Connective Tissue: Cartilage and Bone

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Questions and Answers

What is the primary role of chondrocytes in cartilage?

To form new cartilage tissues from stem cells

To provide rigid support

To maintain and secrete extracellular matrix (ECM) (correct)

To facilitate movement between joints

What characterizes hyaline cartilage among the types of cartilage mentioned?

It provides the greatest flexibility.

It can endure high tensile stress.

It is the most common type of cartilage. (correct)

It is composed mainly of collagen fibers.

Which type of cartilage is specifically known for its strength under stress?

Articular cartilage

Fibrocartilage (correct)

Elastic cartilage

Hyaline cartilage

What happens to chondrocytes as they secrete extracellular matrix (ECM)?

They are pushed away from each other. Signup and view all the answers

Which statement accurately reflects the relationship between chondroblasts and chondrocytes?

Chondroblasts develop into chondrocytes after rapid growth. Signup and view all the answers

What is the primary function of cartilage in the body?

Facilitates gliding movements at joints Signup and view all the answers

Which type of bone cell is primarily responsible for bone resorption?

Osteoclasts Signup and view all the answers

What is the epiphyseal plate's role in long bone development?

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

What is one of the key components that make up cartilage?

Extracellular matrix Signup and view all the answers

What process do osteoblasts primarily engage in at the ossification zone of the epiphyseal plate?

Secretion of osteoid Signup and view all the answers

What happens to the cavity formed during ossification in the epiphyseal plate?

It is filled by lamellae leaving a narrow central canal Signup and view all the answers

Which of the following best describes the condition of osteoporosis?

Bone resorption exceeding bone formation Signup and view all the answers

What is a potential consequence of decreased mechanical stimulation of osteocytes?

Decreased bone density Signup and view all the answers

Where do osteoprogenitor stem cells primarily reside?

In the periosteum, endosteum, and marrow Signup and view all the answers

What characterizes the normal bone structure as compared to osteoporotic bone?

Higher mineral content Signup and view all the answers

What happens to the interstitial lamellae during bone remodeling?

They are formed from partially resorbed osteons Signup and view all the answers

What aspect of osteoporotic bone contributes to its brittleness?

Reduced mineral content Signup and view all the answers

What type of ossification involves the direct differentiation of osteoblasts from mesenchyme?

Intramembranous ossification Signup and view all the answers

Which of the following bones undergoes intramembranous ossification?

Clavicle Signup and view all the answers

Which structure is formed as a result of continuous deposition of bony matrix?

Trabecular bone Signup and view all the answers

In endochondral ossification, what serves as the template for bone formation?

Hyaline cartilage Signup and view all the answers

What replaces woven bone during the bone formation process?

Compact bone Signup and view all the answers

Which bones are primarily formed through endochondral ossification?

Bones of the limbs Signup and view all the answers

What structural component forms when blood vessels invade the trabeculae?

Red marrow Signup and view all the answers

What is the first type of bone formed during ossification?

Woven bone Signup and view all the answers

What is the first step in the process of bone repair following a fracture?

Presence of fracture hematoma Signup and view all the answers

What type of collagen fibers are primarily released from the breakdown of nasal cartilage during bone repair?

Type I Signup and view all the answers

What replaces the soft procallus during the bone healing process?

A hard callus Signup and view all the answers

Which component of bone impedes the distribution of nutrients and oxygen to osteocytes?

ECM Signup and view all the answers

How long does it typically take for bone to heal completely after a fracture?

6 to 8 weeks Signup and view all the answers

Which statement most accurately describes compact bone?

Characterized by the presence of osteons Signup and view all the answers

What is the role of osteoblasts in the bone healing process?

To transform hard callus into primary bone Signup and view all the answers

Which of the following describes the endosteum?

Covers the medullary cavity Signup and view all the answers

What transformation occurs to chondroblasts as they become trapped within lacunae?

They transform into chondrocytes. Signup and view all the answers

What type of growth is characterized by the mitotic division of existing chondrocytes?

Interstitial growth Signup and view all the answers

Which of the following components is part of the inorganic portion of the bone matrix?

Calcium hydroxyapatite Signup and view all the answers

What is the main function of proteoglycans in the organic portion of the matrix?

