Lecture 5: Cell to Cell Adhesions PDF
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Lecture 5 discusses cell-cell adhesions and specialized cell junctions. It details different types of cell adhesions, such as cell adhesion molecules and the extracellular matrix, focusing on the functions and roles of structures like collagen, elastin, and fibronectin. Furthermore, it explains desmosomes, tight junctions, and gap junctions in terms of their function and location, emphasizing their importance in cell-cell communication and tissue integrity.
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**Lecture 5: Cell to Cell Adhesions** Cell to Cell Adhesions & Junction Types **Cell to Cell Adhesions** - Plasma membrane participate in Cell - Cell adhesions: the holding together / adhering to each other. - 3 Different ways cells ar held together - **Cell Adhesion Molecules (CA...
**Lecture 5: Cell to Cell Adhesions** Cell to Cell Adhesions & Junction Types **Cell to Cell Adhesions** - Plasma membrane participate in Cell - Cell adhesions: the holding together / adhering to each other. - 3 Different ways cells ar held together - **Cell Adhesion Molecules (CAMs)** - Membrane proteins that allow cells to hold onto each other - Provide some tissue cohesion as they "velcro" adjacent cells together. - **Extracellular Matrix** - (Extracellular) not inside the cell - Intricate network of fibrous proteins surrounded by interstitial fluid (watery, gel-like substance) composed of complex carbohydrates. - Interstitial Fluid: provides pathway for diffusion of nutrients, waste, and other water-soluble traffic between blood and tissue cells. - Extracellular Matrix Protein - ECM is abundant in Connective tissue, not in epithelial - Fibroblasts: Responsible for making most of the cells (collagen, elastin, fibronectin) in the ECM. - Collagen 1. Description: Cable like fibers 2. Function: Tensile strength (allows cells to not be ripped apart)(integrity of tissue) 3. Most abundant protein in body; half of body protein by weight - Elastin 4. Description: Rubber like protein fibers 5. Function: Stretching and recoil - Fibronectin 6. Description: "function as biological glue" 7. Function: Holds cell in position (promotes cell adhesion) 8. Key Point: Reduced levels relate to tumor metastasis - **Specialized Cell Junctions** - **Desmosomes** (adhering junctions) - additional layer of **STRENGTH** - **Function**: Anchor together two adjacent, non-touching cells - **Facts:** 1. Strongest cell to cell connection 2. Most abundant, can stretch - **Location**: Heart, Skin, Uterus - Cytoplasmic thickening plaque + keratin filament (strong protein) are two structures that make the cell - cell adhesion more rigid (Desmosomes) - **Tight Junctions** (impermeable junctions) - physical removal of space, sowing cells together - **Function:** Adjacent cells binds together to seal off passageway between. - **Location:** found in sheets of epithelial tissue that cover internal cavities 1. Digestive tract - **Facts**: Crohn's disease, IBS, - barrier not intact - **Gap Junctions** (communicating junctions) - forming gap between two cells for better communication. - **Description:** A gap between adjacent cells, linked by small, connecting tunnels. 1. Group of proteins called - **Function:** Allow for ions and small water soluble particles to pass, not large molecules - **Location:** Cardiac and Smooth Muscle - **Use Case:** When a process needs to happen at once, synchronized. (E.g., Heart beat)
