Ch 12 part 3 Muscle Twitches and Crossbridges Activation

The force generated by individual muscle fibers depends on the number of active ______ formed within the muscle fiber.

Muscles contract together in ______ units.

The more ______ that contract together at the same time, the more crossbridges are active, and the greater the force is.

Crossbridges are affected by the amount of ______ released from the sarcoplasmic reticulum.

Crossbridges are affected by the ______ of stimulation.

The force on a rope is greater when more people are ______ on it.

Calcium is moving against its concentration gradient when it is actively pumped back into the sarcoplasmic reticulum from the cytosol during the ______ phase

Calcium moves along its concentration gradient when it moves into the cytosol from the sarcoplasmic reticulum during ______

The decrease in concentration of calcium in the cytoplasm ensures that the muscle does not constantly ______

In real life, multiple muscle fibers and motor units ______ at the same time

Even blinking one's eyes requires the stimulation of multiple ______ cells

Researchers can analyze the contraction of a single muscle fiber in a laboratory by removing a single muscle cell and anchoring it to an experimental device, then use an electrical stimulator to 'zap' the muscle cell and cause a ______

The same number of crossbridges are activated for every action potential that reaches the motor end plate. It's important to note however, that not all muscle twitches are the same in terms of time and amplitude. For example, the extraocular muscle (in the eye) demonstrates a rapid increase and decrease in tension, while the soleus muscle (in the calf) takes much longer to rise and fall. Muscle twitches can be affected by both the diameter of the muscle cell as well as the type of myosin ATPase at the head of myosin. Fast myosin ATPase hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly than slow myosin ATPase. The Three Phases of a Twitch The phases of a muscle twitch are as follows: Latent period - The millisecond time delay between the action potential and the initiation of contraction. This includes the time it takes for the impulse to travel down the nerve, ACh to be released, and all of the reactions that must occur before the filaments begin to slide. No mechanical response occurs during the latent period. Excitation-contraction coupling (ECC) occurs during the latent period. Contraction - This stage begins with crossbridge cycling and the rising levels of cytosolic calcium. Relaxation - Cytosolic calcium is returned to the sarcoplasmic reticulum and the number of crossbridges declines, relaxing the muscle. Note that the relaxation phase is much longer than the contraction phase.

The same number of crossbridges are activated for every action potential that reaches the motor end plate. It's important to note however, that not all muscle twitches are the same in terms of time and amplitude. For example, the extraocular muscle (in the eye) demonstrates a rapid increase and decrease in tension, while the soleus muscle (in the calf) takes much longer to rise and fall. Muscle twitches can be affected by both the diameter of the muscle cell as well as the type of myosin ATPase at the head of myosin. Fast myosin ATPase hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly than slow myosin ATPase. The Three Phases of a Twitch The phases of a muscle twitch are as follows: Latent period - The millisecond time delay between the action potential and the initiation of contraction. This includes the time it takes for the impulse to travel down the nerve, ACh to be released, and all of the reactions that must occur before the filaments begin to slide. No mechanical response occurs during the latent period. Excitation-contraction coupling (ECC) occurs during the latent period. Contraction - This stage begins with crossbridge cycling and the rising levels of cytosolic ______. Relaxation - Cytosolic ______ is returned to the sarcoplasmic reticulum and the number of crossbridges declines, relaxing the muscle. Note that the relaxation phase is much longer than the contraction phase.

The same number of crossbridges are activated for every action potential that reaches the motor end plate. It's important to note however, that not all muscle twitches are the same in terms of time and amplitude. For example, the extraocular muscle (in the eye) demonstrates a rapid increase and decrease in tension, while the soleus muscle (in the calf) takes much longer to rise and fall. Muscle twitches can be affected by both the diameter of the muscle cell as well as the type of myosin ATPase at the head of myosin. Fast myosin ATPase hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly than slow myosin ATPase. The Three Phases of a Twitch The phases of a muscle twitch are as follows: Latent period - The millisecond time delay between the action potential and the initiation of contraction. This includes the time it takes for the impulse to travel down the nerve, ACh to be released, and all of the reactions that must occur before the filaments begin to slide. No mechanical response occurs during the latent period. Excitation-contraction coupling (ECC) occurs during the latent period. Contraction - This stage begins with crossbridge cycling and the rising levels of cytosolic ______. Relaxation - Cytosolic ______ is returned to the sarcoplasmic reticulum and the number of crossbridges declines, relaxing the muscle. Note that the relaxation phase is much longer than the contraction phase.

