Chapter 6 & 7 Flashcards
Ligaments
strong bands of fibrous connective tissue that attach to
bones and hold them together. bones-bones
tendons
strong bands of connective tissue that attach skeletal muscles to bones; muscles-bones
chondroblasts
Hyaline cartilage consists of these specialized cartilage producing cells
chondrocyte
When matrix surrounds a chondroblast, it becomes this rounded cell that occupies a space called a lacuna within the matrix.
perichondrium
double-layered connective tissue sheath covering most cartilage
Articular cartilage
cartilage covering the ends of bones where they come together to form joints, has no perichondrium, blood vessels, or nerves.
appositional growth
chondroblasts in the perichondrium add new cartilage to the outside edge of the existing cartilage.
interstitial growth
chondrocytes within the tissue divide and add more matrix between the existing cells
hydroxyapatite
The inorganic material within the bone matrix that consists
primarily of a calcium phosphate crystal
Osteoblasts
bone-forming cells that have an extensive endoplasmic reticulum and numerous ribosomes.
matrix vesicles
Osteoblasts also release these membrane-bound sacs formed when the plasma membrane buds, or protrudes outward, and pinches off.
Ossification or osteogenesis
formation of bone by osteoblasts.
osteocyte
Once an osteoblast becomes surrounded by bone matrix,
lacunae
The spaces occupied by the osteocyte cell bodies
canaliculi
the spaces occupied by the osteocyte cell processes
Osteoclasts
responsible for the reabsorption, or breakdown, of bone.
ruffled border
Where the plasma membrane of osteoclasts contacts bone matrix and forms many projections
stem cells
Some of the mesenchymal cells become stem cells, which can replicate and give rise to more specialized cell types.
Osteochondral progenitor cells
stem cells that can become osteoblasts or chondroblasts.
Osteogenesis imperfecta
also known as brittle bone disorder. This connective tissue disease is caused by a gene mutation that leads to the production of less collagen than normal or collagen that is abnormal in structure.
woven bone
collagen fibers are randomly oriented in many directions; first formed during fetal development or during the repair of a fracture.
bone remodeling
The process of removing old bone and adding new bone
Lamellar bone
mature bone that is organized into thin sheets or layers called lamellae
spongy bone
consists of interconnecting rods or plates of bone called trabeculae; Between the trabeculae are spaces that, in life, are filled with bone marrow and blood vessels.
Compact bone
denser and has fewer spaces than spongy bone
central canals
contain vessels that run parallel to the long axis
of the bone; lined with endosteum and contain blood
vessels, nerves, and loose connective tissue.
Concentric lamellae
circular layers of bone matrix that surround a common center, the central canal.
osteon or haversian system
consists of a single central canal, its contents, and associated concentric lamellae and osteocytes.
circumferential lamellae
forms the outer surfaces of compact bone; thin plates that extend around the bone
interstitial lamellae
Between the osteons; remnants of concentric or circumferential lamellae that were partially removed during bone remodeling.
perforating canals
how blood vessels from the periosteum or medullary cavity enter the bone; run perpendicular to the long axis of the bone
Long bones
longer than they are wide. Most of the bones of the upper and lower limbs are long bones.
Short bones
round or nearly cube-shaped; bones of the wrist (carpal bones) and ankle (tarsal bones).
Flat bones
have a relatively thin, flattened shape and are usually curved; certain skull bones, the ribs, the breastbone (sternum), and the shoulder blades (scapulae).
Irregular bones
vertebrae and facial bones; have shapes that do not fit readily into the other three categories.
diaphysis or shaft
composed primarily of compact bone, but it can also contain some spongy bone.
articular cartilage
Within joints, the end of a long bone is covered with this hyaline cartilage
epiphysis
part of a long bone that develops from a center of ossification distinct from that of the diaphysis.
Epiphyseal plate
growth plate; Area of hyaline cartilage between the diaphysis and epiphysis; cartilage growth followed by endochondral ossification results in growth in bone length
epiphyseal line
When bone stops growing in length, the epiphyseal plate becomes ossified and is called the epiphyseal line
Medullary cavity
Large cavity within the diaphysis
Periosteum
Double-layered connective tissue membrane covering the outer surface of bone except where articular cartilage is present; ligaments and tendons attach to bone through the periosteum; blood vessels and nerves from the periosteum
supply the bone; the periosteum is where bone grows in diameter
perforating fibers or Sharpey fibers
bundles of collagen fibers that strengthen the attachment of the tendons or ligaments to the bone.
Endosteum
Thin connective tissue membrane lining the inner cavities of bone
sinuses
air-filled spaces some of the flat and irregular bones of the skull have, which are lined by mucous membranes.
intramembranous ossification and endochondral ossification
During fetal development, bone forms in these two patterns which initially produce woven bone, that is
then remodeled and they both look the same: intramembranous ossification (takes place in connective
tissue membranes) and endochondral ossification (takes place in cartilage)
centers of ossification
The locations in the membrane where ossification begins
fontanels or soft spots
The larger, membrane-covered spaces between the developing skull bones that have not yet been ossified
hyaline cartilage model
what the chondroblasts produce as a map of the approximate shape of the bone that will later be formed
bone collar
when the osteoblasts produce compact bone on the surface of the cartilage model
hypertrophy
enlarge
calcified cartilage
when the chondrocytes release matrix vesicles, which initiate the formation of hydroxyapatite crystals in the cartilage matrix.
