Adv. A&P Chapter 10
What muscle type(s) would you expect to find in the cardiovascular system?
Cardiac & smooth
When calcium ions bind to troponin, which of the following then occurs?
The myosin-binding sites on actin are exposed.
To stop motor end plate stimulation, usually acetylcholine is quickly broken down and removed from the receptor by ______.
acetylcholinesterase
Match the thin filament protein and thin filament associated protein names with its function.
actin matches Choice two intertwined strands; each bead has a myosin-binding site tropomyosin matches Choice two intertwined strands; cover myosin-binding sites troponin matches Choice bound to tropomyosin; can bind calcium ions
Cardiac muscle cells use ______ respiration almost exclusively
aerobic
For longer contractions, muscle cells obtain ATP by which process?
aerobic respiration
Smooth muscle cells generally generate ATP through which mechanism?
aerobic respiration
A muscle cell obtains ATP in the short term via what process?
anaerobic respiration
The ATP needed to fuel a 100m sprint would be supplied primarily from ______.
anaerobic respiration
Match the structures of a smooth muscle fiber with their functions.
cytoskeleton network matches Choice intermediate filaments anchoring point between intermediate filaments and the sarcoplasm matches Choice dense body anchoring point between intermediate filaments and the sarcolemma matches Choice dense plaque
The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen ______
debt
Acetylcholine moves across the synaptic cleft by ______.
diffusion
In an isometric contraction, the muscle ______ body movement.
does not produce
Muscular dystrophy results from the lack of or an abnormal structure of which protein?
dystrophin
The connective tissue layer that surrounds individual muscles fibers is called ______.
endomysium
The connective tissue layer that surrounds an entire muscle is called ______.
epimysium
The three connective tissue layers surrounding the individual components of a muscle are the:
epimysium, perimysium, endomysium
The synaptic knob of the neuron is a(n) ______ of an axon.
expanded tip
There is a(n) ______ network of blood vessels delivering blood to muscle tissue.
extensive
In a transverse section of a muscle, you can see that each skeletal muscle is actually composed of many _______ which are bundles of muscle fibers.
fascicles
A piano player uses her hands for brief quick movements. Which muscle fiber type would you therefore predict to be predominant in these muscles?
fast glycolytic
Which of the three skeletal muscle fiber types has the largest diameter and provides both power and speed?
fast glycolytic
The majority of skeletal muscle fibers in the body are ______ fibers.
fast oxidative
If used repeatedly for endurance events, ______ fibers can develop the appearance and functional capabilities of ______ fibers.
fast; intermediate
Type IIa 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
Type IIa fibers have a high resistance to ______.
fatigue
The smaller the motor unit, the ______ the control.
finer
Smooth muscle cells are ______ in shape.
fusiform
With endurance training, it is possible for fast ______ fibers to take on characteristics of fast ______ fibers.
glycolytic; oxidative
Slow muscle fibers are about ______ the diameter of fast muscle fibers.
half
Each myosin strand has a free ______ and an attached tail.
head
When the myosin head finishes pivoting, the ______ detaches and returns to its original cocked position, ready to repeat the cycle.
head
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
The mechanism that allows smooth muscle to maintain muscle contraction without the use of additional ATP is the
latchbridge mechanism
Match each stage of a muscle twitch with the amount of tension generated.
latent period matches Choice there is no tension contraction period matches Choice tension increases relaxation period matches Choice tension decrease
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
Eccentric contractions actively ______ a muscle.
lengthen
Because muscle cells require a huge amount of ATP in order to contract, they have a large number of which organelle?
mitochondria
Cardiac muscle cells contain a large number of ______ to generate the ATP required for their unceasing work.
mitochondria
Slow fibers have a relatively large number of ______. This permits slow muscle fibers to produce a greater amount of ______ than fast muscle fibers while contractions are underway.
mitochondria; ATP
Athletes have more defined muscles than non-athletes even while at rest because they have ______ motor units contracting all the time.
more
The vascular supply to slow muscle fibers is ______ than the network of capillaries around fast muscle fibers.
more extensive
Neurons that stimulate muscle contraction are called ______ neurons.
motor
in a motor unit, a single ______ neuron typically controls numerous muscle fibers in a muscle
motor
Upon release from the synaptic knob, acetylcholine attaches to receptors on the ______.
motor end plate
Muscle tissue is distributed almost everywhere in the body; it is responsible for the _____ of materials within and throughout the body.
