A&P Chapter 10 Connect
Which of the following proteins are found within a sarcomere?
-actin -connectin
When viewed under a light microscope, the light bands, called _________, contain only ______ filaments.
I bands; thin
As a person grows older, muscle tissue has a ______ capacity to recover from disease or injury.
reduced
The cytoplasm of a skeletal muscle cell has a specific name and is known as
sarcoplasm
An individual has better proficiency in performing repeated contractions under aerobic conditions if he or she as a greater percentage of ____ fibers in specific muscles.
slow
contractility
stimulation of muscle cells generates tension within the cell
The superficial fascia is also known as the
subcutaneous layer
ACh is released into this space
synaptic cleft
A nerve signal arrives at this structure
synaptic knob
The motor end plate has folds and indentations to increase the membrane surface are adjacent to the
synaptic knob
The force generated when a skeletal muscle is stimulated to contract is muscle
tension
A cross section of a myofibril through the A band contains which myofilaments?
thick and thin
The striated appearance in skeletal muscle cells is due to size and density differences between ______ and ______ filaments.
thick and thin
In smooth muscle cells, the sarcoplasmic reticulum is sparse, and ____ tubules are absent.
transverse
tropomyosin
two intertwined strands; cover myosin binding sites
When a muscle fiber contracts, which parts of the sarcomere maintain a constant length throughout contraction?
A band
According to the sliding filament theory, the length of the _____ band remains constant, but the ____ zone disappears.
A; H
Blood vessels deliver nutrients and oxygen to the muscle fibers so that they can produce the molecule _______ which is needed for contraction.
ATP
Energy to drive the myosin movement in the sliding filament process is provided in the form of
ATP
The ACh receptors on the motor end plate are ____ ion channels.
Chemically gated
In each helical strand of F-actin, many small, spherical molecules are connected for form a long filament resembling a string of beads. Each spherical molecule is called
G-actin
Match the duration of a single muscle contraction with the source of ATP
Immediate - creatine phosphate Short term - anaerobic respiration Long term - aerobic respiration
body movement
Muscles contract and pull on the tendons that attach the muscles to the bones
The _____ discs that anchor the sarcomere on either end in skeletal muscle are absent form smooth muscle cells.
Z
fascicle
a bundle of muscle fibers
elasticity
a contracted muscle cell recoils to its resting length when the applied tension is removed
extensibility
a muscle cell is capable of extending in length in response to the contraction of opposing muscle cells
The two types of muscle contraction are: a. _____ contraction (when a muscle contracts but does not change in length) and b. _____ contraction (when a muscle contracts and does change in length.)
a. isometric b. isotonic
ACh is an acronym for
acetylcholine
After being generated, the muscle impulse continues to spread throughout the muscle fiber as long as _____ keeps the motor end plate receptors open.
acetylcholine
A tropomyosin molecule is a short, thin, twisted filament that covers small sections of the _____ strands.
actin
The filaments in smooth muscle cells contain which proteins
actin and tropomyosin
Ten minutes into a marathon, your body is relying on _______ cellular respiration for ATP.
aerobic
slow and intermediate fibers require oxygen to produce ATP, so the metabolic reaction within these fibers are termed
aerobic
For longer contractions, muscle cells obtain ATP by which process?
aerobic respiration
a tendon that forms a thin, flattened sheet is called a/an ______
aponeurosis
The endomysium is composed of what type of connective tissue?
areolar
The superficial fascia, composed of _____ and adipose connective tissue, separates muscle from skin.
areolar
Smooth muscle is found where in the respiratory system?
around the bronchioles
cardiac
autorhythmic
The sarcoplasmic reticulum stores ______ ions needed to initiate muscle contraction.
calcium
Functionally, troponin provides a binding site for
calcium ions
When a nerve signal arrives at a synaptic knob, what type of channels open in the membrane?
calcium voltage-gated
posture
contraction of specific skeletal muscles stabilizes joints
After exposure of the active sites on actin, myosin heads attach to the actin and form
cross bridges
myofibrils
cylindrical organelles specialized for contraction
a-band
dark band containing both actin and myosin
Anchoring point between intermediate filaments and the sarcoplasm
dense body
the epimysium of a muscle surrounds
entire skeletal muscle
Muscle cells are said to have what characteristic because they can respond to stimulation from the nervous system?
excitability
The synaptic knob of the neuron is a ____ of an axon.e
expanded tip
In transverse section of a muscle, you can see that each skeletal muscle is actually composed of many _____, which are bundles of muscle fibers.
fascicles
In a muscle, the perimysium surrounds ____ muscle cells
fascicles of
If used repeatedly for endurance events, _____ fibers can develop the appearance and functional capabilities of _____ fibers.
