Ch 6
The Hydroxyapatite, or bone salt crystals makes up the majority of the bone matrix. What percentage does the hydroxyapatite make up?
66%
What is another name for the Osteon?
A Haversian system
The Osteon is what type of structure?
A cyndrical structure parallel to the shaft of the bone.
What is The Epiphyseal Plate?
A layer of hyaline cartilage at the boundary of the epiphysis and diaphysis
Where is cartilage found?
Airways in respiratory system, auricle of ear, articulations, precursor model for bone growth, fetal long bones, and smooth surfaces where bones meet
name the types of bone cells
Osteoprogenitors, Osteoblasts, Osteocytes, and Osteoclasts
How is compact bone oriented?
Parallel oriented tubes of osteons,
Name the two types of bone coverings
Periosteum and Endosteum
Endochondral Ossification Stage 3
Primary ossification center forms in the diaphysis
When does repair start after a bone fracture?
Repair immediately starts
Endochondral Ossification Stage 4
Secondary ossification centers form in the epiphysis
The classification of bones according to what?
Shape
Endosteum
covers most internal surfaces of bones
Medullary, marrow cavity
cylindrical space in diaphysis
Periosteum
dense irregular connective tissue. covers external surfaces of bones
Zone of calcified cartilage
deposited minerals kill the chondrocytes and make matrix opaque Zones of Epiphyseal Plate
Intramembranous Ossification
develops from mesenchyme. Formation of cartilage, forming from the center and working its way out.
Diaphysis
elongated, usually cylindrical, shaft
What does articular cartilage reduce?
friction between articulating bones
Interstitial growth
from inside of the cartilage
Long bones
greater length than width
The skeletal system is an organ system with tissues that do what?
grow and change throughout life
Central Canal
carries blood vessels and nerves, centrally located in the Osteon
Bone Matrix: what are the 1/3 organic components?
cells, collagen fibers, ground substance
Zone of hypertrophic cartilage
chondrocytes not dividing, become enlarged
Interstitial Lamella
"leftover" pieces of old osteons
Compact Bone Organization
..
During aging, bone changes in two ways:
1. Loses ability to produce organic matrix, mainly collagen. 2. loses calcium (Ca++) and other bone salts
Endochondral Ossification
Begins with a hyaline cartilage model
Endochondral Ossification Stage 5
Bone replaces cartilage, except the articular cartilage and epiphyseal plates
What are bones strengthened by?
Calcification
Endochondral Ossification Stage 2
Cartilage calcifies and a periosteal bone collar forms around diaphysis
What are the two types of an Osteon Canal?
Central Canal and Perforating Canal
what are the types of Lamellae?
Concentric Lamella, circumferential lamella, and interstitial lamella
Long Bone Anatomy
Diaphysis, Epiphyses, and Metaphyses
Endochondral Ossification Stage 6
Epiphyseal plates ossify and form epiphyseal lines
True or fase: Mature cartilage is vascular
False. Mature cartilage is avascular
Endochondral Ossification Stage 1
Fetal hyaline cartilage model develops
The Intramembranous Ossification begins from the center and goes out in how many stages?
Four
Describe flat bones
Have compact and spongy (diploë) bone
Which way does appositional growth occur?
In diameter
Which way does interstitial growth occur?
In length
Bone is constantly being remodeled, it is more dense in early adulthood, and less in older adults. There are two types of bone growth, what are they?
Interstitial and appositional growth
Cartilage grows in two patters, what are they?
Interstitial growth and Appositional growth
What are the two general patters of osteogenesis?
Intramembranous and endochondral
Intramembranous Ossification Stage 4
Lamellar (secondary)
Bones
Living organs containing all four tissue types primarily connective tissue.
What are the four classifications of bones?
Long bones, Short bones, flat bones, and irregular bones
What is the first step of repair in bone?
Make a hemotoma, then it converts to cartilage, then to bone
Calcification
Minerals deposited in the matrix. Main store and source of Calcium (2+) and Phosphate (PO4---)
Describe the process of Interstitial Growth
Mitosis of chondrocytes in lacunae forms two chondrocytes per lacunae. Each synthesize and secrete new matrix, the new matrix then separates the cells.
Describe the process of Appositional Growth
Mitosis of stem cells in perichondrium adds chondroblasts to periphery. produce matrix, become chondrocytes forming new lacunae adding to the existing matrix.
There are three major types of arteries and veins in bone, what are they?
Nutrient, Metaphyseal, and Epiphyseal
What does the perforating canal provide?
