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234 Cards in this Set

  • Front
  • Back
The four classes of bone according to shape are
long, short, flat, and irregular.
Examples of long bones are
forearm and thigh bones.
Short bones are shaped like
cubes.
Examples of short bones are
wrist bones and ankle bones.
Flat bones are
platelike structures.
Examples of flat bones are
some skull bones, ribs, and scapulae.
Irregular bones have
a variety of shapes.
Examples of irregular bones are
vertebrae and some facial bones.
Round bones are also called
sesamoid bones.
Sesamoid bones are
small and nodular and embedded within tendons adjacent to joints.
An example of a sesamoid bone is
the patella.
An expanded end of a long bone is called
an epiphysis.
An epiphysis articulates
with another bone.
Articular cartilage is located
on the articulating portion of an epiphysis.
The shaft of a long bone is called
a diaphysis
The shaft of a long bone is called
a diaphysis.
Periosteum is
a tough, vascular, fibrous membrane covering the diaphysis of a bone.
Periosteum functions
to form and repair bone tissue.
Processes provide
sites for attachments of tendons or ligaments.
The wall of the diaphysis is composed of
compact bone.
Compact bone has
a continuous extracellular matrix with no gaps.
The epiphyses are largely composed
of spongy bone.
Spongy bone consists of bony plates called
trabeculae.
A bone usually has
compact bone overlying spongy bone with the relative amounts of each varying in differently shaped bones.
A semirigid tube with a hollow chamber called
the medullary cavity runs through the diaphysis.
Endosteum lines the
medullary cavity and spaces of spongy bone.
Endosteum contains bone
forming cells.
The tissue that fills the spaces of bone is called
marrow.
The two forms of marrow are red
and yellow.
Bone cells are called
osteocytes
Lacunae are
tiny, chambers that contain osteocytes.
Lacunae form
concentric canals around central canals.
Osteoctyes transport
nutrients and wastes to and from nearby cells.
Cellular processes of osteocytes pass through
canaliculi.
The extracellular matrix of bone is composed of
collagen and inorganic salts.
An osteon
is a cylinder shaped unit of compact bone.
The substance of compact bone is formed from
many osteons cemented together
Each central canal contains
blood vessels and nerves.
Perforating canals connect
central canals of osteons.
Perforating canals contain
larger blood vessels and nerves.
Spongy bone is also composed of
osteocytes and extracellular material.
Unlike compact bone the bone cells do not aggregate around
central canals. Instead the cells lie within trabeculae.
Osteocytes get nutrients from
substances diffusing into canaliculi that lead to the surface of trabeculae
Parts of the skeleton begin to form
during the first few weeks of prenatal development.
Bony structures continue to grow until
adulthood.
Bones form by
replacing existing connective tissues.
Intramembranous bones originate
within sheetlike layers of connective tissue.
Endochondral bones originate as
masses of cartilage that are later replaced by bone tissue.
Examples of intramembranous bones are
the broad, flat bones of the skull.
Osteogenesis is
bone development.
During their development
membranelike layers of relatively undifferentiated connective tissue appear
Dense networks of blood vessels supply
the connective tissue layers.
Osteoblasts are bone
forming cells.
Osteoblasts deposit
bony matrix around themselves.
Spongy bone can become
compact bone as spaces fill with bone matrix.
As development continues, osteoblasts may become
surrounded by matrix.
Extracellular matrix enclosing the processes of osteoblasts gives rise to
canaliculi
Once isolated, osteoblasts become
osteocytes.
Periosteum comes from cells of
the undifferentiated connective tissue that persist outside of the developing bone
Compact bone
is formed by osteoblasts on the inside of periosteum.
Intramembranous ossification
is the process of replacing connective tissue to form an intramembranous bone
Endochondral Bones
Most of the bones of the skeleton are endochondral bones
Endochondral bones develop as
masses of hyaline cartilage. Eventually the cartilage decomposes.
As the cartilage decomposes
a periosteum forms from connective tissue that encircles the developing structure.
Blood vessels and undifferentiated connective tissue cells invade
the disintegrating tissue.
Some of the cells differentiate into
osteoblasts.
Osteoblasts form
spongy bone in the spaces previously housed by cartilage.
Endochondral ossification
is the process of forming an endochondral bone by the replacement of hyaline cartilage.
The primary ossification center
is an area in the diaphysis of a long bone in which the bony tissues begin to replace hyaline cartilage.
Secondary ossification centers appear
in epiphyses.
The epiphyseal plate
is a band of cartilage between the primary and secondary ossification centers.
In a long bone, the diaphysis is separated from the epiphysis by
an epiphyseal plate.
The cartilaginous cells form
four layers.
The first layer is composed of
resting cells that do not actively participate in growth.
The first layer anchors
the epiphyseal plate to the bony tissue of the epiphysis.
The second layer includes rows of
many young cells undergoing mitosis.
As new cells appear
the cartilaginous plate thickens.
The third layer is formed by
older cells that are left behind as new cells appear.
The cells of the third layer enlarge and thicken
the epiphyseal plate.
The fourth layer is composed of
dead cells and calcified extracellular matrix.
Osteoclasts break down
