11 - 1250
visceral smooth muscle
(aka single unit smooth mscule) this is found in the walls of viscera (internal orgnas) such as tehe stomach, intstines, uterus, urinary bladder, and many blood vessels
Ca2+ release channels
EC coupling in cardiac muscle involves L-type voltage-gated Ca2+ channels (dihydropyridine receptors) in the membrane of transverse (T) tubules and ____ ____ ____(ryanodine receptors) in the terminal cisternal membrane of the sarcoplasmic reticulum (SR).
L-type voltage-gated Ca2+ channels
Excitation-contraction coupling in cardiac muscle fibers begins as the cardiac muscle action potential travels along the sarcolemma and into the T tubules, where it causes thse channels to open.
hypertrophy
FG fibers of a weight lifter may be 50% larger than those of a sedentary person or an endurance athlete. The increase in size is due to increased synthesis of muscle proteins. The overall result is muscle enlargement due to ______ of the FG fibers
muscle tone
For example, when the muscles in the back of the neck are in normal tonic contraction, they keep the head upright and prevent it from slumping forward on the chest. this is an example of...
small motor units
For instance, muscles of the larynx (voice box) that control voice production have as few as two or three muscle fibers per motor unit, and muscles controlling eye movements may have 10 to 20 muscle fibers per motor unit these desribe muscles that contain (small/big) motor units
facilitated diffusion
Glucose passes from the blood into contracting muscle fibers via ____ _____
glycogen
Glucose passes from the blood into contracting muscle fibers via facilitated diffusion, and it is also produced by the breakdown of _____ within muscle fibers.
cardiac muscle fibers
However, in these type sof muscle fibers, the L-type voltage-gated channels are not arranged in tetrads nor are they mechanically coupled to the Ca2+ release channels
wave summation
If a second stimulus occurs in a skeletal muscle fiber after the refractory period of the first stimulus is over but before the muscle fiber has relaxed, the second contraction will actually be stronger than the first this phenomenon, in whic stimuli arrivng at differnt times cause contractions iwth greater tension, is called..
the second contraction will actually be stronger than the first
If a second stimulus occurs in a skeletal muscle fiber after the refractory period of the first stimulus is over but before the muscle fiber has relaxed, what will happen with regard to the second contraction
unfused (incomplete) tetanus
If a skeletal muscle fiber is stimulated at a higher rate, it can relax only slightly between stimuli
FOG
If more force is needed after alreadey recruited the SO fibers, the motor units of ____ fibers are also recruited
the muscle fiber will respond to the first stimulus but not to the second.
If two stimuli are applied to a skeletal muscle fiber, one immediately after the other, what willl be responded to?
striated muscle smooth
In _____ muscle, an action potential must be generated before contraction can begin. In _____ muscle, however, contraction can occur over a relatively broad range of membrane potentials.
tropomyosin
In a relaxed muscle, myosin is blocked from binding to actin because the strands of ______ cover the myosin-binding sites on actin
aerobic respiration
In activities that last from several minutes to an hour or more, ____ ____ provides nearly all of the needed ATP.
L-type voltage-gated Ca2+ cahnnels
In an action potential with a plateau, the plateau phase is caused by prolonged opening of______ channels, along with the partial opening of voltage-gated K+ channels
L-type voltage-gated Ca2+ channels
In smooth muscle fibers that produce only subthreshold depolarizations, only a few _____ channels open. This allows just a small amount of Ca2+ to enter the sarcoplasm, resulting in a weak contraction
troponin
In smooth muscle fibers, the thin filaments lack _______ and, although they contain tropomyosin, tropomyosin does not cover the myosin-binding sites on actin
ball of the foot weight of the body\ contraction of the muscles
In the body, standing up on your toes is an example of a lever that operates at a mechanical advantage (Figure 11.21a). The fulcrum is the __________. The load is the ________. The effort (E) is the __________ of the calf, which raise the heel off the ground
SO FOG
Leg muscles, which not only support the body but are also used for walking and running, have large numbers of both ___ and ____ fibers
cardiac
Like _____ muscle, single-unit smooth muscle does not require external stimulation to contract because action potentials within the muscle itself are spontaneously generated
dystrophin
Links thin filaments to proteins of sarcolemma
z discs
Narrow, plate-shaped regions of dense material that separate one sarcomere from the next.
smooth msucle cardiac muscle
Normally, _____ muscle is subject to the greatest amount of stretching. For example, each time your stomach fills with food, the muscle in its wall is stretched. ____ muscle is also stretched each time the heart fills with blood
optimum
Normally, resting muscle fiber length is held very close to the _____ by firm attachments of skeletal muscle to bones (via their tendons) and to other inelastic tissues.
sarcolemma and T tubules
Once an action potential is generated in a skeletal muscle fiber, it propagates along the ______ and _______ via continuous conduction, the same mechanism used for propagation of nerve action potentials along unmyelinated axons
Ca 2+
Once an action potential occurs in a contractile muscle fiber, it ultimately causes the muscle fiber to contract by increasing the ____ concentration in the sarcoplasm.
loses (yes)
Once fusion has occurred, the muscle fiber (loses/gains) its ability to undergo cell division.
crossbridges
Once these binding sites are free, myosin heads bind to them to form ______, and the contraction cycle begins.
legs
Others, such as the slow-twitch fibers that move the ___, have contraction and relaxation periods of about 100 msec each
red muscle fibers
(red/white) muscle fibers also contain more itochondria and are supplied by more cappillaries
actin
A contractile protein that is the main component of the thin filament. Each actin molecule has a myosin-binding site to which a myosin head of a thick filament binds during muscle contraction
myosin
A contractile protein that makes up the thick filament. A myosin molecule consists of a tail and two myosin heads, which bind to myosin-binding sites on actin molecules of a thin filament during muscle contraction
ATP
A huge amount of ____ is needed to power the contraction cycle, to pump Ca2+ into the sarcoplasmic reticulum, and for other metabolic reactions involved in muscle contraction
H zone
A narrow region in the center of each A band that contains thick filaments but no thin filaments
M line
A region in the center of the H zone that contains proteins that hold the thick filaments together at the center of the sarcomere
tropomyosin
A regulatory protein that is a component of the thin filament. In a relaxed skeletal muscle fiber, tropomyosin covers the myosin-binding sites on actin molecules, preventing myosin from binding to actin.
troponin
A regulatory protein that is a component of the thin filament. When calcium ions (Ca2+) bind to troponin, troponin undergoes a conformational change that moves tropomyosin away from myosin-binding sites on actin molecules, and muscle contraction subsequently begins as myosin binds to actin.
farther
A shovel functions as lever that operates at a mechanical disadvantage because the load is (farther/closer) from the fulcrum than the effort
several
A single somatic motor neuron innervates (one/several) muscle fibers, but each muscle fiber is innervated by only one somatic motor neuron
one
A single somatic motor neuron innervates several muscle fibers, but each muscle fiber is innervated by only (several/one) somatic motor neuron
alpha actinin
A structural protein of the Z discs that attaches to actin molecules of thin filaments and to titin molecules.
titin
A structural protein that connects a Z disc to the M line of the sarcomere, helping to stabilize the position of the thick filament. Because it can stretch and then spring back unharmed, titin accounts for much of the elasticity and extensibility of myofibrils
myomesin
A structural protein that forms the M line of the sarcomere; it binds to titin molecules and connects adjacent thick filaments to one another.
dystrophin
A structural protein that links the thin filaments of the sarcomere to integral membrane proteins in the sarcolemma, which are attached in turn to proteins in the connective tissue matrix that surrounds muscle fibers. It is thought that this helps reinforce the sarcolemma and helps transmit tension generated by sarcomeres to tendons
nebulin
A structural protein that wraps around the entire length of each thin filament; it helps anchor the thin filaments to the Z discs and regulates the length of the thin filaments during development.
troponin tropomyosin
After the Ca2+ concentration in the sarcoplasm increases, cardiac muscle fibers contract in the same way as skeletal muscle fibers: Ca2+ binds to ______, moving ______ away from myosin-binding sites on actin, and the thick and thin filaments begin sliding past one another.
