A225 Lecture - Bones and Cartilage - 9/4

osteology

the study of bones

osteocytes

mature bone cells that maintain the bone matrix

lacunae

small cavities in bone that can contain osteocytes, or small cavities in cartilage that contain chondrocytes

periosteum

grows bone in width; outer membrane that surrounds bone

dense irregular ct

what tissue makes up periosteum?

bone ct, dense irregular ct, blood vessels and nerves

what tissues make up bones?

compact bone

dense hard outer casting of all bone; composed of osteons

resist forces from weight and movement

function of compact bone

spongy bone

light, thin inner network of bone

resist stress on bones in multiple directions, houses hematopoietic tissue

function of spongy bone

hematopoietic tissue

red bone marrow; produces blood cells

flat bones and at ends of long bones

locations of spongy bone

support, protection, body movement, mineral storage, hematopoiesis

functions of skeletal system

red bone marrow in most spongy bone

where does hematopoiesis occur in children?

flat bones of skull, sternum, ribs, vertebrae, hip bones

axial skeleton

axial skeleton and proximal epiphyses of humerus and femur

where does hematopoiesis occur in adults?

chondrocytes

mature cartilage cells

avascular

is mature cartilage vascular or avascular?

dense irregular ct

what type of tissue makes up cartilage?

perichondrium

dense irregular ct that surrounds cartilage

hyaline, fibrocartilage, elastic cartilage

3 types of cartilage

hyaline cartilage

cartilage that provides a smooth surface for join movement

joints (articular surface), trachea, fetal skeleton

locations of hyaline cartilage

fibrocartilage

cartilage with a wavy pattern that helps withstand compression

intervetebral discs, pubic symphysis, menisci

locations of fibrocartilage

elastic cartilage

cartilage with abundant elastic fibers, provides flexibility and strength

external ear, larynx, nasal tip

locations of elastic cartilage

long bone

bone longer than it is wide

levers, joints, and pivots for body movement

functions of long bone

short bone

bone that is approximately as long as wide

distribute and transfer forces across multiple bones

functions of short bone

flat bone

bone that is relatively thin, have broad surfaces for muscle attachment

irregular bone

bone that comes in irregular and varied shapes

varied functions including attachment and protection

function of irregular bones

diaphysis

cylindrical shaft of bone

medullary cavity

hollow inside of diaphysis

endosteum

dense irregular ct that lines the medullary cavity

yellow bone marrow

this is located in the medullary cavity in adults

epiphysis

end of bone

articular cartilage

hyaline cartilage on the epiphyses

reduce friction between articulating bones

function of articular cartilage

osteoarthritis

articular cartilage wears down, leads to bone against bone

old age, repetitive use of a joint

causes of osteoarthritis

epiphyseal plate

hyaline cartilage plate between diaphysis and epiphysis

lengthwise bone growth

function of the epiphyseal plate

epiphyseal line

thin plate of compact bone between epiphysis and diaphysis

marks the end of bone growth

function of epiphyseal line

articular surfaces of bone

where is periosteum not found?

perforating fibers

fibers that anchor the periosteum to bone

osteoblasts

immature bone cells that secrete osteoid

osteoid

unmineralized bone matrix

osteoclasts

break down and resorb bone; formed from fused red bone marrow cells

osteon

structure unit of compact bone; runs parallel to the length of diaphysis

no

does spongy bone have osteons?

central canal

opening that contains blood vessels and nerves, runs parallel to diaphysis, one per osteon

concentric lamellae

concentric rings of bone matrix

canaliculi

tiny channels that radiate from lacunae

exchange of nutrients and wastes between central canal and osteocytes

function of canaliculi

perforating canals

canals that run perpendicular to the central canal; connect central canals

interstitial lamellae

incomplete remnants of osteons, no central canal

circumferential lamellae

rings of bone that run the entire circumference of the shaft

periosteum

what creates the circumferential lamellae?

ossification

formation and growth of bone tissue

intramembranous ossification

process by which bone forms direction from mesenchymal tissue

flat bones of the skull

Intramembranous ossification produces the ___

endochondral ossification

process in which bone forms from hyaline cartilage

most bones in the body

endochondral ossification produces ___

fetal hyaline cartilage model of bone develops

first step of endochondral ossification

primary ossification center forms in diaphysis

second step of endochondral ossification

secondary ossification centers from in epiphyses

third step of endochondral ossification

bone replaces cartilage except for the articular cartilage and epiphyseal plate

fourth step of endochondrial ossification

epiphyseal plates ossify and form epiphyseal lines

last step of endochondral ossification

12 weeks

primary ossification centers by...

at birth

secondary ossification centers by...

15-25 years

epiphyseal plate is active for about...

fracture hematoma

forms when bone is broken

fibrocartilaginous callus

formed at site of a fracture after fracture hematoma

bony callus

replaces soft callus

fracture hematoma, fibrocartilaginous callus forms, bony callus forms, remodeling occurs

steps for bone remodeling