muscular
How many protein strands are found in each myosin molecule?
2
Where is the perimysium found?
Around individual muscle fascicles
During a muscle twitch, what is the latent period?
Period of time between stimulation and the beginning of contraction.
What is an isometric contraction?
The muscle develops tension without shortening.
As ATP is broken down to ADP by the myosin-head ATPase, what is the released energy used for?
To move the myosin head into its cocked position.
What is the role of neurotransmitters?
To stimulate a target cell.
Within a sarcomere, the ______ band includes the area of overlap between actin (thin) filaments and myosin (thick) filaments.
a
A neuromuscular junction is a synapse between ______ and ______.
a motor neuron; a muscle fiber
What is muscle fiber?
a muscle cell
When the quadratus lumborum muscles on both sides contract, the vertebral column is ______.
extended
The teres major and latissimus dorsi are the primary ______ of the arm at the shoulder.
extensors
Where is the origin of the platysma?
fascia of the upper chest
perimysium
fascicle
Muscle cells are also known as muscle fibers. In a skeletal muscle, muscle fibers are found as bundles called _____________ each enclosed in a connective tissue sheath, called the ____________
fascicle , perimysium
Only ______-twitch fibers can be predominantly glycolytic, using glycolysis to produce ATP.
fast
Due to their shape, muscle cells are also called muscle ___________
fibers
How are the components found in a second-class lever arranged?
fulcrum-resistance-force
What is a synapse?
functional connection between neuron and effector
What is the immediate result of the opening of sodium channels along the sarcolemma (beyond the motor end plate)?
generation of an action potential
Muscle contractions generate ______, which is important for the overall functioning of the body.
heat
The ______ of a sarcomere is composed primarily of actin.
i band
What is the immediate effect of acetylcholine binding to its receptors on the motor end plate?
increased membrane permeability to sodium ions
The concentration of calcium in the sarcoplasm ______ during muscle contraction and ______ when relaxation occurs.
increases; decreases
During an ____________muscle contraction, the muscle either lengthens or shortens, while the tension stays constant.
isotonic
What type of contraction is observed when a muscle shortens?
isotonic
During a muscle twitch, the ________ period occurs between the stimulus and the increase in the force of contraction.
latent
What is the origin of the semispinalis capitis muscle?
lower cervical and upper thoracic vertebrae
What is the insertion of the temporalis?
mandible
Where is the origin of the buccinator?
mandible and maxilla
Which of the following is the insertion of the platysma?
mandible; skin and muscles below the mouth
Which muscle elevates the mandible?
masseter
endomysium
muscle fiber
The process of glycolysis is ______.
anaerobic
Glycolysis is used to produce ATP for muscle contraction and is best described as ______.
anaerobic breakdown of glucose to produce ATP
What is the origin of the sternocleidomastoid muscle?
anterior sternum; upper clavicle
Since slow-twitch fibers are oxidative fibers (using aerobic metabolism), they ______.
are fatigue-resistant
The enzyme acetylcholinesterase functions to ______.
break down acetylcholine in the synaptic cleft
What causes the myosin heads to move into their "cocked" positions prior to them attaching to actin?
breakdown of ATP into ADP and
Contraction of what muscle pulls the cheeks inward?
buccinator
Which muscle helps blow air out of the mouth and is also called the trumpeter muscle?
buccinator
Indicate one of the insertions for the trapezius.
clavicle
An isotonic contraction that results in shortening of muscle length is called a(n) ___________ contraction
concentric
The "cocking" of the myosin heads, hydrolysis of ATP, and the power stroke occur during the ______ phase of skeletal muscle contraction.
contraction
The oxygen needed to recycle lactic acid in the liver and regenerate ATP in skeletal muscle cells is called the oxygen __________
debt
By definition, what is muscle fatigue?
decreased ability of a muscle to contract
When is lactic acid produced?
during anaerobic metabolism
When the ____________________ muscle contracts, the eyebrows are raised, as in an expression of surprise.
epicranius
The action of the ______ is to flex the head and neck to one side (if only one side contracts) and to pull the chin to the chest if both sides contract.
sternocleidomastoid
When the frequency of stimulation of a muscle fiber increases, eventually the individual twitches combine by the process of ___________ which results in a sustained contraction.
summation
The connection between an axon and its target cell is functional, not physical. This functional connection is also called a(n)
synapse
The functional connection between a neuron's process and a target cell is called a(n) ______.
synapse
The functional connection between a neuron's process and a target cell is called a(n) ______.
synaspse
The ____________ muscle originates on the temporal bone and inserts on the coronoid process of the mandible
temporalis
What is the insertion of the scalenes?
