Download Skeletal and Muscular Systems

Skeletal and Muscular
Systems
ETEC 546 CA 3 CRITERIA
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The purpose of this assignment is to address more
advanced features of computer assisted publishing.
The goal is to demonstrate how Power Point
presentation software can add a great deal to the
effectiveness of your lecture and teaching. It is
reasonably powerful, easy to learn, and dynamic.
You can integrate text, clipart, photographs, video,
and audio into the classroom presentation that has
a great deal of visual impact for all learners. There
are additional features that add to its effectiveness.
ETEC 546 CA 3 CRITERIA

Media enhances presentation (text, graphics, images, and sound) X
10
Substance and quality of presentation (depth of video, technical
analysis, overall effort, etc.) X 20
Style, design, layout, uniqueness, etc. X 10
Includes at least ten different slides in presentation X 20
Type with substance and quality of thought (depth of discussion,
critical analysis, etc.) X 20
Grammar and Style (correct punctuation, grammar,
appropriateness, etc.) X 10
Overall quality (text, color, and background are pleasing) X 10
The Skeletal System
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Bones are composed of several kinds
of tissues, and thus they are the
organs of the Skeletal System
Bones are rigid structures
They provide support and protection
for softer tissues
They act together with skeletal
muscles to make body movements
possible
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Bones also house the tissue that
produces blood cells and cells of the
immune system
Bones store inorganic salts
The shapes of individual bones are
closely related to their functions
Classification
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Bones are grouped according to their
shapes-long, short , flat, irregular, or
round.
Parts of a long bone
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Epiphyses at each end are covered
with articular cartilage and articulate
other bones.
The shaft of the bone is called the
diaphysis.
Except for the articular cartilage, a
bone is covered by a periosteum
compact bone provides strength and
resistance to bending
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Spongy bone provides strength where
needed and reduces the weight of
bone.
The diaphysis contains a medulary
cavity filled with marrow.
Microscopic Structure
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Bone cells are called osteocytes.
They are located in minute, bony
chambers called lacunae, which are
arranged in concentric circles around
osteonic canals(haversian canals).
Osteocytes communicate with nearby
cells by means of cellular processes
passing through canaliculi.
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The intercellular material of bone
tissue is largely collagen and inorganic
salts.
The collagen gives bone its strength
and the inorganic salts make it hard
and resistant to crushing.
Compact bone
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In Compact bone, the osteocytes and
layers of intercellular material
clustered concentrically around an
osteonic canal form a cylinder-shaped
unit called an osteon.
Osteonic canals contain one or two
small blood vessels surrounded by
some loose connective tissue.
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Blood in these vessels provides
nourishment.
Osteonic canals travel longitudinally
through bone tissue. They
interconnected by transverse
communicating canals.
Spongy Bones
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Spongy bones is also composed of
osteocytes and intercellular material.
However, the bone cells are not
arranged around osteonic canals.
Instead, the cells occur within the
branching bony plates called
trabeculae.
The cells are nourished by diffusion of
substances into the canaliculi.
Bone development and
Growth
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Parts of the skeletal system begin to
form during the first few weeks of
prenatal development, an bony
structures continue to grow and
develop into adulthood.
Bones form by the replacement of
existing connective tissue in of two
ways.
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Some first appear between sheetlike
layers of connective tissues; they are
called intramembranous bones.
Others begin as masses of cartilage
that are later replaced by bone tissue;
they are called endochondral bones.
Intramembranous Bones
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Examples of intramembranous bones
are the broad , flat bones of the skull.
The primitive cells enlarge and
differentiate into bone forming cells
called osteoblasts which in turn
deposit bony matrix around
themselves.
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As a result , spongy bone is produced
in all directions along the blood vessels
within the layers of primitive
connective tissues.
Later, some of the spongy bone may
be converted to compact bone , as
spaces become filled with bony matrix.
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As development continues, the
osteoblasts may become completely
surrounded by matrix, and in this
manner they become secluded in
lacunae.
At the same time , matrix enclosing
the cellular processes of the
osteoblasts gives rise to canaliculi.
Once they are isolated in lacunae, the
Endochondral Bones
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Most of the bones of the skeleton are
endochondral bones.
Their development proceeds from
masses of hyaline cartilage with
shapes similar to future bony
structures.
Primary ossification center appears in
the diaphysis, while secondary
ossification appear in the epiphyses.
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An ephiphyseal disk remains between
the primary and secondary ossification
centers.
An epiphyseal disk consists of layers of
cells:resting cells, young reproducing
cells, older enlarging cells and dying
cells.
The epiphyseal disk is responsible for
growth in length.
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The epiphyseal disk is responsible for
growth in length.
Long boned continue to grow in length
until the epiphyseal disks are ossified.
Growth in thickness is due to
intramembranous ossification
occurring beneath the periosteum.
The medullary cavity is created by the
action of osteoclasts.?
Homeostasis Of Bone
Tissue
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Bones are continually remodeled by
osteoclasts and osteoblasts.
The total mass of bone remains nearly
constant.
Functions of Bones
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Skeletal parts provide shape ad form
for body structures.
Bones support and protect softer
underlying tissues.
Bones and muscles function together
as levers.
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The red marrow in bones functions in
the production of red blood cells,
white blood cells, and platelets.
The intercellular material in bone
tissue contains large quantities of
calcium phosphate in the form of
hydroxyapatite.
