bones Flashcards
functions of skeletal system
Body support, Organ protection, Body movement, . Mineral storage, Blood cell production.
The principal
minerals stored in bones which are two minerals essential for many
physiological processes.
calcium and phosphorous
stored within bone cavities. If needed,
the lipids are released into the blood and used by other tissues as a source of energy.
adipose tissue
mature bone matrix is normally about ___ organic and ___inorganic
material.
35 ; 65
The organic material consists primarily of
collagen and proteoglycans
The
inorganic material consists primarily of a calcium phosphate crystal called
hydroxyapatite
Brittle bone disease also known as
osteogenesis imperfecta
which means imperfect bone
formation, is a rare disorder caused by any one of a number of faulty genes that
results in either too little collagen formation, or poor quality collagen. As a result,
the bone matrix has decreased flexibility and is more easily broken than normal
bone.
brittle bone disease
bone-building cells. These cells have an extensive endoplasmic reticulum and numerous ribosomes
osteoblasts
Osteoblasts produce
collagen and proteoglycans
high concentrations of Ca2+ and
phosphate ions, forming crystals called
hydroxyapatite
The formation of new bone by osteoblasts is called
ossification or osteogenesis
This type of growth adds new layers to the outer surface of the existing material
appositional growth
Osteoblasts become
osteocytes
Osteocytes account for ___ of bone
cells and are very long-lived, with a life span of up to ____years.
90-95% ; 25 years
Osteocyte cell bodies are housed within the bone matrix in spaces called
lacunae
Osteocyte cell extensions are housed in narrow, long spaces called
canaliculi
are bone-destroying cells
osteoclast
Breakdown of bone is called
bone reabsportion
massive, multinucleated cells and develop from the red bone
marrow cells that also differentiate into specialized white blood cells.
osteoclasts
specialized reabsorption-specific area of the membrane.
ruffled border
Mature bone is called
lamellar bone
It is organized into thin, concentric sheets or layers, called
lamellae
These are mature bone cells located in small spaces called lacunae
osteocytes
Osteocytes are connected to each other through tiny channels that allows them to share nutrients and signals is called
canaliculi
looks porous and has a less dense structure than compact bone
spongy bone
spongy bone contains interconnecting rods or plates of bone known as
trabeculae
The spaces between trabeculae are filled with
bone marrow and blood vessels
forms the solid outer layer of bones and is denser with less space than spongy bone.
compact bone
Blood vessels penetrate this dense bone, running through the central canals.
compact bone
Compact bone also known as
cortical bone
The functional unit of
compact bone is an
osteon or haversian system
composed of concentric rings of matrix, which surround a central tunnel
and contain osteocytes.
osteon
an osteon resembles a circular target; the
bull’s-eye of the target is the
central canal
are lined with endosteum and contain blood vessels,
nerves, and loose connective tissue
central canals
Nutrients in the blood vessels are delivered to the
osteocytes
the center portion of the bone
diaphysis
It is composed primarily
of compact bone tissue, surrounding a hollow center called the
medullary cavity
The ends of a
long bone are called
epiphyses
are mostly
spongy bone, with an outer layer of compact bone.
epiphyses
Within joints, the end of a long
bone is covered with hyaline cartilage called
articular cartilage
located between the
epiphysis and the diaphysis
epiphyseal or growth plate
Growth in bone length occurs at the
epiphyseal plate
When bone stops growing in length, the epiphyseal plate becomes ossified
and is called the
epiphyseal line
The cavities of spongy bone and the medullary cavity are filled with
marrow
the site of blood cell formation
red marrow
mostly adipose
tissue.
yellow marrow
In the fetus, the spaces within bones are filled with
red marrow
connective tissue membrane covering
the outer surface of a bone
periosteum
single cell layer of connective tissue that
lines the internal surfaces of all cavities within bones, such as the medullary cavity
of the diaphysis and the smaller cavities in spongy and compact bone
endosteum
Intramembranous ossification of this membrane begins at approximately the eighth
week of embryonic development and is completed by approximately 2 years of age.