Opportunity for further nutrient delivery
Intramembranous Ossification Stage 1
Ossification centers from within thickened regions of mesenchyme
Intramembranous Ossification Stage 2
Osteiod undergoes calcificaiton
mesenchyme
Stem cells
What are the functions of Cartilage?
Support soft tissues
What are the five functions of bones
Support, Protection, Movement, storage, and Hemopoiesis
The basic structural and functional unit of mature compact bone is what?
The Osteon
Ossification
The formation and development of bone, also knows as osteogenesis
What does endochondral ossification produce?
The majority of bones in the body, primarily the long bones.
What can these changes result in?
This can result in a condition called osteoporosis, decrease in bone density and bone fractures
Osteogenesis
To build bone
True or false: Periosteum does not cover articular cartilages
True. Periosteum does not cover articular cartilages
Intramembranous Ossification Stage 3
Woven (primary) bone and surrounding periosteum form.
The epiphyseal plate consists of five distinct microscopic zones, what are these zones?
Zone of resting cartilage, Zone of proliferating cartilage, Zone of hypertrophic cartilage, Zone of calcified cartilage, and Zone of ossification
Circumferential Lamella
along endosteum and periosteum
Appositional growth
along outside edge of the cartilage
What does the Periosteum act as for blood vessels and nerves?
an anchor
Metaphyses
between diaphysis and epiphysis, contains epiphysial (growth) plate
canaliculi:
between lacunae allowing metabolic interactions between osteocytes
Bone Matrix: what are the 2/3 inorganic components?
bone salt crystals: hydroxyapatite, calcium phosphate and hydroxide ( Ca10(PO4)6(OH)2 )
Where is compact bone found?
external surfaces of long and flat bones
Zone of resting cartilage
farthest from medullary cavity, nearest epiphysis, small chondrocytes in hyaline cartilage
What does the intramembranous ossification produce?
flat bones of the skull, some facial bones, the mandible, and central portion of the clavicle.
Osteoblasts
form bone matrix, builders
Where is spongy bone found?
internal surface of bones. Generally in the Epiphysis and Metaphysis of bone, it is rarely in the diaphysis.
What is the Epiphyseal Plate a site of?
interstitial growth, or bone lengthening
Describe semi-rigid connective tissue
it is not as strong as bone, more flexible, resilient
Epiphyses
knobby, enlarged regions at ends, strengthen joints, attachment site for tendons/ligaments
Osteoclasts
large, multinucleated cells that dissolve bone, releasing calcium (Ca++)
Zone of proliferating cartilage
larger chondrocytes undergoing rapid mitotic cell division, aligned like stacks of coins
What does the process of Interstitial Growth result in?
larger piece of cartilage, the newest cartilage is inside
What does the process of Appositional Growth result in?
larger piece of cartilage, the newest cartilage on outside edges
Where do chondrocytes live?
live in small spaces called lacunae
Osteoprogenitors
mesenchymal stem cells, found in endosteum and periosteum, mitotically produce more stem cells or osteoblasts
Short bones
nearly equal length and width
Describe spongy bone
open lattice of narrow plates: trabeculae
Irregular bones
other/complex shapes
What is the periosteum anchored by?
perforating fibers embedded in the bone matrix
Perforating Canal
perpendicular connections to central canal with blood vessels and nerves
Osteiod
precursor to solid bone matrix
chondroblasts
produce matrix, builders
Osteocytes
reside in lacunae; maintain matrix and communicate with osteoblasts to cause further deposit of bone matrix
Concentric Lamellae
rings of bone around central canal
Endochondral Ossification begins with a hyaline cartilage model and produces the majority of bones in the body. How many stages take place during this ossification?
six
Describe compact bone
solid and relatively dense
How does mechanical stress from exercise, or muscle contraction and gravity effect bone?
stimulates increase in bone density by increased osteoblast activity. Athletes who engage in these types of activities, on average, have greater bone density
Describe the extracellular matrix of bones
sturdy and rigid
Metaphyseal
supply area between the diaphysis and epiphysis
Epiphyseal
supply cells in epiphyseal plate
Nutrient
supply the diaphysis; nerves usually accompany these into the shaft of the bone
chondrocytes
surrounded by matrix
Articular cartilage
thin layer of hyaline cartilage on epiphyses,
Flat bones
thin surfaces
Hemopoiesis
to make blood
Zone of ossification
walls between lacunae break, forming channels that become invaded with capillaries and osteoprogenitor cells
What does the medullary cavity contain?
yellow bone marrow