Transcript y - Mrs Winward Kamiakin High School

Crash course:
Muscular system
Muscle Groups
► Smooth
muscle: smooth, involuntary; found in
internal organs such as digestive tract, uterus,
walls of blood vessels.
► Skeletal muscle: striated, voluntary,
multinucleated; contract rapidly but not for long
periods of time.
► Cardiac muscle: striated, involuntary; found in
the heart; has own control centers.
Muscle Fibers
Muscle Types
Muscle Anatomy
►Each
muscle fiber has a nerve connected
to it; a motor neuron makes contact with
the fiber’s membrane (sarcolemma).
►These motor neurons carry signals from
the central nervous system and cause
muscle contraction.
►Actin and myosin filaments are found in
the center of the fiber.
Muscle Contraction
Nerve impulse travels through the motor neuron, stimulating
the sarcolemma.
► Calcium is released from the sarcoplasmic reticulum; causes
myosin binding sites on actin to become exposed.
► ATP on tip of myosin hydrolyzes; energy transfer changes the
shape of myosin and it binds to actin.
► Energy is then released and myosin relaxes into original
shape, pulling the actin with it.
► New ATP binds to myosin, and process repeats until
contraction is complete.
► Muscle relaxes when the antagonistic muscle contracts (flexor
and extensor).
► Calcium has to be actively tranported back into the reticulum
to reset the system.
► Rigor mortis occurs when no more ATP is available and
calcium is not removed from the sarcomere; muscle stays
contracted.
►
Muscle structure and function
animation
► http://entochem.tamu.edu/MuscleStrucCont
ractswf/index.html
“Myofibrils” song
(My Sharona)
►
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Ooh my little filaments,
filaments --Actin and myosin
myofibrils:
Proteins that are long and
dense, long and dense,
Making up the structure of
the myofibrils.
CHORUS:
Signal from the brain rides
the nerve to the muscle,
Where the myosin inside will
slide past the actin of the
My-my-my-y-y, woo! Muhmuh-muh-myofibrils.
►
►
►
►
Add a little calcium, calcium
To the cytoplasm near the
myofibrils.
It will turn troponin on,
troponin on,
Causing the contraction of
the myofibrils.
CHORUS
Muscles need energy, energy,
Most of which is needed by
the myofibrils.
Myosin burns ATP, ATP
Fueling the contractions of
the myofibrils.
CHORUS