An action potential on the motor neuron
An action potential on the motor neuron
the release of ACh
the release of ACh
a second action potential
a second action potential
muscle fiber
muscle fiber
action potential goes down the T-tubule
action potential goes down the T-tubule
calcium to be released
calcium to be released
from the sarcoplasmic reticulum
from the sarcoplasmic reticulum
tropomyosin is blocking
tropomyosin is blocking
actins binding site for myosin
actins binding site for myosin
Ca binds to troponin
Ca binds to troponin
causing tropomyosin to move and
causing tropomyosin to move and
expose actions binding site for myosin
expose actions binding site for myosin
A cross bridge can now form
A cross bridge can now form
between the actin and myosin head
between the actin and myosin head
ATP already stored in the myosin allows
ATP already stored in the myosin allows
the myosin head to "spring forward"
the myosin head to "spring forward"
(the power stroke)
(the power stroke)
actin is pulled past myosin
actin is pulled past myosin
ATP is broken down to ADP+P
ATP is broken down to ADP+P
by the head of the myosin
by the head of the myosin
The energy released is used to
The energy released is used to
break the actin-myosin cross bridge
break the actin-myosin cross bridge
to pull the myosin head into
to pull the myosin head into
its original position
its original position
to provide energy for
to provide energy for
next cross bridge formation and movement
next cross bridge formation and movement
sarcomeres shorten as cross bridges
sarcomeres shorten as cross bridges
form,move, break and reform
form,move, break and reform
process is repeated throughout as long
process is repeated throughout as long
as calcium and ATP are available
as calcium and ATP are available