Connective Tissue and Extracellular Matrix Quiz

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Questions and Answers

What is one primary function of connective tissue?

  • Synthesis of hormones
  • Storage of genetic material
  • Exchange of gases in the lungs
  • Transport of oxygen and nutrients (correct)

Which component contributes to the pressure forces within connective tissue?

  • Fibrinogen
  • Proteoglycans (correct)
  • Collagen
  • Laminin

Why is bone considered a type of connective tissue?

  • It contains a high amount of living cells
  • It acts primarily in movement
  • It is made predominantly of extracellular matrix (correct)
  • It can store energy as fat

Which of the following is NOT a type of cell connection found in connective tissue?

<p>Neuro junction (D)</p> Signup and view all the answers

How do fibroblasts interact with collagen fibers?

<p>They secrete collagen molecules (C)</p> Signup and view all the answers

What structural property of the cornea contributes to its strength?

<p>Perpendicular stacking of collagen fibers (C)</p> Signup and view all the answers

Which type of collagen is primarily found in bone?

<p>Type I collagen (B)</p> Signup and view all the answers

What characterizes James Morris's condition regarding collagen fibers?

<p>Absence of collagen fibers (C)</p> Signup and view all the answers

What role do integrins play in cellular function?

<p>They convert extracellular signals into cellular adaptations. (C)</p> Signup and view all the answers

Which statement accurately describes fibronectin?

<p>Fibronectin acts as an adapter protein linking integrins and collagen. (D)</p> Signup and view all the answers

How is integrin activity regulated?

<p>By a combination of kinases and phosphatases. (C)</p> Signup and view all the answers

What is the primary function of proteoglycans in connective tissue?

<p>To absorb and distribute pressure forces. (A)</p> Signup and view all the answers

What characterizes gap junctions between cells?

<p>They allow the exchange of small signaling molecules. (C)</p> Signup and view all the answers

What is the function of tight junctions in epithelial tissue?

<p>To form a barrier that prevents water and solutes from passing. (B)</p> Signup and view all the answers

Which type of cellular junction is primarily involved in resisting mechanical stress?

<p>Desmosomes (A)</p> Signup and view all the answers

What characteristic is unique to hemidesmosomes?

<p>They link intermediate filaments to the extracellular matrix. (A)</p> Signup and view all the answers

What role do glycosaminoglycans (GAGs) play in tissue structure?

<p>They contribute to the mechanical properties of tissues by forming gels. (C)</p> Signup and view all the answers

Which type of cell junction utilizes actin filaments for adhesion?

<p>Adherence junctions (C)</p> Signup and view all the answers

What is the primary composition of the basal lamina?

<p>Collagen IV and laminin. (C)</p> Signup and view all the answers

What effect does contraction of the adhesion belt have on epithelial tissue?

<p>It enables changes in the shape of the epithelium. (A)</p> Signup and view all the answers

What regulates the conductance of gap junctions?

<p>Intracellular signaling molecules like dopamine. (C)</p> Signup and view all the answers

What is the primary function of the extracellular matrix (ECM)?

<p>Provide structural and biochemical support to surrounding cells. (A)</p> Signup and view all the answers

Flashcards

What are integrins?

Integrins are transmembrane proteins that connect the cytoskeleton of a cell to the extracellular matrix (ECM). They act as a bridge, allowing the cell to sense and respond to its environment.

What is Fibronectin?

Fibronectin is a protein found in the ECM. It binds to integrins on the cell surface and to other ECM components, such as collagen and other fibronectin molecules. It plays a crucial role in cell adhesion, migration, and wound healing.

How do Integrins communicate?

Integrins are bidirectional, meaning they can transmit signals in both directions: from the outside (ECM) to the inside (cytoskeleton) and vice versa. This allows the cell to respond to changes in its environment and regulate its own behavior.

How is Integrin activity regulated?

Integrin activity can be regulated by intracellular signals. These signals can either activate or deactivate integrins, affecting the cell's ability to attach and detach from the ECM. This allows cells to adapt to their environment and respond to changes.

