Muscular System

Which of these events must occur first to trigger the skeletal muscle to generate an action potential and contract?

acetylcholine (Ach) causes temporary permeability to sodium.

What initiates an action potential on a muscle cell?

acetylcholine binding to receptors on sarcolemma within the neuromuscular junction.

Specific neurotransmitter that stimulates skeletal muscle cells

acetylcholine.

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

acetylcholine.

Enzyme that breaks down acetylcholine (ACh)

acetylcholinesterase.

Electrical current that travels the length of the muscle

action potential.

Primary action of the adductor muscles

adduction.

The movement of a limb toward the body midline

adduction.

Which of these increases as muscle age?

amount of connective tissue in a muscle.

Endomysium covers ____________?

an individual muscle cell.

What changes occur in the sarcomere during muscle contraction?

Z discs move closer together.

When a skeletal muscle is fully contracted, the _______ are closer to the thick filaments

Z discs.

Acetylcholine is?

a neurotransmitter that stimulates skeletal muscle.

Primary action of the deltoid

abduction.

The movement of a limb away from the body midline

abduction.

Neurotransmitters are released upon stimulation from a nerve impulse by the?

axon terminals of the motor neuron.

ALS 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 atrophied.

In order to excite a muscle cell, acetylcholine must?

bind to receptors in the sarcolemma of the muscle cell.

The sarcoplasmic reticulum stores this chemical

calcium ions.

What term refers to a smooth, sustained contraction?

complete tetanus.

Muscle tissue has the ability to shorten when adequately stimulated, a characteristic known as?

contractility.

A muscle twitch results when the muscle is stimulated so rapidly that no evidence of relaxation is seen

false.

A neurotransmitter junction consists of one neuron and all the skeletal muscles it stimulates

false.

The fastest mechanism for producing ATP is aerobic respiration

false.

Primary action of rectus abdominis

flexion.

Type of movement that decreases the angle of the joint

flexion.

Anaerobic glycolysis requires _________ to make ATP

glucose.

What term describes the ability of a muscle to vary its degree of shortening to generate the strength needed to lift w 5 lb wright, a 7 lb weight, and finally a 10 lb weight?

graded responses.

Which of the following is NOT a function of the muscular system?

hematopoiesis.

Which of these characteristics applies only to cardiac muscle tissue?

intercalated.

Type of movement that turns the sole of the foot medially

inversion.

Smooth muscle cells are __________

involuntary.

Contractions in which muscles shorten and produce movement are known as?

isotonic contractions.

What metabolic waster accumulates in muscle with excessive exertion?

lactic acid.

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

lactic acid.

A motor neuron and all of the skeletal muscle fibers it stimulates are termed a?

motor unit.

One neuron and all the skeletal muscles it stimulates is known as a?

motor unit.

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

muscle paralysis and atrophy occur.

An inherited disease that causes muscles to degenerate and atrophy is known as __________.

muscular dystrophy.

Constantly fatigued, difficult swallowing, droopy eyes?

myasthenia gravis.

Anaerobic glycolysis occurs without __________.

oxygen.

Which connective tissue bundles muscle fibers into fascicles?

perimysium.

Type of movement that points toes

plantar flexion.

Which of the following is an example of an isometric contraction?

pushing against an immovable wall.

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

regular exercise.

What can older individuals do to increase muscle strength?

regularly use hand weights and practice leg lifts.

What type of exercise causes increase in muscle size?

resistance exercise.

The movement of a bone around its longitudinal axis

rotation.

Which type of muscle tissue contracts most quickly upon stimulation?

skeletal.

Chemical that enters a muscle cell upon excitation

sodium ions.

Creatine phosphate functions within the muscle cells by?

storing energy that will be transferred to ADP to resynthesizes ATP as needed.

Type of movement that allows you yo carry a soup bowl

supination.

Gap between the axon terminals and the plasma membrane of a neighboring muscle cell

synaptic cleft.

The gap between the motor neuron and the muscle fiber it supplies at the neuromuscular junction is called the?

synaptic cleft.

The epimysium covering on the outside of the muscle can blend into cordlike __________ or sheetlike ____________

tendons; aponeuroses.

A skeletal muscle twitch differs from a tetanic contraction in that _________

the muscle twit h is a brief and "jerky" movement, while the tetanic contraction is prolonged and continuous.

Aerobic respiration requires the use of oxygen to generate ATP

true.

Aerobic, or endurance, exercise involves jogging or biking

true.

Cardiac and skeletal muscle both possess striations

true.

The effect of the neurotransmitter on the muscle cell membrane is to temporarily modify its permeability of ions such as Na+ and K+

true.

The neurotransmitter used by the nervous system to activate skeletal muscle cells is acetylcholine

true.

When a muscle fiber contracts, the I bands in size, the H zones disappear, and the A bands move closet together but do not diminish in lengtj

true.

What mineral is released within muscle cells to trigger contraction?

calcium.

Striated involuntary muscle tissue found in the heart is?

cardiac muscle.

Striated involuntary muscle tissue is classified as _______ muscle

cardiac.

What type if muscle tissue is both striated and involuntary?

cardiac.

What is the function of creatine phosphate?

directly regenerates ATP from ADP within a muscle cell.

Primary action of the erector spinae

extension.