2. Anatomy and Physiology of
Bones
• The bones provide attachment sites for
muscles, enabling complex movement.
• Bones also support and protect internal
organs.
• The organs of the skeletal system are
largely composed of connective
tissues, including bone and cartilage.
• Connective tissue contains cells
separated by matrix that contains
fibers.
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4. Structure of Bone
• The matrix of bone contains mineral salts.
• Bone cells are osteocytes and they lie in tiny
chambers called lacunae.
• Compact bone is highly organized into tubular
osteons, each with a central canal.
• Spongy bone has an unorganized appearance
but is designed for strength.
• Spaces in spongy bone contain red bone
marrow that produces blood cells.
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6. Tissues Associated with Bones
Cartilage
Cartilage has a gel-like matrix with
collagen and elastin fibers; it lacks blood
vessels.
Hyaline cartilage is glassy and is found in
the nose, ends of ribs, and in the larynx.
Fibrocartilage is stronger with thicker
collagen fibers and is found in the disks
between vertebrae.
Elastic cartilage has mainly elastin fibers
and is in the ear flaps and epiglottis.
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7. Dense Fibrous Connective Tissue
Dense fibrous connective tissue contains
fibroblasts are separated by bundles of
collagen fibers.
This type of tissue is found at the flared
sides of the nose, in ligaments that
bind bone to bone, and in tendons that
connect muscles to bone.
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8. Structure of a Long Bone
Bone is covered by fibrous connective
tissue called the periosteum.
The diaphysis (shaft) of a long bone has
a medullary cavity of yellow bone
marrow containing fat.
Hyaline articular cartilage covers the
ends of bones at the joint.
Epiphyses of bones have spongy bone.
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9. Development of bone tissue
Also called osteo genesis or
ossification
Long short and irregular bones develop
in the fetus from rods of cartilage
model
Flat bones develop from membrane
model
Sesamoid bones from tendon model
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10. Bone Growth and Repair
Remodeling of Bones
Bone is a living tissue that is constantly
broken down and built up.
Osteoclasts are derived from monocytes
and break down bone and deposit
calcium in the blood.
Osteoblasts then rebuild the bone and
some become osteocytes in lacunae.
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11. Bone Development and Growth
The embryonic human skeleton is at first
hyaline cartilage, but it is later replaced
by a bony skeleton in a process of
endochondral ossification.
Osteoblasts form a primary ossification
center.
A band of cartilage called a growth plate
separates it from the secondary
ossification center.
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13. • During childhood, long bones continue
to lengthen because of the epiphysis
plate at each side of the bone, which is
made of cartilages continuously
produce new cartilage on its
diaphyseal surface
• This cartilage is then turned to bone
• As long as the cartilage production
matches the rate of ossification the
bone continues to grow and lengthen
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14. Hormonal regulation of bones
Growth hormone and thyroid hormones
Testosterone and oestrogens
Calcitonin and parathyroid hormone
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15. 1. Bones of the Skeleton
The skeleton:
• Supports the body;
• Protects soft body parts;
• Permits flexible movement;
• Blood cells production; and
• Storage for mineral salts, particularly
calcium phosphate.
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16. Classification of the Bones
• The 206 bones of the human may be
classified according to their shape or
whether they are in the axial skeleton
or appendicular skeleton.
• Shapes include long bones, short
cube-shaped bones, flat bones, round
bones, and irregular bones such as
vertebrae.
• The bones are not smooth but have
knobs and processes where muscles
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18. The Axial Skeleton
• The axial skeleton lies in the midline of
the body and consists of the skull, the
hyoid bone, the vertebral column, and
the rib cage.
The Skull
• The skull contains the cranium, which
protects the brain, and also includes
the facial bones.
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19. • Newborns have incomplete skull
bones with membranous fontanels that
grow closed by 16 moths.
• Some skull bones contain sinuses.
