Cartilage and Bone Ch. 6

chondrocytes

cells encased in matrix produced and previously known by chondroblasts occupy small spaces called lacunae maintain the matrix and ensure that it remains healthy and viable avascular

chondroblasts

cells that produce the matrix of cartilage become chondrocytes once they have become encased in the matrix they have produced and secreted

cartilage

semirigid connective tissue that is weaker than bone, but more flexible and resilient cells scattered throughout a matrix of fibers, embedded within a gel-like substance

Diaphysis:

shaft of a long bone; elongated, usually cylindrical

What is the interstitial growth pattern?

1. Chondrocytes housed in lacunae undergo mitotic cell division. 2. Following cell division, the two new cells occupy a single lacuna 3. As the cells begin to synthesize and secrete new cartilage matrix, they are pushed apart and now reside in their own lacunae. 4. The new individual cells within their own lacunae are called chondrocytes. New matrix has been produced internally, and thus interstitial growth has occured.

What is the appositional growth pattern?

1. Stem cells at the perichondrium divide, forming new stem cells and committed cells. 2. The stem cells differentiate into chondroblasts. 3. These chondroblasts, located at the periphery of the old cartilage, begin to produce and secrete new cartilage matrix. As a result, they push apart and become chondrocytes, each occupying its own lacuna. 4. The new matrix has been produced peripherally, and thus appositional growth has occured.

What are the 3 main functions of cartilage?

1. Supporting soft tissue-C-shaped hyaline cartilage rings in trachea 2. Providing a gliding surface at articulations 3. Provide a model for most of the bone formation in the body

What is yellow bone marrow?

As children grow into adults much of the red bone marrow degenerates and turns into a fatty tissue called yellow bone marrow. Adults only have red bone marrow in selected portions of axial skeleton, such as the flat bones of the skull, the vertebrae, the ribs, the sternum (breast bone), and the ossa coxae (hip bones).

hydroxyapatite:

Calcium phosphate and calcium hydroxide interact to form crystals of hydroxyapatite. Ca10(PO4)6(OH)2 These crystals deposit around the collagen fibers in the extracellular matrix.

Long bones:

Greater length than width, elongated cylindrical shaft (diaphysis). Most common bone shape.

Epiphysis:

Expanded, knobby region at each of end of the long bone; strengthens the joint

Osteoblasts:

Formed from osteoprogenitor stem cells; often cuboidal structure; secrete the initial semisolid, organic form of bone matrix called osteoid

Short bones:

Have a length nearly equal to their width. External surfaces covered by compact bone, interior surface is composed of spongy bone.

Epiphyseal line:

In adults, the remnant of the epiphyseal plate, a thin layer of compact bone

What is the two growth patterns of cartilage?

Interstitial and appositional growth

Osteoclasts:

Large, multinuclear, phagocytic cells

Osteocytes:

Mature bone cells derived from osteoblasts that have become entrapped in the matrix they secreted. Reside in lacunae.

Perforating fibers

Numerous strong fibers that anchor the periosteum to the bone, which run perpendicular to the diaphysis

Bone resorption:

Osteoclasts secrete hydrochloric acid, which dissolves the mineral parts (calcium and phosphate) of the bone matrix, while lysosomes within the osteoclasts secrete enzymes that dissolve the organic part of the matrix

What are the cells of the bone?

Osteoprogenitor, osteoblasts, osteocytes, osteoclasts

What is bone connective tissue?

Primary component of the bones of the skeletal system. Also known as osseous connective tissue. Matrix is sturdy and rigid due to deposition of minerals in the matrix, a process called calcification or mineralization.

What is hemopoiesis?

Process of blood cell production. Blood cells are produced in a connective tissue called red bone marrow, which is located in some spongy bone. Contains stem cells that form all of the formed elements of the blood.

Metaphysis:

Region in a mature bone sandwiched between the diaphysis and the epiphysis

What are the functions of bone?

Support and protect Movement Hemopoiesis Storage of mineral and energy preserves

Periosteum

a tough sheath; covers the outer surface of the bone, except for the areas covered by articular cartilage

Resorption lacuna:

depression or pit on the bone surface

Irregular bone:

elaborate, complex shapes

Flat bones:

flat thin surfaces; roughly parallel surfaces of compact bone with a layer of internally placed spongy bone

Medullary cavity

hollow, cylindrical space within the diaphysis (marrow cavity)

What are the three different types of cartilage?

hyaline, elastic, and fibrocartilage

Endosteum

incomplete layer of cells that covers all internal surfaces of the bone, such as the medullary cavity

articulations

joints where two bones meet

avascular

not penetrated by blood vessels

Compact bone:

p. 8

Osteolysis:

release of the stored calcium and phosphate from the bone matrix

lacunae

small spaces occupied by chondrocytes

Osteoprogenitor cells:

stem cells derived from mesenchyme; when they divide they produce another stem cell and a committed cell that matures to become and osteoblast; located in both the periosteum and endosteum

skeletal system

supporting framework for soft tissues of the body composed of dynamic living tissues interacts with all of the other organ systems continually rebuilds and remodels itself Includes: bones of skeleton, cartilage, ligaments, and other connective tissue

Proximal epiphysis:

the end of the bone closest to the body trunk

Distal epiphysis:

the end of the bone farthest from the trunk

Articular cartilage:

thin layer of hyaline cartilage covering the epiphysis at a joint surface