Epithelial Tissues Lecture Notes

This set of flashcards covers key concepts, definitions, and classifications of epithelial tissues as discussed in the lecture.

Epithelial Tissue

A type of tissue that lines body surfaces and cavities, and forms glands.

Connective Tissue

A tissue that supports the other three basic tissues, both structurally and functionally.

Muscle Tissue

Tissue made up of contractile cells responsible for movement.

Nerve Tissue

Tissue that receives, transmits, and integrates information to control body activities.

Membranes (Surface Epithelia)

Epithelial cells organized into sheets that line external and internal body cavities.

Solid Glands

Epithelial cells organized into glands with secretory ducts (exocrine) or without secretory ducts (endocrine).

Transcellular Transport

The movement of molecules through epithelial cells.

Selective Permeability

The ability of epithelial layers to permit certain substances to pass while restricting others.

Tight Junctions

Cell junctions that form a barrier to prevent the passage of substances between cells.

Membrane Specializations

Structures on the surface of epithelial cells that increase surface area, such as microvilli and cilia.

Microvilli

Fingerlike projections on cell surfaces that increase surface area for absorption.

Cilia

Motile structures that propel substances along epithelial surfaces.

Basement Membrane

A thin, acellular layer that separates the epithelium from underlying connective tissue.

Avascularity

The characteristic of epithelial tissue indicating it does not contain blood vessels and receives nutrients by diffusion.

Simple Epithelium

A single layer of epithelial cells that all contact the basal lamina.

Stratified Epithelium

Multiple layers of epithelial cells, with only the deepest layer contacting the basal lamina.

Squamous Cells

Flat epithelial cells.

Cuboidal Cells

Epithelial cells with similar height and width.

Columnar Cells

Tall epithelial cells.

Pseudostratified Epithelia

Epithelial tissue that appears stratified but is in fact a single layer.

Simple Cuboidal Epithelium

Epithelial tissue consisting of a single layer of cube-like cells.

Simple Columnar Epithelium

Epithelial tissue with a single layer of tall cells, often with microvilli or cilia.

Pseudostratified Epithelium

Columnar epithelial tissue that appears to be stratified due to differing cell heights.

Stratified Squamous Epithelium

Epithelial tissue with multiple layers of flat cells, can be keratinized or non-keratinized.

Stratified Cuboidal Epithelium

Epithelial tissue consisting of multiple layers of cube-like cells.

Stratified Columnar Epithelium

Epithelial tissue with multiple layers of columnar cells.

Transitional Epithelium

A type of stratified epithelium that can stretch; typically found in the urinary tract.

Cell Junctions

Structures that connect epithelial cells and help maintain tissue integrity.

Anchoring Junctions (Adherens)

Junctions that stabilize epithelial layers by connecting to the cytoskeleton.

Desmosomes

Adhering junctions that connect intermediate filaments between cells.

Hemidesmosomes

Anchoring junctions that attach epithelial cells to the basement membrane.

Gap Junctions

Communicating junctions that allow transfer of ions and small molecules between adjacent cells.

Cell Adhesion Molecules (CAMs)

Proteins that facilitate cell-cell adhesion and communication.

Exocrine Glands

Glands that secrete substances through ducts to epithelial surfaces.

Endocrine Glands

Ductless glands that secrete hormones directly into the bloodstream.

Merocrine Secretion

A secretion mechanism where substances are released via exocytosis.

Apocrine Secretion

A mechanism where part of the cell is released along with the secretion.

Holocrine Secretion

A type of secretion where entire cells rupture to release their contents.

Lamina Lucida

The layer of the basement membrane closest to the epithelial cells.

Lamina Densa

The layer of the basement membrane adjacent to the connective tissue.

Interdigitations (Lateral Plicae)

Fingerlike projections that interlock adjacent epithelial cells.

Striated Rootlet

A structure anchoring the basal body of a cilium to the cytoplasm.