ch 45 questions and hmwk

During contraction specific regions and subunits of the sarcomere remain unchanged while others do not. From the list below identify the structures and regions that remain constant. 1. A band 2. Actin 3. H zone 4. I band 5 Myosin 6. Z line

1, 2, 5, 6

Resetting: Hydrolysis of ATP provides energy, which causes the cross-bridge to move away from the _______. ADP and Pi remain bound.

H zone

What Musculoskeletal Disease: More common in men, Degeneration of skeletal and cardiac muscle, Refers to a group of diseases

Muscular Dystrophy

What Musculoskeletal Disease: More common in women, Most prevalent bone disease in the U.S.

Osteoporosis

Power stroke: Release of _____ causes the cross-bridge to move toward the Z zone. This moves the actin toward the H zone.

Pi

What Musculoskeletal Disease: Bone is deformed, Most apparent in weight-bearing bones, Also known as osteomalacia

Rickets

an accurate characterization of calcium's role in muscle contraction would state that: (all that apply) a. the release of Ca2+ from the sarcoplasmic reticulum is stimulated by a nerve impulse. b. a high concentration of Ca2+ prevents cross-bridges from occurring. c. Ca2+ ultimately allows contractions to occur by facilitating the binding of actin and myosin. d. T-tubules act as channels for Ca2+ to move into the sarcoplasmic reticulum.

a and c

In an experiment you, the researcher, removes ATP from the system. What would be a likely consequence of the lack of ATP on muscle contraction? a. The cross bridges would remain linked and therefore contraction would stop. b. The tropomyosin filament would not be dislodged preventing contraction. c. The cross bridges would break apart due to the presence of calcium ions enabling some contraction. d. The myosin heads would separate from the actin molecule due to the release of ADP that was previously present.

a. The cross bridges would remain linked and therefore contraction would stop.

The important function(s) of the skeletal system include (all that apply) a. wound repair b. production of blood cells c. production of heat d. structural support e. locomotion f. reservoir for ions

b, d, e, f

If you had a sacromere that was composed of 16 myosin heads, after two cycles of contraction how many ATP molecules would be consumed? a. 64 b. 32 c. 8 d. 16

b. 32

which of the following statements is true? a. a muscle fiber is a collection of cells embedded in connective tissue b. a sarcomere contains both actin and myosin molecules arranged in a parallel fashion c. the function of Ca2+ in contraction is to bind to tropomyosin d. myofibrils are individual muscle cells e. the I band of a sarcomere is the region where thin and thick filaments overlap

b. a sarcomere contains both actin and myosin molecules arranged in a parallel fashion

a disadvantage of an exoskeleton is that it a. cannot protect an animal's internal organs b. must be periodically shed, leaving the animal in a vulnerable state c. does not provide any flexibility for the ease of movement of an animal d. is a soft, easily damaged structure e. cannot protect the outside of the body surface

b. must be periodically shed, leaving the animal in a vulnerable state

When joint movement is the result of antagonistic muscle pairing, a. movement is accomplished by the simultaneous action of one muscle pushing while another muscle is pulling. b. two muscles pull on the joint in opposite directions. c. one muscle group exerts a pulling force while another rotates the joint. d. None of the answers are correct.

b. two muscles pull on the joint in opposite directions.

In an experiment you, the researcher, removes calcium ions from the system. What would be a likely consequence of the lack of calcium on muscle contraction? a. Muscle contraction would occur because the tropomyosin filament would remain dislodged enabling actin and myosin to form cross bridges. b. Muscle contraction would occur since ATP would supply the energy allowing for the movement of myosin heads. c. Muscle contraction would not occur because the tropomyosin filament on the actin molecule would block myosin binding sites preventing the formation of cross bridges. d. Muscle contraction would not occur because ATP requires calcium ions to bind to myosin heads and produce an conformational change.

c. Muscle contraction would not occur because the tropomyosin filament on the actin molecule would block myosin binding sites preventing the formation of cross bridges.

