Download Muscular System PPT

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Over 600 muscles
45% of adult body weight
Bundles of muscle fibers held together
by connective tissue
Nerve stimulation allows contraction
 become short and thick
Contraction depends on myofilaments
 actin and myosin
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Allows the body to move
walking
Blinking, smiling
Also aids in blood pressure
regulation
Posture
Heat Generator
Stabilization of joints
Protection of some organs
Control of peristaltic
contractions used in the
digestive system to move
food
Excitability- receive and
respond to a stimulus
Contractibility- ability to
become short and thick
Extensibility- ability to be
stretched
Elasticity- ability to resume
resting length after stretch
Automaticity- can contract
involuntarily
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Three types
1. skeletal
2. smooth
3. cardiac
Found throughout
the body
Functions vary
based on type
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Sometimes called striated muscle
Are typically attached to bone by
tendons, a tough connective “cord”
Responsible for voluntary movements
running
smiling
clapping your hands
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Agonist: initiates movement of muscle
Antagonist: oppose or reverses movement
Methods of Attachment to Bone
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Tendon- muscle to bone
Fascia- tough, sheet like
Aponeurosis- broad, flat sheet
Origin- end that does not move
Insertion- end that moves when
muscle contracts
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Involuntary control
NOT striated
Aids in Digestive/ Respiratory
movement
Located in:
large and small intestine
stomach
blood vessels
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Function to:
push food through
the digestive system
controls blood flow
through vessels
Most can function in the
absence of nervous
stimulation
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Peristaltic contractions of
smooth muscle move food
through the digestive system
Located only in the heart
Are striated muscles
Controlled by the central
nervous system
Cardio- comes from a Greek
word meaning heart!
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Muscle Tone- state of partial contraction
Adduction- toward body
Abduction- away from body
Rotation- turning around an axis
Flexion- decreasing angle, bending
Extension- increasing angle,
straightening
Circumduction- circle around a joint
Pronation- turning down
Supination- turning up
Dorsiflexion- bending foot up
Plantar flexion- bending foot down
Atrophy- when
muscles
are not used over a
period of
time/ they get smaller
Fibromyalgia- chronic musculoskeletal pain
Muscular Dystrophy- inherited disease
leading to chronic muscle atrophy
Muscle Spasms- sudden involuntary muscle
contraction
Strain- overstretching or injury to a muscle or
tendon
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Medications
Analgesic- relieves pain; Aspirin, Tylenol, and
NSAIDS
Anti-inflammatory- reduce inflammation;
steroids, ibuprofen and NSAIDS decrease
inflammation.
Muscle relaxant- relieves stiffness; Flexeril,
Robaxin.
NSAIDS- Non-steroidal anti-inflammatory
drugs; Ex.Naproxyn
STOP
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Is covered with a layer of
connective tissue
Nerves and blood vessels enter
and exit muscles along this tissue
Structural unit is the muscle fiber
or myofiber
do not typically extend the length of
the muscle
vary in diameter
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Myofibrils make up
75-92% of muscle
volume!
Sarcolemma surrounds muscle fiber
composed of lipid and proteins
is elastic, which allows for muscle contraction and
relaxation
Myofibrils extend the length of the muscle fiber
composed of myofilaments
actin
myosin
Myofibril
Sarcolemma
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Muscle fiber cross-section
Skeletal Muscle
Muscle
Bundles
Sarcomeres
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Muscle Fibers
Myofibrils
Several hundred to several thousand
in one muscle fiber depending upon
diameter
Has striations, or further divisions
called sarcomeres
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Contain protein
filaments
actin- thin filament
myosin- thick filament
Z line is located at
each end
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Z line
A band
I band
Actin
Myosin
Relaxed Muscle
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Occurs when thin filaments slide over thick
filaments
Formation of cross-bridge between myosin and
actin must occur
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Actin filament is pulled when the crossbridge changes shape
causes distance between Z lines to decrease
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Detachment of actin from cross-bridge
Is repeated after myosin-actin cross-bridge
formation
ATP provides energy needed for
contraction and relaxation
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Motor nerve arrives at motor end plate
Acetylcholine, a neurotransmitter, is
released by the motor neuron
diffuses across the synapse, causing release
of calcium ions
allow actin and myosin filaments to form
cross-bridge
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Relaxation occurs when acetylcholine is
no longer present
cholinesterase is responsible for breakdown
of remaining acetylcholine
Calcium is removed and returned to
sarcoplasmic reticulum
Actin-myosin crossbridges are destroyed
Sarcomeres return to resting position
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7. What is the main difference between
tendons and ligaments?
8. What are the three types of muscle
tissue?
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10. Which muscle types are striated?
11. Where can smooth muscle tissues be
found?
12. Actin and myosin are ___________.
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