movement
Match each muscle unit with the connective tissue layer that surrounds it.
muscle matches Choice epimysium fascicle matches Choice perimysium muscle cell matches Choice endomysium
A skeletal muscle cell is also called
muscle fiber
Match the name of the muscle cell component with its function. Instructions
muscle fiber matches Choice metabolic activities; contraction sarcolemma matches Choice regulates entry and exit of materials sarcoplasm matches Choice site of metabolic processes for normal muscle fiber activities sarcoplasmic reticulum matches Choice stores calcium ions needed for muscle contraction T-tubule matches Choice transports the action potential from the sarcolemma throughout the entire muscle fiber
What is the force generated when a skeletal muscle is stimulated to contract called?
muscle tension
The sarcoplasm of a skeletal muscle fiber contains hundreds to thousands of long, cylindrical structures called _____ that extend the length of the cell.
myofibrils
Match the muscle fiber component with its function.
myofibrils matches Choice contain myofilaments that are responsible for muscle contraction thick filament matches Choice bind to thin filaments and cause contraction thin filament matches Choice bind to thick filaments and cause contraction actin matches Choice binding site for myosin to shorten a sarcomere tropomyosin matches Choice covers the active sites on actin when muscle cell is at rest
The H band (or H zone) is more lightly shaded because
only thick filaments are present
Aerobic respiration requires the presence of what molecule?
oxygen
Muscle fibers that rely on aerobic respiration for ATP synthesis contain a high concentration of ______which gives them a reddish appearance.
oxygen
The endomysium contains ______ fibers to help bind together neighboring muscle fibers.
reticular
Thick and thin filaments maintain their ______, whether the muscle is relaxed or contracted.
same length
The motor end plate is a specialized region of the ______.
sarcolemma
The plasma membrane of a skeletal muscle fiber is called the
sarcolemma
Match the name of the component of a muscle fiber with its description.
sarcolemma matches Choice plasma membrane of a muscle fiber muscle fiber matches Choice a muscle cell sarcoplasm matches Choice cytoplasm of a muscle fiber sarcoplasmic reticulum matches Choice smooth endoplasmic reticulum in a muscle fiber T-tubule matches Choice narrow, tubular extensions of the sarcolemma into the sarcoplasm
Within a myofibril, each ______ shortens as the muscle fiber contracts.
sarcomere
Match the structure of a myofibril with its description.
sarcomere matches Choice functional contractile unit of skeletal muscle A band matches Choice dark band containing both actin and myosin H zone matches Choice contains thick filaments only I band matches Choice light band containing thin filaments only
The cytoplasm of a skeletal muscle cell has a specific name and is known as
sarcoplasm
An internal membrane complex in skeletal muscle cells that is similar to the smooth endoplasmic reticulum of other cells is called the
sarcoplasmic reticulum
At the end of contraction, when the stimulation from the nerve impulse ceases, calcium ions are pumped back into the ______.
sarcoplasmic reticulum
During the development of skeletal muscle cells, some myoblasts do not fuse and instead become ______ cells.
satellite
If a skeletal muscle is injured, surrounding _____ cells may be stimulated to differentiate and assist in its repair and regeneration.
satellite or stem
Concentric isotonic contractions actively ______ a muscle.
shorten
Cardiac muscle cells are ______ and thicker than skeletal muscle cells, and they have only ______ nuclei.
shorter; 1-2
Approximately 40-50% of your body weight is _____ muscle.
skeletal
Attached to the skeleton and surrounding the openings of the urinary and gastrointestinal traces are locations of ______ muscle.
skeletal
Maintenance of posture and production of heat are functions of ______ muscle.
skeletal
Somatic motor neurons innervate ______ muscle.
skeletal
The length-tension relationship of _______ muscle cells is limited by the Z discs that are lacking in _______ muscle cells
skeletal; smooth
According to the sliding filament theory, when a muscle contracts, thick and thin filaments ________ past each other, and the ______ shortens
slide; sacromere
The ___________________ explains how muscle fibers shorten during contraction.
sliding filament theory
An individual has better proficiency in performing repeated contractions under aerobic conditions if he or she has a greater percentage of ______ fibers in specific muscles.
slow
Over longer distances, runners who have higher proportions of ______ muscle fibers in their leg muscles are able to outperform runners who have a greater number of ______ muscle fibers in their leg muscles.
slow; fast
Type I muscle fibers contract more ______ than type IIa and IIb muscle fibers.
