Chapter 6

The energy comes from the hydrolysis of ATP

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

All Skeleton Muscles

There are three types of muscle tissue. Which of the following is classified as part of the muscular system?

Supination

Which of these is associated with the hand but actually occurs in the forearm?

Rectus femoris

Which of these muscles extends the knee?

Sternocleidomastoid

Which of these muscles is located in the neck?

external oblique

Which of these muscles is named for the arrangement of its fascicles?

Latissimus Dorsi

Which of these muscles moves the upper limb?

Deltoid

Which of these refers to the shape of a muscle?

become atrophied

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 ________.

ATP binds to the myosin head

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

myasthenia gravis

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 _________

Sternocleidomastoid

Babies born with congenitial torticollis are unable to rotate their head properly and their necks are twisted to one side. The muscle that is affected in congenitial torricollis is the __________ muscle.

the bone that moves when the muscle contracts

A muscle inserts on which of the following?

Calcium ions are stored in the sarcoplasmic reticulum

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

Intercalated Discs

Which of these characteristics applies only to cardiac muscle tissue?

A myosin head bound to actin

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?

amount of connective tissue in a muscle

Which of these increases as muscles age?

regularly use hand weights and practice leg lifts

What can older individuals do to increase muscle strength?

Z discs move closer together

What changes occur in the sarcomere during muscle contraction?

Muscle paralysis and atrophy occur

What happens to a muscle when the nerve supplying that muscle is cut?

acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction

What initiates an action potential on a muscle cell?

directly generates ATP from ADP within a muscle cell

What is the function of creatine phosphate?

regular exercise

What is the key to offsetting the effects of aging on the muscular system?

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

What is the molecular basis of Duchenne's muscular dystrophy?

Lactic Acid

What metabolic waste accumulates in muscle with excessive exertion?

calcium

What mineral is released within muscle cells to trigger contraction?

Calcium ions bind to troponin and change its shape

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

The Sarcomere

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

graded responses

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?

rotation

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

Synergist

What term refers to a muscle that aids another muscle by producing the same movement or reducing undesirable movements?

Complete Tetanus

What term refers to a smooth, sustained contraction?

resistance exercise

What type of exercise causes increase in muscle size?

Cardiac Muscle

What type of muscle tissue is both striated and involuntary?

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

When does cross bridge cycling end?

lactic acid

Which chemical is produced during vigorous exercise when the supply of oxygen is limited or inadequate?

Perimysium

Which connective tissue bundles muscle fibers into fascicles?

Endomysium

Which layer of connective tissue surrounds each skeleton muscle fiber?

acetylcholine

Which neurotransmitter is released by motor neurons at the neuromuscular junction?