Connective Tissue Structures and Functions

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Questions and Answers

What is the principal collagen type found in hyaline cartilage?

Type IV collagen

Type I collagen

Type II collagen (correct)

Type III collagen

Which type of cartilage contains a dense network of coarse type collagen fibers?

Hyaline cartilage

Articular cartilage

Elastic cartilage

Fibrocartilage (correct)

Where is hyaline cartilage NOT found in adults?

Intraarticular cartilage (correct)

Ventral ends of ribs

Walls of large respiratory passages

Articular surfaces of movable joints

What characterizes the matrix of hyaline cartilage?

A firm, hydrated gel of proteoglycans Signup and view all the answers

What role does the perichondrium play for cartilage?

It provides nourishment through blood vessels. Signup and view all the answers

Which of the following best describes elastic cartilage?

Contains abundant elastic fibers Signup and view all the answers

In which location would you expect to find fibrocartilage?

Intervertebral discs Signup and view all the answers

What provides the primary mode of nutrient delivery to articular cartilage?

Diffusion from synovial fluid Signup and view all the answers

What is the function of proteoglycan aggregates in articular cartilage?

They bind a large amount of water and act like a biomechanical spring. Signup and view all the answers

Which type of cartilage is found at the articular surfaces of diarthroses?

Hyaline cartilage Signup and view all the answers

How do collagen fibers in articular cartilage arrange themselves?

They run perpendicular to the surface and then bend gradually. Signup and view all the answers

What role does water play in the cartilage matrix when pressure is applied?

Water is forced out of the cartilage matrix into synovial fluid. Signup and view all the answers

What type of cells are primarily involved in the maintenance of the cartilage matrix?

Chondrocytes Signup and view all the answers

Which component is NOT a principal macromolecule present in all types of cartilage matrix?

Keratin Signup and view all the answers

In which type of cartilage would you most likely find higher concentrations of GAGs and proteoglycans?

Hyaline cartilage Signup and view all the answers

What is the role of cartilage in relation to long bones?

Cartilage guides the development and growth of long bones. Signup and view all the answers

Which of the following locations is elastic cartilage found in?

Auricle of the ear Signup and view all the answers

What component forms the scaffold for elastic fibers in elastic cartilage?

Fibrillin microfibrils Signup and view all the answers

How does the composition of fibrocartilage differ from that of elastic cartilage?

Fibrocartilage includes type I collagen bundles Signup and view all the answers

What gives elastic cartilage its characteristic flexibility?

The elastic fibers present in the matrix Signup and view all the answers

Which of the following statements about fibrocartilage is true?

It can transition into dense connective tissue. Signup and view all the answers

What type of staining is used to identify elastic fibers in cartilage?

Weigert resorcin-fuchsin Signup and view all the answers

Which of the following is a characteristic of the matrix in fibrocartilage?

Contains type I collagen bundles Signup and view all the answers

Which structure surrounds the elastic cartilage similar to that of hyaline cartilage?

Perichondrium Signup and view all the answers

What is the main metabolic process through which hyaline cartilage cells metabolize glucose?

Anaerobic glycolysis Signup and view all the answers

Which hormone is identified as a major regulator of hyaline cartilage growth?

Growth hormone Signup and view all the answers

What layer surrounds most hyaline cartilage tissues, aiding in their growth and maintenance?

Perichondrium Signup and view all the answers

What is a characteristic feature of the chondrocytes in hyaline cartilage?

They exist in lacunae surrounded by the matrix. Signup and view all the answers

What type of fibers primarily compose the perichondrium?

Collagen type I fibers Signup and view all the answers

Which of the following statements about elastic cartilage is true?

It contains abundant elastic fibers in addition to collagen type II. Signup and view all the answers

What happens to chondrocytes as they differentiate from progenitor cells in the perichondrium?

They separate into individual lacunae as they secrete matrix. Signup and view all the answers

Which staining techniques are typically required to demonstrate the elastic fibers in elastic cartilage?

Orcein or resorcin fuchsin Signup and view all the answers

What type of cells are primarily found in the synovial layer mentioned in the content?

Macrophage-like and fibroblast-like cells Signup and view all the answers

What characteristic distinguishes blood capillaries in the synovial fluid from typical capillaries?

They are fenestrated. Signup and view all the answers

What shape is typically associated with fibroblasts based on their morphology?

Spindle-shaped Signup and view all the answers

How do type I collagen molecules self-assemble according to the content?

