muscle contraction/relaxation

What happens after

The neurotransmitter Ach (Acetylcholine) is released from the axon terminal of the motor nueron

Ach diffuses across the synaptic cleft and bind to receptors on the motor end plate. These are ligated-gated receptors that open for Na+ ions

What happens before

Ach diffuses across the synaptic cleft and bind to receptors on the motor end plate. These are ligated-gated receptors that open for Na+ ions

The neurotransmitter Ach (Acetylcholine) is released from the axon terminal of the motor nueron

What happens after

Ach diffuses across the synaptic cleft and bind to receptors on the motor end plate. These are ligated-gated receptors that open for Na+ ions

Na+ ions rush into the muscle fiber, depolarizing it creating an action potential

What happens before

Na+ ions rush into the muscle fiber, depolarizing it creating an action potential

Ach diffuses across the synaptic cleft and bind to receptors on the motor end plate. These are ligated-gated receptors that open for Na+ ions

What happens after

Na+ ions rush into the muscle fiber, depolarizing it creating an action potential

The action potential travels down the T-tubules causing Ca+ to be released from the sarcoplasmic reticulum

What happens before

The action potential travels down the T-tubules causing Ca+ to be released from the sarcoplasmic reticulum

Na+ ions rush into the muscle fiber, depolarizing it creating an action potential

What happens after

The action potential travels down the T-tubules causing Ca+ to be released from the sarcoplasmic reticulum

Calcium ions (Ca++) that are released from the SR binds to troponin to shift tropomyosin exposing the active sites on actin allowing the myosin head to attach forming a cross bridge

What happens before

Calcium ions (Ca++) that are released from the SR binds to troponin to shift tropomyosin exposing the active sites on actin allowing the myosin head to attach forming a cross bridge

The action potential travels down the T-tubules causing Ca+ to be released from the sarcoplasmic reticulum

What happens after

Calcium ions (Ca++) that are released from the SR binds to troponin to shift tropomyosin exposing the active sites on actin allowing the myosin head to attach forming a cross bridge

Myosin head make a "power stroke", pulling actin toward the center of the sarcomere (Z-disk come closer together increasing the zone of myosin and actin overlap)

What happens before

Myosin head make a "power stroke", pulling actin toward the center of the sarcomere (Z-disk come closer together increasing the zone of myosin and actin overlap)

Calcium ions (Ca++) that are released from the SR binds to troponin to shift tropomyosin exposing the active sites on actin allowing the myosin head to attach forming a cross bridge

What happens after

Myosin head make a "power stroke", pulling actin toward the center of the sarcomere (Z-disk come closer together increasing the zone of myosin and actin overlap)

The crossbridge cycle continues as long as ACH is present in the synaptic cleft; Ca++ is allowing myosin to bind actin, and ATP is available to release myosin after the power stroke

What happens before

The crossbridge cycle continues as long as ACH is present in the synaptic cleft; Ca++ is allowing myosin to bind actin, and ATP is available to release myosin after the power stroke

Myosin head make a "power stroke", pulling actin toward the center of the sarcomere (Z-disk come closer together increasing the zone of myosin and actin overlap)

What happens after

The crossbridge cycle continues as long as ACH is present in the synaptic cleft; Ca++ is allowing myosin to bind actin, and ATP is available to release myosin after the power stroke

Ach is broken down by AChe(acetylcholinesterase); closing the Na+ channels and stopping the influx of Na+ ions

What happens before

Ach is broken down by AChe(acetylcholinesterase); closing the Na+ channels and stopping the influx of Na+ ions

The crossbridge cycle continues as long as ACH is present in the synaptic cleft; Ca++ is allowing myosin to bind actin, and ATP is available to release myosin after the power stroke

What happens after

Ach is broken down by AChe(acetylcholinesterase); closing the Na+ channels and stopping the influx of Na+ ions

Once the muscle fibers is no longer depolarized, Ca+ + is pumped back into the SR

What happens before

Once the muscle fibers is no longer depolarized, Ca+ + is pumped back into the SR

Ach is broken down by AChe(acetylcholinesterase); closing the Na+ channels and stopping the influx of Na+ ions

What happens after

Once the muscle fibers is no longer depolarized, Ca+ + is pumped back into the SR

Without Ca++ available, tropomyosin covers the actin site, the actin and myosin filaments spread back out, lengthening the sarcomere as the Z-discs get further apart

What happens before

Without Ca++ available, tropomyosin covers the actin site, the actin and myosin filaments spread back out, lengthening the sarcomere as the Z-discs get further apart

Once the muscle fibers is no longer depolarized, Ca+ + is pumped back into the SR