primary ossification center
area of diaphysis bone formation where the osteoblasts produce bone on the surface of the calcified cartilage, forming bone trabeculae, which changes the calcified
cartilage of the diaphysis into spongy bone.
secondary ossification centers
additional sites of ossification that appear in the epiphyses
zone of resting cartilage
nearest the epiphysis and contains randomly arranged
chondrocytes that do not divide rapidly.
zone of proliferation
The chondrocytes here produce new cartilage through interstitial cartilage growth.
zone of hypertrophy
here the chondrocytes produced in the zone of proliferation mature and enlarge.
zone of calcification
very thin and contains hypertrophied chondrocytes and calcified cartilage matrix. The hypertrophied chondrocytes die, and blood vessels from the diaphysis grow into the area.
rickets
Insufficient vitamin D in children causes this disease resulting from reduced mineralization of the bone matrix.
“adult rickets” or osteomalacia
softening of the bones as a result of calcium depletion.
Vitamin C
necessary for collagen synthesis by osteoblasts. In
children, vitamin C deficiency can retard growth.
scurvy
In both children and adults, vitamin C deficiency can result in scurvy, which is marked by ulceration and hemorrhage in almost any area of the body because normal collagen synthesis is not occurring in connective tissues.
Growth hormone
from the anterior pituitary increases general tissue growth, including overall bone growth, by stimulating interstitial cartilage growth and appositional bone growth.
Thyroid hormone
also required for normal growth of all tissues, including cartilage; therefore, a decrease in this hormone can result in a smaller individual.
Sex hormones
also influence bone growth. Estrogen and testosterone initially stimulate bone growth, which accounts for the burst of growth at puberty, when production of these hormones increases.
bone remodeling
when bone that becomes old is replaced with new bone
basic multicellular unit (BMU)
a temporary assembly of osteoclasts and osteoblasts that travels through or across the surface of bone, removing old bone matrix and replacing it with new bone matrix.
hematoma
localized mass of blood released from blood vessels but confined within an organ or a space.
callus
mass of tissue that forms at a fracture site and connects the broken ends of the bone.
internal callus
forms between the ends of the broken bone, as well as in the marrow cavity if the fracture occurs in the diaphysis of a long bone.
external callus
forms a collar around the opposing ends of the bone fragments.
Parathyroid hormone (PTH)
major regulator of blood Ca 2+ levels. PTH, secreted from the parathyroid glands when blood Ca 2+ levels are too
low, stimulates an increase in the number of osteoclasts, which break down bone and elevate blood Ca 2 + levels
receptor for activation of nuclear factor kappaB ligand (RANKL)
When PTH binds to these receptors, these cells respond by producing this
receptor for activation of nuclear factor kappaB (RANK)
RANKL is expressed on the surface of the osteoblasts and stem cells and can combine with RANK found on
the cell surfaces of osteoclast precursor cells.
osteoprotegerin (OPG)
Osteoclast production is inhibited by OPG, which is secreted by osteoblasts and stem cells.
Calcitonin
secreted from the thyroid gland when blood Ca 2+ levels are too high, decreases osteoclast activity by binding to receptors on the osteoclasts.
open fracture (compound)
occurs when an open wound extends to the site of the
fracture or when a fragment of bone protrudes through the skin.
closed fracture (simple)
If the skin is not perforated in a fracture
complicated fracture
If the soft tissues around a closed fracture are damaged
incomplete fracture
does not extend completely across the bone
complete fracture
the bone is broken into at least two fragments.
greenstick fracture
An incomplete fracture that occurs on the convex side of the curve of the bone
Hairline fractures
incomplete fractures in which the two sections of bone do not separate; common in the skull.
comminuted fracture
complete fracture in which the bone breaks into more than two pieces—usually two major fragments and a smaller fragment.
impacted fracture
one fragment is driven into the spongy portion of the other
fragment.
Linear fractures
run parallel to the long axis of the bone
transverse fractures
right angles to the long axis.
Spiral fractures
take a helical course around the bone
oblique fractures
run obliquely in relation to the long axis
Dentate fractures
have rough, toothed, broken ends
stellate fractures
have breakage lines radiating from a central point.
hormone replacement therapy (HRT)
decreases osteoclast numbers by inhibiting the production of RANKL
Statins
drugs that inhibit cholesterol synthesis; they also stimulate osteoblast activity
bisphosphonates
concentrate in bone.
tubercle or process
If a bone possesses a tubercle (lump) or a process (projection), most likely a ligament or tendon was attached to that tubercle or process during life.
foramen
If the bone has a foramen in it, that foramen was
the opening through which a nerve or blood vessel passed.
sinuses
mucous membrane–lined air spaces that some skull bones contain
axial skeleton
composed of the skull, auditory ossicles, hyoid bone, vertebral column, and rib cage, or thoracic cage.
skull or cranium
protects the brain; supports the organs of vision, hearing, smell, and taste; and provides a foundation for the structures that take air, food, and water into the body.
calvaria or skullcap
The top of the skull
parietal bones
The paired parietal bones are joined at the midline by the sagittal suture
frontal bone
the parietal bones are connected to the frontal bone by the coronal suture
occipital bone
The parietal bones are joined to the occipital bone by the lambdoid suture .
sutural bones
extra small bones that form along the lambdoid suture.
external occipital protuberance
present on the posterior surface of the occipital bone