Calcium

When a muscle contracts, it _____.

States that the muscle fibers shorten as the actin and myosin filaments pull on each other.

Covers the actin and prevents the myosin head from attaching to the actin. 

This type of muscle contraction will fire against a load, but WILL NOT shorten or lengthen.

This type of muscle contraction will fire at a constant, unchanging length.

These types of muscle contraction will fire against a load, and shorten causing movement at the joint.

Which type of contraction, when fired, WILL NOT cause any movement at the joint?

These types of muscle contraction will fire against a load, and LENGTHEN while there is movement at the joint.

Shoveling dirt, kicking a soccer ball, and swinging a baseball or softball bat are examples of what kind of muscle contraction?

Planking, doing a wall sit, carrying a load of firewood, and playing in a tug-of-war where NO ONE is moving are examples of what kind of muscle contraction?

These projections, or myosin heads, that are found on the thick filaments are called _____.

What happens during the power stroke of muscle contraction?

Occurs when a muscle is unable to contract even through it is still being stimulated.

What two proteins prevent the myosin heads from binding to the actin strands?

What substance binds to myosin's "blockers?"

____________ attaches to actin to form the cross bridge.

What is the name of the neurotransmitter released at a neuromuscular junction?

Power stroke will occur when

Given the following events:

1. Acetylcholine broken down.

2. Acetylcholine moves across the synaptic cleft.

3. Action potential reaches the presynaptic terminal of a motor neuron.

4. Acetylcholine combines with a receptor molecule on a skeletal muscle.

5. Action potential produced in a skeletal muscle cell.

Choose the arrangement that lists the events in the order they occur at a neuromuscular junction.

In order for tropomyosin to change conformation, calcium has to bind with _____.

Calcium, that will eventually enter the muscle cell to bind with troponin, is stored in the

What is the definition of oxygen debt?

An oxygen debt occurs in muscles when

The LESS moveable end of a skeletal muscle.

The MORE moveable end of a skeletal muscle.

When muscles contract, it pulls

The muscle that causes the action and does the majority of the work. (there is more than one answer)

The muscles that assist the prime mover.

The muscles that oppose an action.

Muscles that are not used, may shrink/"decay" or undergo a process of _____.

Muscle fatigue occurs when

_____ are "helper muscles" that stabilize joints against dislocation.

A(n) ____________________ is a single stimulus-contraction-relaxation sequence in a muscle fiber. It is a single, short contraction involving only a few motor units.

In a single muscle twitch, the ____________________ occurs when calcium (Ca2+) is being pumped back into the sarcoplasmic reticulum (SR) and actin and myosin stop the binding cycle.

What does the myosin do to the actin?

When a muscle is in a contracted position, what is the relationship between actin filaments?

What is the name of structure #1?

What is the name of structure #2?

The correct sequence of cross- bridge formation is represented by

A sarcomere in relaxed state.

A sarcomere in contracting state.

Identify #1

Identify #2

Identify #3

Identify #4

The point where a motor nerve connects to a muscle.

A maximum level of muscle tension is reached and the muscle stays contracted.

When stimulated by the action potential, the myosin “heads” attach to a receptor site on the actin filament and form a

An electrical charge in the nerve or muscle fiber is known as a(an)

What structure connects the message from the brain to a muscle?

What structure stores and releases calcium ions?

What structure in the muscle disperses the signal out to each muscle fiber?

Which myofibril is thin and light?

Which myofibril is thick and dark?

The point at which the nerve cell reaches the sarcolemma of the muscle fiber is the _____.

The gap between the nerve cell and sarcolemma is the _____.

The energy needed to perform a muscle contraction comes directly from _____.

What is released by axon terminals into the synaptic cleft to stimulate a muscle to contract?

What must rush into a muscle cell to promote its depolarization?