chap 7

Definition of ECM: Understand the Extracellular Matrix (ECM) and its significance in biological systems.
Main Functions of ECM:
- Binds cells together and provides structural support.
- Acts as a reservoir for hormones and morphogens.
- Serves as an area for cell movement, particularly during development, differentiation, growth, and wound healing.
- Examples of ECM include tendons, bones, and kidney glomeruli.
Degeneration of ECM: Recognize the consequences of ECM degeneration.
Assembly of ECM (Collagen): Understand the process by which ECM, particularly collagen, is formed and organized.
Structural Composition of ECM: Identify the various components of ECM and their specific functions.
Molecular Components of ECM: Name the molecular structures that comprise ECM.
Cell Linking to ECM: Explain how cells connect and interact with the ECM.
Unique Characteristics of ECM: Recognize the distinguishing features of ECM.
Cytoskeleton Types: Identify and categorize the different types of cytoskeleton available in cells.
Structural Composition of Cytoskeleton: Describe the individual structural components of cytoskeletons, such as actin filaments, intermediate filaments, and microtubules.
Structure and Function Relationship: Relate the structural properties of cytoskeleton components to their functional roles in cellular dynamics.

Embryonic Layer & Cell Types:
- Ectoderm: Forms the Central Nervous System (CNS), retina (neuroectoderm), pigment cells, neurons, glia, and melanocytes.
- Epithelium: Includes skin, hair, mammary glands (keratinocytes).
- Endoderm: Comprises gut, liver, pancreas, lung, and other glands.
- Mesoderm: Forms the urogenital tract and muscle tissues (e.g., skeletal, cardiac, smooth muscle).
- Connective Tissue: Components include interstitium and blood, featuring various cell types (e.g., myocytes, fibroblasts, leukocytes).

Definition of ECM:
- ECM is a complex material secreted and deposited by cells, forming a network of proteins and carbohydrates.
Functions of ECM:
- Binds and supports cells.
- Serves as a reservoir for biological molecules.
- Facilitates cellular movement during crucial biological processes.

Analogy of ECM:
- Analogy of egg yolks (cells) and egg whites (ECM) illustrates the connectivity and communication role of ECM among cells.
ECM Degeneration: Degeneration is likened to an egg poaching, where loss of water content disrupts the functions and connections within ECM.

Basement Membrane:
- Found in epithelial, endothelial, muscle, fat, and nerve tissues.
Elastic Fibers:
- Present in skin, lungs, and large blood vessels, known for their elasticity.
Stromal or Interstitial Matrix:
- Found in bones, teeth, cartilage, tendons, and ligaments.

Key Receptors for ECM:
- Integrins, dystroglycans, syndecans, and muscle-specific kinase (MuSK) are crucial for cell recognition and response to ECM.

Collagens: Various types provide structural integrity.
Proteoglycans: Serve functions such as binding water and regulating growth factors.
Glycoproteins: Includes laminins, nidogens, fibronectins, and others that link cellular components.
Matricellular Proteins: Such as SPARC, thrombospondins, osteopontin, and tenascins.

Modular Nature:
- Most ECM proteins are large, glycosylated, and contain repetitive domains for versatile functions (e.g., fibronectin type III repeats).

Definition: Specialized layers of ECM near all epithelia and muscle cells; crucial in maintaining structural integrity.

Types of Collagen:
- Type I: Found in skin, tendons, bones, providing tensile strength.
- Type II: Located in cartilage.
- Type IV: Structural component of basement membranes.
Collagen Structure:
- Composed of glycine, proline, and hydroxyproline subunits, typically forming a triple helix.

Synthesis Process:
- Initiated in the Endoplasmic Reticulum (ER) where polypeptide chains form soluble procollagen. Post-translational modifications occur in the Golgi apparatus, followed by secretion and assembly into collagen fibers outside the cell.

Characteristics:
- Composed of a core protein with carbohydrate chains, fostering hydration and space occupation in tissues.
Functions:
- Include shock absorption, water retention, and interaction with collagen fibers.

Also known as hyaluronic acid; provides cell-free space promoting cell migration and proliferation.

Fibronectin:
- A glycoprotein crucial for cell adhesion, migration, and organizing the ECM.
Laminin:
- Vital for cellular adhesion, signaling, and providing a scaffold for tissue structure.

Integrins:
- Essential membrane proteins bridging the ECM to the cytoskeleton, facilitating cell attachment.
Hemidesmosomes:
- Key structures that anchor basal cells to the basal lamina using cytoskeletal attachments.

Diseases Involving Collagen:
- Fibrosis: Excess collagen leading to tissue stiffening.
- Osteogenesis Imperfecta: Mutations in type I collagen leading to brittle bones.
- Scurvy: Vitamin C deficiency impacting collagen stability and function.

Results in various health issues, including arthritis, delayed tissue repair, and increased malnutrition risk, affecting overall physical stability and environmental sensitivity.

Types of Filaments:
- Actin filaments (microfilaments), Intermediate filaments, and Microtubules serve crucial roles in cell mechanics, shape, and intracellular transport.

Essential for establishing cell shape, providing mechanical strength, enabling locomotion, and facilitating intracellular transport.

Importance of ECM:
- Acts as structural support, compartmentalizes tissue, presents signals for cell communication, and guides migration during development and healing.