calcified matrix of bone.
Osteoclasts originate from
monocytes
Osteoclasts secrete acids that
dissolve the inorganic component of the calcified matrix, and their lysosomal enzymes digest the organic components.
Osteoclasts
phagocytize components of the bony matrix.
After osteoclasts remove the extracellular matrix, osteoblasts
invade the region and deposit bone tissue in place of calcified cartilage.
A long bone continues to lengthen while
the cartilaginous cells of the epiphyseal plates are active
Lengthening of the bone is no longer possible once
the ossification centers of the diaphysis and epiphysis meet and the epiphyseal plates ossify.
The medullary cavity forms when
osteoclasts erode bone tissue in the diaphysis
The bone in the central regions of the epiphyses and diaphysis remains
spongy
Hyaline cartilage on the ends persists as
articular cartilage.
Throughout life, osteoclasts
resorb bone tissue and osteoblasts replace bone
About _____% of bone calcium is exchanged each year
3 to 5
Factors that affect bone development, growth and repair include
nutrition, exposure to sunlight, hormonal secretions, and physical exercise.
Vitamin D is necessary for
proper absorption of calcium.
Lack of vitamin D can lead to
the diseases rickets and osteomalacia.
Vitamin A is necessary for
osteoblast and osteoclast activity during normal development.
Vitamin C is required for
collagen synthesis.
Growth hormone stimulates
division of cartilage cells in epiphyseal plates.
In children, the absence of growth hormone leads to
pituitary dwarfism.
An excess of growth hormone before the epiphyseal plates ossify leads to
pituitary gigantism.
In adults, an excess of growth hormone leads to
acromegaly
Thyroxine can
halt bone growth by causing premature ossification of the epiphyseal plates.
Parathyroid hormone
stimulates an increase in the number and activity of osteoclasts which break down bone.
Sex hormones promote
formation of bone tissue.
Sex hormones also stimulate
ossification of the epiphyseal plates.
Females typically reach their maximum heights
earlier than males because the effects of estrogen on the epiphyseal plates are stronger than testosterone
Physical stress stimulates
bone growth
Bones give shape to structures such as
the head, face, thorax, and limbs.
The bones of lower limbs, pelvis, and vertebral column support
the body’s weight.
The bones of the skull protect
the eyes, ears, and brain.
The bones of the thorax protect
the heart and lungs.
Bones of the pelvic girdle protect
lower abdominal and internal reproductive organs
Hematopoiesis
is blood cell formation.
Blood cell formation begins
in the yolk sac.
Later in development, blood cells are made in
the liver, the spleen, and red bone marrow.
Marrow
is a soft, netlike mass of connective tissue within the medullary cavities of bond bones, in the irregular spaces of spongy bone, and in the larger central canals of compact bone tissue.
Red marrow functions
in the formation of red blood cells, white blood cells, and platelets.
Red marrow occupies
the cavities of most bones in an infant.
With increasing age, yellow marrow replaces
red marrow.
Yellow marrow stores
fat
In an adult, red marrow is primarily found in
the spongy bone of the skull, ribs, sternum, clavicles, vertebrae, and hipbones.
Extracellular matrix of bone tissue includes
collagen and inorganic mineral salts
The salts account for about ____% of the extracellular matrix by weight
70
Hydroxyapatites
are tiny crystals of calcium phosphate.
The body requires calcium for
many metabolic processes including blood clot formation, nerve impulse conduction, and muscle cell contraction.
When blood calcium is low
parathyroid hormone stimulates osteoclasts to break down bone tissue to release calcium salts.
Very high blood calcium levels
inhibit osteoclast activity
Calcitonin stimulates osteoblasts to form
bones
Bone tissue contains lesser amounts of
magnesium, sodium, potassium and carbonate ions.
The number of bones in a human skeleton is around
206
Flat bones of the skull are
tightly joined by sutures.
Two major portions of the skeleton are
axial and appendicular.
The axial skeleton contains
skull bones, middle ear bones, the hyoid bone, vertebral column bones, and thoracic cage bones.
The skull is composed
of 8 cranial bones and 14 facial bones.
The hyoid bone supports
the tongue and is attachment for certain muscles that help move the tongue
The hyoid bone is located
in the neck between the lower jaw and the larynx.
The vertebral column consists of
vertebrae, a sacrum, and coccyx.
The distal end of the column is formed by
the sacrum and the coccyx.
Thyroxine can
halt bone growth by causing premature ossification of the epiphyseal plates
The thoracic cage is composed of
12 pairs of ribs and the sternum.
Parathyroid hormone
stimulates an increase in the number and activity of osteoclasts which break down bone
The pectoral girdle is formed by
scapulae and clavicles.
The pectoral girdle is formed by
scapulae and clavicles.
The pectoral girdle connects
the bones of the upper limb to the axial skeleton.
Sex hormones also stimulate
ossification of the epiphyseal plates
The pectoral girdle aids
in upper limb movements.
Each upper limb consists of
a humerus, radius, ulna, carpals, metacarpals, and phalanges
Females typically reach their maximum heights
earlier than males because the effects of estrogen on the epiphyseal plates are stronger than testosterone
The humerus, radius, and ulna articulate at
the elbow.
The wrist bones are called
carpals.
Physical stress stimulates
bone growth
Bones of the pelvic girdle protect

