MUSCULAR
SYSTEM
Kaitlyn Skidmore
Qua’Shaya Hammon
Camille Torres
THE FUNCTIONS OF THE MUSCULAR SYSTEM
The Muscular System:
• Provides Structure
• Aids in Movement
• Production of
Heat
• Stability of Joints
SKELETAL MUSCLE STRUCTURE
MUSCLE FIBER STRUCTURE
Neuromuscular junction- Connection
between the motor neuron and the
muscle fiber
Motor End Plate- The flattened end of
a motor neuron that transmits neural
impulses to a muscle
Neurotransmitter- Cytoplasm at the
distal ends of these motor neuron
axons; rich in mitochondria and
contains many tiny vesicles that stores
chemicals.
Muscle Contraction- A complex
interaction of organelles and
molecules in which myosin binds to
actin and exerts pulling action.
ACTIN AND MYOSIN
Actin:
A protein involved in cell movement:
a protein present in all cells and in
muscle tissue where it plays a role in
contraction.
Myosin:
A muscle protein: a protein in
muscles that helps them contract when
connected with the protein actin.
SLIDING FILAMENT
THEORY
The process of contraction begins with:
The stimulation of a motor neuron, which releases
acetylcholine, causing the chemical, calcium (Ca++) to be
released.
This calcium molecule will shift a troponin, making a site
available for the myosin heads to connect to the actin
molecule creating the contraction.
Once the myosin filament attaches to the actin, ATP
releases
the bond between the two, then a chemical,
acetylcholinesterase, is released to digest the
acetylcholine,
so that it may be recycled and used once again for
contraction.
• Muscle Fatigue: a muscle
exercised strenuously for a
prolonged period may lose
its ability to contract.
• Cramps: is a painful
condition in which a muscle
undergoes a sustained
involuntary contraction.
SKELETAL MUSCLE CONTRACTION TYPES
• Sustained Contractions
• Even when a muscle is at rest, a certain amount of
sustained contraction is occurring in its fibers. This
is called muscle tone.
• Isometric contraction
• The muscle becomes taut, but the attachment(s) do
not move; tensing a muscle
• Isotonic contractions
• The muscle shortens and its attachment(s) move(s).
SMOOTH MUSCLE CONTRACTION
1. A protein, calmodulin binds to
calcium ions (no troponin) and
activates the contraction
mechanism.
2. Most calcium diffuses in to smooth
muscle cells from the extracellular
fluid (reduced SR).
3. Norepinephrine and acetylcholine
are smooth muscle
neurotransmitters.
4. Contraction is slow and sustained.
Prime Mover (agonist) = the primary muscle responsible for a movement.
• The biceps brachii in flexing the arm at the elbow
Antagonist(s) = the muscle(s) in opposition to the action of the prime mover. The antagonist
relaxes (or stretches) during the prime movement.
• The triceps brachii is the antagonist of the biceps brachii when we flex the arm at the elbow.
Synergist(s) = muscles that assist the prime mover.
• The brachialis helps the biceps brachii during elbow flexion.
Origin = the attachment site of the muscle’s tendon to a more stationary bone. It has very less
movement and normally a muscle contracts towards it.
• Some muscles have more than one origin, for example, biceps brachii.
Insertion = the attachment site of the muscle’s tendon to a more movable bone is known as the
muscle’s insertion. It has the greatest motion when the muscle contracts and it tends to be more
distal.
• radius/ulna
ORIGIN AND INSERTION
Origin is the attachment site of the
muscle’s tendon to a more stationary
bone. It has very less movement and
normally a muscle contracts towards
it. Some muscles have more than one
origin, for example, biceps brachii.
Insertion is the attachment site of the
muscle’s tendon to a more movable
bone is known as the muscle’s insertion.
It has the greatest motion when the
muscle contracts and it tends to be
more distal.
ANTAGONIST AND
SYNERGIST
An antagonist muscle is one that works
in opposition to the movement initiated
by an agonist muscle. The antagonist
muscle in a muscle set brings a limb or
other anatomical part back to its initial
position of rest.
A synergist muscle is a muscle which
works in concert with another muscle to
generate movement. These muscles can
work with the agonists or prime movers
which surround a joint, or the
antagonistic muscles, which move in the
opposite direction.
MUSCULAR DYSTROPHY
• Muscular dystrophy is a group of inherited
disorders that involve muscle weakness and loss
of muscle tissue, which get worse over time.
CAUSES AND SYMPTOMS
Muscular dystrophies, or MD, are a group of
inherited conditions, which means they are
passed down through families. They may occur
in childhood or adulthood.
Symptoms include:
• Intellectual disability (only present in
some types of the condition)
• Muscle weakness that slowly gets
worse
• Delayed development of muscle
motor skills
• Difficulty using one or more muscle
groups
• Drooling
• Eyelid drooping (ptosis)
• Frequent falls
• Loss of strength in a muscle or group
of muscles as an adult
• Loss in muscle size
• Problems walking (delayed walking)
TEST/TREATMENTS
The doctor's exam may show:
•Abnormally curved spine (scoliosis)
•Joint contractures (clubfoot, clawhand,
or others)
•Low muscle tone (hypotonia)
And
•Heart testing - electrocardiography
(ECG)
•Nerve testing - electromyography
(EMG)
•Blood testing - including CPK level
•Genetic testing for some forms of
muscular dystrophy
There are no known
cures for the various
muscular dystrophies.
The goal of treatment is
to control symptoms
Summation- Occurs in the neuromuscular junction; it
is the additive effect of several electrical impulses.
Recruitment- contraction of one motor unit and all
muscle fibers at the same time
Sustained contraction- also called a tetanic
contraction, occurs when there is an accumulation of
acetylcholine in the
neuromuscular junction.
-It occurs rapidly, giving no time for the muscle
to relax between stimuli
-Remains constant in a steady state; maximal
muscle contraction
Muscle Tone- continuous and partial contraction of
muscles
-recruitment and summation combined
WORKS CITED
http://www.differencebetween.com/difference-between-origin-and-vs-insertion/
http://www.livestrong.com/article/259009-muscles-that-are-prime-movers/
http://www.wisegeek.org/what-is-a-synergist-muscle.htm
http://topics.wisegeek.org/topics.htm?antagonistmuscle#a=65221&t=default&k=Antagonist%20Muscle&b=1&p=5&s=RelatedTopicsSorter
Default&r=0
http://www.nytimes.com/imagepages/2008/02/11/science/20
080212_MUSC_GRAPHIC.html
http://homepages.ius.edu/KEDMONDS/muscles.htm
http://quizlet.com/3513668/skeletal-muscle-parts-flash-cards/
http://faculty.stcc.edu/AandP/AP/AP1pages/Units5to9/unit9/summatio.htm
http://www.sci.sdsu.edu/movies/actin_myosin_gif.html
http://washhouseanatomy.wikispaces.com/Tyesha+Robinson
http://gifsoup.com/view/4447671/muscle-origin-insertion.html