fast; intermediate
Intermediate fibers contract _____ than slow fibers and _____ than fast fibers.
faster; slower
In a normally functioning muscle, the inability to contract and produce tension is called muscle
fatigue
When the myosin head finishes pivoting, the ______ detaches and returns to its original cocked position, ready to repeat the cycle.
head
temperature regulation
heat is produced as a waste product of energy usage
if a muscle cell is stimulated to contract, allowed to partially relax, then stimulated again, its force of contraction the second time will be
higher
The diameter of a muscle fiber will predict
how much power it will produce
If you strain to push on a wall that does not move, your muscles are in a type of
isometric contraction
Eccentric contractions actively _______ a muscle.
lengthen
I-band
light band containing thin filaments only
myofibril
long, cylindrical contractile element within muscle cell
A motor unit is composed of a single _____ and all of the muscle fibers it controls.
motor neuron
muscle tissue is distributed almost everywhere in the body; it is responsible for the _____ of materials within and throughout the body.
movement
muscle
multiple bundles housing many muscle fibers
Myofibrils are made of
myofilaments
muscle fibers that rely on aerobic respiration for ATP synthesis contain a high concentration of _____ which gives them a reddish appearance.
myoglobin
Smooth muscle cells have a unique protein called _____ light-chain kinase.
myosin
Thick filaments are assembled from bundles of the protein called
myosin
ATP is generated when the enzyme creatine kinase transfers Pi from creatine ______ to ADP.
phosphate
contraction of specific skeletal muscles stabilizes joints and helps maintain the body's ______ by holding the head and trunk erect.
posture
The skeletal muscles arranged in layers along the walls of the abdominal cavity and the floor of the pelvic cavity perform what function?
protection support contraction
As we age, decreased muscle strength is compounded by a tendency toward
rapid fatigue
The plasma membrane of a skeletal muscle fiber is called the
sarcolemma
Within a myofibril, each _____ shortens as the muscle fiber contracts.
sarcomere
a contracting skeletal muscle fiber typically shortens as all of its ______ shorten in length
sarcomeres
within a myofibril, Z discs separate the functional units known as
sarcomeres
At the end of muscle contraction, calcium ions are moved back into the _______ reticulum by ATP-driven ion pumps.
sarcoplasmic
If a skeletal muscle is injured, surrounding ______ cells may be stimulated to differentiate and assist in its repair and regeneration.
satellite
a "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation without an increase in intensity or frequency of stimulation is called ______
summation
The narrow space separating the synaptic knob and the motor end plate is called the
synaptic cleft
The deep invaginations of the sarcolemma that extends into the sarcoplasm of skeletal muscle fibers as a network of narrow membranous tubules are called
transverse tubules
The two regulatory proteins associated with myofilaments are
tropomyosin and troponin
Actin
two intertwined strands; each bead has a myosin binding site
skeletal
voluntary
Individual cardiac muscle cells can be stimulated to generate a muscle impulse ________ stimulation.
without nervous
once started, a muscle impulse will travels along the sarcolemma and into the muscle fiber via the
T-tubules
TF A single myofibril runs the length of the muscle fiber.
TRUE
TF Smooth muscle retains its mitotic ability.
TRUE
TF Your biceps brachii muscle in your arm is an organ.
TRUE
TF smooth muscle cells lack transverse tubules.
TRUE
The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen
debt
A persons tolerance for exercise _____ with age
decreases
A sarcomere is defined as the distance from one Z ______ to the next.
disc
Big muscles like the "quads" which are used for power have ____ motor units.
large
muscle fiber
metabolic activities; contraction
Cardiac muscle cells contain a large number of _____ to generate the ATP required for their unceasing work.
mitochondria
Acetylcholinesterase in the synaptic cleft is needed so that ____ will not continuously stimulate the cell to contract.
ACh
TF After diffusing across the synaptic cleft, ACh binds to receptors on the synaptic knob.
FALSE
________ distribute the muscle impulse throughout the inside of the muscle fiber.
T-tubules
TF a byproduct of anaerobic respiration is lactic acid.
TRUE
TF most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.
TRUE
Calcium ions bind to what protein in a thin myofilament?
