Transcript The Muscular System

“Muscles are the body’s ‘flesh.’ They bulge
and ripple just under the skin, and are
arranged in crisscrossing layers down to
the bones. Their job is to contract and
pull the bones to which they are
anchored. Rarely working alone, they
usually contract in groups, moving bones
at accurate angles and by precise
distances.”
Movement through the shortening of
muscles pulling on bones
 Heat from friction of contractions of
muscles
 Maintaining posture through monitoring
position of body parts
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Extensibility: stretches when pulled
 Elasticity: returns to original shape after
contractions
 Excitability: responds to stimuli
 Contractility: able to shorten in length
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Striated muscles are also known as
Voluntary muscles, since we
control their actions at will.
Striated muscles get their name
from how they appear under a
microscope. If you were to view
striated muscles under a
microscope it would look like a
series of stripes or bands together.
The bands are made up of fibers
called actin and myosin. The Zline, the region between the two
fibers, is what makes the muscle
functional.
40% of adult body weight
The striated muscles are located
in all of the body parts that we
can control. (hands, arms, legs,
feet)
Visceral muscle is also called
Smooth muscle because of
the lack of striations.
 Visceral muscles are
controlled by the nervous
system and hormones. We
can not directly control the
movement of our visceral
muscles.
 Visceral muscles are located
within organs such as the
stomach or lungs. This muscle
type produces peristalsis,
which are contractions,
necessary in the stomach,
blood vessels, and the closing
of bronchioles.
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The Cardiac muscle is only
found in the heart and
makes up the muscular
tissue around the heart
called myocardium
Cardiac muscles contain
striations (like skeletal
muscles) but are
involuntary (like visceral
muscles.)
The job of Cardiac muscles
is to pump blood from the
heart to blood vessels
throughout the body
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http://www.youtube.com/watch?v=gJ3
09LfHQ3M
Muscular fatigue means that someone
cannot exert a sufficient amount of energy
in order to flex a muscle
 Types
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› True weakness- substantial
› Perceived- the feelings of putting in too
much effort in order to complete an easy
task
› Central Muscle Weakness-throughout the
body
› Peripheral weakness-specific muscles
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Tetany is the term used when a disease is causing
the increase of action potential frequency which
leads to the involuntary contraction of muscles
Tetany is only found in voluntary muscles such as
the hands, arms, fingers, and legs
Low levels of Calcium in bones will depolarize the
ions, making them sensitive and disassociate with
the sodium channels. They are not attached to
anything and they are sent to the muscles, causing
a spasm.
“The principle states that if a stimulus is
strong enough to generate a nerve action
potential, the impulse is conducted along
the entire neuron at maximum strength,
unless conduction is altered by conditions
such as toxic materials in cells or fatigue.”
 A muscle contraction requires little effort
and can be done with minimal stimulus
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Muscular Dystrophy is a genetic disorder
that weakens muscles
 It is caused by missing information in
genes which prevents the formation of
necessary protein
 While MD is not contagious, the effects
of the disease can appear gradually
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Duchenne
 Becker
 Emery-Dreifuss
 Limb-girdle
 Facioscapulohumeral
 Myotonic
 Congenital
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Delayed muscle relaxation
Weakness in voluntary muscles (face, arms,
legs) especially the muscles affecting
speech and swallowing
Heart abnormalities
Respiratory problems
Frequent falls
Weakness in lower extremities
Difficulty in simple physical actions
(standing up. Etc.)
A main key to diagnosing MD is personal
medical history
 Tests focusing on muscle/nerve activity
and levels of enzymes in the blood can
determine the type of MD affecting the
person
 Muscle biopsies are sometimes
necessary to see how muscular fibers are
shaped, either extremely large or broken
down
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No known cure
 Scientists are working on detecting the
deformed gene in patients suffering with
MD
 Scientists are also trying to compose
gene and enzyme replacement therapy
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People affected with MD should
continually stretch their muscles to avoid
the stiffening of the affected muscles
 Braces are also applied to make sure
tendons do not over flex
 Medicine can also me administered to
slow down the affects of this disease
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This disease, while affecting everyone, is
mostly common in men
 1 in 30,000 male births
 While the affects of MD can be hidden
until adulthood, the disease is in their
genes from birth
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Myasthenia Gravis is an autoimmune
disease that causes weakness and
fatigue in the muscles
 Commonly, the muscles affecting the
movement of eyelids and facial
expressions are involved
 The muscles that are mainly affected are
overused muscles, but they can improve
with rest
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In a person affected with this disease,
they produce antibodies that attack the
part of the muscle that receives signals
from nerves
 In regular muscle, the nerve impulse
releases acetylcholine. In people
affected with this disease, antibodies
attack that neurotransmitter
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Drooping eyelids
 Difficulty swallowing/breathing
 Slurred speech
 Lack of facial expression
 Failure to move arms and legs
 Weak neck
 Cannot walk properly
 Blurred vision
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Myasthenia Gravis is very hard to
diagnose, seeing that weakness is a
symptom of many other diseases
 Testing muscles and their ability to be
repeatedly moved can tell a doctor if
this person in fact does have Myasthenia
Gravis
 Blood test, focusing on the amount of
acetylcholine can also be conducted
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Medicine can be administered to help
the flow of neurotransmitters
 Immunosuppressive drugs can also be
taken to reduce the production of
antibodies
 There is a procedure that can be done
to remove abnormal antibodies from
blood cells
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This disease is not inherited, seeing that
it’s a malformed protein not an
autoimmune disorder, so anyone has a
chance of getting this disease
 Mostly, this disease attacks women
under the age of 40 and men over the
age of 60
 Many young children will get this disease,
but it will cure itself over one to two years
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This disease attacks the connective tissue
in the body
 The body’s repair mechanism forms
fibrous tissue to be turned into bone
which causes frozen joints after an injury
 Ligaments, tendons, and muscles turn
into bone
 From the womb, the body cannot
control bone production
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Malformed/overgrowth of toes
 Formation of fibrous knots in neck, back,
and shoulders
 Inflammation of joints
 Stiffness from head to feet
 Random tumor-like lumps
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While biopsies can be done, this may
cause the bone-product to progress
even worse
 The appearance of the big toe is
definitely a red flag in diagnosing FOP
 There is an 80% of a doctor
misdiagnosing FOP for another disease
because there is such a lack of
information
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There is no known cure for FOP…yet
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=p