

Epithelial tissues are identified by both the number of layers and the shape of the cells in the upper layers. There are eight basic types of epithelium: six of them are identified based on both the number of cells and their shape; 2 of them are named by the type of cell (squamous) found in them. Epithelial tissue is classified based on the number of cells, the shape of those cells, and the types of those cells.

Epithelial Tissue Cells
Cells	Locations	Function
Simple squamous epithelium	Air sacs of the lungs and  the lining of the heart, blood vessels and lymphatic vessels	Allows materials to pass through by diffusion and filtration, and secretes lubricating substances
Simple cuboidal epithelium	In ducts and secretory portions of small glands and in kidney tubules	Secretes and absorbs
Simple columnar epithelium	Ciliated tissues including the bronchi, uterine tubes, and uterus; smooth (nonciliated tissues) are in the digestive tract bladder	Absorbs; information technology too secretes mucous and enzymes.
Pseudostratified columnar epithelium	Ciliated tissue lines the trachea and much of the upper respiratory tract	Secrete mucous; ciliated tissue moves mucous
Stratified squamous epithelium	Lines the esophagus, oral cavity, and vagina	Protects against abrasion
Stratified cuboidal epithelium	Sweat glands, salivary glands, and mammary glands	Protective tissue
Stratified columnar epithelium	The male urethra and the ducts of some glands.	Secretes and protects
Transitional epithelium	Lines the bladder, urethra and ureters	Allows the urinary organs to expand and stretch

Types of Epithelial Tissue

Epithelial tissue is classified by prison cell shape and the number of cell layers.

Learning Objectives

Classify epithelial tissue by cell shape and layers

Key Takeaways

Cardinal Points

• There are 3 principal cell shapes associated with epithelial cells: squamous epithelium, cuboidal epithelium, and columnar epithelium.
• In that location are three ways of describing the layering of epithelium: simple, stratified, and pseudostratified.
• Pseudostratified epithelium possesses fine pilus-like extensions called cilia and unicellular glands called goblet cells that secrete mucus. This epithelium is described as ciliated pseudostratified epithelium.
• Stratified epithelium differs from simple epithelium in that information technology is multilayered. It is therefore establish where body linings have to withstand mechanical or chemical insult.
• In keratinized epithelia, the almost apical layers (exterior) of cells are dead and and contain a tough, resistant protein called keratin. An example of this is establish in mammalian peel that makes the epithelium waterproof.
• Transitional epithelia are institute in tissues such every bit the urinary bladder where there is a change in the shape of the cell due to stretching.

Key Terms

• simple columnar: A columnar epithelium that is uni-layered.
• pseudostratified epithelium: A type of epithelium that, though comprising only a single layer of cells, has its jail cell nuclei positioned in a manner suggestive of stratified epithelia.
• squamous: Flattened and calibration-like.
• cuboidal: Resembling a cube.
• Keratinized: To produce or become like keratin.
• columnar: Having the shape of a column.

Most epithelial tissue is described with two names. The showtime name describes the number of cell layers present and the second describes the shape of the cells. For case, simple squamous epithelial tissue describes a single layer of cells that are flat and scale-similar in shape.

Epithelial Tissue: There are 3 principal classifications associated with epithelial cells. Squamous epithelium has cells that are wider than they are tall. Cuboidal epithelium has cells whose height and width are approximately the same. Columnar epithelium has cells taller than they are wide.

Unproblematic Epithelia

Simple epithelium consists of a single layer of cells. They are typically where absorption, secretion  and filtration occur. The thinness of the epithelial barrier facilitates these processes.

Simple epithelial tissues are mostly classified by the shape of their cells. The 4 major classes of simple epithelium are: 1) uncomplicated squamous; 2) elementary cuboidal; 3) simple columnar; and iv) pseudostratified.

Unproblematic Squamous

Unproblematic squamous epithelium cells are flat in shape and arranged in a single layer. This unmarried layer is sparse enough to form a membrane that compounds tin can move through via passive diffusion. This epithelial type is found in the walls of capillaries, linings of the pericardium, and the linings of the alveoli of the lungs.

Simple Cuboidal

Elementary cuboidal epithelium consists of a unmarried layer cells that are as tall equally they are wide. The important functions of the uncomplicated cuboidal epithelium are secretion and absorption. This epithelial type is found in the small collecting ducts of the kidneys, pancreas, and salivary glands.

Simple Columnar

Simple columnar epithelium is a single row of alpine, closely packed cells, aligned in a row. These cells are constitute in areas with high secretory role (such as the wall of the stomach), or absorbent areas (as in modest intestine ). They possess cellular extensions (eastward.thousand., microvilli in the small intestine, or the cilia found almost exclusively in the female person reproductive tract).

Pseudostratified

These are elementary columnar epithelial cells whose nuclei appear at different heights, giving the misleading (hence pseudo) impression that the epithelium is stratified when the cells are viewed in cross department.

Pseudostratified epithelium can also possess fine hair-like extensions of their upmost (luminal) membrane called cilia. In this example, the epithelium is described as ciliated pseudostratified epithelium. Ciliated epithelium is found in the airways (olfactory organ, bronchi), just is also establish in the uterus and fallopian tubes of females, where the cilia propel the ovum to the uterus.

Stratified Epithelium

Stratified epithelium differs from unproblematic epithelium by existence multilayered. It is therefore plant where body linings have to withstand mechanical or chemical insults.

Stratified epithelia are more durable and protection is 1 their major functions. Since stratified epithelium consists of two or more layers, the basal cells dissever and push towards the apex, and in the process flatten the apical cells.

Stratified epithelia can be columnar, cuboidal, or squamous type. All the same, it tin can as well take the following specializations:

Keratinized Epithelia

In keratinized epithelia, the about apical layers (exterior) of cells are dead and lose their nucleus and cytoplasm. They contain a tough, resistant poly peptide chosen keratin. This specialization makes the epithelium waterproof, and it is abundant in mammalian skin. The lining of the esophagus is an example of a non-keratinized or moist stratified epithelium.

Transitional Epithelia

Transitional epithelia are found in tissues that stretch and it tin announced to be stratified cuboidal when the tissue is non stretched, or stratified squamous when the organ is distended and the tissue stretches. It is sometimes chosen the urothelium since it is almost exclusively found in the bladder, ureters, and urethra.

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Source: https://courses.lumenlearning.com/boundless-ap/chapter/epithelial-tissue/