Troponin
storage and movement of materials
Voluntary sphincter muscles of the gastrointestinal and urinary tracts can be kept closed or opened
Contraction of a muscle fiber requires that the myosin heads in the thick filament bind to active sites on ____ molecules within the thin filaments.
actin
Which of the following proteins are found in a thin filament?
actin
After breaking your arm, you have a cast on it for three months. When the cast is removed, your arm looks much smaller than it did before. The process called _____ caused this to happen.
atrophy
The rate of rhythmic contraction of cardiac muscle is controlled by the ______ nervous system.
autonomic
troponin
bound to tropomyosin; can bind calcium ions
At an NMJ, the influx of ______ ions into the synaptic knob causes the exocytosis of ACh into the synaptic cleft.
calcium
During contraction of smooth muscle, _____ binds to calcium and activates myosin light chain kinase.
calmodulin
In addition to skeletal muscle, two other types of muscle are found in the body: _______ muscle and _______ muscle.
cardiac and smooth
The wall of the heart is composed of
cardiac muscle
The invaginations of the sarcolemma on the smooth muscle cell are called
caveolae
excitability
cell is responsive to stimuli
A muscle fiber is what level of organization in the body
cellular
The long tails of the myosin molecules in the thick filaments point toward the _____ of the filament.
center
As a result of muscle fiber contraction, thick filaments in neighboring sarcomeres move ______.
closer together
thin filament
composed of actin, troponin, and tropomyosin
thick filament
composed of myosin
There are two types of isotonic contractoins: eccentric and
concentric
h-zone
contains thick filaments only
When smooth muscle is stretched, it responds by
contracting then relaxing
anchoring between intermediate filaments and the sarcolemma
dense plaque
Myosin head attachment and pivoting do not require energy, but ATP is needed for the myosin head cross bridge to ______ from actin and re-cock.
detach
actin
double-stranded contractile protein
tropomyosin
double-stranded regulatory protein
Muscular dystrophy results from the lack of or an abnormal structure of which protein?
dystrophin
After a contraction, muscle returns to its original relaxed position due to it's natural
elasticity
muscle fiber
elongated, multinucleate, cylindrical cell
The majority of skeletal muscle fibers in the body are ____ fibers.
fast glycolytic
Overall, as aging progresses, muscle strength and endurance are impaired, and the individual has a tendency to ______ quickly.
fatigue
intermediate fibers have a high resistance to
fatigue
A skeletal muscle cell is also called a muscle
fiber
sarcomere
functional contractile unit of skeletal muscle
Smooth muscle is composed of short cells that have a ____ shape.
fusiform
With endurance training, it is possible for fast _____ fibers to take on characteristics of fast _____ fibers.
glycolytic; oxidative
in muscle contraction, as increasing numbers of motor units are recruited _____ force is exerted
greater
In a relaxed muscle fiber there are no thin filaments overlapping the thick filaments in the
h zone
Each myosin strand has a free ____ and an attached tail.
head
an increase in muscle fiber size is called
hypertrophy
In ___ tetany, a muscle cell is stimulated so frequently that it is not allowed to relax at all between stimuli
incomplete
Multiunit smooth muscle cells are stimulated
individually
Which of the following structures anchors adjacent cardiac muscle cells together?
intercalated disc
Cytoskeleton network
intermediate filaments
smooth
involuntary
smooth muscle contraction is under ___ control of the nervous system.
involuntary
smooth muscle contraction is under _____ control
involuntary
During an ____ contraction, the length of the muscle does not change.
isometric
The _____ mechanism allows smooth muscle to maintain muscle contraction without the use of additional ATP
latchbridge
In order to predict how much tension a muscle can produce when contracting, it is important to consider the ______ relationship of thick and thin filaments.
length-tension
The vascular supply to slow muscle fibers is _____ than the network of capillaries around fast muscle fibers.
more extensive
The neurons that stimulate muscle contraction are called _____ neurons.
motor
although muscle fibers obey the all-or-none principle, the force of muscle contraction can be varied depending on how many ______ units are used
motor
ACh binds to receptors on this surface
motor end plate
Upon release from the synaptic knob, acetylcholine attaches to receptors on the
motor end plate
During development, many groups of ______ fuse to form single skeletal muscle fibers.
myoblasts
hypertrophy results from an increase in the number of _____ in a muscle cell
myofibrils
As a result of exercise, each muscle fiber develops more myofibrils, and each myofibril contains a larger number of
myofilaments
Myofibrils consist of bundles of short
myofilaments
Muscle cells store oxygen bound to a _____ molecule?
myoglobin
Thick myofilaments are composed of bundles of _______ protein molecules.
myosin
After the cross bridges are formed, ATP is required to detach the _______ and complete the sequence of cyclic events.
myosin heads
The motor neuron transmits the effect of a nerve impulse to the muscle fiber at a
neuromuscular junction
The point where a motor neuron meets a skeletal muscle fiber is called the
neuromuscular junction
When a motor neuron axon terminal and a muscle cell meet is called a
neuromuscular junction
While observing skeletal muscle tissue under the microscope you note that it appears striated. You tell your lab partner this is because
of the arrangement of myofilaments in each sarcomere
An extensive network of blood vessels and nerve fibers extends through both the epimysium and the _______ of a muscle.