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What are the functions of collagen, proteoglycans, and basal lamina in the ECM?

Collagen fibers provide tensile strength, resisting pulling forces. Proteoglycans, containing glycosaminoglycans (GAGs), resist compression due to their water-absorbing properties. Basal lamina, primarily composed of collagen IV and laminin, acts as an adhesive layer between cells and the underlying connective tissue.

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What are tight junctions?

Tight junctions form a seal between cells, preventing the leakage of fluid and solutes between them. They act as a barrier, maintaining the integrity of epithelial tissues, like in the gut lining.

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What are adherence junctions?

Adherence junctions, also known as adhesion belts, are cell-to-cell connections that involve actin filaments. They provide structural support and regulate cell shape, contributing to epithelial tissue integrity.

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What are desmosomes?

Desmosomes are strong cell-to-cell connections involving intermediate filaments, providing mechanical strength and stability to tissues. They are commonly found in tissues subjected to mechanical stress, such as skin.

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What are hemidesmosomes?

Hemidesmosomes connect intermediate filaments of a cell to the ECM. They provide structural support and anchor cells to the underlying tissue, ensuring stability.

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What are gap junctions?

Gap junctions allow the exchange of small molecules (ions, second messengers) between adjacent cells. They act like channels, facilitating communication and enabling the coordinated activity of cells within a tissue.

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What are glycosaminoglycans (GAGs)?

Glycosaminoglycans (GAGs) are negatively charged polysaccharides that attract water molecules due to their charged nature. This creates a gel-like matrix that can resist compression, serving as a shock absorber and providing structural support in tissues like cartilage.

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What are proteoglycans?

Proteoglycans are large complexes composed of proteins and GAGs. They play a crucial role in the ECM, providing structural support and hydration, as well as participating in cell signaling.

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What is basal lamina?

Basal lamina is a specialized ECM layer found beneath epithelial tissues. It acts as an adhesive layer, anchoring epithelial cells to the underlying connective tissue and providing structural support to the epithelium.

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What is epithelial cell polarity?

Epithelial cells exhibit polarity, meaning they have distinct apical and basal surfaces. This allows for specialized functions, such as selective transport and barrier formation.

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What are the different types of cell-cell junctions?

Different cell-cell junctions, such as tight junctions, adherence junctions, desmosomes, hemidesmosomes, and gap junctions, contribute to the organization and function of epithelial tissues. They provide stability, adhesion, and communication between cells.

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What is connective tissue?

Connective tissue is a type of tissue that supports and connects other tissues in the body, providing structural integrity and facilitating the transport of nutrients and oxygen.

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What is collagen?

Collagen is a fibrous protein that provides tensile strength and resistance to pulling forces in the extracellular matrix of connective tissues.

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What is the basal lamina?

The basal lamina is a specialized extracellular matrix that acts as a foundation for epithelial tissues and provides adhesion and support.

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What is bone?

Bone is a type of connective tissue characterized by its rigid and strong structure, which is provided by a matrix of collagen and calcium phosphate.

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What are fibroblasts?

Fibroblasts are cells that produce and secrete collagen fibers, which are essential for the structural integrity of connective tissues.

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What are focal adhesions?

Focal adhesions are specialized structures that link the cytoskeleton of cells to the extracellular matrix, providing a point of contact and communication.

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How is the strength of the cornea achieved?

The perpendicular stacking of collagen fibers in the cornea of the eye provides exceptional strength and resistance to force.

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Study Notes

Extracellular Matrix and Connective Tissue

  • Multicellular organisms have various cell types and fluid spaces in between
  • Connective tissue offers protection from stress and aids transport of oxygen and nutrients
  • Examples include the layers of the gut and other tissues

Connective Tissue and Extracellular Matrix

  • Collagen: Provides pulling forces
  • Proteoglycans: Contribute to pressure forces and adhesion (along with laminin and collagen).
  • Basal lamina: A region where collagen and laminin promote adhesion.