slowly
Although smooth muscle cells have both thick and thin filaments, they are not precisely aligned, so no visible ______ are present.
striations
a "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation is called _______.
summation
The narrow space separating the synaptic knob and the motor end plate is called the ______.
synaptic cleft
A nerve impulse travels through an axon to its ______.
synaptic knob
The motor end plate has folds and indentations to increase the membrane surface area adjacent to the ______.
synaptic knob
A thick cordlike structure that attaches a muscle to a bone is called a(n) ______.
tendon
The force generated when a skeletal muscle is stimulated to contract is muscle
tension
As a result of ACh stimulation, calcium ions are released from the ______ of the sarcoplasmic reticulum.
terminal cisternae
T-tubules are located adjacent to ______, which are reservoirs storing the calcium ions required for muscle contraction.
terminal cisternae
Smooth muscle shows a different length-tension relationship than skeletal muscle because ______.
the arrangement of the thick and thin filaments allows for contraction even when stretched it lacks Z discs but has dense bodies
The epimysium of a muscle surrounds ______.
the entire skeletal muscle
Slow-twitch and fast-twitch muscle fibers differ primarily in ______.
their ATPase which splits ATP
in a sarcomere, the M line serves as an attachment site for the ______ filaments and keeps them aligned during contraction and relaxation.
thick
A cross section of a myofibril through the A band contains which myofilaments?
thick and thin
As the troponin changes shape (due to binding calcium), it moves the ______ molecule to which it is attached, thus exposing the active sites on the G-actin molecules.
tropomyosin
When a muscle fiber is in a relaxed state, the ______ molecules cover the G-actin active sites, preventing interaction between thick filaments and thin filaments.
tropomyosin
The two regulatory proteins associated with thin myofilaments are ______.
tropomyosin and troponin
Calcium ions bind to what protein in a thin myofilament?
troponin
If the sarcoplasm of a muscle cell is flooded with calcium ions, to which protein will they bind?
troponin
Smooth muscle thin filaments do not contain ______ as in skeletal muscle.
troponin
Upon release from the terminal cisternae, some calcium ions bind to ______ causing it to change shape.
troponin
T or F : Smooth muscle cells retains their mitotic ability.
true Unlike skeletal and cardiac muscle, smooth muscle retains its mitotic ability.
A single contraction and relaxation of a muscle fiber is referred to as a muscle
twitch
Skeletal muscle fibers are classified into three types based on what two characteristics?
type of contraction and ATP supply
Autonomic motor neurons that control smooth muscle contraction have bulbous swellings called ______ that contain synaptic vesicles.
varicosities
within a synaptic knob, synaptic ______ contain the neurotransmitter ACh
vesicles
You have hooked a frog calf muscle up to a myogram that records muscle tension. You notice that when you stimulate the muscle to contract, then stimulate it again before it can fully relax, the amount of tension generated in the second contraction is greater than the first contraction. This phenomenon is called ______.
wave summation
Individual cardiac muscle cells can be stimulated to generate a muscle impulse ______ stimulation.
without nervous
Place the events at a neuromuscular junction in order. Instructions Choice 1 of 4. exocytosis of ACh into synaptic cleft toggle button exocytosis of ACh into synaptic cleft Choice 2 of 4. arrival of nerve signal at synaptic knob toggle button arrival of nerve signal at synaptic knob Choice 3 of 4. binding of ACh to motor end plate toggle button binding of ACh to motor end plate Choice 4 of 4. calcium entry into synaptic knob toggle button calcium entry into synaptic knob
1. arrival of nerve signal at synaptic knob 2. calcium entry into synaptic knob 3. exocytosis of ACh into synaptic cleft 4. binding of ACh to motor end plate
Place the events that occur at a neuromuscular junction in order. Instructions
1st matches Choice nerve signal arrives at synaptic knob 2nd matches Choice calcium enters and binds synaptic vesicle 3rd matches Choice ACh is released via exocytosis into the synaptic cleft 4th matches Choice ACh binds receptors on the motor end plate
Each myosin protein molecule in a thick filament consists of ______ strands.
2
Thick filaments are about ______ the diameter of thin filaments.
