CH 4 - PT 1: Epithelial Tissues

Comprehensive vocabulary flashcards reviewing general histology, four basic tissue types, special characteristics and classification of epithelial tissues, and structural varieties of exocrine and endocrine glands.

Tissues

Groups of cells similar in structure that perform a common or related function.

Histology

The study of tissues.

Four Basic Tissue Types

Epithelial, connective, muscle, and nervous tissue.

Epithelial Tissue (Epithelium)

A sheet of cells that covers a body surface or lines body cavities.

Covering and Lining Epithelium

An epithelial form that forms the outer layer of skin, lines open cavities, and covers walls and organs of the ventral body cavity.

Glandular Epithelium

Specialized type of epithelial tissue composed of cells adapted to produce and release chemical substances

Five Distinguishing Characteristics of Epithelial Tissue

1. Polarity, 2. Specialized contacts, 3. Supported by connective tissue, 4. Avascular but innervated, 5. Regeneration.

Apical Surface

The upper free side of epithelial cells exposed to a surface or cavity, which is mostly smooth but may have specialized projections called microvilli.

Microvilli

Specialized fingerlike projections found on some apical surfaces of epithelial cells.

Basal Surface

The lower attached side of epithelial cells that faces inwards toward the body and attaches to the basal lamina.

Basal Lamina

An adhesive sheet that holds the basal surface of epithelial cells to underlying cells.

What is epithelial polarity?

The (top and bottom) of an epithelial tissue: the upper free apical surface bordering an open body space or cavity and a lower basal surface attached to underlying connective tissue via the basal lamina.

Simple Epithelia

Epithelial tissue consisting of a single cell layer, located where a thin barrier is desirable.

Stratified Epithelia

Epithelial tissue consisting of two or more cell layers, located in high-abrasion areas such as the lining of the mouth.

Squamous Cells

Flattened and scale-like epithelial cells with flattened nuclei.

Cuboidal Cells

Box-like, cube-shaped epithelial cells that are approximately as tall as they are wide, with spherical central nuclei.

Columnar Cells

Tall, column-like epithelial cells with tall, thin nuclei usually located closer to the basal surface.

Simple Squamous Epithelium

Simple Cuboidal Epithelium

Simple Columnar Epithelium

Pseudostratified Columnar Epithelium

Stratified Squamous Epithelium

Transitional Epithelium

Gland

One or more cells that make and secrete an aqueous fluid called a secretion.

Endocrine Glands

Ductless glands that produce hormones, secreting them into interstitial fluid to enter the blood.

Exocrine Glands

Glands that retain connecting cells to form ducts through which secretions are transported onto body surfaces or into body cavities.

Goblet Cell

A unicellular exocrine gland that secretes mucus

Categorization Criteria for Multicellular Exocrine Glands

Definition: Categorized by duct structure (simple = unbranched duct; compound = branched duct) and secretory unit shape (tubular = tube-like; alveolar = sac-like; tubuloalveolar = combination of both).

Simple Squamous Epithelium

description: A single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm

functions in diffusion, filtration, and secreting lubricating substances in serosae

located in air sacs of lungs, lining of heart, blood vessels, lymphatic vessels, and serosae.

Simple Cuboidal Epithelium

Description: A single layer of cube-like cells with large, spherical central nuclei

functions in secretion and absorption

located in kidney tubules, gland ducts, and ovary surface.

Simple Columnar Epithelium

Description: A single layer of tall cells with round to oval nuclei; many cells bear microvilli, some bear cilia, layer may contain mucus secreting unicellular glands, (goblet cells)

functions in absorption and secretion of mucus and enzymes

located lines most of the digestive tract, gallbladder, and small bronchi.

Pseudostratified Columnar Epithelium

Description: A single layer of cells of differing heights with nuclei at different levels. May contain goblet cells and cilia.

functions in secreting and propelling mucus

locations: lines the trachea, upper respiratory tract (if ciliated) and sperm-carrying ducts (non-ciliated)

Stratified Squamous Epithelium

Description: A thick epithelium composed of several cell layers with cuboidal/columnar basal cells and flattened surface cells

function: protects underlying tissues in areas subjected to abrasion

location: nonkeratinized type in moist linings of esophagus, mouth, and vagina/ keratinized variety in epidermis of skin.

Transitional Epithelium

Description: An epithelium resembling stratified squamous and cuboidal whose surface cells flatten when stretched

function: stretches readily

location: lines ureters, bladder, and part of the urethra to permit urine distension.

Pseudostratified Columnar Epithelium