Cell Connections (extracellular matrix - cytoskeleton)

  • Tight junction: Seals neighboring cells to prevent molecule leakage
  • Adherence junction: Links actin bundles between cells
  • Desmosome: Links intermediate filaments between cells
  • Hemidesmosome: Connects intermediate filaments to the basal lamina
  • Gap junction: Forms channels for small molecule transport between cells

Collagen Genes

  • Collagen types vary in function and location throughout the body
  • Different types are made from different genes and used in diverse areas of the body
  • Mutations in collagen genes can result in various disorders

Bone as Connective Tissue

  • Bone is a type of connective tissue
  • It possesses a strong structure due, in part, to calcium phosphate deposits
  • Collagen is a major component of bone's extracellular matrix

Collagen Structure

  • Collagen is composed of a single polypeptide chain forming a triple-stranded molecule
  • These molecules form fibrils and then fibers
  • Fibroblasts secrete collagen molecules

Fibroblasts and Collagen

  • Fibroblasts secrete collagen molecules
  • Fibroblasts play a crucial role in organizing collagen fibers

Fibroblast and Matrix Contacts/Interactions

  • Fibroblasts attach to the matrix via focal contacts via integrin proteins
  • Actin cortex and lamelipodium play roles in these adhesions; integrins connect to the matrix and to the cytoskeleton.
  • These adhesions can be formed or broken

Integrins

  • Integrins are crucial to connecting the cytoskeleton to the extracellular matrix
  • They connect with adapter proteins to extracellular components.

Fibronectin

  • Fibronectin links between extracellular and intracellular components.
  • It has collagen and cell adhesion binding sites

Two-way Communication Via Integrins

  • Integrin activity can be regulated by intracellular signals
  • Outside-in and Inside-out pathways
  • This regulation enables cells to attach or detach from the extracellular matrix.

Regulating Integrin Activity

  • Activity regulation of integrins can control cellular behavior
  • Phosphorylation, protein modification involved

Glycosaminoglycans (GAGs)

  • GAGs are negatively charged polysaccharides in tissues like cartilage
  • Hyaluronic acid is a GAG, present in large amounts in cartilage

Proteoglycans

  • Proteoglycans are large complexes formed from proteins and GAGs
  • Aggregation occurs between core proteins, link proteins, and GAGs like chondroitin sulfate and keratin sulfate
  • These structures provide resistance to compression and pressure

Protection Against Pressure

  • GAGs and proteoglycans help protect against focal pressure, such as in the eye.
  • The ability of tissues to resist forces

Epithelium and Basal Lamina

  • Epithelial cells rest on a basal lamina
  • The basal lamina is comprised of collagen IV and laminins
  • Laminins are also linked to integrins on the cell surface

Polarized Orientation of Cells

  • Epithelial cells have apical and basal surfaces
  • These surfaces exhibit different properties

Polarized Cells in Gut Epithelium

  • Intestinal cells have specialized functions based on their position
  • Apical cells are involved in mucus secretion
  • Basal sides are involved in nutrient absorption

Cell-to-cell Contacts in Epithelial Sheets

  • Tight junctions, adherens junctions, desmosomes, and gap junctions connect neighboring cells
  • The proteins that mediate these connections can be regulated

Tight Junctions

  • Tight junctions are important for preventing leakage of molecules between cells.
  • They use occludin and claudin proteins

Adherens Junctions

  • Adherens junctions form a belt-like structure holding cells together.
  • Cadherins bind actin filaments within cells
  • These junctions also play an important role in cell movement/shape changes.

Desmosomes

  • Desmosomes join intermediate filaments to connect cells
  • The cadherin family of proteins are involved in these interactions.

Gap Junctions

  • Gap junctions permit small molecule transport between cells
  • They consist of connexon proteins, which form channels
  • This process can be actively controlled by the cell

Hemidesmosomes

  • Hemidesmosomal structures connect intermediate filaments to the basal lamina
  • They resemble focal contacts, which help migrating cells to stick to a surface.

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Related Documents

ECB Chapter 20: Extracellular Matrix and Connective Tissue PDF

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