7. Epithelium & Glands

Question 1

Top of cell

Answer 1

Apical domain (free surface)

Question 2

Side of cell

Answer 2

Lateral domain

Question 3

Bottom of cell, connected to basal lamina

Answer 3

Basal domain

Question 4

Basal surface attached to underlying basement membrane

Answer 4

Cell to matrix junctions

Question 5

Cell adhesion is the process whereby cells are anchored to each other and to the extracellular matrix (ECM).

Answer 5

Cell adhesion molecules (CAMs)
CAMs are transmembrane proteins that are embedded in the plasma membrane of cells
• Interact with components in the cytoplasm of the cells intracellularly, and other CAMs, specific receptors of other cells or components in the ECM extracellularly to help to anchor the cells.

Question 6

A collection of CAMs

Answer 6

Cell Junctions

Question 7

Cell Adhesion Molecules (CAMs)
Cadherins

Answer 7

Cell to cell adhesion

Question 8

Cell Adhesion Molecules (CAMs)
Selectins

Answer 8

cell to cell adhesion

Question 9

Cell Adhesion Molecules (CAMs)
Immunoglobulin superfamily

Answer 9

Cell to cell adhesion

Question 10

Cell Adhesion Molecules (CAMs)
Integrins

Answer 10

Cell to cell adhesion plus cell to ECM adhesion

Question 11

Lateral Specializations of Cell
Tight Junction

Answer 11

Occluding Junction (zonula occludens)

Question 12

Lateral Specializations of Cell
Anchoring Junctions
Adhering Junctions

Answer 12

Zonula Adherens

Below ZO.

Question 13

Lateral Specializations of Cell
Anchoring Juncitons
Desmosomes

Answer 13

Macula Adherens

Below ZA

Anchors cells to neighbor

Question 14

Lateral Specializations of Cell
Communicating Junctions

Answer 14

Gap junctions

Question 15

Occluding Junctional Complex (cell to cell)
Tight junctions (prevents passage to maintain structure.
Separates the luminal space from the intercellular space and connective tissue compartment.
Localized sealing of the plasma membrane of adjacent cells.
Network of anastomosing strands that surround the apical cell borders.

Answer 15

Zonula Occludens

Question 16

Occluding Junctional Complex (Cell to cell)
Transmembrane proteins
Interactions with actin cytoskeleton via ZO-1,2,3
Functions as a tight seal on apical surface to prevent leakage of larger solute molecules from cell to cell. Allows for smaller particles (ions) to pass between cells.

Answer 16

Claudins & Occludins

Question 17

Flow of allowed solutes
(Pictured answer)

Answer 17

Question 18

Anchoring Junctional Complexes (Cell to Cell)

Answer 18

Includes Zonula Adherens (belt desmosomes) and Macula adherens (desmosomes)

Question 19

Anchoring Junctional Complexes (Cell to Cell)
Lateral adhesion between epithelial cells
Found beneath the zonula occludens
Continuous band or belt that surrounds the entire cell, found just beneath the tight junction
Maintains physical integrity of cells by assisting with cell attachment to adjacent cells (15-20nm apart).
Helps anchor cells (eg muscle cells) to the extracellular matrix through interaction with actin cytoskeleton.

Answer 19

Zonula Adherens

Question 20

Anchoring Junctional Complexes (Cell to Cell)
Zonula Adherens
Transmembrane Protein

Answer 20

E-cadherin (Calcium dependent binding)
Epithelial cadherin

Question 21

Anchoring Junctional Complexes (Cell to Cell)
Macula Adherens
Lateral, localized, spot adhesion between epithelial cells about 30nm apart
Focal dense spots (macula)
Found beneath Zonula Adherens of cells.
Couples the intermediate filaments to the plasma membrane at regions of cell to cell adhesion.

Answer 21

Macula Adherens = Desmosomes

Question 22

Anchoring Junctional Complexes (Cell to Cell)
Macula Adherens
Transmembrane Proteins

Answer 22

Desmocollin & Desmoglein
(Cadherin family, calcium dependent)

Question 23

Anchoring Junctional Complexes (Cell to Cell)
Macula Adherens
Intracellular plaque
Interaction with intermediate filaments of cytoskeleton
Helps with cell to cell adhesion

Answer 23

Plakoglobins & Desmoplakins

Question 24

Complexes in order from top to bottom

Answer 24

1. ZO
2. ZA
3. MA

Goes backwards alphabetically

Question 25

Communicating Junctional Complex (Cell to Cell)
Presents in a variety of tissues
-Epithelium
-Muscle (smooth & cardiac)
-Nerve
Help coordinate activity between adjacent cells

Answer 25

Gap Junctions

Question 26

Communicating Junctional Complex (cell to cell)
Gap Junctions
Transmembrane protein subunits
Align to form a communicating channel connecting the cytoplasm of adjacent cells.
Creates a conduit between two adjacent cells for passage of small ions and informational micro molecules.

Answer 26

Connexin
Half Chanel formed by 6 connexins

Question 27

Increase lateral cell surface
Common in cells engaged in fluid and electrolyte transport (ex. Gall bladder, small intestine)

Answer 27

Lateral interdigitations
Infoldings (plicae) of cytoplasmic processes of adjoining cells.

Question 28

Basal Specialization of Cells

Answer 28

Focal Adhesions & Hemidesmosomes

Question 29

Basal Specializations of Cells
Major Link Transmembrane Proteins: Integrins
Extracellular ligand: Extracellular matrix proteins (ex. Fibronectin)
Cytoskeleton components: Actin filaments
Associated Intracellular Attachment proteins: Vinculin, talin, alpha-actinin, paxillin
Functions: Anchors the actin cytoskeleton to the extracellular maxtrix, detects and transduces signals from outside the cell. Important role in cell migration.

Answer 29

Focal Adhesions

Question 30

Basal Specialization of Cells
Anchoring Junctional Complex
-Cell to extracellular Matrix Junctions
- Helps to anchor epithelial cells to basement membrane
Half of component of desmosome.
Transmembrane protein: Integrins
Interaction with intermediate filaments of cytoskeleton.
Clinical correlation: Bullous pemphigoid.
-Disease characterized by blister formation at epithelial attachment to basement membrane.
-Antibodies directed against BP230 & Type XVII collagen in basement membrane.

Answer 30

Hemidesmosomes