Ca2+ release channels
After the last action potential has propagated throughout the T tubules, these channels close
muscle contraction begins
As a muscle action potential propagates along the sarcolemma and into the T tubules, it causes the release of Ca2+ from the SR into the sarcoplasm, and THIS ends up begining
Ca 2+
As a muscle action potential propagates along the sarcolemma and into the T tubules, it causes the release of _____ from the SR into the sarcoplasm, and muscle contraction begins
skeletal
As in _____ muscle, graded contractions in multi-unit smooth muscle occur by recruitment of additional muscle fiber
cardiac
As in ______ muscle, graded contractions in single-unit smooth muscle occur by increasing the amount of Ca2+ that enters the sarcoplasm of the muscle fibers
smooth
As in cardiac muscle fibers, Ca2+ is removed from the sarcoplasm of a _____ muscle fiber by Ca2+-ATPase pumps in the SR membrane and by Na+-Ca2+ exchangers in the sarcolemma
Na+-Ca2+ exchangers
As in cardiac muscle fibers, Ca2+ is removed from the sarcoplasm of a smooth muscle fiber by Ca2+-ATPase pumps in the SR membrane and by ____________ in the sarcolemma
Ca2+-ATPase
As in cardiac muscle fibers, Ca2+ is removed from the sarcoplasm of a smooth muscle fiber by ______ pumps in the SR membrane and by Na+-Ca2+ exchangers in the sarcolemma
Ca2+
As in cardiac muscle, graded contractions in single-unit smooth muscle occur by increasing the amount of ____ that enters the sarcoplasm of the muscle fibers
additional muscle fiber
As in skeletal muscle, graded contractions in multi-unit smooth muscle occur by recruitment of...
descreases (yes)
As sarcomere lengths become increasingly shorter than the optimum (understretched), the tension that can develop again ______
troponin
As the Ca2+ level in the sarcoplasm drops, Ca2+ dissociates from ______, tropomyosin covers the myosin-binding sites on actin, and the muscle fiber relaxes
tropomyosin
As the Ca2+ level in the sarcoplasm drops, Ca2+ dissociates from troponin, _______ covers the myosin-binding sites on actin, and the muscle fiber relaxes
decreases
As the pumps move Ca2+ back into the SR, the concentration of calcium ions in the sarcoplasm quickly (decreases/increases)
dihydropyridine receptors and Ca2+ release channels
At a given triad, the T tubule and terminal cisternae are mechanically linked together by two groups of integral membrane proteins: WHAT ARE THEY(2)
optimial
At a sarcomere length of about 2.0-2.4 μm (which is very close to the resting length in most muscles), the zone of overlap in each sarcomere is ____, and the muscle fiber can develop maximum tension (100%).
tension
At a sarcomere length of about 2.0-2.4 μm (which is very close to the resting length in most muscles), the zone of overlap in each sarcomere is optimal, and the muscle fiber can develop maximum _____ (100%).
many
Because of the way the varicosities are positioned in smooth muscle, neurotransmitters released by a single autonomic motor neuron regulate (one/few/many) smooth muscle fibers, and each smooth muscle fiber may be regulated by neurotransmitters from different autonomic motor neuron
creatine phosphate
Because the formation of ATP from ______ ____ occurs very rapidly, creatine phosphate is the first source of energy when muscle contraction begins
big motor units
By contrast, muscles responsible for large-scale and powerful movements have large motor units. For example, the biceps muscle in the arm and the gastrocnemius muscle in the calf of the leg have as many as 2000 to 3000 muscle fibers in some motor units this is an example of muslcles that contain (small/big) motor units
rigor mortis
Calcium ions leak out of the sarcoplasmic reticulum into the sarcoplasm and allow myosin heads to bind to actin. ATP synthesis ceases shortly after breathing stops, however, so the myosin crossbridges cannot detach from actin this defines the condition of....
tendon
Connects muscle to bone
fulcrum load effort
Consider the biceps muscle flexing the forearm as an object is lifted (Figure 11.20). When the forearm is raised, the elbow joint is the _____ . The weight of the forearm plus the weight of the object in the hand is the _____. The force of contraction of the biceps muscle pulling the forearm up is the _____
smooth
Contraction and relaxation of _____ muscle in the walls of blood vessels help adjust blood vessel diameter and thus regulate the rate of blood flow.
end plate potential (EPP)
Depolarization of the membrane potential of skeletal muscle fiber, caused by the action of the transmitter acetylcholine at the neuromuscular synapse binding to nicotinic ACh receptors.
different (yes)
Typically, the (same/different) motor units of an entire muscle are not stimulated to contract in unison
skeletal muscle fibers
Unlike most cells of the body, _____ muscle fibers often switch between a low level of activity, when they are relaxed and using only a modest amount of ATP, and a high level of activity, when they are contracting and using ATP at a rapid pace
eleavted
Wave summation and both kinds of tetanus (unfused and fused) occur when additional Ca2+ is released from the sarcoplasmic reticulum by subsequent stimuli while the levels of Ca2+ in the sarcoplasm are (elevated/low) from the first stimulus
Ca 2+
Wave summation and both kinds of tetanus (unfused and fused) occur when additional ___ is released from the sarcoplasmic reticulum by subsequent stimuli while the levels of Ca2+ in the sarcoplasm are still elevated from the first stimulus
away from
When Ca2+ binds to troponin, troponin undergoes a change in shape; this conformational change moves tropomyosin (away from/toward) the myosin-binding sites on actin, and muscle contraction subsequently begins as myosin attaches to actin
loses
When a muscle fiber receives enough stimulation to contract, it temporarily (gains/loses) its excitability and cannot respond for a time
more
When a muscle needs to generate more force during a contraction, ___ of its motor units are activated.
all
When a somatic motor neuron is activated, (one/some/all) of the muscle fibers in its motor unit contract in unison
varicosities
When an action potential occurs along the axon, the ________ release neurotransmitters, which in turn diffuse to smooth muscle fibers in the surrounding area
smooth
When an action potential occurs along the axon, the varicosities release neurotransmitters, which in turn diffuse to ____ muscle fibers in the surrounding area
acetylcholine
When an action potential occurs in a somatic motor neuron, it releases ____ molecules stored in the synaptic vesicles of the synaptic end bulbs
Ca 2+ release channels
When an action potential travels along the T tubule, the DHP receptors detect the change in voltage and undergo a conformational change that ultimately causes what chnanels to open
DHP
When an action potential travels along the T tubule, the ____ receptors detect the change in voltage and undergo a conformational change that ultimately causes the Ca2+ release channels to open
glucose
When muscle activity continues and the supply of creatine phosphate within the muscle fiber is depleted, ____ is catabolized to generate ATP
blocked
When the T tubule is at resting membrane potential, the part of the Ca2+ release channel that extends into the sarcoplasm is (blocked/opened) by a given cluster of DHP receptors, which prevents Ca2+ from leaving the SR
Ca 2+
When the T tubule is at resting membrane potential, the part of the Ca2+ release channel that extends into the sarcoplasm is blocked by a given cluster of DHP receptors, which prevents ____ from leaving the SR
contractile singlue unit smooht msucle fiber
When this tipe of smooth muscle fiber produces an action potential, the action potential can be either a spike potential or an action potential with a plateau
Ca2+ release channels
While muscle action potentials continue to propagate through the T tubules, these types of channels are open
connective tissue
___ _____ surrounds groups of 10 to 100 or more muscle fibers, separating them into bundles called fascicles _____ _____ also surrounds the entire muscle itself (same for both)
aerobic respiratoin
___ _____supplies enough ATP for muscles during periods of rest or light to moderate exercise
muscle tone
____ ____ is also important in smooth muscle tissues, such as those found in the gastrointestinal tract, where the walls of the digestive organs maintain a steady pressure on their contents
thin filaments thick filaments
____ _____ are 8 nm in diameter and 1-2 μm long, while thick filaments are 16 nm in diameter and 1-2 μm long. Both thin and ____ ___ are directly involved in the contraction process
msucle tone
____ _____ of smooth muscle fibers in the walls of blood vessels plays a crucial role in maintaining blood pressure
liver
____ cells can take up some of the lactic acid molecules from the bloodstream and convert them back to glucose
smooth
_____ muscle contractions also move food and substances such as bile and enzymes through the gastrointestinal tract, push gametes (sperm and oocytes) through the passageways of the reproductive systems, and propel urine through the urinary system
smooth muscle
_____ muscle does not consume as much ATP as striated mucsel
skeletal (yes)
______ muscle contractions promote the flow of lymph and aid the return of blood to the heart.
contractions
______ occur because action potentials within cardiac muscle itself are spontaneously generated on a periodic basis
Dihydropyridine receptor
a L-type calcium channel in the muscle cell membrane, activated upon depolarization, couple depolarization signal to release of calcium
I band
a Z disc passes through the center of each.....
