Ch. 11 - Skeletal Tissues

(microscopic structure of bone and cartilage) Cartilage is more

flexible.

(microscopic structure of bone and cartilage) The microscopic structure of cartilage consists of

many collagenous fibers embedded in a firm gel, rather than a calcified matrix.

List the major anatomical components that together constitute an osteon

An osteon consists of lamellae, lacunae, canaliculi & the central canal,

Compact bone (80% of mass)

Appearance: Dense and solid Structure: Osteon (haversian system) Organization of Lamallae: concentric circles Function: protection and physical support

Cancellous (Spongy) bone

Appearance: open space partially filled with a lattice of thin branched structures supporting red bone marrow Organization of Lamallae: trabeculae Function: Supports red bone marrow and contain myeloid tissue which produces blood cells

Compare and contrast the basic structural elements of bone and cartilage

Both bone and cartilage have a matrix that consists of collagen fiber. Both tissues consist of more extracellular substances than cells. In bone, however, the fibers are embedded in a calcified matrix, whereas in cartilage they are embedded in a more flexible material. Bone is a vascular tissue, and cartilage has no blood vessels in it.

During the aging process, adults face the issue of a changing skeletal framework. Describe these changes and explain how these skeletal framework changes affect the health of older adults

Degeneration of bone and cartilage tissue may lead to a loss of bone density. This can make a person prone to fractures. This is particularly a concern among women who suffer from osteoporosis. The loss of bone density may also result in compression of weight-bearing bones, which would negatively affect posture.

Name structure and function of the three types of cartilage

Hyaline cartilage, Hyaline cartilage, Fibrocartilage

Mineral storage

Normally this bone function is responsible for maintaining the homeostatic level of blood calcium. If there is too much calcium in the blood, calcium is stored in the bone. If there is too little calcium in the blood, calcium is removed from the bone.

Hematopoiesis

Normally this bone function would be responsible for the formation of blood cells. This function is carried out by the myeloid tissue or bone marrow.

Explain the functions of the periosteum

The function of the periosteum is to cover the bone and provide an attachment point for muscle tendon fibers. It contains bone-forming and bone-destroying cells and contains the blood vessels that supply the bone.

Describe the structure of a long bone

The long bone contains six structures. The diaphysis is the main shaft of the bone. The epiphyses are the two ends of the bone. The articular cartilage is a thin layer of cartilage that covers the joint surfaces of the epiphyses. The periosteum is a dense, white fibrous membrane that covers the bone. The medullary cavity is a tubelike hollow space in the diaphysis. The endosteum is a thin epithelial layer that lines the medullary cavity.

Describe the microscopic structure of bone and cartilage

The microscopic structure of compact bone is centered around the osteon, or Haversian system.

Compare and contrast the three major types of cells found in bone

The three major cell types found in bone are osteoblasts, osteoclasts, and osteocytes.

Name the two principal chemical components of extracellular bone

The two components are inorganic salts and organic matrix.

Explain why a bone fracture along the epiphyseal plate may have serious implications in children and young adults

Until bone growth is complete, the epiphyseal plate remains between the diaphysis and the epiphysis. The epiphyseal plate allows the diaphysis of a long bone to increase in length. Any serious trauma to this area may affect a child's or young adult's normal bone growth.

Discuss and discriminate between the sequence of steps characteristic of fracture healing

Vascular damage occurring immediately after a fracture results in hemorrhage and pooling of blood that forms the fracture hematoma. As the hematoma resorbs, a bone callus forms, which serves to bind the ends of the broken bone together and stabilizes the fracture. If the fracture is properly aligned and immobilized, the callus tissue will be actively modeled and replaced with normal bone.

(long bone) The periosteum is

a dense, white fibrous membrane that covers the bone.

(Major anatomical components of an osteon) The central canal is

a large canal in the center of the osteon containing blood vessels, lymph vessels, and nerves.

(chemical components of extracellular bone)The organic matrix consists of

a mixture of protein and polysaccharides. The organic matrix gives the bone some resiliency to help resist fracture.

(long bone) The medullary cavity is

a tubelike hollow space in the diaphysis.

A primary ossification center forms when

blood vessels enter the rapidly changing cartilage at the midpoint of the diaphysis. Ossification progresses from the diaphysis toward each epiphysis, and the bone grows in length. s.

(cells found in bone) Osteoclasts

are large, multinucleated cells responsible for the active erosion of bone minerals. They allow bone to undergo continuous change and remodeling.

(cells found in bone) Osteocytes

are mature, nondividing osteoblasts that have become surrounded by matrix and now lie in the lacunae.