the first two ribs
Muscle fatigue is a condition described by ______ and is usually caused by prolonged use of a muscle.
the loss of a muscle's ability to contract
The scalenes have their origins on the ______.
transverse processes of cervical vertebrae
What is the origin of the levator scapulae?
transverse processes of cervical vertebrae
The membranous cellular structures that are important in conducting impulses through the sarcoplasm and in stimulating the release of calcium are called ______.
transverse tubules
What structures are positioned between adjacent cisternae of the sarcoplasmic reticulum?
transverse tubules
Of the following muscles, which one moves the pectoral girdle?
trapezius
Raising, lowering, and rotating the scapula are all functions of the ___________ muscle
trapezius
The fibers of the __________muscle are divided into three groups, each of which acts differently on the scapula.
trapezius
What muscle is comprised of three groups of fibers (upper group, middle group, and lower group). Together they rotate the scapula, but working separately, each group moves the scapula differently.
trapezius
n excitation-contraction coupling, the protein called _____________moves to expose binding sites on the actin filaments that can form cross-bridges.
tropomysin
During excitation-contraction coupling, calcium binds to ______.
troponin
True or false: Muscles generate heat when they contract.
true
When a single muscle fiber contracts when stimulated by a single impulse, the contractile response is called a(n)
twitch
muscle response called a(n) ____________consists of a period of contraction during which the fiber pulls at its attachment, followed by a period of __________________during which the pulling force decreases.
twitch , releaxation
What are thin filaments composed of?
two intertwined strands of actin
Muscle fibers with abundant mitochondria and myoglobin that are typically red in color are called ______ fibers.
type 1
What kind of contraction is generated when an overly shortened muscle fiber is stimulated?
weak contraction
Type IIb or fast-twitch glycolytic fibers are also called ____________ fibers because they contain less myoglobin.
white
What is the location of the sternocleidomastoid muscle?
side of the neck
True or false: Myofilaments shorten during contraction.
False
Which statements correctly describe changes in a skeletal muscle cell during muscle contraction?
Myofilaments overlap during contraction. Sarcomeres shorten during contraction. Muscles shorten during contraction.
Where is acetylcholine (ACh) synthesized?
in the cytoplasm of the motor neuron
What is one origin of the trapezius, a muscle with multiple origins?
cervical and thoracic vertebrae
What generates the force that shortens the sarcomeres to bring about muscle contraction?
myosin cross-bridges pulling on the actin filaments
Which muscle has its origin on the iliac crest
quadratus lumborum
At neuromuscular junctions, acetylcholine binds to ______.
receptors in the muscle fiber membrane
Which of the following is a characteristic of slow-twitch (type I) fibers?
red in color
During which phase are calcium ions actively transported into the sarcoplasmic reticulum?
relaxation
What phase includes these events? (1) Cytoplasmic calcium levels fall; (2) Myosin releases thin filaments; (3) Muscle tension declines.
relaxation
Which statement accurately lists the arrangement of components found in a first-class lever?
resistance-fulcrum-force
Myofibrils are formed by many ______ positioned end-to-end.
sacromeres
During muscle contraction, the sarcomeres shorten because ______.
thick and thin filament slide past one another, increasing their overlap
Correctly list, from superficial to deep, the connective tissue layers associated with a skeletal muscle. Start with the most superficial layer at the top.
epimysium perimysium endomysium
what are the connective tissue layers with the structures they surround.
epimysium , endomysium , perimysium
What term refers to the amount of oxygen needed to re-establish the resting state after exercise?
excess post-exercise oxygen consumption
The connection between the stimulation of muscle fiber and its contraction involves an increase of calcium ions in the sarcoplasm and is called
excitation contraction coupling
What type of muscle fiber is fatigable, and has less myoglobin, a poorer blood supply, and a more extensive sarcoplasmic reticulum than the other categories of fibers?
fast-twitch glycolytic fibers
In a ______-class lever, the fulcrum is located between the force and the resistance.
first
Within a muscle fiber, troponin and tropomyosin are associated with ______.
actin
Which of the following best describes the M line found within sarcomeres?
The M line is in the middle of the H zone, providing an attachment point for the thick filaments.
