Chapter 6 Bone Development & Growth
Elastic Fibers
allow it to snap and recoil back into shape
Cartilage Grows in 2 Ways
appositional growth and interstitial growth
Hyaline Cartilage Location
articular cartilage, costal cartilage, nose, trachea, larynx
Skeleton Subdivided into 2 Divisions: Appendicular Skeleton
bones of the limbs or appendages
Irregular Bones
bones that do not fall into any categories
Skeleton Subdivided into 2 Divisions: Axial Skeleton
bones that lie around the body's center of gravity
Thick Collagen Fibers
can REALLY resist strong compression and strong pulling forces
Elastic Cartilage Location
epiglottis and outer ear
Nutrient Vein
exits nutrient foramen
Perforating Fibers (Sharpey's Fibers) are dense at these points
insertion points for tendons and ligaments that attach to the bone
spongy (trabecular) bone
internal network of bones - composed of small bars of bone and lots of open space filled with bone marrow (red)
osteocyte function and location
occupies the lacuna and their "spider legs" occupy thin tubes called canaliculi which run through matrix and connect neighboring lacuna to one another and the nearest capillaries
Bone Function: Energy Storage
occurs within yellow marrow
epiphyseal line
once long bone has stopped growing, the area is replaced with bone and appear as thin, barely discernible remnants
Nutrient Foramen
opening into canal which gives passage to the blood vessels of the medullary cavity of the bone
Periosteum: Cellular Layer has two cell types
osteoblasts - bone generator - bone depositing cells osteoclasts - bone breaker - remodels bone surfaces throughout our lives
Cartilage in Embryos
predominantly hyaline cartilage
Intramembranous Ossification
process by which bone forms directly from mesenchymal tissue without first being a cartilage; forms membrane bones (produces flat bones of skull and clavicles)
Endochondral Ossification
process in which bone forms by replacing hyaline cartilage; forms endochondrial bone (epiphyseal plate)
Bone Function: Protection
protective case for brain, spinal cord, and vital organs
Bone Function: Movement
provides levers for muscles
Hyaline Cartilage Function
provides support through flexibility and resiliency
What Arises in Red Bone Marrow?
red blood cells, platelets, and most white blood cells
Bone Tissue First Appears in Week 8
replaces most cartilage and mesenchymal membrane in skeleton and unborn baby becomes Fetus.
Bone Function: Mineral Storage
reservoir for minerals (calcium, phosphate)
Fibrocartilage Function
resist both strong compression and strong tension forces
Collagen Fibrils
resist tensile/compression forces
Nutrient Artery
runs inward to supply the bone marrow and spongy bone. branches outward to help supply compact bone
Central Canal (Haversian Canal)
runs through the core of each osteon and contains blood vessels that supply nutrients to the bone cells of the osteon and nerve fibers
diaphysis
shaft of a bone... composed of compact bone
periosteum secured to underlying bone by __________.
sharpey's fibers (perforating fibers) - thick bundles of collagen that can resist tensile forces and run from periosteum to bone matrix
Elastic Cartilage
similar to hyaline cartilage but its matrix contains many elastic fibers along with delicate collagen fibrils
Osteon (Haversian System)
structural unit of the compact bone - a long, cylindrical structure oriented parallel to the long axis of the bone and to the main compression of stresses (resembles rings of tree trunk)
Periosteum 1st Sublayer: Fibrous Layer
superficial layer of dense irregular connective tissue which resist tension placed on the bone during bending
Functions of Bones
support, protection, movement, mineral storage, blood cell formation, energy storage
Osteon Function
weight bearing pillars
Osteocyte Gap Junctions
within the canaliculi, the extensions of neighboring osteocytes touch each other and form gap junctions which allow direct cell transfer of nutrient diffusion from one osteocyte to the next throughout the entire osteon
Main Vessels Serving Diaphysis
nutrient artery and nutrient vein
Embryogenesis
Occurs before week 8 , the skeleton of the human embryo consist only of hyaline cartilage and some membrane of mesenchyme.
At Birth, All Bone Marrow is _______. With Age, More is Converted to _______.
