Lecture 19 Flashcards
What is the extracellular matrix
The material in-between cells that gives tissue its structure and strength. Its called connective tissue
What is connective tissue made up of?
Fibres, fibroblasts and ground substance
What is the purpose of collagen in CT
Provide tensile strength, collagen is a fibrous rope like molecule.
What does collagen consist of?
25% of all protein mass in the body, long stiff triple helix structure. the helixes combine to form collagen fibrils which then combine to give collagen fibres
How does collagen provide tensile strength?
There are intramolecular cross links. Propyl Hydoxylases add OH to some prolines and Lysyl hydroxylases add OH to some lysines
Where is collagen produces in skin and in bone
Skin - Fibroblasts
Bone - Osteoblasts
Explain the production of collagen
Collagen is produced as procollagen inside the cell which has additional peptides on the end of the protein to prevent it converting to collagen. On exiting the cell pro collagen proteinases cut off these peptides to allow the assembly of collagen fibres to form only in the ECM
How do cells attach to the ECM?
Cells attach poorly to collagen therefore an adaptor molecule called fibronectin is needed. Cells attach to fibronectin via transmembrane receptors called integrins.
What are functions of GAGs
Space filling resistant to compression …
What is laminin
The basal lamina is a specialised ECM made up of type IV collagen and laminin. Laminin connects the basal lamina to integrals in the epithelial cells.
What are the key type of cell-cell junctions.
- Tight junction - Leak proof seal
- Adherens and Desmosomes - Cell-cell binding. Adherins join actin bundles together and desmosomes join intermediate filaments together.
- Hemidesmosomes - Anchors intermediate filaments into the basal lamina
- Gap junction - allows molecules and ions through