2
Place the stages of cross-bridge cycling in order. Instructions Choice 1 of 5. calcium binds troponin; myosin-binding site uncovered toggle button calcium binds troponin; myosin-binding site uncovered Choice 2 of 5. power stroke toggle button power stroke Choice 3 of 5. release of myosin head by ATP toggle button release of myosin head by ATP Choice 4 of 5. cross-bridge formation toggle button cross-bridge formation Choice 5 of 5. reset of myosin head toggle button reset of myosin head
A matches Choice Ca2+ binds troponin; myosin-binding sites uncovered B matches Choice cross-bridge formation C matches Choice power stroke D matches Choice release of myosin head by ATP E matches Choice reset of myosin head
Identify the molecules pictured in the neuromuscular junction.
A - moves into the axonal terminal matches Choice calcium ions B - moves into the sarcoplasm matches Choice sodium ions C - moves across the synaptic gap matches Choice acetylcholine D - moves out of the sarcoplasm matches Choice potassium ions
When a muscle fiber contracts, which parts of the sarcomere maintain a constant length throughout contraction?
A band
The arrival of a nerve impulse at the synaptic knob of a motor neuron causes synaptic vesicles to release _________ into synaptic cleft
ACh
Each myosin head in a thick filament can bind to the protein in a thin filament called
Actin
Muscle cells are said to have what characteristic because they can respond to stimulation from the nervous system?
Excitability
Match each property of a muscle cell with its description.
Excitability matches Choice Cell is responsive to stimuli. Contractility matches Choice Stimulation of muscle cells generates tension within the cell. Elasticity matches Choice A contracted muscle cell recoils to its resting length when the applied tension is removed. Extensibility matches Choice A muscle cell is capable of extending in length in response to the contraction of opposing muscle cells.
In a thin filament, individual G-actin molecules are strung together to form ______.
F-actin
True or false: A muscle fiber that is partially shortened can produce a contraction stronger than the contraction it can produce when at its resting length.
False; A muscle fiber at rest generates more force than one partially contracted because there is optimal overlap of thick and thin filaments.
True or false: In smooth muscle contraction the thick and thin filaments slide past one another causing the Z lines to move closer together.
False; There are no Z lines in smooth muscle
True or false: After diffusing across the synaptic cleft, ACh binds to receptors on the synaptic knob.
False; ACh moves from the synaptic knob to receptors on the the motor end plate.
In each helical strand of F-actin, many small, spherical molecules are connected to form a long filament resembling a string of beads. Each spherical molecule is called ______.
G-actin
At maximal contraction of a muscle fiber, the thin filaments are pulled into the ______ zone which disappears.
H
In a relaxed muscle fiber there are no thin filaments overlapping the thick filaments in the ______ zone.
H
In a sarcomere, the ______ zone (or band) is the light, central region of the A band.
H
Match the structure of a sarcomere with its description.
H zone matches Choice lighter region in the middle of an A band M line matches Choice appears as a dark protein disc in center of H zone Z disc matches Choice made of dark proteins that create a zig-zag line I band matches Choice light band containing thin filaments only
The act of shivering is an example of skeletal muscle performing what function?
Heat production
The Z disc is a thin transverse protein structure in the center of the ______ band in a sarcomere.
I
When viewed under a light microscope, the light bands, called ______ bands, contain only ______ filaments.
I; thin
Which are characteristics of glycolytic fibers?
Low concentration of myoglobin, white
The ______ line is a thin, transverse, protein meshwork structure in the center of the H zone of a sarcomere.
M
Match each protein with its function.
MLCK matches Choice phosphorylates myosin calmodulin matches Choice binds calcium MLCP matches Choice dephosphorylates myosin
The skeletal muscles arranged in layers along the walls of the abdominal cavity and the floor of the pelvic cavity perform what function?
Support Contraction Protection
Once started, a muscle impulse will travel along the sarcolemma and into the muscle fiber via the ______.
T-tubules
True or false: A byproduct of anaerobic respiration is lactic acid.
True
True or false: A single myofibril runs the length of the muscle fiber.
True
True or false: In the absence of calcium, troponin attaches to tropomyosin to hold it in place on the surface of the F actin strand.
True
True or false: Smooth muscle cells lack transverse tubules.
True
True or false: Most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.
True Most muscles contain all three muscle types but not in equal amounts.
True or false: Your biceps brachii muscle in your arm is an organ.
True: Organs are made of two or more tissues and muscles contain muscle tissue, nervous tissue, and connective tissue.
True or false: Postural muscles contract continuously when a person is awake to prevent collapse of the body.
True; Keeping the body upright and toned is one of the functions of postural muscles.
