Chapter 10 A&P

The characteristic of muscle that allows it to be passively stretched is:

conductivity. elasticity. excitability. → extensibility. contractility.

Which are possible functions of skeletal muscles?
a: Maintenance of posture
b: Both highly coordinated and localized simple movements
c: Temperature regulation
d: Support of certain body organs
e: Regulation of the movement of material through certain body tracts

a, b, e a, b, c a, b, c, e a, b, c, d → a, b, c, d, e

A skeletal muscle cell can be several inches long. The property of muscle tissue that allows an impulse to travel down the entire length of the cell membrane is:

elasticity. → conductivity. extensibility. contractility. responsibility.

The spring-like property that returns muscle to its original length after a contraction ends is:

extensibility. → elasticity. contractility. treppe effect. conductivity.

In general, a skeletal muscle is composed of:
a: connective tissue sheaths
b: nerves
c: arteries
d: veins
e: muscle fibers

a, b, c, e a, b, d, e b, c, d, e a, b, c, d → a, b, c, d, e

Which is a correct listing of the hierarchy of a skeletal muscle’s components, beginning with the smallest?
a: Myofibrils
b: Muscle fiber
c: Fascicle
d: Skeletal muscle

! a, b, c, d a, c, b, d d, c, b, a c, b, a, d b, c, a, d

Which is the correct order of the connective tissue layers of a skeletal muscle, beginning with the outermost first?
a: Endomysium
b: Epimysium
c: Perimysium

a, b, c b, a, c c, a, b → b, c, a c, b, a

The structure responsible for attaching muscle to bone is a:

sphincter. ligament. fascia. → tendon. myofibril.

A flat, thin structure made of dense connective tissue that serves to attach a muscle to a bone (or to another muscle) is a(n):

! aponeurosis. tendon. perimysium. myolemma. superficial fascia.

The neurons that stimulate muscle contraction are called _____ neurons.

sensory contractile inhibitory → motor association

The multiple nuclei in skeletal muscle cells are the result of the:

! fusion of myoblasts. cytokinesis of embryonic satellite cells. spontaneous development of nuclei in embryonic cells. stimulation of fibroblasts by hormones. action of testosterone on mesenchyme cell.

The membranous network that wraps around myofibrils and holds relatively high concentrations of calcium is known as the:

sarcolemma. T-tubule. → sarcoplasmic reticulum. sarcomere. Golgi body

Invaginations of the muscle cell membrane that extend deep into the cell are known as the:

! T-tubules. terminal cisternae. titin complexes. Z-discs. end plates.

Which are the reservoirs that store the calcium required for muscle contraction?

Synaptic vesicles Synaptic clefts → Terminal cisternae Peroxisomes Mitochondria

Which protein makes up the thick filaments?

! Myosin Actin Tropomyosin Troponin Myopathy

Which is not a protein found in thin filaments?

Actin Troponin Tropomyosin → Sarcomyosin No exceptions; all are found in thin filaments

Each thick filament contains about ______ protein molecules (each molecule has two heads and two braided tails).

! 200

A skeletal muscle cell contains hundreds to thousands of _________, which are complex organelles; they are cylindrical in shape–about 2 micrometers in diameter and as long as the cell.

! myofibrils microfilaments sarcomeres T-tubules sarcolemma

What is the letter associated with the dark bands in a sarcomere?

I → A Z M H

Which letter is associated with the line that is a thin protein structure that serves as an attachment site for thin filament ends?

I A → Z M H

Which letter is associated with a zone (in a relaxed muscle) that is a little more lightly shaded because only thick filaments are present?

I A M Z → H

Which letter is associated with the light band and contains thin filaments only?

! I A M Z H

Which of the myofilaments of a muscle fiber has the active sites to which the heads of the thick filaments will bind?

! Actin Troponin Tropomyosin Myosin Sarcoplasm

A sarcomere is defined as the distance from one _____ to the next adjacent ____ . (The same answer fills in both spaces.)

