HSS2305-L7

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Questions and Answers

What is a primary function of the tunica intima in blood vessels?

To provide structural support to the vessel

To allow for cell signaling between endothelial cells

To regulate blood flow and pressure (correct)

To facilitate nutrient exchange between the blood and surrounding tissues

Which component is not typically found in the tunica adventitia of blood vessels?

Elastic fibers

Connective tissue

Smooth muscle cells (correct)

Collagen fibers

What role does the tunica media play in blood vessel function?

Separating blood from surrounding tissues

Providing a barrier to pathogens

Maintaining the structural integrity of the vessel

Facilitating vasodilation and vasoconstriction (correct)

Why is the extracellular matrix (ECM) significant in tissue organization?

It provides a scaffold that supports cell attachment and tissue integrity. Signup and view all the answers

How do cell-cell interactions influence cell differentiation?

They modulate signaling pathways that guide the differentiation process. Signup and view all the answers

What is the primary function of tight junctions in cell-cell interactions?

Sealing gaps between adjacent cells Signup and view all the answers

Which component of the glycocalyx primarily consists of carbohydrate-containing structures?

Carbohydrates Signup and view all the answers

Which junction connects actin filaments between cells?

Adherens junction Signup and view all the answers

What best describes the role of focal adhesions in cell adhesion?

Anchoring multiple cell types to the extracellular matrix Signup and view all the answers

What is a key feature of hemidesmosomes in terms of their function?

Anchoring intermediate filaments to the ECM Signup and view all the answers

The primary purpose of the glycocalyx in epithelial cells is to:

Mediate cell-cell and cell-substratum interactions Signup and view all the answers

Which junction type allows for the passage of small water-soluble molecules between cells?

Gap junction Signup and view all the answers

Which extracellular component is primarily responsible for providing structural support to tissues?

Basement membrane Signup and view all the answers

What is the primary role of integrins in normal cells regarding their interaction with the ECM?

Promoting motility through adhesion. Signup and view all the answers

Which of the following processes is influenced by outside-in signaling in cells?

Differentiation, motility, and survival. Signup and view all the answers

Which type of junction is primarily responsible for sealing gaps between cells?

Tight junctions. Signup and view all the answers

What feature distinguishes cancer cells from normal cells regarding integrin signaling?

Cancer cells depend less on integrin signaling. Signup and view all the answers

What is a function of focal adhesions in cells?

Anchoring cells to the extracellular matrix while sensing its properties. Signup and view all the answers

Which of the following accurately describes the relationship between cytoskeletal rearrangements and ECM interactions?

Cytoskeletal rearrangements are triggered by ECM interactions. Signup and view all the answers

In which type of junction are intermediate filaments connected between cells?

Desmosomes. Signup and view all the answers

What characteristic of hemidesmosomes is crucial for epithelial cells?

They anchor intermediate filaments to the ECM. Signup and view all the answers

Which of the following best describes inside-out signaling?

Internal signals influencing external cell interactions. Signup and view all the answers

Which statement best describes a role of the extracellular matrix (ECM)?

ECM components are involved in processes such as cell migration and tissue remodeling. Signup and view all the answers

What is a key characteristic of proteoglycans found in the extracellular matrix?

They form complexes linked by hyaluronic acid, supporting structural integrity. Signup and view all the answers

What function do matrix metalloproteinases (MMPs) serve in the extracellular matrix?

MMPs degrade ECM, facilitating processes such as tissue remodeling and cell migration. Signup and view all the answers

How do integrins facilitate cell interactions within the extracellular matrix?

Integrins bind to various ECM proteins and integrate signals between the extracellular and intracellular environments. Signup and view all the answers

Which aspect of proteoglycans contributes to the ECM's hydration and resistance to deformation?

Their ability to bind cations and water because of their highly acidic nature. Signup and view all the answers

What is the primary role of hemidesmosomes in epithelial cells?

Serving as a more permanent anchor to the basement membrane Signup and view all the answers

Which of the following best describes the mechanism of focal adhesions?

They can sense and affect multiple cellular processes additively or synergistically. Signup and view all the answers

Bullous pemphigoid is primarily associated with which type of tissue interaction?

Auto-antibody attack on hemidesmosomal proteins Signup and view all the answers

What type of molecules are integrins primarily responsible for binding?

Proteins in the extracellular matrix (ECM) Signup and view all the answers

What is a major characteristic of the extracellular matrix (ECM)?

It provides structural and biochemical support to surrounding cells. Signup and view all the answers

Which of the following processes is NOT significantly influenced by focal adhesions?

