Connective Tissue And Extracellular Matrix

Front 1

Describe the basic types of extracellular matrices: basement membrane

Back 1

Basement membrane:
- Flexible, thin sheets
- 2D layer underlying
§ All epithelia
§ Muscle cells
§ Fat cells
§ Schwann Cells
- 3 components
§ Collagen type IV
§ Laminin
§ Heparin sulfate proteoglycan (negatively charged and binds to growth factors)
- Functions:
§ Regulates cell survival
§ Cell proliferation or differentiation of attached cells
§ Macromolecular filters (i.e. in glomeruli of the kidney during filtration of fluid passing
from blood to urine)
- Cancer cells become malignant when they can penetrate the basement membranes

Front 2

Describe the basic types of extracellular matrices: interstitial ECM

Back 2

Interstitial ECM
- Collagen always present
- May contain the following: elastin, linker proteins, and hydrated proteoglycans
-

Interstitial ECM Cells
Bone, cartilage, dermis Plentiful Sparse
Other tissues (liver, kidney) Present but less abundant

Front 3

Describe the basic types of extracellular matrices: Provisional ECM

Back 3

Provisional ECM
- Formed from fibrin and other plasma proteins
- Forms during blood clotting

Front 4

Laminin

Back 4

- Disulfide linked trimer consisting of alpha, beta and gamma chain

- Binds heparin, collagen type
IV, and specific integrin receptors

Promotion of cell adhesion migration, proliferation
and differentiation, also plays role in wound repair

- Associated with basement membranes

Front 5

Fibronectin

Back 5

- Dimer; two large proteins joined by disulfide bond

- Can link heparin, collagen, and integrin receptors

Minor amounts in basement membrane Found in ECMs
and in the provisional matrix

In the plasma to help heal wounds

Front 6

Glycosaminoglycans

Back 6

- Proteoglycans : the protein
backbone that GAGs are attached to
o Can be secreted OR
transmembrane proteins

- 4 types of GAG chains in proteoglycans:
o Chondroitin sulfate
o Heparan sulfate/heparin o Keratan sulfate
o Dermatan sulfate Fill extracellular
space b/c its highly hydrated

Front 7

Elastin

Back 7

- Can stretch several fold and
contracted to initial length
- Coiled up when unstretched, then when protein stretches the cross bridges hold it together

- Desmosine and isodesmosine (formed from lysine residues)

- Crucial for lung elasticity

Elastases: hydrolyze elastin (can
be enhanced by smoke) causing the lung to synthesize collagen instead of elastin resulting in less elasticity
--> emphysema








Enriched in ECM tissues that need to be resilient








Large blood vessels and lung

Front 8

Compare and Contrast Network and Fibrillar collagens including structures, functions and distribution;
describe how changers in collagen synthesis or processing can compromise tissue function

Back 8

Fibril forming:
i. Collagens I, II, and III (V, and XI)
ii. Make long fibrils that are usually cross-linked into three-dimensional arrays b. Network Forming:
i. Collagens IV and VII
ii. Polymerize into thin two-dimensional sheets

Front 9

Explain how cells use integrins to interact with various ECM's and how altering integrin function or cellular recognition of the ECM contribute to changes in tissue function

Back 9

Integrins are receptor molecules on cell surfaces that bind and respond to ECM components b. Two subunits
i. Alpha and beta
ii. A bunch of combinations of different numbers of subunits to recognize various ECM
components
c. Connects to the cytosekeleton
d. Regulating integrins can make it attach/detach from cytoskeleton e. IF abberant integrin exists, CANCER can arise
i. Cancer cells have inappropriate integrins
ii. Loss or improper ECM attachment (or alterations of integrin in integrin-mediated intracellular signaling) results in rapid cell growth, invasion and metastasis
f. ECM:
i. Regulate cell adhesion, migration, proliferation and differentiation

Front 10

Distinguish between the resident and migratory cell types within connective tissues

Back 10

Resident Cells:
i. Fibroblasts (which synthesize the ECM)
1. Synthesis, secretion and turnover of extracellular matrix
2. Irregular shape, "stellate" and abundant in ER
3. Active during matrix formation ii. Adipose cells (store and metabolize fat)
1. Lipid storage, synthesis and mobilization, can take up glucose from blood
and synthesize triglyceride
iii. Mast cells and resident macrophages (reside within tissue permanently
1. Ingests foreign matter, ingest dead neutrophils and other cells undergoing
apoptosis




immune response
b. Migratory Cells:


2. Secrete inflammatory molecules, cytokines, and growth factors
3. Large irregular shape, scattered throughout tissue
4. Mast Cells
a. Mast cells are similar to blood basophils and participate in

i. Plasma cells, lymphocytes, eosinophils
ii. Lymphocytes: connective tissue is one of the major sites for immune response
1. Both B and T lymphocytes reside in connective tissue
2. Small cells with cytoplasm and condensed chromatin iii. Plasma cells:
1. B lymphocytes that actively synthesize antibody
2. High in epithelial areas prone to viruses iv. Eosinophils: function in resisting parasite infection

Front 11

Name the different types of connective tissue and describe their key features

Back 11

Connective tissue = extracellular matrix + cells a. Loose connective tissue
i. Cushioning layer throughout the body, loose decondensed, irregular loose network of
network ells
b. Dense irregular
i. Random network of dense collagen fiber bundles ii. Gives strength in many directions
iii. More widespread than regular dense connective tissue (dermis and organ capsules)
iv. Lots of collagen and proteoglycan c. Dense regular tissue
i. Lots of collagen and proteoglycan
ii. Parallel unidirectional stress; resistance or structure d. Adipose tissue
i. Fat; rich in adipocytes e. Reticular connective tissue
i. Found within organs ii. Supports resident cells
f. Elastic tissue:
i. Found in yellow ligaments of vertebral column g. Hard connective tissue
i. Specialized ECM and cells in bone and cartilage