What does A represent?

The tissue that binds muscles into functional groups.
Connective tissue covering the exterior of a muscle organ.

Epimysium

What does B represent?

Within the muscle.
Connective tissue sheath surrounding individual muscle fibers.

Endomysium

What does C represent?

Individual muscle fiber.
Skeletal and smooth muscle cells (but not cardiac muscle cells) are elongated and called___.

Muscle Fiber

What does D represent?

Bundles.
Bundles of muscle cells surrounded by a perimysium

Fascicle

What does E represent?

Around the fascicles.
Connective tissue surrounding muscle fiber bundles.

Perimysium

What does A represent?

A sarcomere is defined as the segment between two neighboring Z-lines. In electron micrographs of cross-striated muscle, the ___.

Z disc

What does B represent?

Within the A-band is a polar region called the ___.

H zone

What does C represent?

Surrounding the Z-line is the region of the ___.

I band

What does D represent?

Following the I-band is the ___.

A band

What does E represent?

Inside the H-zone is a thin ___.

M line

Depends on oxygen delivery and aerobic mechanisms.

Slow (oxidative), fatigue-resistant fibers

Have very fast-acting myosin ATPases and depend upon anaerobic metabolism during contraction.

Fast (oxidative or glycolytic), fatigable fibers

Red fibers, the smallest of the fiber types.

Slow (oxidative), fatigue-resistant fibers

Contain abundant amounts of glycogen.

Fast (oxidative or glycolytic), fatigable fibers

Abundant in muscles used to maintain posture.

Slow (oxidative), fatigue-resistant fibers

A relatively high percentage are found in successful marathon runners.

Slow (oxidative), fatigue-resistant fibers

The strongest stimulus that produces increased contractile force.

Maximal stimulus

The stimulus above which no stronger contraction can be elicited, because all motor units are firing in the muscle.

Maximal stimulus

All skeletal muscle is maintained in a constant, slightly contracted state, spinal reflexes activate groups of motor units alternately

Muscle Tone

Determined by alternating motor units of a muscle organ even when the muscle is at rest.

Muscle Tone

A state of continuous muscular contraction, especially when induced artificially by rapidly repeated stimuli.

Tetanus

Continued sustained smooth contraction due to rapid stimulation.

Tetanus

The situation in which contractions become stronger due to stimulation before complete relaxation occurs.

Wave summation

Temporal aka _____________, occurs because the second contraction occurs before the muscle has completely relaxed.

Wave summation

How a smooth increase in muscle force is produced.

Multiple motor unit summation

The force of contraction is controlled more precisely by recruitment also called __________________.

Multiple motor unit summation

A sacromere is the distance between two ___.

Z disc

The ___ contains only the actin filaments.

I band

The thicker filaments are the ___ filaments.

Myosin

Both actin and myosin are found in the ___.

A band

The myosin filaments are located in the ___.

A band

Serves as the actual "trigger" for muscle contraction by removing the inhibition of the troponin molecules.

Calcium ions

A neurotransmitter released at motor end plates by the axon terminals.

Acetylcholine

Diffusion across the cell membrane results in depolarization.

Sodium Ions

Activate synaptic vesicles in axon terminals.

Calcium ions

Used to convert ADP to ATP by trnsfer of high-energy phosphate group. A reserve high-energy compound.

Creatine phosphate

Destroys ACh.

Acetylcholinesterase

An enzyme located in the synaptic cleft.

Acetylcholinesterase

Once a motor neuron has fired, all the muscle fibers in a muscle contract.
True / False

False

The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment.
True / False

True

The thin filaments (actin) contain a polypeptide sub-unit G actin that bears active sites for myosin attachment.
True / False

True

The force of muscle contraction is controlled by multiple motor unit summation or recruitment.
True / False

True

Eccentric contractions are more forceful than concentric contractions.
True / False

True

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.
True / False

False

Peristalsis is characteristic of smooth muscle.
True / False

True

A contraction in which the muscle does not shorten but its tension increases is called isometric.
True / False

True

During isotonic contraction, the heavier the load, the faster the velocity of contraction.
True / False

False

During isometric contraction, the energy used appears as movement.
True / False

False

One of the important functions of skeletal muscle contraction is a production of heat.
True / False

True

An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops.
True / False

True

Muscle contraction will always promote movement of body parts regardless of how they are attached.
True / False

False

Although there are "no" sacromeres, smooth muscle still possesses thick and thin filaments.
True / False

True

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units.
True / False

True

Cells of unitary (single-unit) smooth muscle are found in the longitudnal and circular muscle layers of the intestine.
True / False

True

A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.
True / False

True

The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.
True / False

True

When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length.
True / False

True

Contractures are a result of a total "lack" of ATP.
True / False

True

Smooth muscles relax when intercellular Ca2+ (calcium ion) levels drop but may not cease contractions.
True / False

True

Which muscle cells have the greatest ability to regenerate?

smooth

Most skeletal muscle contain ___.

a mixture of fiber types

Fatigued muscle cells that recover rapidly are the products of ___.

intense exercise of short duration

The strongest muscle contractions are normally achieved by ___.

increasing the stimulation up to the maximal stimulus

Myoglobin ___.

stores oxygen in muscle cells

What structure in skeletal muscle cells functions in calcium storage?

sacroplasmic reticulum

Immediately following the arival of the stimulus at a skeletal muscle cell there is a short period called the ___ period during which the events of excitation-contraction coupling occur.

latent

Marathons

Aerobic Pathway

25 Meter Swim

Anaerobic Pathway

Weight Lifting

Direct Phosphorylation

A smooth, sustained contraction from rapid stimulation is called ____.

Tetanus

Only ____ muscle cells commonly branch.

Cardiac

Only ______ muscle cells are always multinucleated.

Skeletal

The end of the muscle that typically moves when a muscle contracts is called the _____.

Insertion

In the synaptic cleft of a neuromuscular junction, and enzyme called _____ is always present.

Acetylcholinesterase

The time in which cross bridges are active is called the period of ____.

Contraction