Gene transcription regulation Signup and view all the answers

What types of interactions do cell adhesion molecules primarily facilitate?

Intercellular and ECM interactions Signup and view all the answers

In the context of hemidesmosomes, what role does laminin play?

It binds to integrins and anchors them to keratin filaments. Signup and view all the answers

Which condition is characterized by chronic autoimmune blistering due to hemidesmosomal protein attack?

Bullous pemphigoid Signup and view all the answers

What is the primary function of the tunica media in blood vessels?

Regulating the diameter and blood flow through smooth muscle contraction Signup and view all the answers

Study Notes

Cell-Cell/Cell-ECM Interactions

Apical Surface
- Tight Junctions: Seal gap between cells.
- Adherens Junctions: Connect Actin filaments between cells.
- Desmosome: Connect Intermediate filaments between cells.
- Gap Junction: Allows passage of small water-soluble molecules.
- Hemidesmosome: Anchors intermediate filaments to the ECM in epithelial cells.
- Focal Adhesions: Anchor many cell types to the ECM.

Extracellular Components

Glycocalyx: A cell coat of glycoproteins and glycolipids projecting outwards from the plasma membrane.
- Located at epithelial and endothelial cells.
- Mediates cell-cell and cell-substratum interactions.
- Provides mechanical protection (ECM) affecting ECM assembly, cell migration, and adhesion processes.
- Enables "outside-in signaling" where external environment signals affect differentiation, motility, growth, survival, cytoskeletal rearrangements, proliferation, gene expression, and cell polarity.

Cell-ECM Interactions

Focal Adhesions: Anchor a cell to a substratum.
- Large clusters of integrins commonly seen in vitro but also found in muscle and tendons.
- Disassembled for cell movement or replication.
- Act as sensory structures sensing both chemical and physical properties of the extracellular environment.
Hemidesmosomes: Specialized integrin adhesive structure in epithelial cells.
- More permanent anchor to the basement membrane.
- Laminin of the ECM binds to integrins, which are bound to dense collections of keratin intermediate filaments on a plaque of plectin inside the cell.
Hemidesmosomes - Disease: Bullous pemphigoid is a rare skin condition causing large blisters.
- Auto-antibodies attack a hemidesmosomal protein called bullous pemphigoid antigen 1.
Focal Adhesions vs Hemidesmosomes:
- Focal adhesions are temporary anchors that connect the cell to the ECM, allowing for cell migration and movement.
- Hemidesmosomes provide a strong, permanent anchor that connects epithelial cells to the basement membrane, providing structural support and stability.

Interaction of cells with extracellular materials

Integrins: Membrane-spanning polypeptide chains (α and β) that bind to ECM components such as fibronectin, laminin, proteoglycans, and collagen.
- Non-covalently linked with >100 different pairings possible.
- Integrate extracellular and intracellular environments.
- Can bind Arg-Gly-Asp (RGD) sequences.
Inside-out Signaling: Internal cell signals activate the integrins, influencing ECM binding and adhesion.

Extracellular Matrix

Proteoglycans: ECM protein-polysaccharide complexes containing a core protein with glycosaminoglycans (GAGs) covalently attached.
- GAGs are highly acidic due to sulfate and carboxyl groups, giving them a negative charge.
- Bind cations and H2O, forming a porous, hydrated gel.
- Provide strength and resistance to deformation in cartilage and other ECM.
Proteoglycan Complexes: Proteoglycans bind together, forming larger complexes linked by hyaluronic acid (a nonsulfated GAG).

Extracellular Matrix: Remodeling

Dynamic: ECM components are continuously degraded and reconstructed.
Renewal and Remodelling: Important for embryonic development, wound healing, and cancer metastasis.
Matrix metalloproteinases (MMPs): Zinc-containing enzymes that degrade the ECM.
- Secreted into the ECM or anchored to plasma membranes.
- Digest nearly all ECM components.
- Involved in tissue remodeling, cell migration/invasion, wound healing, and neovasculogenesis.

Primordial Germ Cells

Cell surface protein adheres strongly to a subunit of laminin, facilitating the migration of primordial germ cells along a tract of laminin.

Extracellular Matrix: Proteoglycans & Primordial Germ Cell Migration

Proteoglycans play a pivotal role in the migration of primordial germ cells.
They influence a cell's potential for migration, growth, and differentiation.

Studying That Suits You

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Description

Test your knowledge on the various cell-cell and extracellular matrix interactions. This quiz covers components such as tight junctions, adherens junctions, and the glycocalyx, detailing their roles and significance in cellular functions. Ideal for students studying cellular biology.