! Z disc I band H zone A band M line

Myoglobin is a molecule within muscle cells that can bind:

creatine phosphate. → oxygen. hemoglobin. acetylcholine. ATP

A typical skeletal muscle cell contains approximately _____ mitochondria.

3 30 → 300 3000

The presence of mitochondria and myoglobin facilitate _________ respiration in muscle cells.

! aerobic anaerobic

One feature that helps provide fast energy to a muscle cell is the presence of granules containing the complex carbohydrate:

creatine phosphate. myoglobin. → glycogen. nebulin. hemoglobin.

A motor unit consists of:

multiple motor neurons and multiple muscle fibers. → a single motor neuron and the multiple muscle fibers it controls. multiple motor neurons and the one muscle fiber they control. one synaptic terminal button, a cleft, and an acetylcholine receptor. an end plate, T-tubule, and sarcoplasmic reticulum.

A motor unit within the powerful quadriceps muscle would:

contain several motor neurons. be much like those in the eye muscles. generally contain less than ten fibers. → generally contain several hundred fibers.

Fibers from one motor unit:

are clustered together within one fascicle of the muscle. → are dispersed throughout most of the muscle.

The narrow space that separates the motor neuron and the skeletal muscle fiber in a neuromuscular junction is called the:

motor end plate. synaptic vesicle. → synaptic cleft. synaptic knob. Ach floor.

Which structures are reservoirs that store acetylcholine?

! Synaptic vesicles Synaptic clefts Terminal cisternae Lysosomes Sarcomeres

When an impulse arrives at the knob of the motor neuron, calcium:

enters through active transport pumps and triggers the release of transmitter. → enters through voltage-gated channels and triggers the release of transmitter. exits through active transport pumps and brings transmitter with it. exits through voltage-gated channels and triggers transmitter release. is released from synaptic vesicles.

The way acetylcholine is released from a neuron is:

by a primary active transport pump. by rapid diffusion when a voltage-gated ion channel opens for it. → through exocytosis when a vesicle fuses with the membrane. by conduction through a gap junction from nerve to muscle.

Acetylcholine exerts its effect by:

stimulating the motor neuron’s synaptic knob. → binding to receptors at the motor end plate. activating acetylcholinesterase. allowing calcium to enter the cell.

Which is the neurotransmitter that causes the release of calcium ions from reservoirs within the muscle cell and thereby initiates the steps of contraction?

Acetylcholinesterase Rubitussin → Acetylcholine Serotonin Norepinephrine

The calcium ions involved in skeletal muscle contraction bind to a(n)______ subunit.

myosin actin elastin tropomyosin → troponin

An end plate potential is an event that involves a gain of:

positive charge for the cell, as potassium rapidly enters. → positive charge for the cell, as sodium rapidly enters. negative charge for the cell, as potassium rapidly enters. negative charge for the cell, as sodium rapidly enters

The action potential of a muscle fiber occurs:

at the end plate. → along the sarcolemma and down the T-tubules. within the sarcoplasmic reticulum. in the mitochondria.

The repolarization of the action potential involves the opening of:

chemically gated Na+ channels. voltage-gated Na+ channels. chemically gated K+ channels. → voltage-gated K+ channels.

Which sequence correctly lists the changes that allow the thick and thin filaments to slide past one another in skeletal muscle contraction?

! Attach – pivot – detach – return Pivot – attach – return – detach Attach – detach – pivot – return Return – pivot – attach – detach Pivot – attach – detach – return

During which phase of the crossbridge cycle is ATP split into ADP and Pi?

Immediately preceding the detachment of the myosin head → Immediately preceding the resetting of the myosin head Immediately preceding the power stroke

A power stroke involves:

an actin molecule pulling a myosin molecule toward the M-line. a thin filament shortening in length and thereby shortening the sarcomere. → a myosin head pulling a thin filament toward the center of the sarcomere. a thick filament pushing an actin filament towards the nearest Z-line.