A muscle that functions to cause action is referred to as the ______.
agonist
The increase in the number of activated motor units as the intensity of neuronal stimulation increases is called _____________ or multiple motor unit summation.
recruitment
What is an action of the rhomboid muscles?
retract and elevate the scapula
A muscle that has an increase in its blood supply and its number of mitochondria has probably experienced ______.
an increase in aerobic exercise
What is the action of splenius capitis?
rotate head; pull head into an upright position
What is the action of the sternocleidomastoid?
rotates the head to one side
Within myofibrils, the area between two successive Z lines is called a(n) ______.
sacromere
What term is used for the plasma membrane of a muscle fiber?
sarcolemma
Each myofibril contains many ______________ , each extending from one Z line to the next.
sarcomeres
How many myofibrils and sarcomeres are found in a muscle fiber?
Each muscle fiber contains many myofibrils, each made of many sarcomeres joined end to end.
In a skeletal muscle fiber, each myofibril is surrounded by a network of membranous channels that runs parallel to the myofibril and is called the
sarcoplasmic reticulum
The thick filaments attach to what feature located in the middle of the H zone?
M line
Which end of a skeletal muscle is called its origin?
The end is attached to a relatively unmovable or fixed part of a joint.
During one of the steps of muscle contraction, ATP binds to myosin heads. What happens as a result of that?
The myosin heads are released from the actin filaments.
When is acetylcholine released into the synaptic cleft of a neuromuscular junction?
When a nerve impulse reaches the end of the axon.
What is a motor unit composed of?
a single motor neuron several muscle fibers
Contraction of the trapezius causes rotation of the
scapula
A ______-class lever has its components arranged as fulcrum-resistance-force.
second
The muscle labeled A is the ______ capitis muscle. The muscle labeled B is the ______ capitis muscle.
semispinalis; splenius
Which muscle is located on the side of the chest, originating on the upper ribs and inserting on the medial scapula?
serratus anterior
Where is the insertion of the semispinalis capitis muscle?
occipital bone
In addition to blinking the eye, the _____________oculi compress the tear gland helping the flow of tears over the surface of the eye.
orbicularis
What muscle is located around the eye?
orbicularis oculi
What is the origin of the serratus anterior?
anterior surface of upper ribs
Since slow-twitch fibers are oxidative fibers (using aerobic metabolism), they ______.
are prone to fatigue
Where is the orbicularis oculi located?
around the eye
What is the name of the process on a neuron that carries electrical impulses toward the cell to be stimulated?
axon
Excitation-contraction coupling involves an increase in the concentration of ______ ions in the sarcoplasm.
calcium
During muscle relaxation, calcium levels in the sarcoplasm fall because ______.
calcium is actively transported into the sarcoplasmic reticulum
Which of the following best describes the role of the sarcoplasmic reticulum (SR) when a skeletal myofiber is first stimulated?
calcium is released from the SR into the sarcoplasm
What is the origin of the splenius capitis muscle?
spinous processes of the lower cervical and upper thoracic vertebrae
the _______________ capitis has its origin on the ligamentum nuchae and spinous processes of the lower cervical and upper thoracic vertebrae, and its insertion on the occipital bone.
splenius
Which muscle can rotate the head and laterally flex the neck when acting singly, and bring the head into the upright position when acting on both sides of the body?
splenius capitis
The long muscle in the side of the neck that runs from the base of the skull (behind the ear) to the sternum is the
sternocleidomastoid
The organization of the thin and thick filaments within a muscle cell results in the formation of what muscle feature?
striations
Which muscles rotate the arm at the shoulder?
subscapularis and teres minor
When a muscle fiber is stimulated at a high enough frequency that it doesn't have time to relax, the forces of the individual twitches combine. What is this process called?
summation
Dense connective tissue cords that anchor muscles to bone are called _______________
tendons
The different connective tissue coverings in a skeletal muscle fuse to form cordlike structures called ______________ which attach muscles to bones.
tendons
What forms the striations seen in skeletal muscle?
the arrangement of thin and thick filaments
Within a sarcomere, what is the H zone?
the region within the A band that lacks thin filaments
Describe how action potentials travel from the sarcolemma into the interior of a muscle fiber, resulting in the release of calcium ions into the sarcoplasm.
Action potentials travel along T tubules.
Within a sarcomere, the region within the A band that lacks thin filaments is called the ______.
H zone
Actin (thin) filaments are attached to a Z line, which is located in the middle of what region of the striations?
I band
The region of a sarcomere composed primarily of actin is called the __________
I band
What is the function of the protein called titin within a sarcomere?
It attaches myosin filaments to the Z lines.
In a skeletal muscle cell at rest, where is most of the calcium found?
It is stored in the sarcoplasmic reticulum.
What is the role of creatine phosphate during skeletal muscle contraction?
It is used to quickly regenerate ATP from ADP.
Consider the naming of the temporalis muscle. What does the name tell you about the muscle?
It provides information about the locations of the origins and/or insertions for the muscle.