The same number of crossbridges are activated for every action potential that reaches the motor end plate. It's important to note however, that not all muscle twitches are the same in terms of time and amplitude. For example, the extraocular muscle (in the eye) demonstrates a rapid increase and decrease in tension, while the soleus muscle (in the calf) takes much longer to rise and fall. Muscle twitches can be affected by both the diameter of the muscle cell as well as the type of myosin ATPase at the head of myosin. Fast myosin ATPase hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly than slow myosin ATPase. The Three Phases of a Twitch The phases of a muscle twitch are as follows: Latent period - The millisecond time delay between the action potential and the initiation of contraction. This includes the time it takes for the impulse to travel down the nerve, ACh to be released, and all of the reactions that must occur before the filaments begin to slide. No mechanical response occurs during the latent period. Excitation-contraction coupling (ECC) occurs during the latent period. Contraction - This stage begins with crossbridge cycling and the rising levels of cytosolic calcium. ______ - Cytosolic calcium is returned to the sarcoplasmic reticulum and the number of crossbridges declines, relaxing the muscle. Note that the relaxation phase is much longer than the contraction phase.

The same number of crossbridges are activated for every action potential that reaches the motor end plate. It's important to note however, that not all muscle twitches are the same in terms of time and amplitude. For example, the extraocular muscle (in the eye) demonstrates a rapid increase and decrease in tension, while the soleus muscle (in the calf) takes much longer to rise and fall. Muscle twitches can be affected by both the diameter of the muscle cell as well as the type of myosin ATPase at the head of myosin. Fast myosin ATPase hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly than slow myosin ATPase. The Three Phases of a Twitch The phases of a muscle twitch are as follows: Latent period - The millisecond time delay between the action potential and the initiation of contraction. This includes the time it takes for the impulse to travel down the nerve, ACh to be released, and all of the reactions that must occur before the filaments begin to slide. No mechanical response occurs during the latent period. Excitation-contraction coupling (ECC) occurs during the latent period. ______ - This stage begins with crossbridge cycling and the rising levels of cytosolic calcium. Relaxation - Cytosolic calcium is returned to the sarcoplasmic reticulum and the number of crossbridges declines, relaxing the muscle. Note that the relaxation phase is much longer than the contraction phase.

The same number of crossbridges are activated for every action potential that reaches the motor end plate. It's important to note however, that not all muscle twitches are the same in terms of time and amplitude. For example, the extraocular muscle (in the eye) demonstrates a rapid increase and decrease in tension, while the soleus muscle (in the calf) takes much longer to rise and fall. Muscle twitches can be affected by both the diameter of the muscle cell as well as the type of myosin ATPase at the head of myosin. ______ myosin ATPase hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly than slow myosin ATPase. The Three Phases of a Twitch The phases of a muscle twitch are as follows: Latent period - The millisecond time delay between the action potential and the initiation of contraction. This includes the time it takes for the impulse to travel down the nerve, ACh to be released, and all of the reactions that must occur before the filaments begin to slide. No mechanical response occurs during the latent period. Excitation-contraction coupling (ECC) occurs during the latent period. Contraction - This stage begins with crossbridge cycling and the rising levels of cytosolic calcium. Relaxation - Cytosolic calcium is returned to the sarcoplasmic reticulum and the number of crossbridges declines, relaxing the muscle. Note that the relaxation phase is much longer than the contraction phase.

Fast glycolytic (Type llb) muscle fibers primarily produce ATP anaerobically, through ______.

Fast glycolytic fibers have the largest diameters of all of the muscle fibers, which explains why body builders and power lifters have huge ______.

Fast myosin ______ hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly.

Slow oxidative fibers, located in the smaller motor units, are recruited ______ during exercise.

Fast glycolytic fibers, located in the large motor units, are usually recruited ______ except when the muscle must generate a sudden, large force.

Oxidative fibers primarily produce ATP ______

Glycolytic fibers primarily produce ATP ______

Fast-twitch fibers contract ______, while slow-twitch fibers contract slowly.

In fast-twitch muscle cells, you will find a ______ myosin ATPase.

In slow-twitch muscle cells, you will find a ______ myosin ATPase.

The majority of muscles are composed of many different types of muscle ______, some have a predominance of one type of fiber over the others.

Fast ______ ATPase hydrolyzes ATP faster than slow myosin ATPase and therefore generates cross bridges and tension more quickly than slow myosin ATPase.

Slow myosin ATPase hydrolyzes ATP slower than ______ myosin ATPase and therefore generates cross bridges and tension more slowly.

The extraocular muscle (in the eye) demonstrates a rapid increase and decrease in tension, while the soleus muscle (in the calf) takes much longer to rise and fall due to the different types of ______ ATPase enzymes.

Muscle twitches can be affected by both the diameter of the muscle cell as well as the type of ______ ATPase at the head of myosin.