lower abdominal and internal reproductive organs
Hematopoiesis

is blood cell formation
Blood cell formation begins

in the yolk sac
Later in development, blood cells are made

in the liver, the spleen, and red bone marrow.
Marrow

is a soft, netlike mass of connective tissue within the medullary cavities of bond bones, in the irregular spaces of spongy bone, and in the larger central canals of compact bone tissue.
Red marrow functions

in the formation of red blood cells, white blood cells, and platelets.
Red marrow occupies

the cavities of most bones in an infant.
With increasing age, yellow marrow replaces

red marrow
Yellow marrow stores

fat
In an adult, red marrow is primarily found in

the spongy bone of the skull, ribs, sternum, clavicles, vertebrae, and hipbones
Extracellular matrix of bone tissue includes

collagen and inorganic mineral salts
The salts account for about ____% of the extracellular matrix by weight

70
Hydroxyapatites

are tiny crystals of calcium phosphate
The body requires calcium for

many metabolic processes including blood clot formation, nerve impulse conduction, and muscle cell contraction
When blood calcium is low

parathyroid hormone stimulates osteoclasts to break down bone tissue to release calcium salts
Very high blood calcium levels

inhibit osteoclast activity
Calcitonin stimulates osteoblasts to form

bones
Bone tissue contains lesser amounts of

magnesium, sodium, potassium and carbonate ions
The number of bones in a human skeleton is around