satellite cells
a few myoblasts do persist in mature msucle as these these cells retian the capacity to fuse with one antoher or with damaged msucle fibers to regenerate functional mucle fibers however, the number of new skeletal muscle fibers is not enoguh to compensate for significant skeletal msucle damage or degenration
hinge
a flexible ______ is located wher ethe myosin heads join the myosin tail
troponin
a protein that consists of three gloular subunits -- one that binds to tropomyosin, one that binds to actin, and one thta has binding sites for clacium ions
lever
a regid structure tha can move around a fixed point called a fulcrum
Tropomyosin
a rod shaped protein that joins with other molecules of its same type to form two long strands that wrap around the F actin double helix
aerobic respiration
a series of oxygen requireing reacitons that produce ATP, CO2, water, heat
thin filament
a single ___ ___ contains 2 F actin strands arragned in a double helix
End plate potnetial
a single ___ is typically large neough to depolarize adjacent regions of sarcolemma to threshold, resulting in the generation of a muscle action potential
somatic contract
a single action potential in a _____ motor neuron elicits a single action potential in a skeletal muscle fiber, which in turn causes the skeletal muscle fiber to _____
single
a single nerve AP in a somatic motor neuron elecits a ___- muscle action poteinal in all the skeletal muscle fibers with which it forms synapses
somatic motor neurons
a skeletal muscle recieves input from many of these types of neuons
muscle tone
a small amount of tautness or tension in teh msucel due to weak, involuntary contractions of its motor units (even at rest, skeletal msucle has this)
tetanus
a sustained muscular contraction resulting from a rapid series of nerve impulses
sacrifices speed and range of motion for force
a system operating at a mechanical advantge sacriffices what for what?
triad
a transverse tubule and the two terminal cisterna on either side form this
mechanical advantge becasue the laod is closer to the fulcrum thant he effort
a wheelbarrow functiosn as a lever that operate on a mechanical advantage or disadvantage? why?
varicosities
abnormally enlarged, twisted veins smooth muscle
thick filament
about 300 molecules of ysoin forma single __ ____
SO fibers
about half of the fibers in a typical skletel msucle are _____ fibers
power stroke
action of myosin pulling actin inward (toward the M line)
brain and spinal cord
activation of various motor untis is controlled by the ___ and ____ ____
fewer
aerobic respiration, anaerobic glycolysis produces (more/fewer) ATPs, but it is faster and can occur when oxygen levels are low
nicotinic acetylcholine receptor
after ACh is released into the nueomusclar junction, it diffuses across the synaptic cleft and binds to these on the motor end palte, generateing a deplariznng graded potential
pacemaker potenial
after repolarizion, this "concept" starts to devleop again and the cycle repeasts.. caused by either an increase in Ca 2+ movemnt into the cell or a decrease in K+ movemnt out of the cell
tendons
all of the connenctive tissues of a muscle are continuous with its ____
striations
alternating light and dark bands, that are visible under a light microscope
striatoins
alternating the dark A bands an dlight I band screate the ___ that can be seen in both myofibrils and in whole skeletla and cardiac muscle fibers
asynchronous recruitment
alternation of active motor units to prevent fatigue
one
althoguh singl emyosin molecule has a doubl head, only ___ head binds ot actin at a time
ANS
although cardiac muscle can contract on its own in the absence of external stimulation, it is innervated by the ___ ____ ____, which alters the rate and strength of cardiac muscle contractions
caveolae
although there are no T tublues in smooth msucle, there are small pouch like invagination of the plasmembrne that contain extracelluar Ca 2+ that can be used for muscle ocntractoin these are called...
dihydropyridine receptors
although these channels allow extracellular Ca 2+ to enter the sarcoplasm when activated, their main role in EC coupling is to serve as voltage sensors that trigger the opening of the Ca2+ release channels
small amount
amount of myoglboin context for FG fibebrs
large
amount of myoglobin content for SO fibers
large amount
amount of myoglobin context fo rFOG fibes
creatine phosphate
an energy rich molecule that is found in msucle fibers....most of the excess ATP is used to syntehsize this molecule
Acetylcholinesterase
an enzyme loacted on the end plate membraenn that breaks down any ACh that is present in the synaptic cleft after nerve action potentials in teh ssomatic motor neuron cease
Ca 2+
an increase in the concentration of this ion in teh sarcoplasm starts mmscule contraction, and a decrease stops it
musclar hypertrophy
an increase in the diameter of muscle fibers due to increaed production of mmyofibrils, mitochonfria, sarcopalsmic reticulum, and other organelees
hyperplasia
an increase of the number of fibers growt of skeletal mucsle is unable to do this
connnective tissue
an individual msucle fiber is surrounded by a sheath of thois
crossbridge
ardiac muscle fibers can produce graded contractions (contractions that vary in strength) by increasing the amount of Ca2+ that enters the sarcoplasm, which in turn increases myosin ______ formation.
CA 2+
ardiac muscle fibers can produce graded contractions (contractions that vary in strength) by increasing the amount of ____ that enters the sarcoplasm, which in turn increases myosin crossbridge formation.
NO
are autorhythmic fibers able to contrract
detaches (yes)
as ATP binds to the ATP binding site fo the myosin head, the myosin head (detaches from/attaches to) actin
single unit smooth msucle
as a functional syncytium, ths type of smooth msucle has two typess of cells: a small number of autorhythmic fibers (pacemaker cells, and yes thi is correct), which are uusually groups togehter, and a large number of contractile fibers
Ca 2+ release chnensl
as a reuslt of these channels, more Ca 2_ is released into the sarcoplasm from the SR
varicosities
as axons of the autonomic motor neurons enter smooth muscle, they divide into branches that have swollen regions, calledd.....
This is because the thick filaments crumple as they are compressed by the Z discs, resulting in fewer myosin heads making contact with thin filaments
as sarcomere lengths become increasingly shorter than the optimum (understretched), the tension that can develop again decreases why does this happen?
zone of overlap shortens, which causess fewer myosin heads able to make contact with thin filaments
as the sarcomeres of a msucle fiber are stretched to a longer length (overstetched), what happens to the zone of overalap
I band and H znoe
as thin filaments slide inward, the these two things narrow and eventually disappear altogether when the muscle is maximally contracted
ecccentric isotonic contraction
as you lowe a book to place it back on a table, the previously shortend biceps lengthens in a controlled mnanner whin it continues to contract...this is an example of what type of contraction
cross bridge
at the end of the power storke, the ____ remains firmly attached to actin iuntil it bins another molecule fo ATP
atrial synctium
autorhythmic fibers of the SA node and the contractile fiber sof the atria constitetu this...
slow oxidative fibers
becaue these fibers have many large mitochonrida, they generate ATP mainly be aerobic resporiation, (hence thier aname)
smooth muscle tone
because of this concept, smooth mucsle can sustem long term tone, whicih is important in the gastrointestinal tract, where the walls maintian a steady pressure on food material in the lumen of the tracgt
slow oxidative fibers
because the ATPase in the myosin heads hydrolyzes ATP relatively slowly and the contraction cycle proceeds at a slower pace than in "fast" fibers. As a result, these fibers have a slow speed of contraction
T tubules
because these are opne to the outside of the fiber, they are filled with extrfacellualr fluid muscle APs travel along the sarcolemma and through these, quickly spreading thoughout the msucle fiber
cardiac muscle fibers
because these mucsle fibers rely lmost exclusively on aerobic respiration to generate the ATP they need for muscle contraction. As a result, these fibers contain large numbers of mitochondria
autorhythmicity
builit in rthym involved in cardiac muscle that cuases heartbeat and smooth muscles that prpel food throug gastrointestinal tract
fascicles
bundles of 10 to 100 or more muscle fibers
fascicles
bundles of muscle fibers
calsquestrin
calcium binding protein that is inside the SR...binds Ca2+, enabling even more Cca @+ to be sequestered (stored) within the SR
yes
can EC coupling in a kseletal msucle fiber occur whether Extracellualr Ca 2+ is present or not?
yes
can anaerobic respiration be used to create ATP for smooth muscle?
no
can autorhythmic fibers (in smooth msucle) contract?
yes, but under certain circumstances
can cardiac muscle regenerate
fast oxidativ glycolytic fibers
can generate considerable ATP by aerobic respiration, which gives them a moderate resistance to fatigue Because their intracellular glycogen level is high, they also generate ATP by anaerobic glycolysis
yes
can hormones affect cardiac activity?
yes
can smooht muscle undergo hypertropyh
YES
can smooth msucle fibers undergo hyperplasia to so e exten?