Consider the naming of the triceps brachii muscle. What does the name tell you about the muscle?
It provides information about the number of heads (origins).
What occurs with recruitment?
Many motor units fire, increasing the strength of contraction.
What is oxygen debt?
The amount of oxygen needed to restore the body's resting state after strenuous exercise.
What is the meaning of the term threshold stimulus?
The minimum strength of an electrical impulse that can stimulate contraction in an isolated muscle fiber.
What happens when the quadratus lumborum contracts on one side only?
The vertebral column is flexed laterally.
Choose all characteristics of slow-twitch fibers.
They are also called red fibers. They are well supplied with capillaries and mitochondria. They contain large amounts of myoglobin.
Describe the dark bands in the striations of skeletal muscle fibers.
They are called A bands and include the area of overlap of actin and myosin.
What kind of contraction is generated when an overly shortened muscle fiber is stimulated?
a weak contraction
What is stored in the synaptic vesicles of axons of motor neurons?
acetylcholine
When a nerve impulse reaches the end of the motor neuron axon, what is released into the synaptic cleft?
acetylcholine
During excitation of a muscle fiber, which one of the following events comes immediately after the release of acetylcholine from the motor neuron?
acetylcholine diffuses across the synaptic cleft
Which of the following is the enzyme that breaks down acetylcholine in the synaptic cleft?
acetylcholinesterase
Receptors for the neurotransmitter ______________ are found in the sarcolemma at a neuromuscular junction.
ach
In a muscle contraction, the force that shortens the sarcomeres comes from the myosin cross-bridges pulling on the ___________ filaments
actin
The process of a neuron, its axon, conducts electrical impulses called _____________ ________________ towards the end of the axon that innervates a target cell.
action potentials
What is the action of the orbicularis oris?
closes lips; protrudes lips
What is the action of the orbicularis oculi?
closes the eye, as in blinking
What is the first source of energy that is used to convert ADP to ATP after a contraction in a skeletal muscle cell begins?
creatine phosphate
Describe the Z line that is seen within striations of skeletal muscle.
direct attachment for the thin filaments; bisects the I band
Which of the following describes the action of the epicranius?
elevates eyebrows; draws scalp forward; wrinkles forehead
What is the action of the masseter?
elevates mandible
What is the action of the levator scapulae muscle?
elevation of scapula
Indicate three characteristics of skeletal muscle fibers.
elongated cells multinucleated cylindrical shape
What is the connective tissue layer that surrounds individual muscle fibers within a muscle?
endomysium
epimysium
entire muscle
The insertion for the ______ muscle is the skin around the eye.
epicranius
The occipital bone serves as the origin for what muscle?
epicranius
Each skeletal muscle is surrounded by a layer of fibrous connective tissue called the ______________----
epimysium
The layer of connective tissue that closely surrounds each skeletal muscle is called the ______.
epimysium
What type of contraction involves the development of tension but no change in length?
isometric
During high-intensity exercise, anaerobic metabolism results in the production of pyruvic acid, which is then converted to __________
lactic acid
What type of contraction involves the development of tension but no change in length?
large motor unites (more muscle fibers)
Which type of motor unit produces more force when recruited?
large motor unites (more muscle fibers)
What four pairs of muscles are considered muscles of mastication?
lateral pterygoid masseter temporalis medial pterygoid
Which of the following are muscles that move the pectoral girdle?
levator scapula rhomboid major serratus anterior trapezius
When a part of the body moves, the muscles and bones responsible for the movement act as a mechanical device known as a(n)
levers
The muscles of mastication include the medial and lateral pterygoid, _____________ and _____________
masseter and temporalis
What is the insertion of the sternocleidomastoid muscle?
mastoid process of the temporal bone
What is the insertion of the rhomboid major?
medial border of scapula
Which of the following is the insertion of the levator scapulae?
medial border of the scapula
Which of the following is the insertion of the serratus anterior?
medial border of the scapula
Because of the increased oxygen use and ATP production during aerobic training, muscle cells will increase their number of ______.
mitochondria
The aerobic phase of cellular respiration occurs in the organelles called the
mitochondria
The aerobic phase of cellular respiration, which produces ATP for muscle contraction, occurs in what organelle?
mitochondria
A motor unit is comprised of a ______ and the ______ that it controls.
motor neuron; muscle fibers
Neurons that control skeletal muscle are called
motor neurons
Typically, a skeletal muscle only contracts when it is stimulated by its corresponding
motor nueron
What occurs during a concentric contraction?