After being generated, the muscle impulse continues to spread throughout the muscle fiber as long as ______ keeps the motor end plate receptors open.
acetylcholine
The motor end plate has large numbers of ______ receptors.
acetylcholine
Receptors in the motor end plate bind with the neurotransmitter ______ released from the synaptic knob.
acetylcholine or ACh
A tropomyosin molecule is a short, thin, twisted filament that covers small sections of the ______ strands.
actin
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
Slow and intermediate fibers require oxygen to produce ATP, so the metabolic reactions within these fibers are termed ______.
aerobic
Ten minutes into a marathon, your body is relying on __________ cellular respiration for ATP.
aerobic
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 in which of the following locations?
around blood vessels in the wall of the small intestine in wall of the uterus
Smooth muscle is found where in the respiratory system?
around the bronchioles
The connective tissue layers in muscle provide protection, distribution sites for blood vessels and nerves, and a means of ______ to the skeleton.
attachment
The rate of rhythmic contraction of cardiac muscle is controlled by the
autonomic nervous system
The ______ feature of cardiac muscle cells is responsible for the repetitious, rhythmic heartbeat.
autorhythmic
Contractile proteins in smooth muscle are arranged ______.
between dense bodies and dense plaques
Cardiac muscle cells are ______ and contain ______ nuclei.
branched; 1-2
At an NMJ, the influx of ______ ions into the synaptic knob causes the exocytosis of ACh into the synaptic cleft.
calcium
The cyclic events of "attach, pivot, detach, return" continue as long as ________ions remain bound to the troponin.
calcium
When an action potential travels down T-tubules to the terminal cisternae of the SR, what ion is released into the sarcoplasm?
calcium
When a nerve signal arrives at a synaptic knob, what type of channels open in the membrane?
calcium voltage-gated
During contraction of smooth muscle, ______ binds to calcium and activates myosin light chain kinase.
calmodulin
The sarcolemma of smooth muscle cells has small invaginations called ______.
caveolae
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
The ACh receptors on the motor end plate are ______ ion channels.
chemically gated
The enzyme acetylcholinesterase resides in the synaptic
cleft
As a result of muscle fiber contraction, thick filaments in neighboring sarcomeres move ______.
closer together
The type of tetany in which a muscle cell is stimulated so frequently that it is not allowed to relax at all between stimuli is called
complete
A (An) _______ contraction of the arm muscles allows you to lift a book from the table, whereas a (an) ______ contraction of the arm muscles allows you to lower the book back down to the table.
concentric; eccentric
Which of the following proteins are found within a sarcomere?
connectin actin
Muscles are considered organs because they are composed not only of muscle tissue but also ______ tissue and nervous tissue
connective
When smooth muscle is stretched, it responds by ______.
contracting then relaxing
The shortening of muscle cells is called _______, a property that allows muscle cells to cause body movement.
contraction
The expansive sheet of dense irregular connective tissue that separates individual muscles is called the ______.
deep fascia
In smooth muscle cells, thin filaments are attached to ______.
dense bodies
The epimysium of a muscle is composed of ______ connective tissue.
dense irregular
Muscle tissue demonstrates the property of _____ when it is done contracting and returns to its resting length.
elasticity
In a muscle there are concentric layers of connective tissues. From deep to superficial these connective tissue layers are the
endomysium, perimysium, epimysium
The motor neuron axon travels through the epimysium and perimysium and enters the ______, where it delivers a nerve impulse to an individual ______.
endomysium; muscle fiber
When a nerve impulse reaches the end of an axon of a neuromuscular junction, calcium flows ______ the synaptic knob.
into
Smooth muscle contraction is under ______ control.
involuntary
Smooth muscle contraction is ______, resistant to ________ and usually sustained for an extended period of time
involuntary; fatigue
Multiunit smooth muscle is found in which of the following locations?
iris of the eye arrector pili muscles in the skin
Curare is a plant toxin used by indigenous people of South America in their blowguns to paralyze prey. What is a feasible mechanism of action for this drug?
it binds to and blocks ACh receptors on the motor end plate
Smooth muscle cells have a ______ mechanism that allows them to contract with more power and use less ATP than a skeletal muscle cell.
latch bridge
Muscle fibers contain cylindrical structures called myofibrils, which are composed of ______.
myofilaments
Myofibrils are made of ______.
myofilaments
Termination of the nerve impulse at an NMJ results in the passive sliding of ______ back to their original state.
myofilaments
Muscle cells store oxygen bound to a
myoglobin molecule
Smooth muscle cells have a unique protein called ______ light-chain kinase.
myosin
Thick filaments are assembled from bundles of the protein called
myosin
After the cross bridges are formed, ATP is required to detach the ______ and complete the sequence of cyclic events.
myosin heads
Thick myofilaments are composed of bundles of
myosin protein molecules.