Bind collagen and calcium Signup and view all the answers

Which of the following ions is NOT commonly found in the inorganic portion of the bone matrix?

Chloride Signup and view all the answers

What role do osteoclasts primarily serve in bone tissue?

Bone resorption Signup and view all the answers

Which growth pattern is more significant during postnatal development?

Appositional growth Signup and view all the answers

What substance primarily contributes to the pink staining of the organic matrix when using eosin?

Collagen fibers Signup and view all the answers

What type of cartilage is primarily composed of Type II collagen?

Elastic cartilage Signup and view all the answers

What structure within bone allows for communication between osteocytes?

Canaliculi Signup and view all the answers

How does the permeability of the ECM differ between bone and cartilage?

Bone ECM is less permeable than cartilage ECM Signup and view all the answers

In which part of the bone does secondary ossification occur around the time of birth?

Epiphyses Signup and view all the answers

What produces the synovial fluid within joints?

Specialized cells in the synovial membrane Signup and view all the answers

What is the initial step in the process of chondrogenesis?

Rounding up of mesenchymal cells Signup and view all the answers

What is the role of the perichondrium in cartilage formation?

It decreases the capacity for cartilage repair. Signup and view all the answers

During chondrogenesis, what differentiation occurs after mesenchymal cells undergo mitosis?

Development of chondrocytes Signup and view all the answers

Which condition is characterized by the deterioration of cartilage in joints?

Osteoarthritis Signup and view all the answers

What is a common consequence of damaged cartilage in osteoarthritis?

Bone-on-bone contact during movement Signup and view all the answers

In chondrogenesis, what is the primary function of chondroblasts after their formation?

To secrete extracellular matrix Signup and view all the answers

Which population is commonly affected by osteoarthritis?

Older adults and occasionally younger individuals Signup and view all the answers

What results from the separation of chondrocytes during chondrogenesis?

They start secreting their own matrix. Signup and view all the answers

What primarily characterizes the interterritorial matrix in cartilage?

Higher glycosaminoglycan content Signup and view all the answers

Which cells are primarily responsible for synthesizing the extracellular matrix in cartilage?

Chondroblasts Signup and view all the answers

What is a distinct characteristic of cartilage compared to other connective tissues?

Avascularity Signup and view all the answers

What feature is associated with chondroblasts during cartilage formation?

They undergo mitosis. Signup and view all the answers

Which type of cartilage is known for its durability and high proteoglycan content?

Hyaline cartilage Signup and view all the answers

What is the primary location of chondroblasts within the cartilage structure?

In the periphery of the inner chondrogenic layer Signup and view all the answers

Which of the following statements is true about glycosaminoglycans (GAGs) in cartilage?

GAGs are found in high concentrations in the extracellular matrix. Signup and view all the answers

What differentiates the interterritorial matrix from the territorial matrix?

Lighter staining due to lower proteoglycan content Signup and view all the answers

What is housed within a lacuna in bone tissue?

Osteocytes Signup and view all the answers

Which lamellae are found immediately beneath the periosteum?

External circumferential lamellae Signup and view all the answers

What describes interstitial lamellae in bone tissue?

They are remnants of partially destroyed osteons. Signup and view all the answers

What characteristic is specific to ground bone preparations?

It shows well-defined lacunae and canaliculi. Signup and view all the answers

What happens to the inorganic matrix during decalcification?

It is removed to visualize organic matrix cells. Signup and view all the answers

What component of osteons is primarily responsible for nutrient and waste exchange?

Canaliculi Signup and view all the answers

What is the primary function of the central canal within an osteon?

To contain blood vessels and nerves Signup and view all the answers

How are the internal circumferential lamellae positioned relative to the bone marrow cavity?

They circle around the marrow cavity. Signup and view all the answers

What primarily forms the framework supporting soft tissues in the body?

Cartilage Signup and view all the answers

Which component is predominantly found in cartilage and contributes to its properties?

Extracellular matrix (ECM) Signup and view all the answers

What condition is characterized by decreased bone density and increased risk of fractures?

Osteoporosis Signup and view all the answers

Which growth process is essential for the lengthening of long bones during development?

