Essentials of Human Anatomy and Physiology(11) Activity Lab 6

How does the myosin head obtain the energy required for activation? The energy comes from the direct phosphorylation of ADP by creatine phosphate. The energy comes from the hydrolysis of ATP. The energy comes from oxidative phophorylation. The energy comes from the hydrolysis of GTP.

The energy comes from the hydrolysis of ATP.

What structure is the functional unit of contraction in a skeletal muscle fiber? The junctional folds of the sarcolemma The sarcomere The triad The cross bridge

The sarcomere

What changes occur in the sarcomere during muscle contraction? The thin filament shortens. A band decreases in length. Z discs move closer together. I band increases in length.

Z discs move closer together.

Which neurotransmitter is released by motor neurons at the neuromuscular junction? acetylcholinesterase potassium sodium acetylcholine

acetylcholine

What initiates an action potential on a muscle cell? ATP myosin cross bridges binding to actin acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction acetylcholinesterase

acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction

There are three types of muscle tissue. Which of the following is classified as part of the muscular system? Select the best answer. all muscle tissue, including muscle of arteries, eyes, and the heart the heart all skeletal muscles

all skeletal muscles

Which of these increases as muscles age? Select the best answer. amount of connective tissue in a muscle muscle mass muscle strength

amount of connective tissue in a muscle

ALS (amyotrophic lateral sclerosis) is a disease that destroys nerve cells that control skeletal muscle activity. Without neural stimulation, skeletal muscles eventually waste away and mobility is impossible. In other words, skeletal muscles __________. become flaccid become atrophied lose muscle tone lose muscle tone and become flaccid

become atrophied

What mineral is released within muscle cells to trigger contraction? calcium ATP potassium sodium

calcium

What type of muscle tissue is both striated and involuntary? cardiac muscle smooth muscle skeletal muscle visceral muscle

cardiac muscle

What term refers to a smooth, sustained contraction? muscle twitch isometric contraction isotonic contraction complete tetanus

complete tetanus

Which of these terms refers to the shape of a muscle? biceps deltoid mastoid rectus

deltoid

What is the function of creatine phosphate? triggers anaerobic respiration makes oxygen available for aerobic respiration catalyzes aerobic respiration directly regenerates ATP from ADP within a muscle cell

directly regenerates ATP from ADP within a muscle cell

Which layer of connective tissue surrounds each skeletal muscle fiber? aponeurosis epimysium endomysium perimysium

endomysium

Which of these muscles is named for the arrangement of its fascicles? adductor longus deltoid temporalis external oblique

external oblique

What term describes the ability of a muscle to vary its degree of shortening to generate the strength needed to lift a 5 lb weight, a 7 lb weight, and finally a 10 lb weight? isometric contractions isotonic contractions graded responses twitch

graded responses

Which of these characteristics applies only to cardiac muscle tissue? intercalated discs stimulated by hormones involuntary striations

intercalated discs

What metabolic waste accumulates in muscle with excessive exertion? ADP carbon dioxide creatine lactic acid

lactic acid

Which chemical is produced during vigorous exercise when the supply of oxygen is limited or inadequate? glycogen lactic acid carbon dioxide creatine

lactic acid

Which of these muscles moves the upper limb? external oblique latissimus dorsi trapezius brachialis

latissimus dorsi

Amelie, a 29-year-old woman, complained to her doctor of being constantly fatigued and having difficulty swallowing. Her speech is slurred and her eyelids are droopy. Amelie most likely has __________. torticollis myasthenia gravis tetanus Duchenne's muscular dystrophy

myasthenia gravis

Which connective tissue bundles muscle fibers into fascicles? tendons perimysium endomysium epimysium

perimysium

Which of these muscles extends the knee? rectus femoris biceps femoris gastrocnemius tibialis anterior

rectus femoris

What is key to offsetting the effects of aging on the muscular system? sleeping 6-8 hours per night taking vitamins regular exercise drinking plenty of water

regular exercise

What can older individuals do to increase muscle strength? Select the best answer. get sufficient rest every day regularly use hand weights and practice leg lifts

regularly use hand weights and practice leg lifts

What type of exercise causes increase in muscle size? infrequent exercise anaerobic exercise aerobic exercise resistance exercise

resistance exercise

What term describes the rotation of a bone around its longitudinal axis? circumduction dorsiflexion rotation inversion

rotation

Babies born with congenital torticollis are unable to rotate their heads properly and their necks are twisted to one side. The muscle that is affected in congenital torticollis is the __________ muscle. zygomaticus sternocleidomastoid deltoid platysma

sternocleidomastoid

Which of these muscles is located in the neck? occipitalis sternocleidomastoid buccinator deltoid

sternocleidomastoid

Which movement is associated with the hand but actually occurs in the forearm? dorsiflexion inversion supination opposition

supination

What term refers to a muscle that aids another muscle by producing the same the movement or reducing undesirable movements? fixator synergist antagonist prime mover

synergist

A muscle inserts on which of the following? the bone that moves when the muscle contracts the bone that does not move when the muscle contracts the synergist the antagonist

the bone that moves when the muscle contracts

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment? Calcium ions bind to troponin. Acetylcholine binds to receptors in the junctional folds of the sarcolemma. ATP binds to the myosin head. ADP and inorganic phosphate are bound to the myosin head.

ATP binds to the myosin head.

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. Calcium ions are stored in the nuclei. Calcium ions are stored in the mitochondria. Calcium ions are stored in the transverse tubules.

Calcium ions are stored in the sarcoplasmic reticulum.

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge? Calcium bound to troponin ATP bound to a myosin head A myosin head bound to actin Troponin bound to tropomyosin

A myosin head bound to actin

What specific event triggers the uncovering of the myosin binding site on actin? Sodium ions bind to troponin and change its shape. Calcium release channels open in the sarcoplasmic reticulum, and calcium levels rise in the sarcoplasm. Calcium ions bind to troponin and change its shape. Calcium ions bind to tropomyosin and change its shape.

Calcium ions bind to troponin and change its shape.

When does cross bridge cycling end? Cross bridge cycling ends when ATP binds to the myosin head. Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin. Cross bridge cycling ends when calcium release channels in the sarcoplasmic reticulum open. Cross bridge cycling ends when calcium ions are passively transported back into the sarcoplasmic reticulum.

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

What is the molecular basis of Duchenne's muscular dystrophy? Calcium channels at the axon terminal fail to open. There is a shortage of acetylcholine at neuromuscular junctions. Muscle fibers lack a protein that helps to maintain the sarcolemma. Myosin and actin remain fixed in place.

Muscle fibers lack a protein that helps to maintain the sarcolemma.

What happens to a muscle when the nerve supplying that muscle is cut? The muscle hypertrophies. Muscle paralysis and atrophy occur. Muscular dystrophy develops. Myasthenia gravis develops.

Muscle paralysis and atrophy occur.