• Infections in the mastoid sinuses can
lead to mastoiditis, an inflammation
that can lead to deafness.
• The major bones of the cranium
include the frontal, parietal, temporal,
occipital, ethmoid, and sphenoid
bones.
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22. • At the base of the occipital bone is the
foramen magnum through which the
spinal cord attaches to the brain.
The Facial Bones
• The facial bones include the mandible
(lower jaw), maxillae (upper jaw and
anterior hard palate), zygomatic bones
(cheek bones), and the nasal bones.
• Ears are only elastic cartilage.
• The nose is a mixture of bones,
cartilage, and fibrous connective
tissue.
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24. The Hyoid Bone
• The hyoid bone located above the
larynx is the only bone in the body that
does not articulate with another bone.
• The hyoid bone anchors the tongue
and serves as the site of attachment
for the muscles associated with
swallowing.
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25. The Vertebral Column
• The vertebral column consists of 33
vertebrae, and supports the head and
trunk, protects the spinal cord and
roots of spinal nerves, and serves as a
site for muscle attachment.
• Scoliosis is a sideways curvature of
the spine.
• The first and second cervical vertebrae
are the atlas and axis that allow the
head to pivot.
• Intervertebral discs act as padding.
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27. The Rib Cage
• The rib cage is composed of the
thoracic vertebrae, the ribs with their
associated cartilages, and the
sternum.
• The rib cage protects the heart and
lungs, and expands during inhalation.
The Ribs
• There are 12 pairs of ribs attached to
the thoracic vertebrae.
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28. • The upper seven pairs of the ribs
attach to the sternum (true ribs); the
next three pairs connect indirectly to
the sternum by means of common
cartilage (false ribs), and the last two
pairs are called floating ribs because
they have no connection at all to the
sternum.
The Sternum
• The sternum consists of the
manubrium, the body, and the xiphoid
process that fuse during fetal
development.
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30. The Appendicular Skeleton
• The appendicular skeleton consists of
the bones of the pectoral girdle, arms,
pelvic girdle, and legs.
The Pectoral Girdle and Arm
• The pectoral girdle includes the clavicle
(collarbone) and scapula (shoulder
blade).
• The arm is made up of the humerus
(upper arm), and ulna and radius
(forearm).
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31. • Tendons forming a socket for the humerus
are the rotator cuff.
• Vigorous rotations of the arm can damage
the rotator cuff muscles and tendons.
• The glenoid cavity of the scapula also
articulates with the humerus.
• The bones of the hand are: eight carpal
bones, five metacarpal bones, and
phalanges of the fingers and thumb.
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38. The Pelvic Girdle and Leg
The pelvic girdle is made of two coxal
bones; the pelvis is composed of the
pelvic girdle, sacrum, and coccyx.
In the leg, the femur is the longest and
strongest bone; the femur articulates
with the coxal bones at the acetabulum.
The patella is the kneecap and the tibia
and fibula form the lower leg.
Bones of the foot are: tarsal bones,
calcaneus (heel), metatarsal bones, and
phalanges.
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41. Differences between the male
pelvic and female
The shape of the female pelvic allows
for the passage of the baby
The female pelvic have lighter bones
More shallow and rounded brim
Generally roomier
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47. 2. JOINTS
• A joint is the site at which any two or
more bones articulate or come
together
• Joints allow flexibility and movements
of the skeleton and allow attachment
between bones
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48. Articulations/JOINTS
• There are three types of joints
(articulations):
• Fibrous joints such as the sutures of
the cranium, are immovable.
• Cartilaginous joints, like those
between the ribs and sternum or the
vertebral discs, are slightly movable.
• Synovial joints consist of a membrane-
lined synovial capsule that is freely
movable.
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52. Characteristic of synovial
Joints
All synovial joints have certain
common characteristics
• Articular or hyaline cartilage- reduce
shock and friction.
• Has a joint fibrous Capsule or capsular
ligaments- for structural support and
stability.