A drug that inhibited acetylcholinesterase would result in:

a failure to stimulate the muscle due to decreased Ach release. → enhanced stimulation of the muscle due to decreased Ach breakdown. enhanced stimulation of the muscle due to enhanced Ach release. poor muscle stimulation due to enhanced Ach breakdown

For relaxation to occur:

! Ach receptors close and Ca++ channels on the sarcoplasmic reticulum close. Ach receptors close and Ca++ channels on the sarcoplasmic reticulum open. Ach receptors open and Ca++ channels on the sarcoplasmic reticulum close. Ach receptors open and Ca++ channels on the sarcoplasmic reticulum open.

For relaxation to occur:

calcium leaves the sarcoplasmic reticulum, troponin binds calcium and blocks the binding sites on actin. calcium enters the myofibril, it detaches from myosin, and the binding sites on myosin become inactive. → sarcoplasm calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actin. extracellular calcium levels fall, calcium is pumped into the myofibril, and tropomyosin slides away from actin.

When a muscle relaxes:

crossbridges form and muscle extensibility returns the muscle to rest length. crossbridges form and muscle elasticity returns the muscle to rest length. → crossbridges stop forming and muscle elasticity returns the muscle to rest length. crossbridges stop forming and muscle extensibility returns the muscle to rest length

The phosphagen system is used for:

immediate ATP needs and is dependent on oxygen. → immediate ATP needs and is not dependent on oxygen. long term ATP needs and is dependent on oxygen. long term ATP needs and is not dependent on the presence of oxygen.

Glycolysis is an:

aerobic process that occurs in the cytosol. aerobic process that occurs in the mitochondria. → anaerobic process that occurs in the cytosol. anaerobic process that occurs in the mitochondria

The net energy yield from one glucose molecule through the process of glycolysis is:

! 2 ATP. 6 ATP. 34 ATP. 36 ATP

For a sprint lasting 60 seconds, ATP is supplied initially by:

aerobic respiration but eventually by anaerobic respiration. → the phosphagen system but primarily by glycolysis. myokinase but primarily by creatine kinase. the phosphagen system but primarily by aerobic respiration. oxidative phosphorylation, but eventually by the phosphagen system.

Oxidative fibers are:

! red and fatigue-resistant. red and fatigable. white and fatigue-resistant. white and fatigable

The type of fibers specialized to continue contracting for extended periods of time, as would be required in running a marathon, for example, are _____ fibers.

fast → slow intermediate

The vascular supply to slow muscle fibers is ______ the network of capillaries around fast muscle fibers.

! more extensive than less extensive than the same as that of

"Intermediate fibers" is another name for:

fast, glycolytic fibers. → fast, oxidative fibers. slow, glycolytic fibers. slow, oxidative fibers

Which fibers dominate many of the back and calf muscles that contract almost continually to maintain posture?

! Slow Fast Intermediate

Muscles of the eye and hand have a high percentage of _______ fibers.

! fast slow

Events of excitation contraction coupling, such as the release of calcium from intracellular stores, occur during the ________ period of a muscle twitch.

relaxation contraction → latent

Release of crossbridges and a decline in muscle tension characterize the _______ period of a twitch.

contraction latent → relaxation

The increase in muscle tension that occurs with an increase in the intensity (voltage) of a stimulus is called:

! recruitment. treppe. wave summation. incomplete tetany

Consider the difference between lifting a light pad of paper versus a heavy text book. The primary way the level of force of muscle contraction is controlled is by:

! recruiting a different number of motor units. activating different regions of the muscle. activating the motor units at a different frequency. altering the number of crossbridges each individual fiber uses.

"Staircase" and "warm up" are alternative names for ___________, an increased muscle response to a constant stimulus.

wave summation → treppe multiple motor unit summation incomplete tetany isotony

In a lab, wave summation is demonstrated by increasing the _________ of the stimulus.

intensity → frequency capacitance warm up time

Muscle tone is a result of _________ nervous system activity, and it acts to _________ joint position.