NO cardiac muslce? this is because the duration of the refractory period is about as long as the duration of contraciotn, so the cardiac mucsle fiber cannot b reecited until its previous contraction is lamost over
can summation of contractions and tetanus ouccur in
high capcaity, by aerobic respiration
capacitty for generating ATP and method use for SO fibers
low capcaity, by anaerobic glycolysis
capacity for generating ATP and method used for FG fibers
intermediate capacity, by both aerobic respiration and anaerobic glycolyusis
capcaity for generating ATP and method used fo rFOG fibers
many
capillary ammoujt fo rSO fibers
few
capillary amount for FG fibers
many
capillary amoutn for FOG fibers
contractile protiens
Proteins that generate force during muscle contractions.
structural porteions
Proteins that keep the thick and thin filaments of the myofibrils in proper alignment, give the myofibrils elasticity and extensibility, and link the myofibrils to the sarcolemma and extracellular matri
acetylcholine
Recall that skeletal muscle contracts only after it is activated by ____ released by action potentials in its motor neurons
SEE DIAGRAM ON 392
SEE DIAGRAM ON 392
SEE DIAGRAM ON 391
SEE DIAGRMA ON 391
see picutre on 410
SEE PICTURE ON 410
sphincters
Temporary storage of food in the stomach or urine in the urinary bladder is possible because smooth muscle ____ close off the outlets of these organs
Ca 2+ release chnanels
The Ca2+ that enters a smooth muscle fiber through L-type voltage-gated Ca2+ channels also serves as trigger Ca2+ that binds to and opens THESE channels int he memrbaen of the SR
A band
The dark, middle part of the sarcomere that extends the entire length of the thick filaments and also includes those parts of the thin filaments that overlap with the thick filaments
extensibility and elastcity
The part of the titin molecule that extends from the Z disc is very elastic. Because it can stretch to at least four times its resting length and then spring back unharmed, titin accounts for much of the ______ and _____ of myofibrils.
troponin
The released calcium ions combine with ____, which in turn undergoes a conformational change that causes tropomyosin to move away from the myosin-binding sites on actin
tropomyosin
The released calcium ions combine with troponin, which in turn undergoes a conformational change that causes ______ to move away from the myosin-binding sites on actin
frequency
The total force or tension that a single muscle fiber can produce depends on the ____ of stimulation, he length of the muscle fiber before contraction begins, and the diameter of the muscle fiber.
length
The total force or tension that a single muscle fiber can produce depends on the frequency of stimulation (the rate at which the muscle fiber is stimulated by a motor neuron), the ____ of the muscle fiber before contraction begins, and the diameter of the muscle fiber.
fast glycolytic fibers
They contain large amounts of glycogen and generate ATP mainly by anaerobic glycolysis these dscribe what fibers?
independenyl
Thus, the atria and ventricles contract (dependly/independently) of each other, with the atria contracting before the ventricles
oxygen
Thus, when ____ is present, glycolysis, the Krebs cycle, and the electron transport chain occur.
ion channesl
To enter the sarcoplasm, calcium ions move across the sarcolemma of the smooth muscle fiber or the membrane of the SR by passing through ____ channels smooth msucle
15 seconds
Together, stores of creatine phosphate and ATP provide enough energy for muscles to contract maximally for about ___ seconds
NO neurotransmitters released by a single autonomic motor neuron regulate many smooth muscle fibers, and each smooth muscle fiber may be regulated by neurotransmitters from different autonomic motor neurons due to how varicosities are positioned
in a given smooth msucle fiber, are the receptors fo rneurotransmitters confined to a specifci receptor region like they are a tthe motor end plate of a skeletal msucle?
twitch
in a laboratory, this can be produced by surgically removing a msucle form an animal and then electrically stimulating it
yes
in cardiac msucle, are transverse tubuluees present?
troponin and torpomyosin
in cardiac msucle, what are the important regulatory proteions for ontractions
No
in cardiac muscle fibers, are the L type voltage gaes channels mechanicalyl coupled to the Ca 2+ reelase channels?
No
in cardiac muscle fibers, are the L type voltage gated channels arragned in tetrads?
Acetylcholine and norepinephrine released by autonomic motor neurons.
in cardiac muscle, contraction is regulated by (think molecules)
some
in cardiac muscle, how much SR is there?
SR and ectracellular fluid
in cardiac muscle, where is the soure(s) of Ca 2+ for contraction
sarcoplasmic reticulum
in relaxed muscle ifber, this stores calcium ions
SR, NOT sarcoplasm
in releaxed muscle, where is the concentration of CA 2+ higher?
troponin and tropomyosin
in skeletal msucle, what are the reulgatory proteins for contraction
Acetylcholine released by somatic motor neurons.
in skeletal mucsle, contraction is regulated by... (think molecule/s)
yes
in skeletal muscle, are transverses tubuluespresent?
abundant
in skeletal muscle, how musch SR is there?
no
in skeletal muscle, is there autorhythmicity ?
Ca 2+ induced Ca 2+ release
in smooht muscles, contrary to cardiac, this phenomenon provides only a small maount of the Ca 2_ required for contractio becasue the SR is present ins small amounts and therefore has only a small inttacellular Ca 2+ resrve
calmodulin
in smooth mscule, as the Ca 2+ concentration in the sarcoplasm decreases, Ca 2+ dissociates from _______, and myosin light chain kinase becomes inactive
inactive
in smooth mscule, as the Ca 2+ concentration in the sarcoplasm decreases, Ca 2+ dissociates from calmodulin, and myosin light chain kinase becomes (inactive/active)
dense bodies
in smooth msucle fibers, the thin filaments attch to structures which are functionally similar to Z discs instriated muscle fibers...these are called
relatively smlall intracelluar Ca 2+ reseve
in smooth msucle, how musch intracellualr calcium is there in the SR
calmodulin
in smooth muscle ifbers, Ca 2+ binds to this reuglatory protein int he sarcoplasm that is similar in structure to tropnonin
phosphorylated myosin heads bind to actin, and muscle contraction begins
in smooth muscle, after the mysoin heads are phosphorylated, what happens
phosphoryated
in smooth muscle, contraction ocurs once the myosin heads of the thick filaments are ______
yes
in smooth muscle, do L-type voltage-gated Ca2+ channels oepn in a graded fashion?
small amount
in smooth muscle, how much SR is there
yes, in single unit smooth msucle
in smooth muscle, is there autorhymicity
myosin light chain kinase (MLCK)
in smooth muscle, the Ca 2+ -calmodulin complex activates this enyzme that is rpsent in the cytoplasm...this enzyme then phosphorylates light chians in the myosin heads
clamodulin and myosin light chain kinase
in smooth muscle, what are the importnat reuglatory proetions for contraction
myosin heads must be pohsphorylated by MLCK
in smooth muscle, what must happen to the mysoin heads for contraction to cause
(1) pacemaker potentials (2) slow wvae potentials
in smooth muscle... what are the two types of spontaneous depolarizations that can occur in authorhytmic fibers of single unit smooth mucsle
autorhymic fibers
in smooth muscle.... these cannot contract, but instead generate APs spontaneously (like cardiac)
(!) most comes form the extacellualr fluid (2_ rest comes form the SR
in smooth muscles, Ca 2+ flows into smooth msucle sarcoplasm from these tow sources:
no
in smooth muslce, are trasnverse tubules prsente
L-type voltage-gated Ca2+ channels
in smoothh muscle, these open in a GRADED fasion: as the sterngth fothe epolarization increases, more channels open. what channel?
Acetylcholine and norepinephrine released by autonomic motor neurons; several hormones; local chemical changes; stretching
in smoth mscule, contraction is regulated by...
that fiber only
in stimulateion of one multi unit smooth muscle fiber, how many fibers end iup contracting?
contraction of adjacent fibers occurs
in stimulation of one single unit smooth muscle fiber, how many fibers end up contracting
NO! in striated muscle, myosin heads are not present in the center of the thick filament
in strited muscule, are musoin ehads present in the center of the thick filament?
contractile fibers
in the heart .... these fibers consittute the bulk of the walls of the atria and tehe ventricles
asynchronous recrutiment
in this mode of motor unit recreutiment, the smallet motor untis are recrutied first, with progressivley larger motor untis addeddif the task required more force...