• Synovial membrane which secretes
synovial fluids- assist in nourishment and
reduce friction.
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53. The of synovial fluids
1. Nourishes the structures within the
joint cavity
2. phagocytosis
3. Acts as a lubricant
4. Prevents the ends of the bones from
being separated
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55. • The knee, which is a synovial joint,
also has pads of cartilage called
menisci that add stability to uneven
surfaces within the knee, along with
fluid-filled sacs called bursae that ease
friction between the tendons and
ligaments.
• There are different kinds of synovial
joints based on the movements they
permit.
• Most movable are the ball-and-socket
joints, such as the shoulder or hip
joints.
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57. 3. Skeletal Muscles
Humans have three types of muscle tissue:
• Smooth muscles lack striations and
comprise involuntary muscle in internal
organs.
• Cardiac muscle cells are striated,
cylindrical and branched; fibers are
intercalated to allow contractions to
spread quickly.
• Skeletal muscle fibers are striated,
multinucleate, and voluntary.
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58. Skeletal Muscles Work in Pairs
• Skeletal muscle is covered in layers of
fibrous connective tissue called fascia.
• A skeletal muscle has an origin on the
stationary bone; the end of the muscle
that moves is the insertion.
• Prime movers do most of the work but
are assisted by synergists.
• Whole muscles work in antagonistic
pairs; for example, the biceps flexes the
lower arm and the triceps extends it.
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61. Nomenclature
Skeletal muscles are named according
to:
• muscle size,
• muscle shape,
• location,
• direction of fibers,
• number of attachments, and
• action of the muscle.
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69. Mechanism of Muscle Fiber
Contraction
• The sarcolemma (plasma membrane)
of a muscle fiber forms transverse
tubules (T tubules) that extend into the
fiber and almost touch the
sarcoplasmic reticulum which stores
calcium ions.
• The sarcoplasmic reticulum encases
hundreds up to thousands of
myofibrils, the contractile portions of
muscle fibers.
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78. Myofibrils and Sarcomeres
• Myofibrils that run the length of a
muscle fiber are divided into
contractile units called sarcomeres.
• A sarcomere extends between two
dark lines called Z lines.
• The arrangement of myosin (thick)
filaments and actin (thin) filaments in a
sarcomere accounts for striations or
banding patterns of myofibrils.
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80. Sliding Filaments
Impulses travel through T tubules to the
sarcoplasmic reticulum, which releases
Ca2+, and the muscle fiber contracts.
When sarcomeres shorten, actin filaments
slide past myosin filaments.
The movement of actin filaments in relation
to myosin filaments is called the sliding
filament theory of muscle contraction.
During the sliding process, the sarcomere
shortens, but the filaments remain the
same length.
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81. Muscle Innervation
The motor neuron axon bulb is separate
from the sarcolemma at a synaptic cleft
within the neuromuscular junction.
Synaptic vesicles in the axon bulb release
the neurotransmitter acetylcholine (Ach)
that binds to protein receptors on the
muscle fiber sarcolemma.
Next, impulses to travel down T tubules
and calcium leaves the sarcoplasmic
reticulum, resulting in myofibril
contraction.
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83. • Two other proteins are associated with
the actin filament: tropomyosin, that
winds about the actin filament, and
troponin that occurs at intervals along
the tropomyosin threads.
• Calcium ions bind to troponin, allowing
tropomyosin to shift position to expose
myosin binding sites.
• A myosin filament is composed of many
myosin molecules, each containing a
head with an ATP binding site.
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85. Myosin heads function as ATPase
enzymes, and once they break down ATP,
the myosin heads are ready to attach to
the next set of myosin binding sites on
actin myofilaments.
The release of ADP + (P) causes the head
to change its position; this is the power
stroke that causes the actin filament to
slide toward the center of a sarcomere.
When the myosin head catalyzes another
ATP, the head detaches from actin, and
the cycle begins again.
