The Muscular System

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The Muscular System

• By Clair, RJ, Daphne, and Hallie

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The Muscular System

• Muscles are the bodys 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.

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Functions of Muscles

• 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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Characteristics of Muscles

• 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 Muscle

• 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 Z-line, 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)

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Visceral Muscles

• 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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Cardiac Muscle

• 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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Skeletal Muscle Contractions

• http//www.youtube.com/watch?vgJ309LfHQ3M

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Fatigue

• Muscular fatigue means that someone cannot exert
  a sufficient amount of energy in order to flex a
  muscle
• Types
• 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

• 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.

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The All or None Principle

• 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
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Muscular Dystrophy(MD)

• 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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Types of MD

• Duchenne
• Becker
• Emery-Dreifuss
• Limb-girdle
• Facioscapulohumeral
• Myotonic
• Congenital

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Signs and Symptoms

• 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.)

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How to Diagnose MD

• 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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Treatments for MD

• 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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Self Help

• 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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Who gets MD?

• 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
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Myasthenia Gravis

• 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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Myasthenia Gravis Cont.

• 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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Signs and Symptoms

• 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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How this disease is diagnosed

• 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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Treatments

• 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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Who is affected by this?

• This disease is not inherited, seeing that its
  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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FOP
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Fibrodysplasia Ossificans Progressiva(FOP)

• This disease attacks the connective tissue in the
  body
• The bodys 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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Signs and Symptoms

• 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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Diagnosing this disease

• 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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Treatments

• There is no known cure for FOPyet

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The End

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