Connective Tissue I Flashcards
Features of connective tissue
- Formation of ECM
- form superficial and deep fascia, covering of muscle, bone, cartilage, among other tissues
Functions of CT
- provide structural support for specialized tissues and organs
- conduct and control the exchange of nutrients, metabolites, and signaling ligands between different cell types in organs and blood
- directly control the behavior and functions of cells that contact the ECM:
- control of epithelium polarization
- guidance and regulation of cell migration through the ECM
- control of cell proliferation, migration, metabolism
- defense against bacteria
- control of tissue formation, organization, and modification
- control of inflammation and repair due to injury
Name the connective tissue cell types
- mesenchymal stem cells
- fibroblasts
- myofibroblasts: have contractile properties allowing for contraction during wound healing
- adipocytes
- Osteoblasts and osteocytes
- Chondrocytes
- SOME smooth muscle around blood vessels
Immigrant blood-derived cells
- lymphocytes
- Macrophages: derived from monocytes
- neutrophils
- mast cells: derived from basophils
- Osteoclasts: derived from monocytes
Fxns of Macrophages
- engulf invading microorganisms
- promote angiogenesis
- remodel damaged tissue
- remodel normal developing tissue and organs as part of morphogenesis.
ECM Components
- Collagen
- Elastic fibers
- Ground substance
Describe collagen, its types and functions
- The collagens are fibrous proteins of very similar primary sequence to each other; collagen proteins aggregate to form fibers of varying sizes and organizations.
- three intertwined helices
1. Fibrillar collagen: large collections of collagen called fibrils.
2. Fibril-associated collagen: decorate the surface of collagen fibrils, linking collagen fibrils to each other.
3. Network-forming collagens: small collagen fibers that contribute to the basal lamina.
Types of collagen modification
intracellular:
-Synthesized in ER, post-translationally modified, assembled into triple helix
Extracellular:
-N and C termini of collagen are cleaved to generate fragments called N-telo peptides (values can be measured in blood for certain diseases)
- formation of collagen bundles and end-to-end polymers
- enzymes form cross-links b/w collagen molecules.
Describe elastic fibers
Elastic fibers are found in connective tissues that require distensibility and resiliency. Elastic fibers contain the proteins elastin and fibrillin that assemble into stretchable and resilient fibers and sheets.
Describe the ground substance, including its components
Ground substance = hydrated aqueous gelatinous material
components:
- proteoglycans
- other secreted proteins and glycoproteins
- inorganic and small organic solutes
- water
Describe proteoglycans
Proteoglycans contain a protein core attached to very large acidic polysaccharides, called glycosaminoglycans (GAGs). GAGs are long polymers of carbohydrate molecules (polysaccharides).
Features of proteoglycans:
1. highly negatively charged
- attract a lot of water
- Rigid extended structure causes them to rapidly form gels
- some proteoglycans also bind to activate/inactivate other proteins
List the processes of wound healing and inflammation
- blood clotting and inflammation
- proliferation and differentiation
- Tissue remodeling
Describe the process of blood clotting and inflammation
- Damage to tissue causes release of signaling molecules, leading to the recruitment of platelets for clot formation.
- Mast cells are recruits, which release histamine to cause vasodilation.
- Cytokines released from white blood cells and fibroblasts promote more white blood cells recruitment and differentiation of fibroblasts.
Describe the process of proliferation and differentiation of fibroblasts and other cells
- fibroblasts are stimulated to divide
- Fibroblasts are stimulated to secrete more ECM.
- Other stem cells are stimulated to regenerate tissue (epithelia/muscle)
- Various factors induce angiogenesis
