Anatomy Muscular System

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

Z discs

Endomysium covers

an individual muscle cell

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

motor unit

Aerobic, or endurance, exercise involves jogging or biking

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 active skeletal muscle cells is acetylcholine

true

The sarcoplasmic reticulum wraps like a sleeve around the myofibril and stores and releases calcium

true

During skeletal muscle contraction, myosin heads attach to binding sited associated with

actin filaments

The movement opposite to abduction is

adduction

A muscle group that works with and assists the action of a prime mover is a

antagonist and fixator

Muscles that perform opposite actions to one another are termed

antagonists

The sarcoplasmic reticulum stores this chemical

calcium ions

Why are calcium ions necessary for skeletal muscle contraction?

calcium triggers the binding of myosin to actin

Striated involuntary muscle tissue is classified as

cardiac muscle

Striated involuntary muscle tissue found in the heart is

cardiac muscle q

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

contractility

The heads of the myosin myofilaments are called ______ when they link the thick thin filaments together during skeletal muscle contraction

cross bridge

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

false

A neuromuscular junction consists of one neuron and all the skeletal muscle it stimulates

false

Bundles of muscle fibers are known as aponeuroses

false

Isometric contractions produce movement when filaments slide past one another and the muscle shortens

false

The fastest mechanism for producing ATP is aerobic respiration

false

thick filaments are made of a protein called actin

false

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

motor unit

The plasma membrane of a skeletal muscle cell is called the

sarcolemma

A sarcomere is

the contractile unit between two z discs

Which one of the following is composed of myosin protein

thick filaments

Cross bridges are created when myosin heads bind to

thin filaments

Abduction and adduction are antagonists actions

true

Aerobic respiration requires the use of oxygen to generate ATP

true

All types of muscle have endomysium individual muscle cells

true

Cardiac and skeletal muscle both possess striations

true

The striations seen in skeletal muscle are actually alternating dark A and light I bands.

true

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

true

Electrical current that travels the length of the muscle

Acetycholinesterase

Specific neurotransmitter that stimulates skeletal muscle cells

Acetylcholine

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

Acetylcholine causes temporary permeability to sodium

Enzyme that breaks down acetylcholine

Action Potential

-Muscle tissue found only in the heart -Muscle tissue composed of branching cells and intercalated discs

Cardiac Muscle

Which of the following can actually shorten during a muscle contraction

Sarcomere

-Voluntary Muscle -Muscle Tissue that is multinucleate -Muscle tissue that maintains, body position, and stabilizes joints

Skeletal Muscle

-Muscle tissue that forms valves to regulate the passages of substance through internal body openings -Muscle tissue that activates arrector pili muscles to stand hairs on end -Performs very slow, sometimes rhythmic, contractions

Smooth Muscle

Chemical that enters a muscle cell upon excitation

Sodium ions

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

Acetylcholine is

a neurotransmitter that stimulates skeletal muscle

the mechanical force of contraction is generated by

a sliding of thin filaments past thick filaments

Neurotransmitters are released upon stimulation from a nerve impulse by the

axon terminals of the motor neuron

Contractions in which muscles shorten and produce movement are known as

isometric contractions

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

bending below the elbow

In order to excite a muscle cell, acetylcholine must

bind the receptors in the sarcolemma of the muscle cell

Anaerobic glycolysis requires ________ to make ATP

both oxygen and glucose

A smooth, sustained contraction is called

fused, or complete, tetanus

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

hematopoiesis

The condition of skeletal muscle fatigue can be best explained by

insufficient intracellular quantities of ATP due to excessive consumption

Smooth muscle cells are

involuntary

The least movable point of muscle attachment to a bone is termed its

origin

The point of muscle attachment to an immovable or less movable bone is known as the

origin

Anaerobic glycolysis occurs without

oxygen

An elaborate and specialized network of membranes in skeletal muscle cells that function in calcium

sarcoplasmic reticulum

This ______ is an organelle that wraps and surrounds the myofibril and stores calcium

sarcoplasmic reticulum

Which type of muscle tissue contracts most quickly upon stimulation

skeletal

The gap between the axon terminal of a motor neuron and the sarcolemma of a skeletal muscle cell is

synaptic cleft

the epimysium covering on the outside of the muscle can blend into cordlike _______ or sheetlike ________

tendons; aponeuroses