• To briefly describe the structure of bone and the two ways in which it is formed ch 17 dent anat

Fig. 17.17, A and B, shows the openings of these Haversian systems as circular structures known as __________. The __________blood vessels of the Haversian systems are connected with other blood vessels running __________ to them and traveling through tubes called__________. These arteries interconnect with one another, bringing _____________ to the inside of bone.

Haversian lamellae longitudinal perpendicular, Volkmann's canals, or nutrient arteries blood

Bone is about ________________________________ with the rest made up of collagen, ground substance, and water. It is covered on the outside with a _______ layer of _________. As was indicated earlier, the outer layer of the periosteum is _______, and the inner layer is composed of cells that become _________ and can form bone. .

50% hydroxyapatite crystals double, periosteum fibrous, osteoblasts

In the center of bone is a cavity, generally referred to as the marrow cavity. This space serves as a site of __________________. Later in the person's life, the marrow cavity in many bones changes into storehouses for ____. The inner wall of the marrow cavity is lined by an _______________, which forms ______________ on the inside during remodeling of bone-in-bone growth

blood cell production, fat endosteum, modified bone

Endochondral Formation The cartilage is then invaded by ________, which replace the cartilage with bone. As bone replaces cartilage, it does so in two end sections called the ___________ and a center section, the __________

bone cells epiphyses, diaphysis

Before the arteries reach the marrow cavity, they actually go through a ____________and enter the marrow cavity as ________

capillary bed , venules

Endochondral Formation The second way in which bone forms is called endochondral bone formation. With this type of bone formation, __________ is first formed, covered by ___________; the inner layer of the perichondrium contains cells that become __________, which produce a cartilage model of the future bone shape.

cartilage, perichondrium chondroblasts

Intramembranous Formation (pt 2) The outer layer is made up of _________, and the inner layer is made up of _______________ that become __________ and form more bone.

collagen, osteogenic cells ,osteoblasts

Haversian systems are best seen in a _______________ of the arms or legs (see Fig. 17.17, A and B). These same systems exist in flat bones and in some irregular-shaped bones of the skull. In flat bones the marrow cavities are very ____________ and are known as _____________.

cross section of long bones narrow, diploë

In addition to this type of growth in long bones and vertebrae, certain important areas of the bones in the bottom of the skull also grow ____________, which allows for lengthening of the bones from within and at the bone surface

endochondrally

the _________ lining of the marrow cavity is similar to an __________ lining of a vein. Then veins carry the blood and new cells produced by the marrow cavity back out of the bone and into the venous circulation of the body and back to the heart.

endosteal, endothelial

Intramembranous Formation (pt 2) Osteoblasts that get _______ within their own matrix stop forming more bone and become known as ___________. These cells play a role in the nutrition of bone.

entrapped , osteocytes

The area between Haversian systems also has ________ bone cells and layers known as ___________. These are parts of older Haversian systems that have been _______________ by newer systems. This bone _______________ is known as bone remodeling.

entrapped, interstitial lamellae partly destroyed and replaced resorption and apposition

Endochondral Formation Between each epiphysis and diaphysis is a block of cartilage known as the ___________. Within this plate is an __________________ that causes the plate to lengthen; then some of either side of the plate is converted to bone, and the bone thus grows in length. Without that block of cartilage, the bone would be unable to have a ______________.

epiphyseal plate interstitial growth of cartilage directional growth

The osteoblasts lining this tube begin to secrete bony layers and eventually entrap themselves as osteocytes. These layers continue building and ____________ until the ______________________.

fill in the tube , blood vessel is completely surrounded

Intramembranous Formation (pt 2) These cells secrete__________, __________, and then ______________.

ground substance, collagen fibers, hydroxyapatite crystals

Compact or Dense Bone This is the _____________. What makes bone hard? Bone is made up of cells called osteoblasts (meaning bone __________) or osteocytes (meaning bone ______) and collagen fibers and ground substance. Bone also has microscopic crystals of a substance called _______________. These crystals of calcium and phosphates are found packed into the ground substance and fibers between cells, giving bone its hardness. If a bone is placed in an acid substance, the crystals dissolve, and only the other three components are left. Consider the following experiment in which a chicken bone is placed in vinegar. After a few days, the chicken bone can be bent into a pretzel shape. Vinegar, which is acetic acid, dissolves the crystals, which makes the bone flexible.

hard outer layer of bone, formers, cells hydroxyapatite

Most of the bone growth in the head area is of the _____________

intramembranous type

Once bone has developed, all of it tends to appear the same microscopically. Without studying the bone while it was developing, you would not be able to determine from the final microscopic appearance whether it developed ___________________________.

intramembranously or endochondrally

Intramembranous bone formation. Osteoblasts secrete components and become trapped in the mix. They are then referred to as osteocytes. Space occupied by these osteocytes is referred to as ________. To the left a multinucleate osteoclast can be seen destroying bone.

lacuna

Spongy or Cancellous Bone This is the bone tissue that is found in the __________. It is usually referred to as . ____________. Small bridges of bone have space in between, and these spaces function as either blood-producing or fat-storing tissue.

middle of bone, bone marrow

Intramembranous Formation Similar to cartilage, bone forms in ________________. One way is by__________________, or formation within tissue. Bone forms in regular connective tissue by some of the primitive _____________ cells becoming _________ cells. These osteoblast cells are soon surrounded by a double-layered structure called _____________.

more than one way intramembranous bone formation mesenchymal, osteoblast periosteum

Within the Haversian system, ______ are passed on to the entrapped osteocytes ________ to the blood vessel, and they, in turn, pass the nutrients on to the cells ________________________. Blood is also carried into the marrow spaces, where more blood cells are ________ and passed _________bone.

nutrients, closest, farther from the blood vessels manufactured, out of

It is important that bone be nourished with blood because it is a constantly changing structure. A perfect example is orthodontic treatment (Fig. 17.18). The tooth movement is only possible because bone is able to change and remodel itself as the tooth moves. Cells called _____________ are involved in this remodeling process. The suffix clast means something that ____________, and the prefix osteo means bone; thus osteoclasts are bone-destroying cells. Osteoblasts and osteoclasts work together to change bone constantly as stresses are placed on it (Table 17.2).

osteoclasts, destroys

_Around these blood vessels are gathered many trapped bone cells, referred to in their trapped state as _________. This arrangement of blood vessels and osteocytes is called a ______________(see Fig. 17.17, A and B), a series of blood vessels running parallel to one another along the length of the bone. As bone grows, these blood vessels lying on the surface go through a series of changes whereby bone surrounds blood vessels, resulting in a hollow tube in the bone with a blood vessel in the middle.

osteocytes Haversian system

Intramembranous Formation (pt 2) The crystals grow and ______ tightly together, and the forming bone _______.

pack, hardens

Endochondral Formation Perichondrium is eventually replaced by _____________. When the pituitary gland stops producing growth hormone, the _____________, and the bone is no longer in three sections but __________.

periosteum epiphyseal plate disappears unites as one

Bone is also deposited on its own surface by _____________. These layers formed by periosteum and lying immediately _______ to it are known as__________________. On the inside, adjacent to the ________ spaces, are layers produced known as _________________.

periosteum adjacent, circumferential lamellae marrow, endosteal lamellae