1. Skeletal system
Chap. 7
Intro. to Bones

2. Function = framework of body, protect organs, anchor skeletal muscles for movement.
Skeleton = Greek for “ dried up body”
a) axial = longitudinal
b) appendicular = arms and legs
c) joints, cartilage & ligaments
Bones = give the body shape
Functions = support, protection, movement, storage of fat in cavities and Ca+2 & P, and blood cell formation

3. BONE CLASSIFICATION ( BASED ON SHAPE) 206 BONES!!
Compact = dense, smooth & homogeneous pg. 131
Spongy = small needle like pieces w/ lots of open spaces
Long bones : longer than wide. Shaft w/ 2 heads mostly compact = all limbs
Short bones : cube-shaped; mostly spongy; ankle, wrist
Flat bones : thin, flattened, usually curved. Two thin compact layers w/ spongy in between.
Ex: skull, ribs, sternum
Irregular : ex. vertebrae, hips

4. Bone Markings-- Table 7.2 pg. 142
all T’s = projections except facet
projections/ processes (grow out)
depressions/ cavities (indentions)

5. Structure of a Long Bone Fig. 7.1 pg. 132
Diaphysis (shaft) most of length = compact covered with periosteum (fibrous connective)
Epiphyses = ends of long bone (thin compact w/ spongy)
Articular Cartilage = covers epiphyses, glassy, smooth, slippery; low friction at joints, movement
Epiphyseal line/plate = where growing occurred/ occurs
In Adults= storage area for fat (yellow marrow) medullary cavity
Infants= red marrow ( RBC’s are formed!) ( only found in adult flat bones & epiphyses of long bones

6. Osteocytes = mature bone cells…
found in cavities w/ matrix called lucunae =in circles called lamellae which are central canals called Haversian Canals
Each canal = Haversian System or osteon (pg. 108 and 133)
Canaliculi = small canals connecting all bone cells to nutrient supply ** bone heals quickly
Preforating Canals a.k.a Volkmann’s Canals = run _l_ Haversian & connect to compact bone
Bone is one of the hardest materials is light weight & can resist tension = Ca+2 gives hardness; collagen gives flexibility

7. BONE FORMATION (GROWTH & REMODELING)
Osteoblasts vs. Osteoclasts
Embryos = hyaline cartilage young child = mostly bone except nose & ribs
Ossification = process of bone formation
Hyaline cartilage is covered with bone forming cells called Osteoblasts
Cartilage is digested away= opening up to medullary
cavity with new bone.
** Bones remodel continuously due to…
Ca+2 levels in the blood.
a. Low osteoclasts eat up matrix releasing Ca=+2
High Ca+2 is deposited in bone
2. Pull of gravity and muscles of skeleton depending on activity of person (where matrix is grown)