206

Flat bones of the skull are

tightly joined by sutures
Two major portions of the skeleton are-

axial and appendicular
The axial skeleton contains

skull bones, middle ear bones, the hyoid bone, vertebral column bones, and thoracic cage bones
The skull is composed

of 8 cranial bones and 14 facial bones
The hyoid bone supports

the tongue and is attachment for certain muscles that help move the tongue
The hyoid bone is located

in the neck between the lower jaw and the larynx
The vertebral column consists of

vertebrae, a sacrum, and coccyx
The distal end of the column is formed by

the sacrum and the coccyx
The coccyx is also called the

tailbone
The thoracic cage is composed of

12 pairs of ribs and the sternum
The appendicular skeleton consists of

bones of the pectoral girdle, upper limbs, pelvic girdle, and lower limbs
The pectoral girdle is formed by

scapulae and clavicles
The pectoral girdle connects

the bones of the upper limb to the axial skeleton
The pectoral girdle aids

in upper limb movements
Each upper limb consists of

a humerus, radius, ulna, carpals, metacarpals, and phalanges
The humerus, radius, and ulna articulate at

the elbow
The wrist bones are called

carpals
The bones of the palm are called

metacarpals
The pelvic girdle is formed by

two coxae bones
Bones in the fingers are called

phalanges
A human skull usually consists of
22 bones
Sinuses are air
filled cavities in cranial bones
Sinuses
reduce the weight of the skull and increase the intensity of the voice by serving as resonant sound chambers
The eight bones of the cranium are
1 frontal bone, 2 parietal bones, 1 occipital bone, 2 temporal bones, 1 sphenoid bone and 1 ethmoid bone
The facial skeleton consists of
13 immovable bones and a movable lower jaw bone
At birth, the skull is incompletely developed with
fibrous membranes connecting the cranial bones
Fontanels
are membranous areas of an infantile skull
Fontanels permit
some movement between the bones so that the developing skull is partially compressible and can slightly change shape
Eventually fontanels
close and cranial bones grows together.
The vertebral column extends
from the skull to the pelvis and forms the vertical axis of the skeleton
The vertebral column is composed of
vertebrae that are separated by intervertebral discs
The vertebral column supports
the head and the trunk of the body
The vertebral column protects
the spinal cord
The spinal cord passes through

a vertebral canal
An infant has
33 separate bones in the vertebral column
The sacrum is formed by
five fused vertebrae
The coccyx is formed by
four fused vertebrae
An adult vertebral column has
26 bones
The four curvatures of the vertebral column are
thoracic, sacral, cervical, and lumbar
The cervical curvature develops when
a baby begins to hold up its head
The lumbar curvature develops when
a child begins to stand.
There are ___ cervical vertebrae
7
The atlas is the ____ vertebra
1st cervical
The axis is the _____ cervical vertebra
second
The dens
is a process that projects upward and lies in the ring of the atlas as the head is turned from side to side, the atlas pivots around the dens.
There are ___ thoracic vertebrae
12
The facets of thoracic vertebrae articulate with
ribs
There are ____ lumbar vertebrae
second
Lumbar vertebrae are located
in the small of the back
The coccyx
is the lowest part of vertebral column Sitting presses on the coccyx, and it moves forward, acting like a shock absorber.
The thoracic cage includes
the ribs, thoracic vertebrae, the sternum, and the costal cartilages that attach the ribs to the sternum
The usual number of ribs is
24
The true ribs are the first
7 pairs of ribs
The false ribs are the
last five pairs of ribs
Floating ribs are
the last two pairs of false ribs
The four parts of the pectoral girdle are
two clavicles and two scapulae
The pectoral girdle supports
the upper limbs and is an attachment for several muscles that move the arm
Usually the female iliac bones compared to male
flared than those of the male The female hips are usually wider than those of the male The angle of the female pubic arch may be greater than that of the male The female pelvic cavity is usually wider in all diameters than that of the male The bones of the female pelvis are lighter and show less evidence of muscle attachments.
Bone Life Span Changes
incremental decrease in height begins at about age 30.
Compression fractures of the vertebrae may contribute to loss of height. As calcium levels fall, bones become brittle and prone to fracture
As you age
osteoclasts come to outnumber osteoblasts
By age 35 all adults start to
lose bone mass
Trabecular bone shows signs of aging
first
Compact bone loss begins around the age of
40
To preserve skeletal health
avoid falls, take calcium supplements, get enough vitamin D, avoid carbonated beverages, and get regular exercise