Endochondral ossification Signup and view all the answers

Which layer of connective tissue surrounds cartilage and plays a role in its development?

Perichondrium Signup and view all the answers

What occurs during the ossification zone of the epiphyseal plate?

Bone tissue is deposited on calcified cartilage Signup and view all the answers

What is the result of applying constant traction to the bone using braces?

Bone remodeling occurs Signup and view all the answers

What happens to the alveolar bone when pressure changes after brace removal?

New bone is formed on one side and resorption occurs on the other Signup and view all the answers

Which type of cell is primarily involved in resorption during the bone remodeling process?

Osteoclasts Signup and view all the answers

What is formed as a result of osteoclast attachment at the site of resorption?

Resorption bay Signup and view all the answers

How does the process of bone remodeling generally support health?

It adapts to mechanical stress through deposition and resorption Signup and view all the answers

What is the first step in the process of bone repair following a fracture?

Presence of fracture hematoma Signup and view all the answers

What replaces the soft procallus during the bone healing process?

Woven bone Signup and view all the answers

What is directly responsible for the movement of teeth when braces are applied?

Alteration of the alveolar bone through remodeling Signup and view all the answers

During which stage of the remodeling process do osteoclasts form cavities in the bone?

Resorption stage Signup and view all the answers

Which component of bone impedes the distribution of nutrients and oxygen to osteocytes?

ECM Signup and view all the answers

How long does it typically take for bone to heal completely after a fracture?

6 to 8 weeks Signup and view all the answers

Which statement most accurately describes compact bone?

It is characterized by the presence of osteons. Signup and view all the answers

What structure is formed as a result of continuous deposition of bony matrix?

Haversian system Signup and view all the answers

What process transforms the procallus into a hard callus in bone healing?

Osteoblast activity Signup and view all the answers

Which of the following accurately describes the role of macrophages in bone repair?

They remove the hematoma. Signup and view all the answers

What is the most widely distributed type of cartilage in the body?

Hyaline cartilage Signup and view all the answers

Which feature differentiates articular cartilage from most other hyaline cartilage?

It is not covered by perichondrium. Signup and view all the answers

What is the first step that occurs in the process of chondrogenesis?

Formation of mesenchymal condensations Signup and view all the answers

What type of cartilage is characterized by its ability to resist compression due to its high water content?

Hyaline cartilage Signup and view all the answers

In articular cartilage, what is the primary component that contributes to its semi-rigid consistency?

Water bound to hyaluronan Signup and view all the answers

Which of the following best describes the structure of articular cartilage?

A dense meshwork of type II collagen fibers Signup and view all the answers

Which of the following conditions results in nasal cartilage perforation and collapse?

Saddle nose deformity from cocaine use Signup and view all the answers

What type of growth primarily occurs in cartilage during development?

Interstitial and appositional growth Signup and view all the answers

What type of growth is primarily characterized by the differentiation of new chondroblasts from progenitor cells?

Appositional growth Signup and view all the answers

What makes up approximately 50% of the dry weight of bone matrix?

Calcium hydroxyapatite Signup and view all the answers

Which component serves an important role in binding collagen and calcium in the bone matrix?

Osteonectin Signup and view all the answers

Which of the following is primarily seen in articular cartilage and involved in the growth of the epiphyseal plates?

Interstitial growth Signup and view all the answers

Chondroblasts become trapped within lacunae and differentiate into which type of cell?

Chondrocytes Signup and view all the answers

Which organic components are important for the structure of the bone matrix?

Type I collagen fibers and proteoglycans Signup and view all the answers

Which ions are commonly found in the inorganic portion of the bone matrix?

Calcium and citrate Signup and view all the answers

What is the principal role of osteoclasts in the bone tissue?

