Transitional Epithelium Characteristics

Epithelium (Part 1 of 3)

Origin

• Epithelial tissue is derived from all three primary germ layers, depending on the type and location of the epithelial tissue.

Characteristics and Functions

• Epithelium lines all body cavities, covers all body surfaces, and constitutes the glands of the body.
• Characteristics of epithelium include cellularity, polarity, attachment to a basement membrane, avascularity, innervation, and high regeneration capacity.
• Functions of epithelium include physical protection, selective permeability, secretion, and sensation.

Classification

• Epithelium can be classified in two ways: based on the number of cell layers and based on the shape of the cells.
• Transitional epithelium is specialized for distension and is found lining most of the urinary tract.

Types of Epithelium

• There are four types of simple epithelium: simple squamous epithelium, simple cuboidal epithelium, simple columnar epithelium, and pseudostratified columnar epithelium.
• Simple squamous epithelium is composed of a single layer of squamous cells and is found lining the alveoli of the lungs, lining blood vessels, and in the membranes lining internal body cavities.
• Simple cuboidal epithelium is composed of a single layer of cuboidal cells and is found in the epidermis, where its main functions are absorption and secretion.

Glands

• Glands are formed by invaginations of epithelial tissue into the underlying connective tissue.
• Glands can be classified as either exocrine or endocrine, depending on how they release their secretions.
• Exocrine glands maintain their connection to the epithelial surface via ducts, which carry their secretions to the surface.
• Endocrine glands lack ducts and release their secretions, which are hormones, directly into the bloodstream.

Skeletal System 1 - Introduction

What is the Skeletal System made of?

• The skeletal system is the framework that provides structure to the rest of the body and facilitates movement.
• The skeletal system is made up of bones.

Skin (Part 3 of 3)

Body Membranes

• Body membranes are composed of epithelium with underlying connective tissue.
• Types of body membranes include serous membranes, mucous membranes, and skin (also known as the cutaneous membrane).
• Serous membranes line internal body cavities, including the thoracic and abdominopelvic cavities, and reflect onto the surface of some organs.
• Mucous membranes line body passageways, such as the respiratory, gastrointestinal, and genitourinary tracts.

Epithelium (Part 1 of 3)

Origin

• Epithelial tissue is derived from all three primary germ layers, depending on the type and location of the epithelial tissue.

Characteristics and Functions

• Epithelium lines all body cavities, covers all body surfaces, and constitutes the glands of the body.
• Characteristics of epithelium include cellularity, polarity, attachment to a basement membrane, avascularity, innervation, and high regeneration capacity.
• Functions of epithelium include physical protection, selective permeability, secretion, and sensation.

Classification

• Epithelium can be classified in two ways: based on the number of cell layers and based on the shape of the cells.
• Transitional epithelium is specialized for distension and is found lining most of the urinary tract.

Types of Epithelium

• There are four types of simple epithelium: simple squamous epithelium, simple cuboidal epithelium, simple columnar epithelium, and pseudostratified columnar epithelium.
• Simple squamous epithelium is composed of a single layer of squamous cells and is found lining the alveoli of the lungs, lining blood vessels, and in the membranes lining internal body cavities.
• Simple cuboidal epithelium is composed of a single layer of cuboidal cells and is found in the epidermis, where its main functions are absorption and secretion.

Glands

• Glands are formed by invaginations of epithelial tissue into the underlying connective tissue.
• Glands can be classified as either exocrine or endocrine, depending on how they release their secretions.
• Exocrine glands maintain their connection to the epithelial surface via ducts, which carry their secretions to the surface.
• Endocrine glands lack ducts and release their secretions, which are hormones, directly into the bloodstream.

Skeletal System 1 - Introduction

What is the Skeletal System made of?

• The skeletal system is the framework that provides structure to the rest of the body and facilitates movement.
• The skeletal system is made up of bones.

Skin (Part 3 of 3)

Body Membranes

• Body membranes are composed of epithelium with underlying connective tissue.
• Types of body membranes include serous membranes, mucous membranes, and skin (also known as the cutaneous membrane).
• Serous membranes line internal body cavities, including the thoracic and abdominopelvic cavities, and reflect onto the surface of some organs.
• Mucous membranes line body passageways, such as the respiratory, gastrointestinal, and genitourinary tracts.

Epithelium (Part 1 of 3)

Origin

• Epithelial tissue is derived from the three primary germ layers of the embryo, depending on the type and location of the epithelial tissue.

Characteristics and Functions

• Epithelium lines all body cavities, covers all body surfaces, and constitutes the glands of the body.
• Characteristics of epithelium include cellularity, polarity, attachment to a basement membrane, avascularity, innervation, and high regeneration capacity.
• Functions of epithelium include physical protection, selective permeability, secretion, and sensation.

Classification

• Epithelium can be classified in two ways: based on the number of cell layers and based on the shape of the cells.
• When the epithelium is relaxed, the basal cells resemble cuboidal cells and the apical cells are large and rounded.
• When the epithelium is stretched, the apical cells resemble squamous cells.
• Transitional epithelium is specialized for distension and is found lining most of the urinary tract.

Glands

• Glands are formed by invaginations of epithelial tissue into the underlying connective tissue.
• Glands can be individual cells (such as goblet cells) or multicellular organs (such as sweat and salivary glands).
• Glands can be classified as either exocrine or endocrine, depending on how they release their secretions.
• Exocrine glands maintain their connection to the epithelial surface via ducts, which carry their secretions to the surface.
• Endocrine glands lack ducts and release their secretions, which are hormones, directly into the bloodstream.

Types of Epithelium

• There are four types of simple epithelium: simple squamous epithelium, simple cuboidal epithelium, simple columnar epithelium, and pseudostratified columnar epithelium.
• There are four types of stratified epithelium.

Simple Epithelium

• Simple squamous epithelium is composed of a single layer of squamous cells and is found lining the alveoli of the lungs, lining blood vessels, and lining the internal surfaces of the heart chambers.
• Simple cuboidal epithelium is composed of a single layer of cuboidal cells and is involved in absorption and secretion.
• Simple columnar epithelium is composed of a single layer of columnar cells.
• Pseudostratified columnar epithelium is composed of a single layer of columnar cells, but appears stratified due to the different heights of the cells.

Learn about the characteristics of transitional epithelium, its function, and its location in the urinary tract. Identify how it differs from other types of epithelium.