9 Review Questions B

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All of the following are functions of muscle EXCEPT

protection

An entire skeletal muscle is surrounded by

epimysium

As an axon enters a muscle, it branches into a number of axonal terminals, each of which forms a neuromuscular junction with a single muscle fiber. A motor neuron and all the muscle fibers it supplies is called a

motor unit

During muscle contraction, all of the following occur EXCEPT

hemoglobin concentration in muscle fibers increases.

What is the ion released from the terminal cisternae that combines with troponin and removes the blocking action of tropomyosin, resulting in formation of cross bridges?

Ca2+

Each skeletal muscle fiber is controlled by a neuron at a single

neuromuscular junction

In a skeletal muscle fiber, which of the following best describes the composition of the structure known as a triad?

Terminal cisterna, transverse tubule, and terminal cisterna

In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in an overlapping of actin and _________.

myosin

Interactions between actin and myosin filaments of the sarcomere are responsible for

muscle contraction

The all-or-none response of a muscle fiber means that

a muscle fiber responds maximally to threshold stimulation or NOT at all.

The dense layer of collagen fibers that surround an entire skeletal muscle is the

epimysium

The functional unit of a skeletal muscle fiber is the

sarcomere

Which statement below does NOT represent a role of ionic calcium in muscle contraction?

Triggers diffusion of Na+ out of the cells

The space between the neuron and the muscle is the

synaptic cleft.

The term that means a continued mild or partial contraction of an entire muscle is muscle

tone

The type of muscle contraction in which the muscle fibers produce increased tension but the muscle neither shortens nor lengthens is called

isometric.

the role of calcium ions in the contraction of skeletal muscle?

Calcium ions bind to the troponin-tropomyosin complex and remove their inhibitory action on actin/myosin interaction

the following statements about smooth muscle is true?

Fibers are small and spindle-shaped.

following statements is INCORRECT

Skeletal muscles are responsible for the pumping action of the heart.

the following substances increases in quantity during repetitive muscle contraction?

Lactic acid

The sequence of electrical changes that occurs along the sarcolemma when a muscle fiber is stimulated is known as the

action potential.

In the early stage of repolarization, the sarcolemma is restored to its initial polarized state initially by

K+ diffusing rapidly out of the muscle fiber.

During repolarization, the initial events restore only the electrical conditions while the Na+/K+ pump restores the

ionic conditions.

the following moves Ca2+ back into the tubules of the SR after a contraction?

The ATP-dependent calcium pump

the following allows recoil of the muscle fiber when contraction ends?

Elastic filaments

the following binds calcium ions in a smooth muscle causing contraction?

Calmodulin

the following events is something a smooth muscle can do but cardiac and skeletal muscle can not do?

Grow by hyperplasia or an increase in the number of cells.

the following types of muscle is found in the eye and are used to regulate the size of the pupil?

Multiunit smooth muscle

All of the following terms refer to the ability to receive and respond to a stimulus except

contractility.

Elasticity refers to the ability of a muscle fiber to

recoil and resume its resting length after being stretched.

the following muscles is voluntary?

the muscle that extends the arm at the elbow

the following are characteristics of skeletal muscle contraction except

it can contract for long periods of time without tiring.

Unlike cardiac and smooth muscle, skeletal muscle

must be stimulated by nerve endings to initiate contraction.

A sarcomere is part of a

myofibril.

The epimysium is

the overcoat of dense irregular connective tissue that surrounds the whole muscle.

the following statements about "indirect attachments" of muscle is incorrect?

The epimysium of the muscle fuses with the periosteum of the bone.

the following characteristics is not unique to skeletal muscle fibers?

They are striated

The plasma membrane of a muscle cell is known as the

sarcolemma.

"Cross bridges" that link between the thick and thin filaments are formed by the

globular head of thick filaments

The function of the protein "dystrophin" is to

links the thin filaments to integral proteins.

the following is thought to be an autoimmune disease of acetylcholine receptors?

Myasthenia gravis

The binding of acetylcholine molecules to acetylcholine receptors would lead to all of the following except

sodium would leave the muscle cell.

The refractory period in which the muscle will not contract if stimulated occurs during __________ of the muscle cell.

repolarization.

What would happen if the calcium level in the sarcoplasm was kept high?

The cell would calcify and die

What is the cause of rigor mortis

Calcium influx into the cell after death causes rigor mortis.

The difference in the speed and duration of contraction of a twitch contraction in different muscles through-out the body is due to the

enzyme variations in different muscles

the following would produce a " treppe" effect on muscle contraction?

Applying the same strength stimulus for a long period of time.

In an isotonic eccentric muscle contraction, the muscle generates force as it

increases its length

The presence of creatine phosphate in the muscle provides

additional energy to the contracting muscle

Where does 95% of the energy needed for contraction come from during moderate exercise?

ATP provides 95% of energy during moderate exercise.

The alternating contraction and relaxation of opposing layers of smooth muscle is referred to as

peristalsis

the following characteristics is unique to smooth muscle?

the absence of striations.

Cardiac muscle control is voluntary.

False

Communication between nerve and muscle fiber occurs at specialized junctions called neuromuscular junctions

True

Cross-bridges are portions of the actin molecules.

False

During the recovery period following exercise, the body's need for oxygen is increased.

True

In isotonic contractions, the muscle changes in length and the tension remains constant through most of the contractile period.

True

Lactic acid is an end product of anaerobic fermentation that causes muscle fatigue.

True

Muscles that exert very fine control (such as the muscles controlling movements of the fingers and eyes) have large motor units.

False

One of the functions of the smooth muscle tissue is to force blood from the heart into the major arteries.

False

The area of the sarcomere that contains only thin and titin elastic filaments is the I band.

True

The neurotransmitter that stimulates skeletal muscle is adrenalin.

False

The sequence of events which forms the link between electrical activity in the sarcolemma and the initiation of a contraction is called excitation-contraction coupling.

True

The skeletal muscle complex known as the triad consists of the transverse tubule and the terminal cisternae

True

The space between the neuron and the muscle is the synaptic knob.

False

The type of muscle fiber that is most resistant to fatigue is the fast fiber.

False

Cross-bridges occur when myosin combines with the active site on actin.

False

Cross bridge attachment to actin requires K+.

True

In the initial stages of repolarization the ionic conditions are restored returning the membrane to its resting potential.