CA 2+ induced CA 2+ releae (CICR)
in this phenomena, the extracellluar Ca 2+ triggers the release fo addiitonal Ca 2_ from the SR
concentric isotonic contraction
in this type of contraciotn, the tension generated is great enough to exceed the load and the muscle shortens, pulling on another structure (such as a tendon) to produce movement
cardiac muscle fibers
in this type of msucle fiber, each L type votlage gated Ca 2+ channel in the T tubule membraen is clsoe to, and has an efffect on, only one Ca 2+ release channel in the SR memrane
cardiac muscle,
in this type of muscle, refractory is long enough such that tetanus and summation of contractions does not occur
smooth msucle
in this type of muscle, the thick filamnet contain myosin, adn the entire length of each thick filament has myosin heads projecting form it -- an arragnemnt that helps this muslce exert a considereable amount of tension during contraction
smooth muscles
in this type of muscle....because the thick and thin filaments hav eno regular pattern of overlap, the fibers of this musle do not exhibti striations
pyruvic acid obtained from the glycolysis of glucose, fatty acids from the breakdown of triglycerides, and amino acids from the breakdown of proteins
in what way can pyruvic acid be obatined?
Z discs
ince the thin filaments on each side of the sarcomere are attached to ___ ____ discs, when the thin filaments slide inward, the __ ____come closer together and the sarcomere shortens. Shortening of the sarcomeres causes shortening of the whole muscle fiber, which in turn leads to shortening of the entire muscle same thing for both
caveolae
indentations in sarcolemma; may act like T tubules smooth msucle they ccontain extracellular Ca 2+ that cna be used for muscle contraction
length tension relationship
indicated how the forcefulness of muscle contractin (tension) depends on the length of the sarcomeres within a msucle fiber BEFORE contraction begins
G actin
individual actin moleccuels are known as this because they are globular proteions
fatigue
insufficent oxygen, depletion of glycogen and other nutrients, buildup of lactic acid and ADP, and failure of action potentials in teh motor neuron to release enough ACh these are all asscoiated wtih...
shivering
involuntary contraction of skeletal muscles....can increase the rate of heat prooduction
extracellualr
is Ca 2+ induced ca 2+ release, ______ Ca 2+ triggers the release of addiitonal Ca 2_ form the SR
slower
is aerobic repsiraiotn faster or slower than anaerobic glycolysis
yes
is cardiac muscle, is there autoryhmicity?
YES!! (yes)
is it true that a smooth muscle fiber can contact in response toa subtrhehold stimullus (that does not give rise to AP) and even ocontract when there is no chagne in membrane potenial>
yes
is it true that as the strength of the depoolarizaiot increase, more L-type voltage-gated Ca2+ channels open (smooth muscle depoariziiaotn)
NO multi-unit smooth muscle is not autorhythmic nor does it behave as a functional syncytium. All of the cells in multi-unit smooth muscle are contractile fibers that act as independent units
is multi unit smooth muscle autorhymic? does it behave as a functional syncytium?
No
is there troponin in smooth muscle ?
contraction period
lasts about 10-100 msec...during this period, Ca 2+ binds to troponin, myosin-binding sites on actin are exposed, and myosin crossbridgesform peak tension develops in ht emsucle fiber
latent period
lasts about 2msec..its a brief delay that occurs between application of stimulus and the beggining of contraction
before
length-tension relationship for a skeletal muscle fiber, which indicates how the forcefulness of muscle contraction (tension) depends on the length of the sarcomeres within a muscle fiber (after/before) contraction begins
cardiac muscle
like ____ mscule, signle unit smooth muscle is autorhythmic and behaves as a functional syncytium
cardiac musle fibers
like skeletal muscle fibers, ___ muscle fibers are striated due to th epresence of repating sarcomeres consisting of thick and thin filaments that have a reular pattern of overlapping
M line
line that is located in the middle of the sarcomere
heart
location of cardiac muscle
most comonly attached by tendons to bones
location of skeletal mucsle
walls of hollow viscera, airways, iris and cilliary body of eye, arrector pili muscles of skin
location of smooth muscle
muscle fibers
long, slender cells that make up muscles wach skeletal muscle comprises of hyndred of thousands of these that are arranged parralel to one antoher
contract or releax
many smooth muscle fibers ____ or ____ in response to stretching, hormones, or local factors such as changes in pH, oxygen and carbon dioxide levels, temperature, and ion concentrations
functional syncytium
mass of interconnected muscle fibers acting as a single coordinated unit this term describe tis concept
many
mitchondria amount for SO fibers
few
mitochondria amount for FG fibers
many
mitochondria amount for FOG fibers
Duchenne muscular dystrophy
most common form of muscular dystrophy the gene that codes for the protein dystrophin is mutated, so little or no dystrophin is present in the muscle fiber. Without the reinforcing effect of dystrophin, the sarcolemma tears easily during muscle contraction, causing muscle fibers to rupture and die
mechncail disadvantage
most levers in your body operate at a mehcnaicl advantge or disadvantage
creatine phosphate
most of the excess ATP use used to syntehsize this....
diffuses out of skeeltal muscle fiber into the bloodstream
most of the lactic acid produced by anaerobic glycolysis goes hwere?>
extensors
msucles such as the triceps that cuase extension of a limb are known as....
ture
much fo heat generaated by muscle is used ot maintain normal body temperature
sarcolemma
muscle cell membrane
structural proteins
muscle contrians these types of protiens that contribute to the laigment, stability, extensibility and elasticity of myofibrils
myofibrils
muscle fibers that hvae a thicker diamete have more _____
antagonistic muscles
muscle pairs arranged to work against each other to move a joint
sliding filament mechanism
muscle shortens during contraction because thick and thin filaments lside past one another, a mehcanism called
isometric contraction
muscles contract in this fashion in order to maintain postuer and for suppoprting objects ina fexed position
flexors
muscles such as the bicpes are referred to as ____ becaue they promote flexion of a limb
antagonistic msulce
muscles that promtoe opposite acitons at the smae joint
isometric ocntractions
occur when you try to lift n object that is too hevay for you to move type of contraction
repolarizing phase
occurs in skeletal muscle...caused by closure of the voltage gated Na+ channels and opening of the voltaged gagedd K+ channels
smooth muscle
of the three muscle ypes, whic has the greatest power of regeentration
mysoin binding site
on each G actin there is this site where the myosin head can attach
I band
on either side of the A band is a light area called.... this contains the rest of the thin filaments but NO thick filaments
calcium ions
on the onset of contraction, the sarcoplasmic reticulum release this into the sarcoplasm
thick and thin filaments
once Ca 2+ release channel open, large amounts of Ca 2+ flow out of the SR into the sarcoplasm around these filaments (2)
Ca 2+
once Ca 2+ release channel open, large amounts of ____ flow out of the SR into the sarcoplasm around the thick and thin filaments
troponin
once calcium is in the sarcoplasm, what does it bind to ?
phosphate group
once the eneregized myosin head ttaches to the mysoin binding site on actin, what is released
ADP
once the power stroke occursm, ____ is released from the myosin head
store operated channels
opeing these channels in the sacolemma allos Ca @+ to enter teh sarcoplasm form extracellular fluid....the enterin Ca 2+ can be used for contaction or to repolensih the depleted Ca 2_+ stores inthe SR
terminal cisternae
release fo Ca 2+ from the ___ ___ of the sarcoplasmic reticulum triggers muscle contraction
second
roder fo recrutiment fo rFOG fibers
sarcoplasm
sarcolemma surrounds the....
see p413 diagram
see p413 diagram
myosin
shaped like two golf clubs twisted together: the _____ tail resembles the twisted golf club handles and the ____ heads look like the golf club heads
fast oxidative glycolytic fibers
similar to slow oxidative fibers, they contain large amounts of myoglobin and many blood capillaries. Thus, they also have a dark red appearance.
largest
size of fiber diameter for FG ifbers
intermediate
size of fiber diameter for FOG fibers
smallest
size of fiber diameter for SO fibers
true
size of the motor units that are activated in a muscle affects the amount of tension the muscle can generate
red msucle fibers
skeletal mjsucels that have high myoglobin content
acetylchonine
skeletal muscle contracts only when stimulated by ______ released by a nerve action potential in a somatic motor neuron
myoblasts
skeletal muscle fiber arises during embryonic development from the fusion of many small, undifferentiated cells called ____
white muscle
skeletal muscle fibers that have a low content of myoglobin are called this ...tehy appear lighter
voluntary (somatic)
skeletal muscle nervous control (vol or invol)
fast
skeletal muscle spped of contaraction?
depolarinzing phase
skeletal muscle...caused by opening of voltage gated Na+ channels
yes
skeletal muscle: are contractile prooteins organized into sarcomeres?
stratiated
skeletal muscle: striated or not?
graded contractions
skeletal muscles can produce these, which are contractions that vary in strength dpeending on how much force is needed by the muscle to suppoort the particular object
skiiped paragrpah on 396
skiiped paragrpah on 396 ("The metabolic changes that occur during..."