Where a motor neuron axon terminal and a muscle cell meet is called a
neuromuscular (synaptic) junction
Synaptic knob, motor end plate, and synaptic cleft are parts of 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
Within a myofibril, Z discs separate the functional contractile units known as
sarcomeres
The attachment of ACh to the receptor on the motor end plate causes the receptor to open, allowing _____ ions to enter muscle fiber
sodium
A cross section of a myofibril through the H zone contains which myofilaments?
thick only
In a sarcomere, Z discs serve as anchors for ______.
thin filaments
Single unit muscle cells contract ____.
together
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
In a muscle cell at rest, the myosin heads of a thick filament point ______ the sarcomere.
toward the ends of
The deep invaginations of the sarcolemma that extend into the sarcoplasm of skeletal muscle fibers as a network of narrow membranous tubules are called ______.
transverse tubules
Which can cause muscle fatigue?
-build up of intracellular P1 - insufficient Ca2+ - Na+ or K+ imbalances (357)
Which are characteristics of oxidative fibers?
-red -good for endurance - high concentration of myoglobin - use aerobic respiration (352)
Place the steps of cross-bridge cycling in order. Instructions Choice 1 of 4. power stroke toggle button power stroke Choice 2 of 4. cross-bridge formation toggle button cross-bridge formation Choice 3 of 4. release of myosin head toggle button release of myosin head Choice 4 of 4. reset myosin head toggle button reset myosin head
1. cross-bridge formation 2. power stroke 3. release of myosin head 4. reset myosin head
Place the following events found in cross bridge cycling in the correct sequence.
1. myosin heads bind to actin 2. myosin heads pivot towards the M line 3. ATP releases the myosin heads 4. ATPase re-cocks the myosin heads
According to the sliding filament theory, the length of the ______ band remains constant, but the ______ zone disappears.
A; H
Acetylcholinesterase in the synaptic cleft is needed so that ______ will not continuously stimulate the cell to contract.
ACh
Glycolysis and aerobic respiration are used to generate ______ in muscle fibers.
ATP
Slow fibers or type 1 fibers are also called ____ fibers because they contain the pigment myoglobin
SO, red, oxidative
The muscle that surrounds the opening to your esophagus and opens reflexively to allow you to swallow food is what type of muscle?
Sphincter
Deep invaginations of sarcolemma are called ______.
T-tubules
The discs that anchor the sarcomere on either end in skeletal muscle that are absent from smooth muscle cells are called
Z
As cross-bridges form, the myosin heads pivot toward the center of the sarcomere. This action pulls the thin filaments toward the sarcomere center, causing the ______ to move closer together as the sarcomere shortens.
Z discs
Match each event at a neuromuscular junction with its location.
a nerve signal arrives at this structure matches Choice synaptic knob ACh is released into this space matches Choice synaptic cleft ACh binds to receptors on this surface matches Choice motor end plate
Multiunit smooth muscle cells are stimulated ______.
individually
Which of the following structures anchors adjacent cardiac muscle cells together?
intercalated disc
Cardiac muscle cells form Y-shaped branches and join to adjacent muscle cells at junctions called
intercalated discs
The calcium needed to activate smooth muscle contraction originates in the ______ around the cell.
interstitial fluid
Match the component of a muscle cell with its description.
myofibrils matches Choice cylindrical organelles specialized for contraction thick filament matches Choice composed of myosin thin filament matches Choice composed of actin, troponin, and tropomyosin actin matches Choice double-stranded contractile protein tropomyosin matches Choice double-stranded regulatory protein
After you stop running, you notice that you keep breathing heavily for some time. This is because your body is in ______.
oxygen debt
An extensive network of blood vessels and nerve fibers extends through both the epimysium and the _____ of a muscle.
perimysium
The connective tissue layer that surrounds each muscle fascicle is called ______.
perimysium
The immediate supply of ATP for use in muscle contraction is generated by the ______ system.
phosphagen
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 truck erect.
posture
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
As you struggle to twist open a jar, more motor units are called into action until you finally generate enough force to open it. This is an example of ______.
recruitment
After stimulation of ACh receptors, a muscle impulse spreads quickly along the ______ and into the muscle fiber along T-tubules.
sarcolemma
