A & P chapter 10

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What is the basic function of all muscle tissue?

generate muscle tension

When the sarcomere contracts and shortens__________.

the A band stays the same

The storage and release of calcium ions is the key function of the:

sarcoplasmic reticulum.

A group of skeletal muscle fibers together with the surrounding perimysium form a(n):

fascicle

The Na+/K+ pump helps a muscle cell maintain a state of:

resting membrane potential.

A crossbridge forms when:

a myosin head binds to actin.

Which of the following steps of the crossbridge cycle occurs immediately before the power stroke?

A crossbridge forms.

As myosin heads complete the power stroke, actin filaments:

slide toward the M line of the sarcomere.

Which of the following causes myosin to detach from actin?

An ATP molecule binds to myosin.

In the absence of ATP in the muscle, which of the following is most likely to occur?

Some myosin heads will remain attached to actin molecules, but are unable to perform a power stroke.

The narrow space between the axon terminal and the motor end plate is called the:

synaptic cleft

Stimulation of acetylcholine (ACh) receptors by ACh will primarily result in:

sodium ions entering the muscle fiber.

The end-plate potential is:

a depolarization caused by sodium ion movement into the cytosol.

The neurons of patients with multiple sclerosis are unable to transmit action potentials down the axon. How will that affect skeletal muscle stimulation?

The muscle will not be stimulated and therefore will not contract.

The active ingredient of Botox, botulinum toxin, blocks the release of ACh from the axon terminal. An overdose of Botox will most likely result in:

muscle paralysis at the site of injection.

What are the components of a triad?

Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule

Excitation-contraction coupling results in an increase of calcium ion concentration:

in the cytosol of the muscle fiber.

Predict the effect of Tetrodotoxin, a powerful blocker of voltage-gated sodium ion channels:

There will be no action potential generated in the muscle fiber.

In preparation for contraction, calcium ions bind to:

troponin

The protein that binds to actin when tropomyosin moves off of the active sites of actin, is:

myosin

Which of the following can cause relaxation?

End of neural stimulation

When the sarcolemma repolarizes and returns to rest:

the inside of the sarcolemma is more negatively charged than the outside.

The progressive stiffening of muscles after death, known as rigor mortis, is due to:

ATP depletion, which leads to high cytosolic calcium and inability of crossbridges to detach.

Rank from the first to the last steps in stages involved in a twitch contraction

latent, contraction, relaxation

The main immediate source of ATP (lasting about 10 seconds) as muscle contractions begin comes from:

creatine phosphate

What is a necessary reactant for glycolytic, or anaerobic, catabolism to proceed?

glucose

Wave summation, in which the muscle can only partially relax between contractions, will lead to__________.

unfused tetanus

Compared to Type I fibers, Type II fibers__________.

can generate faster, more powerful contractions

The type of contraction that causes a skeletal muscle to lengthen is called__________.

isotonic eccentric contraction

Which type of contraction causes a skeletal muscle to shorten?

isotonic concentric contraction

Which of the following is not one of the factors that contribute to muscle fatigue?

excess post-exercise oxygen consumption

What do skeletal muscle contractions share in common with smooth muscle contractions?

Both types of contractions result from thick and thin filaments sliding past one another.

When muscle fibers contract, the tension is transmitted to the _____.

fascicle

Which of the following properties of muscle cells would you expect to be the most involved in producing Joe’s muscle spasms?

Contractility

What is the type of chemical reaction used to rebuild ADP into ATP?

dehydration synthesis

Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products?

glycolysis

Which of the following processes produces 36 ATP?

Krebs cycle and oxidative phosphorylation

The "rest and recovery" period, where the muscle restores depleted reserves, includes all of the following processes EXCEPT __________.

Pyruvic acid is converted back to lactic acid.

Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP?

white fast twitch fibers

Complete the reaction below: ADP + creatine phosphate → creatine + __________

ATP

If oxygen is not available, the muscle fiber will produce ATP by__________.

anaerobic catabolism

Which of the following proteins forms elastic filaments?

titin

Which of the following is NOT one of the three major components of a typical eukaryotic cell?

ribosome

Which of the following acts as the digestive system of the cell, breaking down materials?

lysosome

Where in a typical eukaryotic cell would you expect to find genes?

in the DNA within the cell’s nucleus

Which of the following statements about cells is FALSE?

Cells join together to form organelles, which then form our organs and organ systems.

