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Slide 1
Kaitlyn Skidmore QuaShaya Hammon Camille Torres
Slide 2
THE FUNCTIONS OF THE MUSCULAR SYSTEM The Muscular System:
Provides Structure Provides Structure Aids in Movement Aids in
Movement Production of Heat Production of Heat Stability of Joints
Stability of Joints
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SKELETAL MUSCLE STRUCTURE
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MUSCLE FIBER STRUCTURE
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Neuromuscular junction- Connection between the motor neuron and
the muscle fiber Motor End Plate- 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.
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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.
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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.
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Muscle Fatigue: a muscle exercised strenuously for a prolonged
period may lose its ability to contract.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.Cramps: is a painful
condition in which a muscle undergoes a sustained involuntary
contraction.
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SKELETAL MUSCLE CONTRACTION TYPES Sustained
ContractionsSustained Contractions Even when a muscle is at rest, a
certain amount of sustained contraction is occurring in its fibers.
This is called muscle tone.Even when a muscle is at rest, a certain
amount of sustained contraction is occurring in its fibers. This is
called muscle tone. Isometric contractionIsometric contraction The
muscle becomes taut, but the attachment(s) do not move; tensing a
muscleThe muscle becomes taut, but the attachment(s) do not move;
tensing a muscle Isotonic contractionsIsotonic contractions The
muscle shortens and its attachment(s) move(s).The muscle shortens
and its attachment(s) move(s).
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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. 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.
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Prime Mover (agonist) = the primary muscle responsible for a
movement. The biceps brachii in flexing the arm at the elbowThe
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.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.The brachialis helps the biceps
brachii during elbow flexion. Origin = the attachment site of the
muscles 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.Some muscles have more
than one origin, for example, biceps brachii. Insertion = the
attachment site of the muscles tendon to a more movable bone is
known as the muscles insertion. It has the greatest motion when the
muscle contracts and it tends to be more distal.
radius/ulnaradius/ulna
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Insertion is the attachment site of the muscles tendon to a
more movable bone is known as the muscles insertion. It has the
greatest motion when the muscle contracts and it tends to be more
distal. Origin is the attachment site of the muscles 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. ORIGIN AND INSERTION
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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. ANTAGONIST AND SYNERGIST
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Muscular dystrophy is a group of inherited disorders that
involve muscle weakness and loss of muscle tissue, which get worse
over time. Muscular dystrophy is a group of inherited disorders
that involve muscle weakness and loss of muscle tissue, which get
worse over time. MUSCULAR DYSTROPHY
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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) Intellectual disability (only present in some types of
the condition) Muscle weakness that slowly gets worse Muscle
weakness that slowly gets worse Delayed development of muscle motor
skills Delayed development of muscle motor skills Difficulty using
one or more muscle groups Difficulty using one or more muscle
groups Drooling Drooling Eyelid drooping (ptosis) Eyelid drooping
(ptosis) Frequent falls Frequent falls Loss of strength in a muscle
or group of muscles as an adult Loss of strength in a muscle or
group of muscles as an adult Loss in muscle size Loss in muscle
size Problems walking (delayed walking) Problems walking (delayed
walking)
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TEST/TREATMENTS The doctor's exam may show: Abnormally curved
spine (scoliosis) Joint contractures (clubfoot, clawhand, or
others) Low muscle tone (hypotonia) And 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
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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