slow oxidative fibers
slow-twitch, fatigue-resistant fibers are adapted for maintaining posture and for aerobic, endurance-type activities such as running a marathon this describes what type of fibers
actin
smooth msucle Once the phosphate groups are removed, the myosin heads are unable to bind to _____, and the smooth muscle fiber relaxes
contractile single unit smooth muscle fibers
smooth msucle these cannot initiate APs, but they are excited and tehn contract in response to APs conducted to them by autorhymic fibers
ANS
smooth msucle is innervated by motor neurons of .....
multi unit smooth mucle
smooth msucle... gap junctions are rate in this type of smooth muscel, so as a result, the fibers must be stimulated individually by nerves to contract
ANS
smooth muscle fibers contract or relax in response to neurotransmitters released from the ___ think nervous systme...
motor neurons
smooth muscle is innervated by the ___ neurons of the ANS
involuntary
smooth muscle nervous contorl (vol or invol)
myosin light chain kinase
smooth muscle protein kinase; when activated by Ca2+-calmodulin, phosphorylates myosin light chain
slow
smooth muscle speed of contraciton
contractile fibers
smooth muscle... these fibers are able to contract, but they cannot intiaite APs...they become excited and tehn conntract togehter in repsone to APs conducted to them from the autorhymic fibers
pacemaker potential
smooth muscle... this is a spontanneous depolariziano that always reaches threshold and therefore tirggers the production of an AP (in autorhymic fibers of single unit smooth msucle)
nto straited (smmooth)
smooth muslce: striated or not
dense bodies
some of these are disperse throughout the sarcoplasm; others are attached to the sarcolemma....bundles of intermediate filaments, which are part of the cytoskeleton, also attach to these and stretch form one of these to another
slow wave potential
sometimes, for these thigns, threshold is reached an an AP is generated on other occasions, threshold is not reached and an AP does not occur it is cycls of alternating depolarizaiotn and repolariziaotn smooth muscle
intercalated discs
specialized connections between myocardial cells containing gap junctions and desmosomes
pericytes
stem cells found in asssociation with blood cpaillaries adn small veins that can give rise to new smooth musce fibers
sphincters
storage is accomplished by sustianed contractions of ringlike bands of smooth muscle callled ____
titin
structural protein that connects a Z disc to the M line of the sarcomere, threby helping stabilize the positino of the thick filament
M line
supporting protiens that hold the thick filaments toghether at the center of the H zone form the _____ ____
true
t.f: Although extracellular Ca2+ does enter the sarcoplasm of a skeletal muscle fiber through L-type voltage-gated Ca2+ channels when the cell is excited, studies have shown that EC coupling in a skeletal muscle fiber can occur whether extracellular Ca2+ is present or absent
true
t/f: Action potentials always have the same size in a given neuron or muscle fiber.
true
t/f: All of the myosin heads of a given thick filament do not proceed through the steps of the contraction cycle at the same time.
true
t/f: Although the total number of skeletal muscle fibers usually does not increase, the characteristics of those present can change to some extent.
true
t/f: Because each skeletal muscle fiber arises during embryonic development from the fusion of many small, undifferentiated cells called myoblasts (Figure 11.3a), a mature skeletal muscle fiber has multiple nuclei
true
t/f: Because glycolysis does not require oxygen, it can occur whether oxygen is present (aerobic conditions) or absent (anaerobic conditions).
true
t/f: Because of the buildup in the Ca2+ level, the peak tension generated during fused tetanus is 5 to 10 times larger than the peak tension produced during a single twitch.
Ture
t/f: Because the NMJ is usually near the midpoint of the muscle fiber, once the muscle action potential arises, it propagates through the muscle fiber membrane in both directions away from the NMJ toward the ends of the fiber.
ture
t/f: Many skeletal muscles are also controlled subconsciously to some extent For example, your diaphragm continues to alternately contract and relax without conscious control so that you don't stop breathing
true
t/f: Some fibers, such as the fast-twitch fibers that move the eyes (described shortly), have contraction periods as brief as 10 msec and equally brief relaxation periods. Others, such as the slow-twitch fibers that move the legs, have contraction and relaxation periods of about 100 msec each
true
t/f: The asynchronous activity of the myosin heads during repeated contraction cycles is responsible for the continuous inward movement of the thin filament: If all of the myosin heads attached to and then detached from actin at the same time, the thin filament would slide back to its resting position between power strokes
true
t/f: The atria (upper chambers) and ventricles (lower chambers) of the heart behave as two distinct functional syncytiums
true
t/f: Thus, the atria and ventricles contract independently of each other, with the atria contracting before the ventricles. This allows the ventricles to fill with blood from the atria before the ventricles eject blood out of the heart to the rest of the body
true
t/f: Whereas stimulation of one single-unit smooth muscle fiber causes contraction of adjacent fibers, stimulation of one multi-unit smooth muscle fiber causes contraction of that fiber only
TRUE
t/f: Within a particular motor unit, all of the skeletal muscle fibers are of the same type.
true
t/f: a cardiac muscle fiber cannot be reexcited until its previous contraction is almost over. For this reason, summation of contractions and tetanus do not occur in cardiac muscle.
true
t/f: duration of the refractory period varies with the muscle involved. Skeletal muscle has a short refractory period of about 1 msec; cardiac muscle has a longer refractory period of about 250 msec.
true
t/f: in a smooth muscle, the receptors for neurotransmitters are located along the entire surace of the cell
true
t/f: like neurons and skeletal muscle fibers, cardiac muscle fibers have a refractory period
true
t/f: most skeletal muscles contain a micture of all three fibers
ture
t/f: one nerve action potentials in the somatic motor neuron cease, ACh is no longer released.
true
t/f: present in cardiac muscle fibers are transverse (T) tubules and a moderately developed sarcoplasmic reticulum (SR)
true
t/f: single-unit smooth muscle does not require external stimulation to contract because action potentials within the muscle itself are spontaneously generated
TRUE
t/f: the ATP levels in fatigued muscle often are not much lower than those in resting muscle
true
t/f: the force of muscle fiber contraction can vary; a muscle fiber is capable of generating a much greater force than the one that results from a single twitch
true
t/f: the length of thick and thin filaments is the same in both relaxed and contracted muscles
true
t/f: the muscle fibers of a motor unit are dispersed throughout a muscle rather than clustered together
TRUE
t/f: the number of skeletal muscle fibers is set before you are born, and most of these cells will last you a lifetime.
ture
t/f:For example, muscle fibers vary in their content of myoglobin, the red-colored protein that binds oxygen in muscle fibers
TRUE
t/f:the width of the A band and the individual lengths of the thick and thin filaments remain unchanged
AV node
tallows the action potential to be conveyed form atrial synctium to the ventricular synctium
true
teh actual duration of each period of the msucle twitch seqeuence depends on the muscle fiber
fast oxidative glycolytic fibers
tehse are intermediate in diameter betweeeen the other two types of fibers
fast oxidative glycoytic fibers
tehse fibers can generate considerable ATP by aerobic respiration, which gives them a moderate resistance to fatigue
single unit (visceral) smooth muscle fibres
tehse muscle fibers connect to one another by gap junctions and contract in unison (smooth muscle)
isometric contraction
tension increases greatly without a change in msucle length
isotonic contraction
tension remains constant as mscule length descresaes or increases
Electromyography (EMG)
test that measures the electrical activity (muscle action potentials) in resting and contracting muscles
stress relaxatoin resposnse
thanks to this response, even though smooth muscle in the walls of blood vessels and hollow organs such as the stomach, intestines, and urinary bladder can stretch, the pressure on the contents within them changes very little. After the organ empties, the smooth muscle in the wall rebounds, and the wall retains its firmness
depolarizing phase and repolarinz phase
the AP generated in an autorhthmic single unit smooth msucle ifber consists of two phases:
thick filaments
the M line proteions bind to titin and connect adjacent _____ filaments to one antoher
elasticity
the ability of a msucle to return to its original length and shape after contraction or extension
extesniblity
the ability of msucle to stretch wihtou being damaged
contractilit
the ability of muscle to contract forefully when adequately stimulated
flexion
the act of bending a limb at a joint
extension
the act of straightening out a limb at a joint
smooth muscle
the action of this muscle is usually involuntary, and some muscles apart of this group ohave autorhythmicity
oxygen debt
the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose
T tubules
the arragnemmetn of these things ensures that the AP excites all parts of the msucle fiber at essentially the same instant
insertion
the attachemnt to the msulcles other tnedon to the more movable bone
origin
the attachment of a msucles tendon to the more stationary bone;
centricular syncytium
the autorhythmic fibers of the ventricles (AV bundle, bundle branches, and Purkinje fibers) and the contractile fibers of the ventricles constitute the....
antagonistic muscles
the biceps and triceps are examples of these becaues they promtoe opppostie actions at the same joint
glycolysis
the breakdown of glucose by enzymes, releasing energy and w molecules ofpyruvic acid.
lactic acid
the buildup of this is thought to be responsible for muscle soreness that is felt during strenouos exercice
myofibrils
the contractile elemnets of muscle fibers...they contain overlapping thick and thin filaments
ATP and Ca 2+ level near the thin filament is sufficeintly high
the contraction cycle repeates as long as what two things are present
sarcoplasm
the cytoplasm of a muscle fiber
A band
the dark middle part of the sarcomere this extends the entire length of the thick filaments. towards each end of this is a zone where the thick and thin filaments overlap
alpha-actinin
the dense material of the z discs contain these molecules these molecules bidn to actin molecules of the thin filament and to titin
opeing of L-type voltage gated Ca 2+ channels
the depolarizinng phase in an autorhythmic single unit smooth muscle fiber is caused by the opeing of what?
anaerobic glycolysis
the entire process by whcih the breakdown of glucose gives rise to lactic acid when oxygen is absent or at a low concentration is referred to as....
