Epithelial Overview

These flashcards cover key concepts related to the Tissue Level of Organization, specifically focusing on different types of epithelial tissues, their characteristics, functions, and various gland types.

Tissue

A group of cells similar in structure working together to perform a common function.

Types of Tissue

The four main types of tissue in the body: epithelial, connective, muscle, and nervous.

Epithelial Tissue

Covers exposed surfaces, lines internal passageways, and forms glands.

Avascular

Refers to tissues that lack blood vessels, getting nutrients through diffusion from underlying connective tissue.

Junctions

Structures that connect neighboring cells; types include tight junctions, desmosomes, and gap junctions.

Basement Membrane

A layer of collagen and glycoproteins that attaches epithelium to the underlying connective tissue.

Simple Squamous Epithelium

Composed of a single layer of flat cells, allowing for diffusion and found in areas like air sacs of lungs.

Simple Cuboidal Epithelium

Consists of a single layer of cuboidal cells typically involved in secretion and absorption, found in kidney tubules.

Simple Columnar Epithelium

A single layer of tall cells that often feature goblet cells and is involved in secretion and absorption, found in the digestive tract.

Stratified Squamous Epithelium

Multiple layers of cells with flat cells on the free surface, providing protection in areas like the skin and mouth.

Transitional Epithelium

A type of epithelium that can change shape, allowing organs like the bladder to stretch.

Pseudostratified Columnar Epithelium

Appears stratified but is a single layer where all cells touch the basement membrane, often ciliated and found in the respiratory tract.

Exocrine Glands

Glands that secrete their products into ducts leading to the surface of the body.

Endocrine Glands

Glands that secrete hormones directly into the bloodstream without ducts.

Merocrine Secretion

A method of secretion where substances are expelled via exocytosis without loss of cell structure, as in sweat glands.

Apocrine Secretion

A method of secretion where part of the cell's cytoplasm is lost along with the secretion, as occurs in mammary glands.

Holocrine Secretion

A method in which the entire cell fills with secretion, ruptures, and is replaced by new cells, as seen in sebaceous glands.

Goblet Cells

Unicellular glands found in epithelial tissues that secrete mucus.

Cilia

Hair-like structures on some epithelial cells that help move substances across the cell surface.

Microvilli

Small finger-like projections that increase surface area for absorption and secretion in epithelial cells.