Resorbing bone tissue Signup and view all the answers

Study Notes

Cartilage

A type of connective tissue
Composed of cells and an extracellular matrix (ECM)
Three main types of cartilage: hyaline, elastic, and fibrocartilage
Hyaline cartilage is the most common type and provides non-rigid support
Elastic cartilage provides support with high flexibility
Fibrocartilage provides strength under stress
Cartilage is responsible for providing the framework supporting soft tissues
It guides development and growth of long bones
Found in the ear, nose, and walls of the respiratory tract
Chondrocytes are round, mature cells surrounded by ECM, and lie within lacunae
Chondrocytes may occur singly or in clusters, known as isogenous groups or aggregates
Cells in an isogenous group are daughter cells from a mitotic event
As chondrocytes continue secreting ECM, they get pushed away from one another
The primary role of chondrocytes: to maintain ECM (also secretes)

Bone

A type of connective tissue that provides support, protection, and movement to the body
Contains organic and inorganic components
Composed of different types of cells including osteoblasts, osteocytes, and osteoclasts
Bone surfaces are covered by periosteum and endosteum
Periosteum: fibrous outer layer of bone
Endosteum: thin membrane that lines the medullary cavity
Osteoblasts are responsible for bone formation and are located on the bone surface
Osteocytes are mature bone cells that are located within the bone matrix
Osteoclasts are responsible for bone resorption and degradation
Bone classification: long, short, flat, irregular, and sesamoid
Bone growth, remodeling, and repair are continuous processes involved in maintaining bone structure

Bone Growth, Remodeling, and Repair

There are two main types of ossification: intramembranous and endochondral ossification
Intramembranous ossification involves the direct differentiation of mesenchymal cells into osteoblasts
Examples of bones formed by intramembranous ossification: flat bones of the skull, Fontanelles, mandible and maxilla, and clavicle
Endochondral ossification involves the use of pre-existing hyaline cartilage as a template for bone formation
Examples of bones formed by endochondral ossification: bones of the limbs
The epiphyseal plate is responsible for longitudinal bone growth
Osteoporosis: a common condition in the elderly resulting in poor bone turnover where bone resorption exceeds formation
Bone repair involves the formation of a fracture hematoma, procallus, hard callus, and woven bone, followed by the formation of compact bone.
Bone healing takes approximately 6-8 weeks to complete

Clinical Applications

Osteoporosis: A condition characterized by decreased bone density and increased bone fragility. It often occurs in the elderly and can lead to fractures.
Cartilaginous Repair: Cartilage has a limited ability to heal due to its avascular nature. Injuries to cartilage can lead to osteoarthritis.
Growth Plate Injury: Injuries to the epiphyseal plate can affect bone growth, especially in children and adolescents.

Cartilage

Tough, durable form of supporting connective tissue
Characterized by cells embedded in an extracellular matrix (ECM) with high concentrations of Glycosaminoglycans (GAGs) and proteoglycans
Interacts with collagen and elastic fibers
Avascular, meaning it does not have blood vessels
Interterritorial Matrix: Lighter staining due to lower proteoglycan content
Territorial Matrix: Stains more intensely with hematoxylin due to higher proteoglycan content
Perichondrium: Outer layer of dense connective tissue that surrounds most cartilage, important for growth and repair

Cells

Chondroblasts: Immature cartilage forming cells, found in the inner chondrogenic layer, responsible for secreting ECM
Chondrocytes: Mature cartilage cells, reside in lacunae within the ECM, maintain the cartilage matrix
Mesenchymal Stem Cells: Found within the inner chondrogenic layer, can differentiate into chondroblasts and contribute to cartilage formation

Chondrogenesis

Process of cartilage formation from mesenchyme
Chondrogenesis involves:
Rounding Up of Mesenchymal Cells: Mesenchymal cells aggregate and condense
Mitosis and Differentiation: Mesenchymal cells divide and differentiate into chondroblasts
Matrix Secretion: Chondroblasts secrete matrix components
Lacunae Formation: Chondroblasts become trapped within lacunae

Cartilage Growth

Interstitial Growth: Occurs within the cartilage itself, chondrocytes divide and secrete new matrix, seen in articular cartilage and epiphyseal plates
Appositional Growth: Occurs at the surface of the cartilage, new chondroblasts differentiate from perichondrium, contributes to growth in thickness

Types of Cartilage

Hyaline Cartilage:
- Most common type
- Found in articular surfaces, nose, trachea, larynx, ribcage
- Matrix is rich in type II collagen fibers, clear and glassy appearance
Elastic Cartilage:
- Found in the ear, epiglottis
- Matrix contains elastic fibers, gives it flexibility
Fibrocartilage:
- Found in intervertebral discs, pubic symphysis
- Matrix is dense and contains thick collagen fibers, provides strength and support

