Anatomy LE 2: Cartilage and Bone

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Questions and Answers

What is the primary characteristic of cartilage?

It is a type of nervous tissue with high concentrations of elastic fibers

It is a type of epithelial tissue

It is a type of connective tissue with high concentrations of GAGs and proteoglycans (correct)

It is a type of muscle tissue with high concentrations of collagen

What is the main function of cartilage in the body?

To protect the body from external damage

To facilitate the movement of muscles

To provide a framework for soft tissues (correct)

To produce hormones and regulate body functions

What allows cartilage to bear mechanical stress?

The presence of blood vessels

The presence of GAGs and proteoglycans (correct)

The presence of lymphatic vessels

The presence of nerve endings

What is the function of fibrocartilage in the body?

To absorb shock and facilitate sliding regions within joints Signup and view all the answers

What is the characteristic of cartilage that allows for almost friction-free movements of the joints?

Its smooth surface Signup and view all the answers

How do cartilage cells receive nutrition?

Through diffusion from vascularized outer covering Signup and view all the answers

What is the function of cartilage in synovial joints?

To absorb shock and facilitate sliding regions within joints Signup and view all the answers

What is the role of cartilage in the respiratory tract?

To form the framework supporting soft tissues Signup and view all the answers

What is the characteristic that distinguishes fibrocartilage from other types of cartilage?

Abundant type I collagen Signup and view all the answers

What is the function of type I collagen fibers in fibrocartilage?

To bear mechanical stresses Signup and view all the answers

Why is the matrix of fibrocartilage more acidophilic?

Due to low proteoglycan content Signup and view all the answers

What is the origin of cartilage in chondrogenesis?

Mesenchyme Signup and view all the answers

What is the first step in chondrogenesis?

Rounding up of mesenchymal cells Signup and view all the answers

What is the result of mitosis in chondroblasts?

Differentiation into chondroblasts Signup and view all the answers

What is the location of chondrocytes in cartilage?

In the lacunae Signup and view all the answers

How do chondrocytes obtain nutrients?

Through diffusion from blood vessels or synovial fluids Signup and view all the answers

What is the purpose of perichondrium in cartilage?

Not present in fibrocartilage Signup and view all the answers

What is the periosteum composed of?

Double layer of CT Signup and view all the answers

What type of collagen is found in the outer fibrous layer of the periosteum?

Type I collagen Signup and view all the answers

Which cells are found in the osteogenic layer of the periosteum?

Osteoprogenitor cells Signup and view all the answers

What is the function of osteoblasts?

Secrete osteoid and form bone matrix Signup and view all the answers

What is the name of the protein synthesized by osteoblasts?

Osteocalcin Signup and view all the answers

What is the first visible step in calcification?

Mineralization of osteoid Signup and view all the answers

What is the shape of active osteoblasts?

Columnar Signup and view all the answers

What is the name of the fibers that bind periosteum to the bone?

Perforating fibers Signup and view all the answers

Where is the periosteum absent?

At articular surfaces Signup and view all the answers

What happens to the inorganic matrix during decalcification?

It is removed Signup and view all the answers

What is the function of osteocytes?

To deposit calcium and mineral salts Signup and view all the answers

During endochondral ossification, what happens to the hyaline cartilage model?

It undergoes degeneration Signup and view all the answers

What penetrates the primary ossification center?

Blood capillaries Signup and view all the answers

What is formed in the diaphysis during endochondral ossification?

Primary ossification center Signup and view all the answers

What is the function of osteoprogenitor cells?

To secrete osteoid Signup and view all the answers

What happens to the woven bone in the primary ossification center?

It is replaced by compact bone Signup and view all the answers

What forms in the epiphysis at the time of birth?

Secondary ossification center Signup and view all the answers

What is the result of bone collar formation?

Impeded diffusion of oxygen and nutrients Signup and view all the answers

What is the function of the epiphyseal plate?

Bone elongation Signup and view all the answers

What is the end result of the continuous deposition of bony matrix?

Formation of compact bone Signup and view all the answers

What is the typical order of the overlapping zones in the epiphyseal plate?

From diaphysis to epiphysis Signup and view all the answers

What is the role of blood vessels in the formation of trabecular bone?

They infiltrate the trabeculae and become red marrow Signup and view all the answers

What is the outcome when the ossification centers fuse?

The bone reaches its full stature Signup and view all the answers

What is the significance of the epiphyseal plate in childhood?

It promotes bone elongation Signup and view all the answers

What is the type of cartilage used as a template in endochondral ossification?

Hyaline cartilage Signup and view all the answers

What is the outcome of the fusion of ossification centers?

The formation of epiphyseal lines Signup and view all the answers

What type of bone is formed through the process of endochondral ossification?

Both long and short bones Signup and view all the answers

Study Notes

Periosteum

Double-layered connective tissue (CT) surrounding the outer bone surface
Vascularized structure, absent at articular surfaces
Outer fibrous layer consists of dense CT with type I collagen, small blood vessels, and fibroblasts
Inner osteogenic layer features osteoprogenitor cells, osteoblasts, osteoclasts, and inactive bone lining cells
Perforating/Sharpey fibers bind periosteum to bone, acting as a glue

Bone Cells

Osteoblasts
- Arise from mesenchymal stem cells, located at bone matrix surface
- Active osteoblasts are cuboidal or columnar with basophilic cytoplasm
- Secrete osteoid (organic bone matrix) located between osteoblast layer and pre-existing bone
- Synthesize osteocalcin and alkaline phosphatase, critical for hydroxyapatite crystal formation
Osteocytes
- Mature bone cells, originating from trapped osteoblasts in lacunae
- Involved in maintaining bone matrix and regulating mineral content

Cartilage

Tough, durable connective tissue characterized by cells embedded in an extracellular matrix (ECM) rich in glycosaminoglycans (GAGs) and proteoglycans
Avascular structures with no lymphatic vessels or nerves, obtaining nutrition through diffusion from the perichondrium

Functions of Cartilage

Supports mechanical stress and movement, found in intervertebral discs and synovial joints
Provides smooth articulating surfaces for nearly friction-free joint movements
Serves as a framework supporting soft tissues, such as in the ear and nose

Endochondral Ossification

Involves the conversion of hyaline cartilage into bone, crucial for long and short bone formation
Primary ossification centers develop in the diaphysis and are invaded by blood vessels carrying osteoprogenitor cells
Secondary ossification centers arise in the epiphysis at birth
Growth plate (epiphyseal plate) facilitates bone elongation and consists of five overlapping zones

Chondrogenesis

Process of cartilage formation from mesenchymal cells
Involves rounding up and condensation of mesenchymal cells, mitosis, and differentiation into chondroblasts
Chondroblasts secrete matrix, become trapped in lacunae, and differentiate into chondrocytes

Fibrocartilage

Hybrid tissue composed of hyaline cartilage and dense connective tissue
Contains type I collagen fibers, providing resistance to tensile forces
Lacks perichondrium, receiving nutrition via diffusion from local blood vessels or synovial fluid

Summary of Learning Objectives

Characterization of cartilage and bone histology, including parts and functionalities
Classification of cartilage types based on composition and histology
Explanation of bone formation, growth, repair processes, and regenerative capacities

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