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When blood calcium concentration is
low, osteoclasts resorb bone, thus
releasing calcium salts.
When concentration is high,
osteoblasts are stimulated to form
bone tissue and store calcium salts.
Bones store small amounts of sodium,
magnesium, potassium, and carbonate
ions.
Organization of the
Skeleton
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The skeleton can be divided into axial
and appendicular portions.
The axial skeleton consists of the skull,
hyoid bone, vertebral column, and
theoretic cage.
The appendicular skeleton consists of
the pectoral girdle, upper limbs, pelvic
girdle, and lower limbs.
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Usually there are 206 bones in the
human skeleton but the number may
vary.
Extra bones in sutures are called
wormian bones.
The Muscular System
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Muscles, the organs of the muscular
system, consist largely of cells that are
specialized to undergo contractions.
During these contractions, chemical
energy from nutrients is converted in
to mechanical energy, or movement.
When muscle cells contract, they pull
on the parts to which they are
attached.
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This action usually causes movement,
as when joints of the legs are flexed
and extended during walking. But at
other times, muscular contractions
resist motion, as when they help hold
body parts in postural positions.
Muscles are also responsible for the
movement of body fluids such as
blood and urine.In addition they
function in heat production, which
Structure of Skeletal
Muscles
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Skeletal muscles are composed of
nerve, vascular, and various connective
tissues, as well as skeletal muscle
tissue.
Skeletal muscles and their parts are
covered with facia.
Other connective tissues surround cells
and groups of cells within the muscle’s
structure.
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Fascia is a part of a complex network
of connective tissue that extends
throughout the body.
Skeletal Muscle fibers
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Each skeletal muscle fiber represents a
single muscle cell, which is the unit of
contraction.
Muscle fiber are cylindrical cells with
numerous nuclei.
The cytoplasm contains mitochondria,
a sarcoplasmic reticulum, and
myofibrils.
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Striations are produced by the
arrangement of the actin and myosin
filaments.
Transverse tubules extend from cell
membrane into the cytoplasm and are
associated with the cisternae of the
sarcoplasmic reticulum.
Neuromuscular Junction
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Muscle fibers are stimulated to
contract by motor neurons.
The motor end plate of a muscle fiber
lies on one side of a neuromuscular
junction.
In response to a nerve impulse, the
end of a motor nerve fiber secretes a
neurotransmitter, which diffuses across
the junction and stimulates the muscle
Motor Units
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One motor neuron and the muscle
fibers associated with it constitute a
motor unit.
Finer movements can be produced in
muscles whose motor units contain
small numbers of muscle fibers.
Skeletal Muscle
Contraction
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Muscle fiber contraction results from a
sliding movement within the myofibrils
in which actin and myosin filaments
merge.
Roles of Myosin and Actin
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Cross bridges of myosin filaments can
form linkages with actin filaments.
The reaction between actin and
myosin filaments generates the force
of contraction.
When a fiber is at rest, troponin and
tropomyosin molecules interfere with
linkage formation.
When calcium ions are present, the
Stimulus for contraction
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Muscle fiber is usually stimulated by
acetylcholine released from the end of
a motor nerve fiber.
Acetylcholine causes muscle fiber to
conduct an impulse that reaches the
deep parts of the fiber by means of
the transverse tubules.
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A muscle impulse signals the
sarcoplasmic reticulum to release
calcium ions.
Linkages form between myosin and
actin, and the actin filaments move
inward, shortening the sarcomere.
The muscle fiber relaxes when calcium
ions are transported back into the
sarcoplasmic reticulum.
Energy sources for
contraction
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ATP supplies the energy for muscle
fiber contraction.
Creatine phosphate stores energy that
can be used to synthesize ATP as it is
decomposed.
Active muscles depend on cellular
respiration.
Muscular Responses
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Threshold stimulus is the minimal
stimulus needed to elicit a muscular
contraction.
If a muscle fiber contracts at all, it will
contract completely-all or none
response.
At low intensity stimulation, relatively
small numbers of motor units contract.
At increasing intensities of stimulation,
Staircase Effect
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An inactive muscle undergoes a series
of contractions of increasing strength
when subjected to a series of stimuli.
The staircase effect seems to be due
to failure to remove calcium ions form
the sarcoplasm rapidly enough.
Sustained Contractions
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A rapid series of stimuli may produce a
summation of twitches and a
sustained contraction.
When contractions fuse , the strength
of contraction may increase due to
recruitment of fibers.
Even when a muscle is at rest, its
fibers usually maintain tone-that is,
remain partially contracted.
Isotonic and Isometric
Contractions
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When a muscle contracts and its ends
are pulled closer together, the
contraction is called isotonic.
When a muscle contracts but its
attachments do not move, the
contraction is called isometric.
Most body movements involve both
isometric and isotonic contractions.
Skeletal Muscle Action
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The movable end of a skeletal muscle
is its insertion, and the immovable end
is its origin.
Some muscles have more than one
origin or insertion.
Sometimes the end of a muscle
changes its function in different body
movements.
Interaction of Skeletal
Muscles
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Skeletal muscles function in groups.
A prime mover is responsible for most
of a movement. Synergists aid prime
movers.
Antagonists can resists the movement
of a prime mover.
Smooth movements depend upon
antagonists’ giving way to the actions
of prime movers.
Nomenclature
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Muscle names often describe sizes,
shapes, locations, actions, number of
attachments, or direction of fibers.
The End.