(1) to convert lactic acid back into glycogen stores in the liver (2) to resynthesize creatine phosphate and ATP in mscucle fibers (3) to replace the oxygen removed from myoglobin
the extra oxygen that is innaken is used to "pay back" or restore metabolic conditions of the resting level in three ways...
smooth msucle fibers
the fibers of this type of muscle LACK transvere (T) tubules and have only a smalll amount of sarcoplasmic reticulum for storage of Ca 2+
muscle fatigue
the inability of a muscle to maintain force of contraction after prolonged activity
fatigue
the inadequate relase of clacium ions form the SR, resulitnig in a delcine of Ca 2+ concentration in the sarcoplasm would likely cause this.....
mechanical disadvantage
the laod is further from the fulcrum than the effort
acting like
the main component of hte thin filament
slow wave potentians
the meahncims underlying this is thought to involve Na+ movmeent out of the cell caused by periodic changed in the activity fo the Na+/K+ pumps it is cycles of alternaitn depolarisziaotn and repolarizioatn that do not necessarily reach threshold
Ca 2+ - ATPase pumps
the membrane of the sarcoplasmic reticulum contains active transport proteins that constanttly transport Ca 2+ form the sarcoplasm into the SR what is the anme of this pump?
single unit smooth muscle
the most common type unit of smooth muscle..... fibers contract together as a signle uni aka, visceral smooth mscule
M line
the myosin tail of each myosin molecule points towards the __ line int eh cneter of the sarcomere
acetylcholine
the neurotransitter released at the NMJ... has an excitatory effect on neuromusclular transmission
sarcolemma
the plasma membrane of a muscle fiber multiple nuclei of a skeletal muscle fiber are located just beath this..
motor unit recruitment
the proces of increasing the number of active motor units
Ca 2+ induced Ca 2+ release
the process by which extracellular Ca 2+ triggers the release of additoinal Ca 2+ from the SR
smooth mscule tone
the prolonged presence of Ca 2+ in the caroplasm for smooth muscle provides this state of continued partial contration, referred to as...
motor end plate
the region of muscle fiber memebrane opposite the synaptic end bulbs
caused by closure of L-type voltage gated Ca 2+ channels and the opening of voltage gated K+ channels
the repolarizing phase in an autorhythmic single unit smooth muscle fiber is caused by the closure of what and opening of?
glycogen
the sarcoplasm contains this, which is a large polysaccharide consistsing of thousands of glucose molecules covalently linked together
smooht muscle
the sarcoplasm of this type of the fiber sof this contains both thicka nd thin filaments, but they are nto arragned in orderly sarcomeres, as in striated msucle
excitation contraction coupling
the sequence of events that links the muscle AP to msucle contraction
motor unit
consists of a somatic motor neuoron plys all the muscle fibers it innervates
myosin
consists of six polypeptide chains: two large heavy chains and four small light chains. These polypeptide chains are arranged in such a way that the _____ molecule has a rodlike tail and two globular heads
isotonic contraction
constant tension....contractions where the tension devleoped by the msucle reminas lamost constant while the msucle changes its length
triad
constists ofa transcers (T) tubule and two oppsoing terminal cisternae (lateral sacs) of the SR
I band
contains the rest of the thin filamnets but no thick filamens
slow
contracation vleocity for SO fibers
fast
contraciton velocity fo FOg fibers
gap junctions
contractile fibers become excited and then contract together in response to action potentials conducted to them from autorhythmic fibers via ____ _____
latch state
contractile state of some smooth muscles; force can be maintained for prolonged periods w/ very little energy use; cross-bridge cycling slows to the point when phosphorylated cross-bridges become dephosphorylated while still attached to actin
thick thin
contraction in smooth msucle is tiriggered by calcium induced changes in the ____ filaments, whereas contraction in straited msucle is triggered by calcium induced cahgned in the ____ filamnets
flexion
contraction of the biceps muscle causes flexion of the forearm at the elbow joint, which means that the forearm moves toward the arm this is an exmaple of what type of movement
extension
contraction of the triceps muscle causes ____ of the forearm at the elbow joint, meaning that the forearm moves away from the arm this is an example fo what type of movemnt
smooth muscle
contraction of this muscle type starts more slowly and lasts much longer than contraction of striated muscles
fast
contraction velcoity for FG fibers
isometric contraction
contraction where the nsion generated is not enough to exceed the load, adn the muscle does nto change length
tendon
cord of connective tissue that ataches the msucle toa bone
dense bodies
cytoplasmic structure to which thin filaments of a smooth muscle fiber are anchored
mechanical disadvantgae
deos a shovel operate at a mechanical advantage or disadvantgae
fatigue
depeltion of creatine phosphate is asscoaited with this
each L-type voltage-gated Ca2+ channel in the T-tubule membrane is close to, and has an effect on, only one Ca2+ release channel in the SR membrane
describe how each L type voltage gated Ca 2+ channael in the T tubulbe membrane is situated in reelation to a Ca @+ release channel in the SR memerbane for cardiac muscle fibers
terminal cisternae (lateral sacs)
dilated end sacs of the sarcoplasmic reticulum thee butt against a T tubule form both sides
NO
do cardiac muscle require any external stimulation to contract?
NO
do contractile fibers have the ability to intiiate action potentials?
NO
do smooth muscle contain transver tubules?
yes
does EC coupling in cardiac muscle involve L type voltagae gated Ca 2+ gahannels (dihydropyridine receptors) in the membrane of transverse (T) tubules and Ca2+ release channels (ryanodine receptors) in the terminal cisternal membrane of the sarcoplasmic reticulum (SR)?
NO
does glycolysis requrie oxygen?
yes
does mature skeletal musle fibers have lost the ability to undergo cell divsion? (yes or no)
slow
does smooth muscle relax slow or fast?
NO In smooth muscle fibers, the thin filaments lack troponin and, although they contain tropomyosin, tropomyosin does not cover the myosin-binding sites on actin
does tropomyosin cover the myosin binding sites on actin in SMOOTH muscle?
eccentric isontinc contraction
duirng one of these contractions, the tensio exerted by the myosin crossbridges resists movement of a load (nad slows the lengthening process
power stroke
during __ ____ of the contraction cycle, crossbridges pivot, pulling the thin filaments past the thick filament toward the cetner of the sarcomere
IP3 gated channels
during the process that uses this receptor, the neurotransmitter orhomone binds to a GPCR that activates thee enzyme phosphlizase C, which in turn causes the prodution of 2nd messengers IP3 and DAG...IP# eventually binds to these channels in the SR memerbame, cauisn the rerelease fo Ca 2+ ions from the SR into the sarcopalsm
latent period
during this time, the events of the EC coupling occur: the msucle AP sweeps along the sarcolemma and into the T tubules, causing the release of clacium ions form the sarcoplasmic reticulum
3p to 32 ATP
each molecule of glucose catabolized under aerobic conditions yields about how much ATP
Each molecule of glucose catabolized via anaerobic glycolysis yields two molecules of lactic acid and two molecules of ATP
each molecule of gluocse catabolized vai anaerovic glycolysis yields how many molecules of lactic acid and how many moelcules of ATP?