(cells found in bone) Osteoblasts

are small cells that synthesize and secrete a specialized organic matrix called osteoid, which is the important part of the bone matrix.

(chemical components of extracellular bone) Inorganic salts consist of

calcium and phosphate crystals called hydroxyapatite. Other inorganic substances, such as magnesium and sodium, are also found in bone.

(microscopic structure of bone and cartilage) No canal system or blood vessels

exist in cartilage.

(bone formation ) In intramembranous ossification

groups of cells in a membrane differentiate into osteoblasts. They secrete matrix material and collagenous fibers. The Golgi apparatus of these osteoblasts secretes a compound called mucopolysaccharide, and the endoplasmic reticulum secretes collagen. Large amounts of ground substance accumulate around each osteoblast, and numerous collagen fibers become embedded in the ground substance. This constitutes the organic matrix. As the matrix calcifies, the trabeculae join in a network to form spongy bone. Eventually, the spongy bone will be covered by plates of compact bone.

Fibrocartilage

has a small quantity of matrix and abundant fibrous elements. It is strong and rigid and usually is associated with regions of dense connective tissue. Fibrocartilage is found in the symphysis pubis, in the intervertebral disks, and near the point of attachment of some large tendons and bones.

(structure and function of the three types of cartilage) Elastic cartilage

has fewer collagen fibers than hyaline cartilage and a large number of elastic fibers. It is yellowish and is found in the external ear, the epiglottis, the eustachian tube, and the nasal cavity.

(microscopic structure of bone and cartilage) The bone cells are located

in small spaces in the lamellae called lacunae.

There are two forms of cartilage growth

interstitial and appositional.

(long bone) The endosteum

is a thin epithelial layer that lines the medullary cavity.

(long bone) The articular cartilage

is a thin layer of cartilage that covers the joint surfaces of the epiphyses.

(microscopic structure of bone and cartilage) Cartilage cells also lie in

lacunae, but nutrients must diffuse through the matrix to get to them.

The layers of bone material that build up to form cylindrical units of bone tissue are

lamellae

Bone-making cells are called _____

osteoblasts

(structure and function of the three types of cartilage) Hyaline cartilage

resembles milk glass. It is semitransparent and has a bluish cast. The two principal chemical compounds that make up hyaline cartilage are chondroitin sulfate and a gel-like polysaccharide secreted by chondrocytes. Hyaline cartilage forms articular cartilage of bones, costal cartilage, the rings of the trachea and bronchi, and the tip of the nose.

(microscopic structure of bone and cartilage) The cells are connected to the other cells and the osteon by

small canals called canaliculi.

Interstitial growth occurs when

the cartilage cells in the substance of the tissue mass divide and begin to secrete additional matrix. This is possible because of the soft and pliable nature of the matrix.

Appositional growth occurs when

the cells in the inner layer of the perichondrium begin to divide and secrete matrix on the surface of the cartilage, causing an increase in size. Bone growth can occur by apposition in intramembranous bone when the cells of the periosteum add matrix to the outside of the bone. In endochondral bone, a type of interstitial growth occurs when the epiphyseal plate lays down more cartilage, and ossification occurs from the diaphysis of the bone outward, adding length to the bone.

Secondary ossification centers appear in

the epiphyses, and growth begins toward the diaphysis until bone length is complete. A layer of cartilage called the epiphyseal plate remains between the epiphysis and the diaphysis. The epiphyseal plate allows the bone to grow in length by thickening, and ossification occurs on the side nearest the diaphysi

(long bone) The diaphysis is

the main shaft of the long bone.

(microscopic structure of bone and cartilage) Concentric layers of calcified matrix (lamellae) surround

the osteon, which contains blood and lymph vessels and nerves.

(bone formation ) In endochondral ossification,

the pattern of the bone has been formed by cartilage. This cartilage model develops a periosteum, which produces a ring or collar of bone. Soon after the collar of bone appears, the cartilage begins to calcify.

(long bone) The epiphyses are

the two ends of the bone.

(microscopic structure of bone and cartilage) Bone cells are found in the

trabeculae, nutrients are delivered to the cells, and waste products are removed by diffusion through tiny canaliculi that extend to the surface of the spicules.

(microscopic structure of bone and cartilage) In cancellous bone the microscopic structure is based on

trabeculae, which consist of needlelike bone spicules.

Bone density can be increased by ______.

weight-bearing exercise

(Major anatomical components of an osteon) An osteon consists of lamellae

which are concentric cylinder-shaped layers of calcified matrix

(Major anatomical components of an osteon) canaliculi

which are small canals radiating in all directions from the lacunae, connecting them to one another and to the large central canal.

(Major anatomical components of an osteon) lacunae

which are spaces in which bone cells lie