perimysium
As you hold a barbell and begin to flex your arm in a curl, your biceps brachii slowly lifts the weight by using more and more motor units. This phenomenon, which increases the strength of the contraction, is referred to as
recruitment
in skeletal muscle experiences markedly ______ ______, it loses both mass and tone.
reduced stimulation
sarcolemma
regulates entry and exit of materials
The endomysium contains _____ fibers to help bind together neighboring muscle fibers.
reticular
After stimulation of ACh receptors, a muscle impulse spreads quickly along the _____ and into the muscle fiber along T-tubules.
sarcolemma
myofilament
short contractile proteins of two types: thick and thin
In an isotonic contraction, the muscle fibers ______, resulting in movement.
shorten or lengthen
Cardiac muscle cells are ______ and thicker than skeletal muscle cells, and they have only _____ nuclei.
shorter; 1-2
sarcoplasm
site of metabolic processes for normal muscle fiber activities
Approximately 40-50% of your body weight is _____ muscle.
skeletal
Which is not a connective tissue component of a muscle?
skeletal muscle fibers
The length-tension relationship of ______ muscle cells is limited by the z-discs which are lacking in _____ muscle cells.
skeletal; smooth
Type I muscle fibers contract more _____ than type IIa and IIb muscle fibers.
slowly
The sodium-potassium exchange pump maintains a higher concentration of which ion outside the sarcolemma?
sodium
sarcoplasmic reticulum
stores calcium ions needed for muscle contraction
relaxation period
tension decreases
contraction period
tension increases
An action potential travels down the sarcolemma, through the t-tubules, to the
terminal cisternae
As a result of ACh stimulation, calcium ions are released from the _____ of the sarcoplasmic reticulum.
terminal cisternae
Parts of the sarcoplasmic reticulum that appear as blind sacs perpendicular to the fiber's length are called ________
terminal cisternae
latent period
there is no tension
In a sarcomere, the M-line serves as an attachment site for the ______ filaments and keeps them aligned during contraction and relaxation.
thick
Under the light microscope, the dark (A) bands observed in skeletal muscle contain ________ filaments
thick and thin
In sarcomere, Z discs serve as anchors for
thin filaments
As you sit there reading this your muscles, even your relaxed ones are not completely relaxed and soft. This is because they have some background tension called resting muscle
tone
t-tubule
transports the action potential from the sarcolemma throughout the entire muscle fiber
An action potential is carried along the sarcolemma, then down _________ tubules to the terminal cisternae of the sarcoplasmic reticulum.
transverse
spread of a muscle impulse along the sarcolemma, then down the ______,causes calcium ions to leak out of the rR into the sarcoplasm of the muscle fiber
transverse tubules
In a skeletal muscle cell, two terminal cisternae and the centrally placed T-tubule from a structure called a
triad
When a muscle fiber is in a released state, the _____ molecules cover the G-actin active sites, preventing interaction between thick filaments and thin filaments.
tropomyosin
If the sarcoplasm of a muscle cell is flooded with calcium ions, to which protein will they bind?
troponin
upon release from the terminal cisternae, some calcium ions bind to _____ causing it to change shape.
troponin
autonomic motor neurons that control smooth muscle contraction have bulbous swellings called ______ that contain synaptic vesicles.
varicosities
In a sarcomere , the __ zone (or band) is the light , central region of the A band ?
H
which are characteristics of oxidative fibers?
-high concentration of myoglobin -good for endurance -use aerobic respiration -red
Which can cause muscle fatigue?
-insufficient Ca2+ -Na+ or K+ imbalances -build up of intracellular Pi
Smooth muscle shows a different length-tension relationship than skeletal muscle because
-it lacks z discs but has dense bodies -the arrangement of the thick and thin filaments allows for contraction even when stretched
In which activities are muscles in an isometric contraction?
-pushing on a locked door -sitting up very straight -holding a yoga pose
A neuromuscular junction contains a
-synaptic cleft -motor end plate -synaptic knob
Place the following events in the correct order of occurrence once ACh diffuses across the synaptic cleft of a NMJ
1. ACh binds to receptors on the motor end plate 2. the resulting action potential moves down the sarcolemma 3. the action potential moves down the t-tubules 4. the action potential reaches the terminal cisternae of the SR 5. calcium ions are released into the sarcoplasm
Place the steps of cross-bridge cycling in order:
1. cross-bridge formation 2. power stroke 3. release of myosin head 4. reset myosin head
The sodium-potassium exchange pump moves ____ sodium ions out of the cell for every ____ potassium ions it brings in.
3;2