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87. Whole Muscle Contraction
Basic Laboratory Observations
In the laboratory, muscle contraction can
be studied by using an excised frog
muscle (gastrocnemius) and
stimulating it with electricity.
Muscle contraction is recorded as a
myogram and is described in terms of a
single muscle twitch or sustained
contraction called tetanus.
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88. A muscle twitch is divided into three
stages: the latent period, or time between
stimulation and when the contraction
begins; the contraction period, during
which the muscle shortens; and the
relaxation period, when the muscle
returns to its former length.
A muscle fiber contracts in an all-or-none
fashion.
The contraction of a whole muscle varies
in strength depending on the number of
muscle fibers contracting.
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90. Muscle Tone in the Body
In the body, muscles exhibit tone, in
which some fibers within a muscle are
always contracting.
Maintenance of muscle tone requires
muscle spindles.
Recruitment and the Strength of
Contraction
As the intensity of nervous stimulation
increases, more and more motor units
are activated; this is recruitment.
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91. Energy for Muscle Contraction
A muscle fiber has three ways to acquire
ATP after muscle contraction begins:
(1) creatine phosphate, built up when a
muscle is resting, donates phosphates
to ADP, forming ATP;
(2) fermentation with the concomitant
accumulation of lactic acid quickly
produces ATP; and
(3)oxygen-dependent aerobic respiration
that occurs within mitochondria.
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92. The three pathways for acquiring ATP
work together during muscle
contraction.
Myoglobin, an oxygen carrier similar to
hemoglobin, is synthesized by muscle
cells and accounts for the reddish-
brown color of skeletal muscle.
Myoglobin serves as an extra source of
oxygen during aerobic respiration in
muscles.
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93. Oxygen Debt
When a muscle uses up its available
supplies of oxygen, oxygen debt occurs,
and the muscle cells switch to anaerobic
means of supplying energy.
Fermentation results in oxygen debt
because oxygen is needed to complete
the metabolism of lactate; lactate builds
up in muscle tissue in the absence of O2.
Repaying the oxygen debt requires
replenishing creatinine phosphate and
disposing of lactate.
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94. Energy and Muscle Contraction
Exercise and Size of Muscles
Lack of exercise causes atrophy or
shortening of muscle fibers.
Frequent exercise can cause hypertrophy
or increase in muscle size.
Regular exercise has many health
benefits, including enhancing mood
and relieving depression.
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95. Slow-Twitch and Fast-Twitch
The muscles of some individuals have
many slow-twitch fibers.
These fibers are aerobic and have steady
power and endurance, enhancing
performance at a sport such as cross-
country running.
Muscles of others have many fast-twitch
fibers.
These fibers are anaerobic, have explosive
power but fatigue easily, enhancing
sports like weight lifting.
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97. Chapter Summary
Bone is an active living tissue that grows
and undergoes repair.
The fetal skeleton is cartilaginous and is
soon replaced by bone.
Bones are constantly being broken down
and rebuilt by two specialized cells.
Skeletal bones are divided into those of
the axial skeleton and those of the
appendicular skeleton.
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98. Joints are classified according to
anatomy; only one type is freely
movable.
Skeletal muscles work in antagonistic
pairs to move bones in opposite
directions.
Muscles permit movement but have other
functions as well.
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99. A chain of events lead from nervous
stimulation to muscle fiber contraction.
At the neuromuscular junction, the
nervous stimulus is passed from nerve
fiber to muscle fiber.
In muscle fiber contraction, the protein
myosin breaks down ATP.
In the body, muscles have tone, and vary
in the strength of contraction.
Muscle fibers contract in an all-or-none
fashion.
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100. The three sources of ATP for muscle
contraction are aerobic respiration,
creatine phosphate breakdown, and
fermentation.
Muscle fibers differ in capabilities; some
are better for one function or sport than
others.
Exercise has many health benefits aside
from increasing the strength and
endurance of muscles.
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