Ch 6 Cartilage & Bone 🦴

Cartilage

Semirigid connective tissue that is weaker than bone, but flexible and resilient.

What are the function of cartilage?

• Supporting tissues

• Providing a gliding surface at articulations (joints), where two bones meet.

• Providing a model for the formation of most of the bones in the body.

What are the three types of cartilage?

• Hyaline cartilage

• Elastic cartilage

• Fibrocartilage

Hyaline Cartilage

Fibrocartilage

Elastic Cartilage

Distribution of cartilage

Interstitial growth

Occurs within the internal regions of cartilage through a series of four steps

1. Chondrocytes housed within lacunae are stimulated to undergo mitotic cell division.

2. Following cell division, two cells occupy a single lacuna; they are now called chondroblast.

3. As chondroblasts begin to synthesize and secrete new cartilage matrix, they are pushed apart. These cells now reside in their own lacuna and are called chondrocytes.

4. The cartilage continues to grow in the internal region as chondrocytes continue to produce more matrix.

Appositional growth

An expansion along the outside edge, or periphery of the cartilage, usually under the perichondrium.

1. Undifferentiated stems cells deep to the perichondrium begin to divide. (Notes: The perichondrium contains mesenchymal calls as well as these stem cells.)

2. The dividing cells results in new undifferentiated stem cells and cells that differentiate into chondroblasts. These chondroblasts are located at the periphery of the old cartilage, where they begin to produce and secrete new cartilage matrix.

3. As a result of matrix formation, the chondroblast push apart and become chondrocytes, with each occupying its own lacuna. The cartilage continues to grow at the periphery as chondrocytes continue to produce more matrix.

What are the functions of bone and bone connective tissue?

• Support and protection

• Movement

• Hematopoiesis: The process production of formed elements in the blood.

• Storage of mineral and energy reserves

Classification of bone by shape

Long bones

• Greater length than width

• Most common shape

• Have elongated, cylindrical shaft (diaphysis)

• Upper limb: Arm, forearm, palm, and fingers

• Lower Limb: Thigh, leg, sole of the foot, and toes.

Short bones

• Length nearly equal to their width

• External surfaces are covered by compact bone

• Interior is composed of spongy bone

• Carpals and tarsals

• Sesamoid bones

• Patella

Flat bones

• Flat and thin surface

• Composed of roughly parallel surfaces of compact bone with a layer of internally placed spongy bone

• Provide extensive surfaces for muscle attachment

• Protect underlying soft tissue

• Roof of the skull

• Scapulae

• Sternum

• Ribs

Irregular bones

• Elaborate, complex shapes

• Do not fit into any of the preceding categories

• Compact bone covering internal spongy bone

• Vertebrae, hip bones, ethmoid, sphenoid bones.

Skeletal system