In a highly organized, lengthwise arrangement. Signup and view all the answers

Which feature is observed in the electron micrographs of collagen fibrils?

Characteristic cross striations with alternating dark and light bands. Signup and view all the answers

What primarily fills the extracellular matrix (ECM) in dense regular connective tissue?

Collagen bundles Signup and view all the answers

What visual characteristic is associated with fibrocytes in tendon tissue?

Sparse cytoplasm with numerous thin cytoplasmic processes. Signup and view all the answers

What happens after the assembly of type I collagen fibrils?

They connect to form larger collagen fibers. Signup and view all the answers

Study Notes

Synovial Membrane

Synovial membrane consists of fibroblast-like and macrophage-like cells
Synovial membrane does not have a basement membrane or junctional complexes, despite resembling epithelium
Synovial membrane blood capillaries are fenestrated, allowing exchange of materials between the blood and synovial fluid

Tendons and Ligaments

Dense regular connective tissue
Tendons contain long, parallel bundles of collagen fibers, separating elongated nuclei of fibrocytes
Thin cytoplasm of fibrocytes is divided into numerous processes extending between adjacent collagen fibers

Fibroblasts

Have large, active nuclei and eosinophilic cytoplasm
Cytoplasm tapers off in both directions along the axis of the nucleus
Nuclei are clearly visible, but the eosinophilic cytoplasmic processes resemble collagen bundles in H&E-stained sections

Assembly of Type I Collagen

Rod-like triple-helix collagen molecules (300 nm long) self-assemble in a highly organized lengthwise arrangement with overlapping regions
Collagen fibrils are assembled by the regular overlapping arrangement of subunits
Fibrils have characteristic cross striations (alternating dark and light bands) when observed in the EM
Fibrils assemble into larger collagen fibers visible by light microscopy
Fibers often form into even larger bundles and linked together by other collagens

Articular Cartilage

Collagen fibers run perpendicular to the tissue surface and then bend gradually to form a broad arch parallel to the surface
Proteoglycan aggregates bound to hyaluronic acid and collagen fill the space among collagen fibers, binding large amounts of water
Acts as a biomechanical spring in articular cartilage
When pressure is applied, water is forced out of the cartilage matrix into the synovial fluid
When pressure is released, water is attracted back into the interstices of the matrix, facilitating nutrient exchange and waste removal

Hyaline Cartilage

Found in articular surfaces of movable joints, walls of large respiratory passages (nose, larynx, trachea, bronchi), ribs and sternum, and epiphyseal plates of long bones
The dry weight of hyaline cartilage is 40% collagen embedded in a firm, hydrated gel of proteoglycans and structural glycoproteins
Most of the collagen is type II, though minor types are present
Aggrecan (250 kD) is the most abundant proteoglycan, with 150 GAG side chains of chondroitin sulfate and karatan sulfate
Cartilage cells and matrix often shrink during preparation, resulting in irregular shapes and retracted chondrocytes from the matrix.
Chondrocytes respire under low-oxygen tension
Glucose is metabolized by anaerobic glycolysis

Perichondrium

Dense connective tissue covering hyaline cartilage
Contains collagen type I and fibroblasts
Inner layer contains progenitor cells for chondroblasts, which divide to differentiate into chondrocytes

### Elastic Cartilage

Possesses a network of elastic fibers in addition to collagen type II, giving it a yellowish color in the fresh state
Found in the auricle of the ear, walls of external auditory canals, auditory tubes, epiglottis, and cuneiform cartilage.
Elastic fibers are usually demonstrated with orcein or resorcin fuchsin staining
Perichondrium is similar to that found in hyaline cartilage

Fibrocartilage

A combination of hyaline cartilage and dense connective tissue, with gradual transitions between the tissues
Found in intervertebral discs, attachments of certain ligaments, and the pubic symphysis
Chondrocytes produce a matrix containing type II collagen
Fibrocartilage often contains a sparse matrix around chondrocytes
Regions with chondrocytes and hyaline matrix are separated by type I collagen bundles and scattered fibroblasts
Proteoglycans are less abundant in the matrix, making it more acidophilic than hyaline or elastic cartilage.

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Description

This quiz covers key aspects of the synovial membrane, tendons, ligaments, and fibroblasts. Learn about their cellular composition, structural characteristics, and the unique properties of type I collagen assembly. Test your understanding of connective tissue in this focused assessment.