Chronic Inflammation 5

Question 1

Tissue repair depends not only on growth factor activity but also on interactions between _____________.

Answer 1

cells and ECM components

Question 2

The ________ is a dynamic, constantly remodeling macromolecular complex synthesized locally, which assembles into a network that surrounds cells.

Answer 2

ECM

Question 3

ECM occurs in two basic forms:

Answer 3

1. Interstitial matrix.
2. Basement membrane.

Question 4

Functions of ECM:

Answer 4

1. Sequesters water, providing turgor to soft tissues.
2. Sequesters minerals, giving rigidity to bone.
3. Regulates the proliferation, movement, and differentiation of the cells living within it.
4. Serving as a reservoir for growth factors.
5. Synthesis and degradation of ECM accompanies morphogenesis, wound healing, chronic fibrotic processes, and tumor invasion and metastasis.

Question 5

Interstitial Matrix - form 1:

Answer 5

This is present in the spaces between cells in connective tissue, and between epithelium and supportive vascular and smooth muscle structures

Question 6

It is synthesized by ___________ (e.g., fibroblasts) and tends to form a three-dimensional,amorphous gel.

Answer 6

mesenchymal cells ,

Question 7

Its major constituents are:

Answer 7

1. Fibrillar and nonfibrillar collagens.
2. Fibronectin.
3. Elastin.
4. Proteoglycans.
5. Hyaluronate

Question 8

Basement Membrane - form 2:

Answer 8

The random array of interstitial matrix in connective tissues becomes highly organized around epithelial cells, endothelial cells, and smooth muscle cells, forming the specialized basement membrane.

Question 9

The basement membrane lies beneath the epithelium and is synthesized by overlying ________ and underlying _________.

Answer 9

epithelium, mesenchymal cells.

Question 10

Its major constituents are:

Answer 10

Amorphous nonfibrillar type IV collagen and laminin.

Question 11

Roles of the Extracellular Matrix

Answer 11

1. Mechanical support
2. Control of cell growth: ECM components can regulate cell proliferation
3. Maintenance of cell differentiation
4. Scaffolding for tissue renewal: The integrity of the basement membrane or the stroma of the parenchymal cells is critical for the organized regeneration of tissues.
5. Establishment of tissue microenvironments: Basement membrane acts as a boundary between epithelium and underlying connective tissue
6. Storage and presentation of regulatory molecules: For example, growth factors like FGF and HGF

Question 12

There are three basic components of ECM:

Answer 12

1. Fibrous structural proteins (collagens and elastins) which confer tensile strength and recoil.
2. Water-hydrated gels (proteoglycans and hyaluronan) which permit resilience and lubrication.
3. Adhesive glycoproteins that connect the matrix elements to one another and to cells.

Question 13

1. Collagen

Answer 13

• The collagens are fibrous structural proteins that confer tensile strength.
• Collagens are composed of three separate polypeptide chains braided into a ropelike triple helix.
• The collagen proteins are rich in hydroxyproline and hydroxylysine.

Question 14

Type of collagen:

Answer 14

• Some collagen types (e.g., types I, II, III, andV) form fibrils.
• The fibrillar collagens form a major proportion of the connective tissue in healing wounds and particularly in scars.
• The tensile strength of the fibrillar collagens derives from their cross-linking, which is the result of covalent bonds.
• This process is dependent on vitamin C

Question 15

Other collagens are nonfibrillar and may form:

Answer 15

Basement membrane (type IV).
Components of other structures such as intervertebral discs (type IX).
Dermal-epidermal junctions (typeVII).

Question 16

2. Elastin

Answer 16

• important in the walls of large vessels (which must accommodate recurrent pulsatile flow).
• well as in the uterus, skin, and ligaments.
• Morphologically, elastic fibers consist of a central core of elastin surrounded by a meshlike network of fibrillin glycoprotein.
• Like collagens, elastins require a glycine in every third position, but they differ from collagen by having fewer cross-links
• Marfan syndrome

Question 17

Proteoglycans

Answer 17

• form highly hydrated compressible gels conferring resilience and lubrication (such as in the cartilage in joints).
• They consist of long polysaccharides called glycosaminoglycans.

Question 18

Hyaluronan,

Answer 18

a huge molecule composed of many disaccharide repeats without a protein core, is also an important constituent of the ECM.
Because of its ability to bind water, it forms a viscous, gelatin-like matrix.

Question 19

Adhesive Glycoproteins and Adhesion Receptors
- Adhesive glycoproteins and adhesion receptors are structurally diverse molecules involved in

Answer 19

cell-to-cell adhesion, the linkage between cells and ECM, and binding between ECM components.

Question 20

The adhesive glycoproteins include: __________ (major component of the interstitial ECM) and _______ (major constituent of basement membrane).

Answer 20

fibronectin
laminin

Question 21

Fibronectin

Answer 21

synthesized by a variety of cells, including fibroblasts, monocytes, and endothelium.
- Fibronectin messenger RNA (mRNA) has two splice forms, which generate tissue and plasma fibronectin.

Question 22

Fibronectin

Answer 22

Tissue fibronectin forms fibrillar aggregates at = wound healing sites.
Plasma fibronectin binds to fibrin to form the = provisional blood clot of a wound

Question 23

Laminin

Answer 23

• The most abundant glycoprotein in basement membrane
  Function:
• Mediating attachment to basement membrane.
• Modulate cell proliferation, differentiation, and motility.

Question 24

Integrins

Answer 24

• Family of transmembrane heterodimeric glycoproteins
composed of a and & chains that are the main cellular receptors for ECM components, such as fibronectins and laminins.