Bone Composition & Structure Flashcards
What is the main ingredient of the matrix material in both compact and spongy bone?
Calcium salts or hydroxyapatities which make up 65% of the matrix
What is the importance of osteoid in bone?
Osteoid is the soft, felxible part of the matrix that allows bones to give slightly as muscles pull on them. It allows bones to resist breakage from tension or bending forces often called “stress” on the bone. Osteoid gives flexibilty becasue it is made of proteoglycan and collagen fibers.
When do the cells called osteoblasts become osteocytes? How does this affect the location of osteoblasts in a formed bone?
Since osteoblasts create bone. Once surrounded by the bone they have made they lose their ability to make bone and become osteocytes. (They do keep the existing bone healthy though). This means that in any bone of the body there are no osteoblasts within the bone tissue itself that can be used for growth or repair.
How is the turning of osteoblasts into osteocytes in bone related to the importance of the periosteum and endosteum.
Since osteoblasts are not within bone tissue itself the periosteum and endosteum are used to provide these cells for the bone. The periosteum is a soft tissue covering bones that provides a layer of osteoblasts on the outer surface of the bone. The endosteum is a soft tissue lining the bone marrow cavity, so it provides a second layer of osteoblasts on the inner surface of the bones.
What do the cells called osteoclasts do to the bone? In what two ways is this useful?
Osteoblasts secrete acid and enzymes that break down/dissovle bone. They do this for 1) remodeling, the gradual tearing down and rebuilding of bones that adapts them to stress and for 2) calcium homeostatsis (keeping calcium at the right level). Specifically, they help keep blood calcium levels from falling too low– they help correct hypocalcemia.
Where are the spongy and compact bone found in a typical long bone of the body?
Compact bone covers the entire bone surface (shaft and rounded ends). Spongy bone is found inside the knobby ends (epiphyses), filling the space inside them. The Shaft (diaphysis) contains only compact bone and is hollow in the center (medullary cavity).
What critical role does red bone marrow have? Besides the medullary cavity, where can it be found? What two other names does it have?
Red bone marrow creates all the blood vessels, both RBC’s and WBCs. It is found in any spongy bone ( within the open spaces) especially in adults because of most RBM in marrow cavities turns into yellow bone marrow. It is also called myeloid tissue and is an example of reticular connective tissue.
The periosteum has two layers. What is the outer layer made of and what is its purpose? What is the inner layer made of and what is its purpose?
The top layer is dense irregular c.t. that is used to help tendons attach skeletal muscle to bone. Sharpey’s fibers assist in this. The inner layer is made of osteoblasts and provides these cells for growth, remodeling, and repair of bone.
