Cell Membrane 3

Question 1

-Some cell types move freely in the body –> Ex: ?
-Many others are packed into tight communities –> Ex: ?

Answer 1

Some cell types move freely in the body
 Blood cells, and some immune system cells
Many others are packed into tight communities
 Tissues

Question 2

Cell junctions consist of ?complexes that provide contact between:
1. ?
2. ?

DIFFERENT FUNCTIONS ? (6)

Answer 2

Cell junctions consist of multiprotein complexes that provide contact between:
neighboring cells or
between a cell and the extracellular matrix.

DIFFERENT FUNCTIONS
1. Bond cells together
2. Reduce stress placed upon cells
3. Build up the paracellular barrier of epithelia
4. Control the paracellular transport
5. Enable communication between neighboring cells
6. Adhesion of cells to extracellular matrix

Question 3

1. EPITHELIAL TISSUES ?
2. CONNECTIVE TISSUES?

Answer 3

1. EPITHELIAL TISSUES
   Attachments between cells are made by cell-cell junctions.
   Cells are anchored onto the basal lamina through cell-matrix junctions.
2. CONNECTIVE TISSUES
   Formed by ECM produced by cells that are distributed sparsely in the interstitial matrix (fibroblasts)

Question 4

TYPES OF CELL-CELL JUNCTIONS ? (3)

TYPES OF CELL-MATRIX JUNCTIONS ? (1)

Answer 4

TYPES OF CELL-CELL JUNCTIONS
1. TIGHT JUNCTIONS
2. CELL-CELL ANCHORING JUNCTIONS
a. ADHERENS JUNCTIONS
b. DESMOSOMES
3. GAP JUNCTIONS (communicating junctions)
channel-forming junctions

TYPES OF CELL-MATRIX JUNCTIONS
1. CELL-MATRIX ANCHORING JUNCTIONS a. ACTIN LINKED CELL-MATRIX JUNCTIONS b. HEMIDESMOSOMES

Question 5

1. TIGHT JUNCTIONS
   -Seal gap between ? cells
   * Seal is ? ? (diffusion barrier)
    Impermeable to macromolecules
    Permeability to ions and other small molecules varies
    Serve as selective permeability barriers for paracellular transport
   Mostly at apical location
   Found in epithelial cells
   i.e.; lining of the intestinal mucosa, bladder, respiratory tract

Answer 5

1. TIGHT JUNCTIONS (zonula occludens, or occluding junction)
   Seal gap between epithelial cells
   * Seal the intercellular space from luminal environment * Seal is not absolute (diffusion barrier)
    Impermeable to macromolecules
    Permeability to ions and other small molecules varies
    Serve as selective permeability barriers for paracellular transport
   Mostly at apical location
   Found in epithelial cells
   i.e.; lining of the intestinal mucosa, bladder, respiratory tract