Science 7.3-7.4 Flashcards
longer than they are wide
long bones
roughly cube shaped, nearly as wide as they are long
short bones
which often have the job of protecting vital organs
flat bones
Any bone that cannot be easily clas-sified into one of the first three categories is considered a
irregular bone
The bone’s shaft
diaphysis
each bulged end
epiphysis
gives the bone great strength and rigidity
compact bone
the dense compact bone is replaced by a lightweight, porous tissue called what
spongy bone
special tissue that manufactures red blood cells and white blood cells for the body’s circulatory and immune systems
red marrow
the core of the diaphysis is a hollow, cylindrical
cavity, like a tunnel running the length of the bone
medullary cavity
the red marrow in the medullary cavity is replaced by a fatty substance called
yellow marrow
The hardness of bone is caused by microscopic crystals of a mineral substance
hydroxyapatite
a tough, resilient protein that serves the same purpose as the steel rods in reinforced concrete, helping to prevent the mineral crystals from being pulled away from each other
collagen
special cells that constantly move through your bones, removing old materials to make room for new
Osteoclasts
move into the Haversian canals behind the osteoclasts, constructing new collagen fibers and hydroxyapatite crystals as they go; blood vessels also enter the canals, supplying the osteoblasts with nutrients
osteoblasts
, a disease in which the bones are weak and deformed
rickets
bones adjust their shapes to the physical stress placed upon them.
wolff’s law
cartilage forms were complete, osteoblasts began to move through them, replacing the soft, rubbery cartilage with collagen-reinforced hydroxyapatite
ossification
A break or crack in a bone
fracture
occurs when a bone breaks cleanly in two
transverse fracture
the bone cracks and bends but remains held together by its collagen fibers
a greenstick fracture
bone is twisted or exposed to sudden impact at either end
spiral fracture
when part of a bone is broken into multiple fragments.
comminuted fracture
occurs when a bone cracks or breaks but does not pierce through the skin
simple fracture
occurs when the broken bone pierces through the skin
compound fracture
places where bones join
joints
they join the bones rigidly together
immovable joints
they make some bending and twisting movements possible
slightly movable joints
allow a wide range of motion
freely movable joints
bones are held together by strong bands of fibrous connective tissue called what
ligaments
fluid that lubricates joints
synovial fluid
allows a bone to move back and forth in a single plane, like a door swinging on its hinges
hinge joints
The most freely movable joints
ball-and-socket joints
type of joint that allows only rotating
movement
pivot joint
in which one bone merely slides across the surface of another
gliding joint
a saddle-shaped portion of one bone nestles into a saddle-shaped portion of another bone
saddle joint
inflammation of the joints
arthiritus
when the ligaments of a joint are overstressed
sprain
a joint is overstressed to the extent that a bone pops out of alignment and must be relocated
dislocation
primary function is to move the parts of the skeleton
skeletal muscles
specialized for relatively slow, powerful, and prolonged contractions
smooth muscles