the function of Ca2+ in skeletal muscle contraction is to a. cause an allosteric change in myosin so it detaches from actin b. provide the energy necessary for the movement of the cross-bridge c. expose the myosin binding sites on the thin filaments d. stimulate an action potential in the muscle fiber e. do a and c only

c. expose the myosin binding sites on the thin filaments

Which of the following statements about movement and locomotion is false? a. terrestrial animals and flying animals expend energy to provide lift b. swimming animals typically expend energy to provide thrust but not lift c. flexors and extensors are examples of muscles called agonists d. flexors cause bending at a joint e. extensors cause straightening of a limb

c. flexors and extensors are examples of muscles called agonists

What is the role of calcium in muscle contractions? a. to spread the action potential through the T-tubules b. to break the cross-bridges as a cofactor in the hydrolysis of ATP c. to bind with troponin, changing its shape so that binding sites on the actin filament are exposed d. to re-establish the polarization of the plasma's membrane following an action potential e. to transmit the action potential across the neuromuscular junction

c. to bind with troponin, changing its shape so that binding sites on the actin filament are exposed

the protein that provides strength and flexibility to bone is a. actin b. myosin c. myoglobin d. collagen e. elastin

d. collagen

During contraction of a muscle, calcium ions bind to... a. the tropomyosin molecule b. the sarcoplasmic reticulum c. the actin myofilament d. the troponin molecule e. the sarcolemma

d. the troponin molecule

For animals adapted to it, swimming is energetically the cheapest form of locomotion because of a. the streamlined body forms of aquatic animals b. the slow speed of locomotion of many swimmers c. the buoyancy of water d. a and c only e. a b and c

e. a b and c

Muscle contraction is caused by a. actin filaments sliding past myelin filaments. b. myosin filaments sliding past each other. c. actin filaments sliding past each other. d. myelin filaments sliding past each other. e. actin filaments sliding past myosin filaments.

e. actin filaments sliding past myosin filaments.

Which, if any, of the following is not a function of the vertebrate skeleton? a. structural support b. protection of internal organs c. Ca2+ reserve d. blood cell production e. all of the above are functions of the vertebrate skeleton

e. all of the above are functions of the vertebrate skeleton

the function of ATP during muscle contraction is to a. cause an allosteric change in myosin so it detaches from actin b. provide the energy necessary for the movement of the cross-bridge c. expose the myosin-binding sites on the thin filaments d. do all of the above e. do a and b only

e. do a and b only

Muscle fibers that have a large number of mitochondria, contain large amounts of myoglobin, and exhibit low rates of ATPase activity are called __________ fibers. a. slow-glycolytic b. fast-glycolytic c. intermediate d. fast-oxidative e. slow-oxidative

e. slow-oxidative

A bundle of muscle cells is known as a __________.

fascicle

A muscle cell is also known as a muscle _______.

fiber

Repeated units of arranged filaments occur across the length of the ________.

myofibril

Detaching: ATP binds to _________ causing the cross-bridge to detach.

myosin

One complete sequence of arranged filaments is a unit called a ___________.

sarcomere

T/F? The sequence of cross-bridge formation and myofilament movement will be repeated as long as calcium ions are present.

true

Binding: When _____ levels are high, cross-bridges can bind to actin.

Ca2+

If you were running an experiment and interrupted the interaction between thin and thick filaments, what would be the most likely result on sarcomere contraction? a. The sarcomere would not be able to contract therefore the H zone and I band would remain the same in size. b. The sarcomere would still contract causing the H zone to disappear but the I band would not be reduced in size. c. The sarcomere would not be able to contract therefore the H zone would remain unchanged but the I band would still reduce in size. d. The sarcomere would still contract causing the H zone to disappear and the I band to reduce in size.

a. The sarcomere would not be able to contract therefore the H zone and I band would remain the same in size.

Which of the following statements about H zones and I bands is TRUE? a. the H zones contain only myosin, while the I bands contain only actin b. the H zones contain only myosin, while the I bands contain both actin and myosin c. the H zones and the I bands each contain both actin and myosin d. the H zones contain only actin, while the I bands contain only myosin e. the H zones contain both actin and myosin, while the I bands contain only actin

a. the H zones contain only myosin, while the I bands contain only actin

stimulation of a muscle fiber by a motor neuron occurs at a. the neuromuscular junction b. the transverse tubules c. the myofibril d. the sarcoplasmic reticulum e. none of the above

a. the neuromuscular junction

The filaments form the foundation of muscle structure. The thin filament is ________, and the thick filament is _________.

actin, myosin