Red; Yellow
Bone Tissue Has Organic Components
- 35% of bone tissue mass - include cells, fibers, and ground substance - contribute to flexibility and tensile strength that allow bone to resist stretching and twisting
Bone Tissue Has Inorganic Components
- 65% of bone tissue mass - consist of hydroxyapatites (mineral salts)... primarily calcium phosphate - provide bone with exceptional hardness (resist compression)
Osteogenesis/Ossification (Process of Bone-Tissue Formation) Occurs Three Times During Life
1) formation of bony skeleton in embryos 2) bone growth until early adulthood 3) bone thickness, remodeling, and repair in adults
Flat Bone
Generally thin with two wafer-like layers of compact bone sandwiching a thicker layer of spongy bone between them.
Elastic Cartilage Function
cartilage is very elastic and able to tolerate repeated bendings
Periosteum
connective tissue membrane that covers the diaphysis and richly supplied with nerves and blood vessels
what is a cartilage?
connective tissue which contains no nerves or blood vessels, consists if chondrocytes, and an abundant extracellular matrix
Cartilage Extracellular Matrix
consist of 60-80% water and is very resilient
Endosteum is Osteogenic = ?
contains both osteoblasts and osteoclasts
Typical Piece of Cartilage
contains cartilage and perichondrium
Fibrocartilage
contains rows of thick collagen fibers alternating with rows of chondrocytes, each of which is surrounded by a layer of cartilage matrix
Articular Cartilage
covers the epiphyseal surface in place of the periosteum; composed of hyaline cartilage and provides a smooth surface to prevent friction at joint surfaces
Short Bone
cube shaped and contain more spongy than compact bone
Periosteum 2nd Sublayer: Cellular Layer
deep osteogenic (bone producing) layer that abuts the compact bone and contains two cell types
Compact Bone
dense outer layer of bone - looks smooth and homogenous
Short, Irregular, and Flat Bones lack ?
diaphysis and a medullary (marrow) cavity
epiphyseal plate
disc of hyaline cartilage that grows during childhood to lengthen the bone
Lamella
each osteon ring is called THIS, which is a layer of bone matrix in which collagen fibers and mineral crystals align and run in a single direction
Why Does a Bone Break Cause Profuse Bleeding?
filled with blood where blood originates (blood vessels)
Bone Function: Support
form the framework that supports the body and cradles soft organs
Appositional Growth
growth from outside - chondroblasts in the perichondrium produce the new cartilage tissue by actively secreting matrix
Interstitial Growth
growth from within - lacunae bound chondrocytes inside the cartilage divide and secrete new matrix, expanding cartilage from within
Bone Function: Blood Cell Formation
hematopoiesis (occurs within red marrow)
Medullary Cavity "Marrow Cavity"
hollow central cavity of the shaft that is a storage region for adipose tissue/yellow marrow
Cartilage in Adults
hyaline cartilage replaced by more rigid bone, ossified cartilage
3 Types of Cartilage Tissues
hyaline cartilage, elastic cartilage, fibrocartilage
Diploe (Spongy Bone)
in flat bones the internal spongy bone is called _________
what is a perichondrium?
layer of dense irregular connective tissue that surrounds the cartilage and acts as girdle to resist tension from multiple directions.
Perforating Canals (Volkmann's Canal)
lie 90 degrees to the Central Canal and connect the blood and nerve supply of the periosteum to that of the Central Canals and Medullary (Marrow) Cavity
Fibrocartilage Location
ligaments, intervertebral discs, and menisci
Long Bone
longer than they are wide, generally consisting of a shaft with heads at either end
How are bones living tissues?
made up of osteocytes and contain different types of tissues.
Trabeculaue of Spongy Bone
marrow is found here for flat, short, and irregular bones
Osteocytes
mature spider shaped bone cells that are essential for maintaining bone matrix
Hyaline Cartilage
most abundant cartilage; has chondrocytes in lacuna; and has collagen fiber in matrix to form networks and resist compression forces and moderate pulling forces
Why Does It Hurt When You Break a Bone?
nerves. bones are innervated
epiphysis
the ends of the long bone... composed of a thin layer of compact bone that encloses the spongy bone and covered with a thin layer of articular cartilage (hyaline)
Why Does Cartilage Stop Growing in the Late Teens?
the skeleton stops growing and chondrocytes stop dividing
bone matrix
thin sheets (lamella) made up of: calcium salts, phosphate, collagen; hard substance that surrounds living bone cells
Endosteum
thin, connective tissue membrane that covers the internal bone surfaces, covers the spongy bone, and lines the central canals of osteon