Ch. 6 Flashcards
where is perichondrium found
surrounds cartilages
function of perichondrium
resists outward pressure, and functions in growth and repair of cartilage, springs back to original shape
what similarities to the different types of cartilages share?
cell type: chondrocyte located in lacunae, matrix contains fiber and jelly like ground substance
what type of cartilage is most abundant in the body
hyaline cartilage
what do the chondrocyte of hyaline cartilage look like
spherical
what type of fibers are found in hyaline cartilage
collagen
function of hyaline cartilage
provides support though flexibility
what is elastic cartilage mainly composed of
many elastic fibers
function of elastic cartilage
able to tolerate repeated bending
where in the body can elastic cartilage be found
epiglottis, and cartilage of external ear
function of fibrocartilage
resists strong compression and strong tension, intermediate b/t hyaline and elastic cartilage
where in the body can fibrocartilage be found
pubic symphysis, menisci of knee, and annulus fibrosis
what two ways does cartilage grow?
appositional and interstitial growth
appositional growth
chondroblasts in surrounding perichondrium produce new cartilage
interstitial growth
chondrocytes w/in cartilage divide and secrete new matrix
when does cartilage stop growing?
when the skeleton stops growing
what types of tissue does bone contain
bone connective tissue, nervous, blood, cartilage, and epithelial
function of bones
support, movement, protection, mineral storage, blood cell formation, and energy metabolism
what type of components make up bone tissue and what are their proportions
35% organic components and 65% inorganic components
list the type of organic components found in bone
cells, fibers, and ground substance
list the types of inorganic components found in bone tissue
mineral salts that invade bony matrix
organic components found in bone contribute to what?
flexibility and tensile strength
inorganic components found in bone contribute to what?
provide exceptional harness, and resists compression
what are the three types of cells in bone that either produce or maintain bone
osteogenic cells, osteoblasts, and osteocytes
osteogenic cells
see cells that differentiate into osteoblasts
osteoblasts
actively produce and secrete bone matrix (osteoid)
osteocytes
keep bone matrix healthy
what are osteoclasts and where are they found
w/in bone tissue, responsible for resorption of bone by secreting hydrochloric acid and lysosomal enzymes
what are the 4 classifications of bones
long, short, flat, and irregular
describe long bones
longer than wide; a shaft plus ends
describe short bones
roughly cube-shaped
describe flat bones
thin and flattened, usually curved
describe irregular bones
various shapes, do not fit into other categories
describe compact bone
dense outer layer of bone
describe spongy (cancellous) bone
internal network of bone
what are trabeculae
little “beams” of bone, open spaces b/t trabecular filled w/ marrow
what similarities do flat, short, and irregular bones share apart from long bones
contain bone marrow but no marrow cavity, instead have Diploe (internal spongy bone of flat bones)
what are the 3 broad categories of bone markings
projections for muscle attachment, surfaces that form joints, depressions, and openings
tuberosity
large rounded projections; may be roughened
crest
narrow ridge of bone; usually prominent
trochanter
very large, blunt, irregularly shaped process
line
narrow ridge of bone; less prominent than a crest
tubercle
small rounded projection or process
epicondyle
raised area on or above a condyle
spine
sharp, slender, often pointed projection
process
any bony prominence
head
bony expansion carried on a narrow neck
facet
smooth, nearly flat articular surface
condyle
rounded articular projection, often articulates w/ a corresponding fossa
foramen
round or oval opening though a bone
groove
furrow
fissure
narrow, slitlike opening
notch
indentation at the edge of a structure
fossa
shallow basin-like depression in a bone, often serving as a n articular surface
meatus
canal-like passageway
sinus
cavity w/in bone, filled w/ air and lined w/ mucous membrane
describe osteons
long cylindrical structures, structurally resemble rings of a tree in cross section
function of osteons
support
what do osteons contain
lamellae, central canal, perforating canals, canaliculi
ossification (osteogenesis)
bone tissue formation
intramembranous ossification
membrane bones formed directly from mesenchyme
endochondral ossification
other bones develop initially from hyaline cartilage
type of bones that develop from endochrondral ossification
all bones except some bones of skull and clavicles
in endochondral ossification where are bones modeled
in hyaline cartilage
describe epiphyseal plates of growing bones
cartilage organized in stacks, chondroblasts at top divide quickly, pushing epiphysis away from diaphysis which lengthens entire long bone
describe the process of growth in the epiphyseal growth areas
older chondrocytes signal surrounding matrix to calcify, then die/disinitegrate, leaves long trabecular (spicules) of calcified cartilage on diaphysis side, trabeculae partly eroded by osteoclasts, osteoblasts cover trabecular w/ bone tissue, trabecular finally eaten away from tips by osteoclasts
during childhood and adolescence how do bones lengthen
entirely by growth of the epiphyseal plates, cartilage replaced w/ bone connective tissue as quickly as it grows, epiphyseal plate maintains constant thickness
what happens as adolescence draws to an end
chondroblasts divide less often, epiphyseal plates become thinner, cartilage stops growing and replaced by bone tissue
when do long bones stop lengthening
when diaphysis and epiphysis fuse
osteoblasts role
add bone tissue to external surface of the diaphysis
osteoclasts role
remove bone from the internal surface of the diaphysis
what is appositional growth
growth of a bone by addition of bone tissue to its surface
where is the growth hormone produced
pituitary gland
purpose of thyroid hormone
ensures that skeleton retains proper proportions
what are the two types of sex hormones
estrogen and testosterone
function of sex hormones
promote bone growth, later induces closure of epiphyseal plates
how many mg of calcium may enter or leave the adult skeleton each day
500 mg
how often is cancellous bone of the skeleton replaced
every 3-4 years
how of ten is compact bone replaced?
every 10 years
where does bone deposit and removal take place
periosteal and endosteal surfaces
how dos osteoclast accomplish its job
crawls along bone surfaces secreting concentrate HCL, lysosomal enzymes are leased to break down bone tissue
what is osteoclast derived from
hematopoietic stem cells
what is osteoporosis
characterized by low bone mass, bone reabsorption outpaces bone deposition
osteomalacia
occurs in adults- bones are inadequately mineralized
rickets
occurs in children- analogue to osteomalacia
osteosarcoma
form of bone cancer
function of mesoderm
gives rise to embryonic mesenchyme cells
function of mesenchyme
produces membranes and cartilage
until what age does the skeleton grow
18-21
during which stages of life does bone formation exceeds rate of bone reabsorption
children and adolescents