Clinical Correlations

Arthritis: Degenerative disease characterized by joint pain, stiffness, and swelling
- Osteoarthritis: Wear and tear arthritis, damage to articular cartilage
- Rheumatoid Arthritis: Autoimmune disease, inflammation and destruction of joint tissues

Bone

Specialized connective tissue characterized by its rigidity and hardness
Matrix:
- Organic Portion: Type I collagen, proteoglycans, glycoproteins
- Inorganic Portion: Calcium hydroxyapatite, calcium phosphate, other ions
Cells:
- Osteoblasts: Responsible for bone formation
- Osteocytes: Mature bone cells, maintain bone matrix
- Osteoclasts: Responsible for bone resorption

Bone Histology

Osteons: Basic structural unit of compact bone, composed of concentric lamellae surrounding a central canal
Lamellae: Thin layers of bone tissue, contain collagen fibers arranged in a specific pattern
Canaliculi: Narrow channels that connect lacunae, allowing for nutrient and waste exchange
Lacunae: Spaces within the bone matrix where osteocytes reside
Periosteum: Outer fibrous layer surrounding bone, important for growth and repair
Endosteum: Inner lining of the marrow cavity, contains osteogenic cells

Histologic Preparations

Ground Bone: Unpreserved bone, ground thin for light microscopy, shows lamellar structure, lacunae, and canaliculi
Decalcified Bone: Bone treated to remove inorganic portion, allows for visualization of cells, collagen fibers, and organic matrix

Bone: Definition and Components

Bone is a connective tissue with rigidity and hardness.
Composed of matrix (inorganic and organic) and cells (osteoblasts, osteocytes, and osteoclasts).
The organic portion of bone is rich in Type I collagen fibers, staining pink with eosin, and has minimal ground substance.
The inorganic portion contains calcium hydroxyapatite (most abundant), calcium phosphate (significant amount), and other ions like HCO3-, Citrate, Mg 2+, K+, Na+.

Cartilage: Definition and Components

A connective tissue with cells and an extracellular matrix (ECM).
ECM is composed of specialized cells called chondrocytes located in cavities called lacunae.
Chondroblasts are trapped within lacunae and differentiate into chondrocytes.
Chondrocytes continuously multiply and secrete matrix, leading to new cartilage formation.

Cartilage Growth

Interstitial growth: Occurs within pre-existing cartilage.
Appositional growth: Occurs on the surface of pre-existing cartilage.

Bone Functions

Provides structural support to the body.
Protection of vital organs.
Storage of calcium and phosphate minerals.
Production of blood cells in the bone marrow.
Facilitates movement through joints.

Bone Growth, Remodeling, and Repair

Bone Growth: The growth plate (epiphyseal plate) is responsible for longitudinal bone growth.
Bone Remodeling: Occurs throughout life, balancing bone formation (by osteoblasts) and bone resorption (by osteoclasts). This process is influenced by mechanical stress, ensuring the skeleton adapts to changing demands.
Bone Repair: The process of healing broken bones, involving stages like hematoma formation, procallus formation, callus formation, and bone remodeling.

Clinical Applications

Osteoporosis: A disease characterized by reduced bone density, leading to increased fracture risk.

Epiphyseal Plate

Plays a vital role in longitudinal bone growth.
Consists of hyaline cartilage with distinct zones: resting, proliferating, hypertrophic, and calcified cartilage zone.
Cartilage is progressively replaced by bone, leading to bone elongation.
The growth plate is responsible for the length of long bones, ceasing growth at maturity.

Review Questions

What are the major components of bone and cartilage?
What are the different types of cartilage and where are they found?
How do bones grow and remodel?
What are the stages of bone repair?
What is osteoporosis and how does it affect the body?

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Description

Explore the essential characteristics of cartilage and bone, two vital types of connective tissue. This quiz covers various cartilage types, including hyaline, elastic, and fibrocartilage, and their functions in the body. Test your knowledge on the structure, role, and significance of these tissues in providing support and protection.