Module 5: Cartilage and Bone

diaphysis

tubular shaft that runs between proximal and distal ends of the bone

epiphysis

layer of hyaline cartilage in growing bone

filled with spongy bone & red marrow

metaphysis

narrow area that contains epiphyseal plate

medullary cavity

hollow region in diaphysis

filled with yellow marrow

spongy bone

cancellous bone, contains osteocytes housed in lacunae

trabeculae

provide balance to compact bone to make them a little lighter and easy to move

lattice-like trix spikes

compact bone

provides support and protection

denser, stronger of the bone tissue types

nutrient artery

vein that supplies the diaphysis enters through nutrient foramen

epiphyseal arteries

supplies blood to/from the epiphysis

periosteum

fibrous membrane outer surface of bone

edosteum

membranous lining of medullary cavity where bone growth, repair, and remodeling occur

osteoclast

bone resorption

found on bone surfaces & sites of old/injured bone

osteoblast

bone formation

found in growing portions of bone (& periosteum and endosteum)

osteocyte

primary cell of mature bone and most common type of bone cell

found in lacunae/matrix

osteogenic cells

undifferentiated with high mitotic activity

only bone cells that divide to form osteoblasts

red marrow

hematopoiesis takes place (production of red blood cells)

yellow marrow

adipose tissue; source of energy

osteon

microscopic structural unit of compact bone

central canal

contains blood vessels, nerves, lymphatic vessels

runs down the center of each osteon

concentric lamellae

provide structural integrity to individual osteons to help compact bone resist twisting and compression forces along its axis

circumferential lamellae

resist overall twisting of entire bone and play a key role in appositional growth

lacunae

osteocytes located inside these spaces

found at borders of adjacent lamellae

canaliculi

allows nutrients to transport to osteocytes and wastes to be removed

connects with canaliculi of other lacunae and eventually the central canal

perforating canal

when vessels and nerves branch off to extend to periosteum and endosteum

intramembranous ossification

compact and spongy bone develop directly from sheets of mesenchymal CT

endochondral ossification

bone develops by replacing hyaline cartilage

cartilage = template

periosteal bone collar

wraps around diaphysis of developing cartilage model during fetal long bone growth

structural support, cartilage death, ossification trigger

intersitial bone growth

process by which long bones lengthen from within division, growth, and ossification of cartilage and epiphyseal plate

epiphyseal plate

area of growth in long bone

layer of hyaline cartilage where ossification occurs in immature bones

appositional bone growth

bones increase in diameter while they increase in length

bone remodeling

continuous process where mature old bone is broken down and replaced with new bone tissue

rickets

bone disorder: bones are soft and weak and prone to deformities

osteomalacia

metabolic bone disease that causes bones to soften and weaken due to lack of proper mineralization

osteoarthritis

wear-and-tear of cartilage protecting bones breaks down

osteopenia

mineral density is deficient—warning sign for progression to osteoporosis

osteoporosis

bone density decreases making bones fragile

long bone

function as levers; they move when muscle contracts

found in arms, legs, fingers, toes

short bone

provide stability, support, limited motion

found in carpals of wrists and tarsals of ankles

flat bone

point of attachment for muscles and often protect internal organs

found in skull, scapulae

irregular bone

complex shape i.e. spinal vertebrae

sesamoid bone

protect tendons by helping overcome compressive forces & mechanical lever to allow muscle/tendon to greater torque about a joint

pneumatized bone

decrease weight of skull & for sinuses

hollow/contains numerous air pockets

chondrocytes

cartilage cells that occupy lacuna spaces

chondroblasts

young, active cells that build cartilage by secreting extracellular matrix made of collagen

hyaline cartilage

most common type of cartilage

short & dispersed collagen fibers

strong & flexible

fibrocartilage

thick bundles of collagen fibers dispersed through matrix

found in menisci in knee joint

elastic cartilage

elastic fibers & collagen

supports and provides elasticity

periochondrium

dense irregular CT that encapsulates cartilage

articular cartilage

thin layer of cartilage that reduces friction and acts as shock absorber

interstitial cartilage growth

expansion of cartilage from within tissue through division of existing cells and formation of new matrix

appositional cartilage growth

new cartilage is added to surface of existing tissue increasing width/thickness