Cytoskeleton, Microvilli, Cilia, Stereocilia, and Epithelial Junctions – Vocabulary Flashcards

Vocabulary flashcards covering key terms related to the cytoskeleton, microvilli, cilia, stereocilia, and epithelial cell junctions as described in the notes.

Microvilli

Finger-like apical projections that increase surface area for absorption; form the brush border; supported by actin filaments.

Brush border

Dense array of microvilli on absorptive cells, increasing surface area for absorption; may include a glycocalyx.

Stereocilia

Long, irregular, non-motile microvilli; found in the epididymis and some sensory epithelia; primarily for absorption.

Cilia

Motile, hair-like projections that beat to move fluids; 9+2 microtubule arrangement.

Cilium (singular)

A single ciliary projection with the 9+2 axonemal structure.

Flagellum

A single, long motile projection (e.g., sperm tail) that propels the cell.

9+2 microtubule arrangement

Axoneme structure of motile cilia/flagella: nine outer doublets surrounding two central microtubules, essential for motion.

Actin filament

Thin cytoskeletal filament forming the core of microvilli and vital for cell structure and movement.

Glycocalyx

Sugar-rich layer on microvilli that aids lubrication, protection, and cell recognition.

Epididymis

Male reproductive structure where stereocilia are prominent; site of sperm maturation.

Ependymal cells

Ciliated epithelial cells lining brain ventricles; move cerebrospinal fluid (CSF).

Basal lamina

Part of the basement membrane underlying epithelia; rich in type IV collagen; anchors cells to connective tissue.

Hemidesmosome

Anchoring junction attaching epithelial cells to the basal lamina; links intermediate filaments to the basement membrane.

Tight junction (occluding junction)

Junction that seals intercellular space to prevent paracellular solute passage.

Zonula adherens

Belt-like adherens junction encircling the cell, linking to actin filaments for cell–cell adhesion.

Desmosome

Anchoring junction linking intermediate filaments of adjacent cells; provides mechanical strength.

Gap junctions

Intercellular channels allowing direct passage of ions and small molecules between cells; enables coordinated function.

Connexin

Transmembrane proteins forming gap junction channels, critical for permeability and function.

Intermediate filament

Cytoskeletal component providing mechanical strength; crucial for cell adhesion structures like desmosomes and hemidesmosomes.

Basement membrane

Specialized extracellular matrix underlying all epithelia, providing structural support and anchoring; comprises basal lamina and reticular lamina.

Function of tight junctions

To form a selective permeable barrier between epithelial cells, preventing the paracellular passage of solutes and fluid.

Function of gap junctions

To allow direct cell-to-cell communication and rapid passage of ions and small molecules, synchronizing cellular activities.

Axoneme

The central core structure of motile cilia and flagella, characterized by its 9+2 microtubule arrangement, essential for cellular motility