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