Which of the following proteins is a component of thick filaments?

myosin

Which of the following is a characteristic of smooth muscle?

contain actin and myosin

Which of the following organelles synthesizes proteins?

ribosome

While studying the properties of a muscle in the laboratory, you observe that the muscle is involuntary and does not have striations or T-tubules. You determine that this muscle is__________.

smooth muscle

The liver is an organ that can synthesize lipids, such as cholesterol, and detoxify poisons, such as alcohol. Which of the following organelles will be abundant in liver cells?

smooth ER

What structure is the functional unit of contraction in a skeletal muscle fiber?

sacromere

Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?

Calcium ions are stored in the sarcoplasmic reticulum.

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?

ATP binds to the myosin head.

How does the myosin head obtain the energy required for activation?

The energy comes from the hydrolysis of ATP.

What specific event triggers the uncovering of the myosin binding site on actin?

Calcium ions bind to troponin and change its shape.

When does cross bridge cycling end?

Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.

What characteristic is not descriptive of cardiac muscle tissue?

Voluntary muscle contractions

Where are receptors for acetylcholine located?

motor end plate

During muscle contraction, myosin crossbridges bind to active sites on __________.

actin filaments

Deep inward extensions of the sarcolemma form a tunnel-like network inside the muscle cell known as __________.

transverse tubules (T-tubules)

When muscle fibers are stimulated so frequently they do not have an opportunity to relax, they are experiencing __________.

fused or complete tetanus

What is the functional contractile unit of the myofibril?

Sarcomere

The increase in muscle tension that is produced by increasing the number of active motor units is called __________.

recruitment

Through which ATP-generating mechanism can long-lasting muscle contractions be sustained?

Oxidative catabolism

Which statement best describes the function of myoglobin?

Myoglobin stores oxygen in muscle cells.

The degree to which a muscle cell can stretch depends on its __________.

extensibility

The fastest muscle contraction would be produced by a __________.

type IIb fiber

The storage and release of calcium ions is the key function of the __________.

sarcoplasmic reticulum

In response to physical inactivity, we expect to see muscles __________.

atrophy

The plasma membrane of a muscle cell is known as the __________.

sarcolemma

Type I fibers lack __________.

speed

Between the start of the latent period and the start of the contraction period, there is a time interval during which the muscle cannot respond to another stimulus. This brief period is known as the __________.

refractory period

The synapse of a motor neuron with a muscle fiber is known as the __________.

neuromuscular junction

A pathway of ATP production that results in the formation of lactic acid is __________.

glycolytic catabolism

The type of contraction in which length of the muscle fibers does not change is called __________.

isometric

Which of the following wraps and surrounds an individual skeletal muscle fiber?

Endomysium

What anchors thin and elastic filaments in place within the myofibril?

Z-disc

The end plate potential is generated by the influx of _______ into the motor end plate.

sodium

Acetylcholine is released from the synaptic terminus in response to

An action potential arriving at the synaptic terminus

The term "synaptic cleft" refers to

The gap between the neuron and the muscle fiber

The sodium channels of the motor end plate are

Ligand-gated channels

The end plate potential is

A local depolarizaton

The channels that open in the sarcolemma surrounding the motor endplate and generate an action potential are

voltage gated channels

The term "propagate" when referring to an action potential means

spread

In order to trigger a muscle contraction, an action potential must reach the

triads

A triad consists of

Two terminal cisternae and a T-tubule

________ is released from the SR in response to arrival of an action potential

Ca++

Tropomyosin

Covers actin active sites

Troponin has three subunits. Which of the following does NOT bind to one of these subunits?

myosin

Choose the correct sequence of events that occur in preparation for contraction

Action potential arrives at triad, calcium is released from the terminal cisternae, calcium binds to troponin, tropomyosin exposes the actin active sites

Hydrolysis of ATP is responsible for

Recocking of the myosin heads

The binding of ATP to myosin is responsible for

Release of the myosin heads from the actin active sites

The release of ADP and Pi from myosin occurs during

the power stroke

The myosin heads return to their low-energy (relaxed) state during

the power stroke

The power stroke

Pulls the thin filaments toward the M lines

During muscle fiber relaxation, calcium channels in the SR close because

The resting membrane potential is restored

During muscle fiber relaxation

Calcium is pumped back into the SR

Acetylcholinesterase in the synaptic cleft degrades acetylcholine, allowing

Ligand-gated sodium channels to close

Sarcolemma repolarization during relaxation

Restores the resting membrane potential

Which aspect of muscle relaxation requires ATP?

Pumping calcium ions back into the SR

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