! involuntary, stabilize involuntary, continuously vary voluntary, stabilize voluntary, continuously vary

Which contraction occurs when you try (unsuccessfully) to move a wall?

! Isometric Isotonic

When a muscle is isometrically contracted, its length _______ change.

does → does not

The top long distance runners probably have _______ proportion of slow muscle fibers in their leg muscles.

! a higher a lower the same

The most prevalent of skeletal muscle fibers in the body are _____ fibers.

slow → fast intermediate

One of the reasons you might struggle to lift a heavy object if you tried to lift it with your arm at a fully extended posture is that:

in extension, the proximity of Z discs to thick filaments restricts the sliding movement within sarcomeres. → full extension results in decreased overlap between thick and thin filaments in the muscle. in that posture, some myosin heads overlap actin in the wrong orientation and tug actin in the wrong direction. motor neurons cannot release as much Ach in that posture

Increased phosphate ion concentration is believed to contribute to fatigue by interfering with:

calcium release from the sarcoplasmic reticulum. levels of available ATP to provide energy for contraction. → phosphate release by myosin heads during crossbridge cycling. Ach release by synaptic knobs of motor neurons

Which may occur as a result of muscle atrophy?

Reduction in muscle size Fibers become weaker Muscle loses tone Fibers waste away and die → All choices are correct

With increased age, skeletal muscles show:

! a decrease in the number of myofibrils. an increase in muscle fiber diameter. no change in oxygen storage capability. increased glycogen reserves. a tendency to fatigue less rapidly.

The main way a body builder’s muscles become larger is:

by an increase in the number of muscle cells. → by an increase in the size of muscle cells.

A term that describes the change in muscle following a lack of exercise is:

proliferation. hypertrophy. convergence. → atrophy. myofascia

The type of muscle fibers that have only a single nucleus, both thick and thin filaments, but no Z discs, are:

skeletal. cardiac. → smooth. cardiac and smooth. cardiac and skeletal.

Growth of the uterus during pregnancy is accomplished by _________ of its smooth muscle.

neither hypertrophy nor hyperplasia → both hypertrophy and hyperplasia hypertrophy but not hyperplasia hyperplasia but not hypertrophy

The latchbridge mechanism of myosin heads is a property of ________ muscle.

cardiac skeletal → smooth

To initiate a smooth muscle cell contraction, calcium enters the cell and binds to:

troponin, which then activates myosin light chain kinase. → calmodulin, which then binds to and activates myosin light chain kinase. a myosin head, which then activates calmodulin. myosin light chain kinase, which then hydrolyzes ATP. a phosphatase, which then removes the tropomyosin blockade

The branch of the nervous system that helps govern smooth muscle contraction is the _______ nervous system.

! autonomic somatic

When smooth muscle is stretched for a prolonged period of time, it responds by:

contracting. → relaxing

Smooth muscle tissue in which cells are individually sent signals to contract (rather than contracting in unison) is referred to as:

single-unit. → multiunit.

The iris of the eye contains:

…

The most abundant form of smooth muscle is:

! single-unit, which is also known as visceral smooth muscle. cardiac muscle, which is also known as visceral smooth muscle. multiunit, which is also known as visceral smooth muscle. multiunit, which is also known as varicose muscle. single-unit, which is also known as somatic nervous system muscle

Rather than tightly coupled synapses between neurons and muscle cells, single-unit smooth muscle contains:

gap junctions that connect neurons to smooth muscle cells. varicosities of a subset of muscle fibers so that individual cells can be separately stimulated. → diffuse junctions where neuron varicosities are responsible for neurotransmitter release. plaques and caveolae that contain multiple hormone receptors for discrete endocrine control

This sarcomere depicts relaxed muscle. Number 1 denotes the

! A band H zone Z disc M line I band

This sarcomere depicts relaxed muscle. The M line is noted by number

1 3 → 4 5

The type of muscle fibers that are striated, form Y-shaped branches, and have junctions called intercalated discs are:

skeletal. → cardiac. smooth. voluntary. skeletal and voluntary.