Skeletal system
Interstitial growth
(Inside bone) Chondrocytes divid/ add new matter to exisiting
Appositional growth
(Outside bone). Chondrocytes in perichondrium add to outside edge
Functions of the skeletal system
1- support 2-protection 3-movement 4-storage (calcium and phosphorus 5-blood cell production
Bone matrix is made up of what?
35% organic, collagens and proteoglycans 65% inorganic, calcium phosphate crystal called HYDROXYAPATITE
Short bones
Are round or nearly cubed shaped. Bones in wrist and ankle
Bone without mineral
Bends
Interstitial lamellae
Between osteons and are remnants of concentric or circumferential lamellae that were partially removed during bone remodeling
Osteoclasts
Bone destroying cells, they breakdown (reabsorption) Ca+2 and phosphate ions for use in metabolic process.
Osteoblast
Bone forming cells which have extensive endoplasmic reticulem and ribosomes. Produce colleges and proteoglycins
Lamellar bone
Bone organized into thin sheets or layers thick called lamellae. Osteocytes within their lacunae are arranged in layers sandwiched between lamellae.
Skeltal system has 4 components
Bones cartilage tendons and ligaments
Concentric lamellae
Circular layers of bone matrix that surround a common center
Intermembranous ossification
Connective tissue, centers of ossification expand, flat bones of head.
Spongy bone
Consists of interconnecting rods or plates of bone called TRABECULAE
Compact bone
Denser bone that has fewer spaces than spongy bone. Blood vessels enter the substance of bone itself by Haversian canals:
Perichondrium
Double layer connective tissue sheath covering most cartilage.
Ossification
Formation of bone by osteoblasts
Irregular bones
Have shapes that do not fit into the other 3 categories. Sphenoid bone.
Tendons
How Skeletal muscles attached to bones
Cartilage associated with bones
Hyaline cartilage
Articulate cartilage
Hyaline cartilage that covers the ends of bones where they come together to for joints. Has no perichondrium blood vessels or nerves.
Bone shapes
Long vs flat Short Irregular
Long bones
Longer than wide. Most are bones of the upper and lower limb
Osteocytes
Made when osteoblasts is surrounded by bone matrix
Chondrocytes
Maintain cartilage. When matrix surrounds a chondroblast.
Chondroblast
Make cartilage. Hyaline cartilage consists of specialized cells and produce a matrix surrounding themselves.
Stem cells
Mesenchymal cells that can replicate and give rise to more specialized cell types.
Bone cell categorys
Osteoblasts, osteocytes, osteoclasts
Ruffles boarder
Osteocyte cell membrane differentiates into a highly folded form
Bone remodeling
Process of removing old bone and adding new bone. Woven bone is remodeled to form lamella bone
Flat bones
Relatively thin flattened sharp and are usually curved. Certain skull bones, ribs and breastbone
Lacuna
Rounded cell that occupies space.
Perforating canals (Volkmann canals)
Run perpendicular to the long axis of bone. Not surrounded baby concentric lamellae but pass through concentric lamellae. Nutrients enter and waste products exit through these
Bone without collagen
Shatters
Fontanels
Skull bones that have not yet been ossified. (Soft spots)
Sinuses
Some of flat and irregular bones of skull have air filled spaces
Lacunae
Space occupied by osteocytes cell bodies
Canaliculi
Spaces occupied by osteocytes cell processes ( little canals)
Osteochondral progenitor cells
Stem cells that can become osteoblasts or chondroblast. Located in inner layer of perichondrium.
Woven bone
The collagen fibers are randomly oriented in many directions. First formed during fetal development or during repair or fracture.
Trabeculae
Thin and consist of several lamellae. No blood vessels penetrate. Are oriented along the lines of stress within a bone
Circumferential lamellae
Thin plates that extend around bone which are very thin and can sometimes be so thin that no osteons exit
