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Questions and Answers
What is the primary role of epithelium in the body?
What is one function of endothelium within blood vessels?
Which layer of the skin is composed of dense, irregular connective tissue?
Which process is NOT primarily regulated by interactions between cells and their environment?
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What critical function does skin serve beyond being a covering?
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How do cells primarily maintain their defined relationships in tissues?
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Capillaries are lined with what type of cells?
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What element is critical for the 3-D organization of tissues and organs during embryo development?
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What is the primary role of the glomerular basement membrane (GBM) in the kidneys?
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Which condition is characterized by a thickened glomerular basement membrane (GBM)?
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What type of collagen is most abundant in the human body?
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What is a possible effect of Vitamin C deficiency related to collagen?
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Which type of collagen is primarily found in the cartilage?
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What genetic condition is associated with collagen type I abnormalities?
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What role does hydroxylated proline play in collagen structure?
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Which type of collagen provides mechanical support with flexibility and is found in basement membranes?
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Which condition presents with distinct facial appearance, bruising, and skin thinning due to type III collagen issues?
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What is the main source of collagen production in the body?
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What is the primary function of tight junctions in cell-cell interactions?
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Which type of junction connects actin filaments between cells?
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What role does the glycocalyx play in cellular interactions?
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Which structure anchors intermediate filaments to the extracellular matrix?
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What is the primary component of the extracellular matrix that strengthens tissue?
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What is one of the main functions of the endothelial cells?
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Which disease is characterized by damage to the glycocalyx?
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What is a primary role of the extracellular matrix (ECM)?
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Which of the following best describes the basement membrane?
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In which of the following ways does the basement membrane assist epithelial cells?
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What is the significance of the dynamic nature of the extracellular matrix?
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Which of the following is NOT a function of the basement membrane?
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How does the extracellular matrix contribute to tissue repair?
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What is the primary function of fibronectin in the extracellular matrix?
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Which sequence allows fibronectin to bind to integrins?
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What structural feature do laminins share?
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Which cells primarily secrete fibronectin?
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What is a primary role of laminin in embryonic development?
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Which components does fibronectin NOT bind to?
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How are fibronectin monomers structured?
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Which of the following is a function of laminin?
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Study Notes
Extracellular Interactions
- Cells in multicellular organisms are organized into tissues
- Cells interact with each other and extracellular materials
- These interactions regulate cell migration, growth, differentiation, and 3D tissue organization
Tissues
- Epithelium: A thin layer of tightly packed cells that cover surfaces and line cavities
- Examples: epidermis (outer layer of skin)
- Endothelium: Specialized epithelium found inside blood vessels and lymphatic vessels
- Single cell layer, controls bloodflow, regulates blood pressure, facilitates nutrient and waste exchange
Cell-Cell/Cell-ECM Interactions
- Apical Surface:
- Tight Junctions: Seal gap between cells
- Adherens junctions: Connect actin filaments between cells
- Desmosome: Connects intermediate filaments between cells
- Gap Junction: Passage of small water-soluble molecules
- Hemidesmosome: Anchors intermediate filaments to extracellular matrix
- Basal Surface:
- Focal adhesions: Anchors many cell types to ECM
Extracellular Components
- Glycocalyx: Cell coat of glycoproteins and glycolipids that project outward from the plasma membrane
- Located at epithelial and endothelial cells
- Mediates cell-cell and cell-substratum interactions
- Provides mechanical protection
- Extracellular Matrix (ECM): Organized network of extracellular material
- Provides physical and biochemical signals
- Basement Membrane is part of the ECM, located beneath epithelial tissue and surrounds blood vessels, nerve fibers, muscles, and fat cells
- Separates adjacent tissues, provides mechanical support, generates signals for cell survival, serves as substratum for cell migration, and acts as a barrier to macromolecules
Basement Membrane in Disease
- Glomerular basement membrane (GBM) filters blood in the kidney
- Abnormal GBM impairs kidney filtration
- Examples:
- Diabetes: GBM thickens
- Basement membrane disease: GBM becomes thin
- GoodPasture’s syndrome: GBM is disrupted and thin
Basement Membrane Roles
- For Epithelium:
- Anchorage: Anchors epithelial cells to connective tissue
- Filtration: Controls substance exchange between epithelium and adjacent tissues
- Compartmentalization: Separates epithelium from connective tissue
- Cell differentiation and regeneration: Guides epithelial cell differentiation and repair
- For Endothelium:
- Structural support: Provides a foundation for endothelial cells
- Selective barrier: Regulates molecule passage between blood and tissues
- Cell migration and repair: Aids endothelial cell migration and proliferation during angiogenesis and wound healing
- Maintains separation: Prevents mixing of endothelial cells with underlying tissues
Extracellular Matrix Proteins
- Collagen: Main structural protein in ECM, most abundant protein in the human body, has high tensile strength
- Types:
- Fibrillar: Assemble into rigid, cable-like fibrils that package into thicker fibers. Found in skin, tendons, vasculature, cornea, bone, and organs
- Non-Fibrillar: Non-helical lattice arrangement with globular domains found in basement membranes.
- Types:
- Fibronectin: Glycoprotein secreted by fibroblasts, initially soluble, cells use it to build insoluble matrix
- Plays a major role in cell adhesion, growth, migration, differentiation, wound healing, and embryonic development
- Laminin: Family of extracellular glycoproteins, organized into a cross-shaped molecule
- Binds to cell-surface receptors, other laminin molecules, proteoglycans, and collagen of the basement membrane
- Important for cell migration, growth, and differentiation
Collagen - Structure
- α chains of collagen: Contain hydroxylated proline residues
- Contribute to stability of the triple helix structure
- Vitamin C adds hydroxyl groups to lysine and proline, crucial for collagen structure
- Vitamin C deficiency: Leads to scurvy (poor wound healing, hair changes, skin bleeding)
Collagen - Types and Genetic Mutations
- Type I: Most abundant, found in tendons, skin, vessel walls, fibrocartilage, bones, and teeth
- Mutations: Osteogenesis Imperfecta (brittle bone disease)
- Type II: Makes up 50% of cartilage protein
- Mutations: Dwarfism
- Type III: Found in wound healing, vessel walls, skin, intestines, and the uterus
- Mutations: Ehlers-Danlos Syndrome (type 4)
Fibronectin - Structure
- Binds to integrins (membrane-spanning receptor proteins) via Arg-Gly-Asp sequence
- Also binds to ECM via collagen, fibrin, and proteoglycans
- Protein dimer: Composed of 2 nearly identical monomers linked by disulfide bonds, containing distinct modules
Laminin - Functions
- Plays a pivotal role in the migration of primordial germ cells (PGCs)
- PGCs arise in the yolk sac and travel to the developing gonad via regions rich in laminin.
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Description
Explore the fundamental interactions between cells and their surrounding extracellular matrix in multicellular organisms. This quiz covers the organization of tissues, various types of epithelium, and the specific cell-cell and cell-ECM junctions that facilitate critical biological processes. Test your knowledge on how these interactions impact cell behavior and tissue formation.
