Part 4

the structure of bone gives it strength, the ability to grow and repair itself. also has the ability to serve as a reservoir minerals and cells needed elsewhere in the body the bone dynamic’s nature is possible because it is living tissue containing cells, collagen matrix, and minerals

Osteocytes are star shaped cells that maintain bone and are able to sense physical stresses Osteoblast make bone and osteoclast break it down

Performed by osteoclast and it removes calcium from bone so it can enter the bloodstream Neurons use calcium to communicate with each other and rely upon its presence in extracellular fluid for normal muscle contraction inhibition Low levels of plasma calcium causes tetany (an involuntary and continuous contraction of skeletal muscle). Blood clotting and other vital metabolic reactions require calcium as well.

Osteoclasts liberate calcium from bone-bound reserves but when too much calcium is depleted from the bone osteoporosis results causing bones porous of minerals and make them weak and brittle

Osteoblast secretions allow mineralization in bones, a process that is inhibited elsewhere in the body This mineral deposition is in the form of hydroxyapatite a calcium phosphate salt Osteoblast produce a highly organized collagen matrix to which extracellular hydroxyapatite binds

Collagen protein gives bone flexibility, while the minerals that encrust those fibers give them strength brittle bone disease (osteogenesis imperfecta) results from the genetically based corruption of bone’s collagen matrix

In compact bone, the mineral-laden collagen matrix is organized into long concentric layers called lamellae, layers of bones, tissues or cell walls Between each lamella are microscopic pockets or lacunae where bone cells reside

Call communication between the lacunae occurs through microscopic tunnels (canaliculi) which transverse lamellae

a grouping of concentric lamellae is called an osteon and contains a central canal within its innermost ring called the central (haversian) canals and perforating (Volkmann’s) canals.

are passageways for nerves and blood vessels haversian canals and their contents, running parallel within the center of each osteon, connect by way of perpendicular and oblique perforating Volkmann’s canals.

bone that makes up bone plates of the skull and the periphery of most other bones

has few osteons compared to compact (dense) bone The spongy bone contained with compact bone allows bone to be lighter and serves as a location for bone marrow to reside

A soft material within spongey bone and medullary cavity of long bones.

is a site of blood formation and plays a role in the immune system

presents within the medullary cavity of adult long bones is primary composed of adipose tissue The longest long bone of the adult body is the femur, so it contains the largest amount of yellow bone marrow

Bones that have a pronounced longitudinal axis, provide the mechanical advantages of levers where they articulate with other bones. Some of these points of articulation allow the associated bones to move in a hinge-like fashion relative to each other.

Hinge joint found in each elbow and knee allows flexion and extension of the more distal bone along only one plane The shoulders and hips are locations where long bones articulate with other bones in ball and socket joints. Ball and socket joints allow for abduction, adduction, circumduction, and rotation of the associated long bone

ex. Bones of the wrist, ankles, and patella short bones have a width similar to their hight and articulate as gliding joints

Flat bones are thin bones that have a plat-like shape such as bones of the cranium, connect with each other at fused joints called sutures

Bones that dont fit flat, long, or short are irregular bones

Articulation of the skeleton is made possible through its association with soft tissue: cartilage, tendons, ligaments and the periosteum that covers bones

the primary structural protein of connective tissue

Tough connective tissue that attaches muscle to bone

a tough connective tissue that attaches bone to bone