The locations in the membrane where intramembranous ossification begins are
called
centers of ossification
expand to form a bone
by gradually ossifying the membrane.
centers of ossification
have the oldest bone, and
the expanding edges the youngest bone
centers
soft spots, are the larger,
membrane-covered spaces between the developing skull bones that have not yet
been ossified
fontanels
The bones eventually grow together, and
all the fontanels have usually closed by ____ years of age.
2
The formation of cartilage begins at approximately the end of the _____ of theembryonic development
fourth week
Endochondral ossification of some of this cartilage starts at
approximately the
eighth week
produced by cells
called chondrocytes (KON-droh-sites), and has the approximate shape of the
future bone. The cartilage model is surrounded by perichondrium.
hyaline cartilage model
A hyaline cartilage model is produced by cells
called
chondrocytes
Once osteoblasts begin to produce bone, the
perichondrium becomes the
periosteum
The osteoblasts produce compact bone
on the surface of the cartilage model, forming a
bone collar
occurs as a result of continuous cell division of the
chondrocytes within the cartilage model.
Interstitial growth
occurs as a result
of cell division at the surface of the cartilage model, and under the
perichondrium.
appositional growth
hypertrophy or
enlarge
the chondrocytes in the center of the cartilage model
absorb some of the cartilage matrix resulting in
hypertrophy or enlargement
also initiate the formation of hydroxyapatite crystals
in the cartilage matrix
chrondrocytes
enlarged lacunae
with thin walls of calcified matrix is. result of
death of chrondrocytes
forms as osteoblasts produce bone on the surface of the calcified cartilage. The
osteoblasts transform the calcified cartilage of the diaphysis into spongy bone.
primary ossification center
Osteoclasts remove bone from the center of the diaphysis to
form the
medullary cavity and cells to form red bone marrow
created in the epiphyses by osteoblasts that migrate into the epiphysis. the spaces in the epiphyses do not
enlarge to form a medullary cavity as in the diaphysis.
Secondary ossification center
After a person’s bones have stopped growing, the epiphyseal plate regresses into
a “scar,
” called the
epiphyseal line
occurs between approximately 12 and 25 years of age,
depending on the bone and the individual.
closure of the epiphyseal plate,
bone that
becomes old is replaced with new bone in a process called
bone remodeling
localized mass of
blood released from blood vessels but confined within an organ or a space.
hematoma
mass of bone tissue that forms at a fracture site. Several days after the fracture, blood vessels grow into the clot
callus
produce collagen and other
extracellular materials to form granulation tissue, the precursor to healed tissue
fibroblast
a connective tissue that contains
collagen, ground substance, and other organic
molecules, as well as water and minerals.
bone
cartilage
covering
(reduces wear
and tear on the
joint surfaces)
cartilage
muscle to bone attachment
tendon
bone to bone
ligament
minimal movement (stabilizer)
ligament
Longer than
they are wide
long bones
Has a central
shaft
long bones
Mostly
located on the
upper and
lower limbs
long bones
This shape
enhances their
functional
movement of
the limbs.
long bones
Long as they
are wide.
short bones
Allows
stability and
facilitates
some
movement
short bones
Relatively
thin, flattened
shape.
flat bones
They are well
suited to
provide strong
barrier around
soft organs.
flat bones
Have shapes
that do not fit
readily into
the other
three
categories
irregular bones
Occurs when osteoblasts begin to
produce bone in connective tissue
membranes.
Primarily happens in skull and
clavicle.
intramembranous
Occurs when osteoblasts begin to
produce bone in the hyaline cartilage.
Primarily happens in bones except
skull and clavicle.
endochonral
Formation of bone by osteoblasts
bone ossification
Involves the synthesis of an organic
matrix containing collagen and
proteoglycans and the addition of
hydroxyapatite crystals to the matrix.
bone ossification
Can be either INTRAMEMBRANOUS or
ENDOCHONDRAL
bone ossification
Involves the removal of existing bone
by osteoclasts and the deposition of
new bone by osteoblasts
bone remodeling
Responsible for changes in bone
shape, bone repair, adjustment of
bone to stress, and calcium ion
regulation
bone remodeling