muscle shortens
Long bundles of contractile proteins found in the sarcoplasm are called ______________________
myofibrils
The sarcoplasm of a muscle fiber contains many parallel structures made of proteins. These structures are called ______.
myofibrils
A graph depicting the forces of contraction of a muscle fiber over time is called a(n)
myogram
Actin molecules are globular and have binding sites to which the heads of a(n) _______________ molecule can attach.
myosin
The globular actin proteins making up thin filaments have binding sites for ______.
myosin
Each thick filament is composed of many molecules of ______________each of which is consists of two twisted protein strands with globular parts called ___________________
myosin , heads
A skeletal muscle will typically only contract when stimulated by its motor neuron at the ______.
neuromuscular junction
The type of synapse formed between a motor neuron and a muscle fiber is called a(n) ____
neuromuscular junction
What is the function of acetylcholine?
neurotransmitter that stimulates the muscle to contract
In order to communicate with a target cell at a synapse, a neuron releases
neurotransmitters
What type of chemical is released by neurons? These chemicals then bind to effector cells.
neurotransmitters
What muscle closes the lips?
orbicularis oris
Which of the following serves as the insertion of the buccinator?
orbicularis oris at an angle of mouth
The end of a muscle that is fixed (relatively immovable) is called its ______.
origin
The orbicularis ___________ inserts on the skin of the lips.
oris
The orbicularis _________ encircles the mouth, while the orbicularis __________surrounds the eye.
oris oculi
What is the alternative term for excess post-exercise oxygen consumption?
oxygen debt
The trapezius, the rhomboid major and minor, and the levator scapulae are all muscles that move the ______ __________
pectoral girdle
What is the name of the connective tissue layer that separates a skeletal muscle into fascicles?
perimysium
List the four components of a lever.
pivot point object to move force rigid bar or rod
Considering their type of metabolism, which type of fiber is prone to fatigue?
predominantly glycolytic type II fibers
The ______________are repeating units within muscle fibers that act as the functional units of muscle contraction.
sarcomeres
The cytoplasm of a muscle fiber is called the
sarcoplasm
The cytoplasm of a muscle fiber is called the ______________
sarcoplasm
What is the name of the network of membranous channels that surrounds each myofibril within a muscle fiber?
sarcoplasmic reticulum
Which muscle type has multinucleated cells that are cylindrical in shape?
skeletal muscle
The term muscle tone, or tonus, refers to the fact that ______.
skeletal muscles maintain a state of partial contraction even when they are at rest
Which of the following is the insertion of the zygomaticus minor?
skin and muscles at the corner of the mouth
______-twitch fibers always use aerobic metabolism and are therefore called oxidative fibers.
slow
Which type of motor unit is more easily stimulated and, thus, is recruited first?
small motor units (fewer muscle fibers)
Action potentials spreading along the sarcolemma of a muscle fiber result from the opening of ______ channels in the sarcolemma.
sodium
The binding of acetylcholine to its receptors on the motor end plate results in increased membrane permeability to ________________ions and potassium ions.
sodium
When a nerve stimulates a skeletal muscle fiber, the response of the sarcolemma is to increase its permeability to ______.
sodium
The response of the sarcolemma to stimulation by a nerve impulse is to open ______.
sodium channels, allowing sodium to enter the cell
Intertwined strands of actin make up part of the ______ filaments.
thin
Troponin and tropomyosin are part of the ___________ filaments within muscle myofibrils.
thin
The protein called ______________ anchors myosin filaments to the Z lines.
titin
When describing the roles of muscles in an action, what is the role of the agonist?
to cause an action
The main function of the sarcoplasmic reticulum (SR) is ______.
to store calcium ions
The continuous state of partial contraction maintained by muscles even when they are at rest is called muscle
tone
What is the name of the invaginations of the sarcolemma that extend through the muscle fiber?
transverse (T) tubules
Numerous openings in the sarcolemma of a muscle fiber lead down into structures called the ______.
transverse tubules
True or false: The sarcoplasmic reticulum releases calcium into the cytoplasm when a muscle impulse moves down into the muscle fiber along the T tubules.
true
True or false: The transverse tubules are located between structures called cisternae.
true
True or false: Within a myofibril, each I band is bisected by a Z line to which the thin filaments are attached.
true
The quadratus lumborum inserts on the ______.
twelfth rib upper lumbar vertebrae
A sarcomere extends from one ______ to the next.
z line
What is the origin of the zygomaticus major?
zygomatic bone
What muscle pulls up on the corner of the mouth, causing you to smile?
zygomaticus
Which two muscles are responsible for drawing the corner of the mouth upward, as in smiling and laughing?
zygomaticus major and minor