tropomyosin
each of these molecules wthin a given strand extends along approximately 7 G actin molecules
mechanical disadvantgae
elbow joint, the biceps muscle, and the bones of the forearm this forms what type of advantgae
initial popsition of myosin
energize myosin is in coked position, where myosin head is 90 degrees...products of ATP hydrolysis (ADP and phsphate) are still atttahc to mysoin head
hypertrophy
enlargemetn of existing cells
creatin kinase
enzyme that catalyzes the transfer of one of the high energy phosphate gorups from ATP to creatine, forming creatine phospahte and ADP (reversible reaction)
smooth mucsle
even though this type of mucle in the walls of bloood vessels and hollow organs (stomahc, intestines bladder) can stretch, the pressure on the contents within them changes very little
myofibrils
extend throughout the sarcoplasm contractile element of the skeletal msucle fiber
low
fatigue resistence for FG fibers
intermediate
fatigue resistence for FOG fibers
high
fatigue resistence for SO fibers
large
fiber diagmets of cardiac muscle
very larg
fiber diameter of skeletal msucle
small
fiber diameter of smooth msucle
sarcoplasmic reticululm
fluid filled system of membranous sacs...encircles each myofibril
inversely related
for a concentric contraciont, the load and the velocity of muscle shorteing are related in what way
yes
for action potentials in contractile single unit smoothmuscle fibers, a spike ptoetial is usually quicker than a plateua poteitnal yes/no
yes
for cardiac muslce: aree contractile protiens organizd into sarcomeres?
gap junctions
for single unit smooth muscle... the fibers connect to one another by ___ ____, forming a network through which action potentials can spread
SR
for skeletal msucle, what is the source of Ca 2+ for contraction
most of the Ca 2+ needed for contraction in smoth msucle comces form the EXTRACELLULAR LFUID
for smooth msucle, where does most the the Ca 2+ come from needed for contraction?
L-type voltage-gated Ca2+ channels,
for smooth msucles... for both spike potentials and action potentials with a plateau, the depolarizing phase is caused by the opening of these type cof channel and the repolarizing phase is caused by the closure of L-type voltage-gated Ca2+ channels and the opening of voltage-gated K+ channels
SR and extracellular
for smooth muscle, what are the source(s) of Ca 2+ for contraction
no
for smooth muscle: are contractile poretins organizedd inot sarcomeres?
concentric isotonic contractions
for this type of contraction, the load and velocity of shortening are inversely related
myosin
functions as a motor protien in all three types of muscle tissue
F actin
g actin molecules are also linked together to fomr a long polwer callledd.... this is named so becaue it is fibrous structure
thermogenesis
generation of heat when the muscle contracts
high
glycogen stores for FG fibers
intermediate
glycogen stores for FOg fibers
low
glycogen stores for SO fibers
Ca 2+ rlease channnels
has foot processes (4 of them) Each foot process comes in contact with one of the four DHP receptors in a tetrad
ontraction
he increase in sarcoplasmic Ca2+ concentration that triggers _____ of a smooth muscle fiber can be caused by the opening of one or more of the following types of channels: voltage-gated, Ca2+ release, receptor-activated, IP3-gated, store-operated, and mechanically-gated
thin filaments
he myosin heads project outward from the shaft in a spiraling fashion, each extending toward one of the six _____ ____ that surround each thick filament
aerobic respiration
he pyruvic acid formed by glycolysis in the cytosol enters mitochondria, where it undergoes a series of oxygen-requiring reactions called ____ that produce a large amount of ATP
pacemaker cells (autorhytmic fibers)
heart cells that regularly produce spontaneous electrical impulses
autorhythmicity
heart's ability to control its own contractions
asynchronous recruitment
helps avoid fatigue during sustained muscle contractions, refers to different motor units taking turns maintaining muscle tension, and makes an entire muscle seem to contract smoothly.
Because none of the myosin heads can bind to thin filaments, the muscle fiber cannot contract, and tension is zero.
hen a skeletal muscle fiber is stretched to 170% of its optimal length, there is no overlap between the thick and thin filaments. what does this mean for the mysoin heads binding to thinfilaments, contraction, and tension genratied?
isometric contraction
hilding a book steady using an outstretched arm this uses what type fo contraction
low
how high are tehe nergy demands of smooth msucle
small groups of motor units are alternatively active and inactive In a constantly shifting pattern
how is muscle tone sustained wiht regard to motor units?
30 or 32
how many molecules of ATP are produced under aerobic conditions
mutliple
how many muclei do muscle have?
Because SR is present in small amounts in smooth muscle, it provides only a small portion of the Ca2+ needed for contraction.
how much Ca 2+ does the SR provide for contractoin in SMOOTH mscule?
-90 mV
how much is th eresting membrane potential of skeletal muscle
rarely would occur when tremendous trength is necessary, like moving a car off of someone
how often does fused tetanus occur? what stiautoins?
fast glycolytic fibers
hypertrophy of what fibers results in msucle enalrgement, when comparing a weight lifter to an endureance runner
mechanical advantage
if a load is closer to the fulcrum than the effort, then onyl a relatively small effort is required to move a large load over a small distacne
fused (complete) tetanus
if a skeletal fiber is stimulated at an even higher rate that it does not relax at all....it produces a smooth sustained contaction in which individual twitches cannot eb dtected and maximum tension is reached
FG
if maximal force is required, motor units of ____ fibers are also called into action
aerobic respiration
if sufficeint oxygen is present, the pyruvic acid formed by glycolysis enters the mitochondria, wher eit udnergoes this proessential
mitochondria
if sufficent oxygen is present, pyruvic acid formed form glycolysis goes where?
mechanical disadvantgae
if the load is further form the fulcrum than the effort, then a relativel ylarge effort is required to move a small loa
SO
if weak contractions suffice to perform a task, only ____ motor units are activated (type of fiber)
troponin actin
in STRIATED muscle fibers, Ca2+ binds to ____, causing tropomyosin to move away from myosin-binding sites on actin. Once the myosin-binding sites are exposed, myosin attaches to ______, and muscle contraction begins
muscle tone
the state of balanced muscle tension that makes normal posture, coordination, and movement possible
rigor mortis
the stiffening of the body after death
neuoromuscular junction
the synapse between a somatic motor neuron and a skeletal muscle fiber
smooth muscle
the thin filaments of this type of muscle contain actin and tropomyosin, but troponin is absent
titin
the third most plentiful protein in the skeletal muscle very heavy molcule spans half a sarcomere, form Z disc to an M line
the number of muscle fibers that are contracting in unison, which is determined by the size and number of motor units that are activated.
the totla tension a WHOLe muscle can produce depends on what?
A band
the width of this thing and the individuals lengtnhs of the thick and thin filament remain UNCHANGED
dihydropyridine receptors
their main role in EC coupling is to serve as voltage sensors that trigger the opening of the Ca2+ release channels
intercalated iscs
these -- in cardiac muscles -- contain desmosomes and gap jucntions
gap junctions
these allow muscle action potentials to spread from one cardiac muscle fiber to antoehr they are part of initercallated discs
autorhymic fibers
these are also known as pacemaker cells
dihydropyridine receptors (DHP)
these are located in the T tubule membrane they are L-type voltage gated Ca 2+ channels (L for long lasting because they remain open forr long periods of time in response to activation) that are arragned in clusters of four known as tetrads
varicositties
these are potns of release of neurotransmitters in smooth msucle
Ca 2+ release channels
these are present in the terminal cisterrnal membrane of the SR...they are also knonw as ryanodine recepotrrs (ryanodine binds to them)
sarcomeres
these are reperating units of a myofibril (this is how thin and thick filaments inside a myofibril are arranged)
slow oxidative fibers
these are smallest in diamet and thys are the least powerful type of msucel fibers appear dark red because they contian large amounts of myoglobbin and many blood capillaries
fast glycolytic fibers
these are the largest fibers in diameter and contain the most myofibrils
tropomyosin and troponin
these are the two regulatory proteins that are part of theh thin filanet
intercalated discs
these are uniwue to cardiac muscle fibers...they are microscopic sturctures that are irrgular trasnver thicking of the sarcolemma that connect the ends fo cardiac muscles fibers to one another
satellite cells
these cells divide slowly and fuse with existing fibers to assist in both muscle growth and repair of damged fibers, alllowing skeletl muscle to regneerate to a limited extent
autorhymic fibers
these constitute only a small number of fibers that form the ocnduciton system of the heart
myosin heads
these contain the light chains and the remaining portions of the heavy chains
fast glycolytic fibers
these fast-twitch fibers are adapted for intense anaerobic movements of short duration, such as weight lifting or throwing a ball, but they fatigue quickly.
contractile fibers
these fiber become excited and then contract together in response to action potentials conducted to them from autorhythmic fibers via gap junctions
fast oxidative lgycolyrtic fibers
these fibers are fast ebcause ATPase in theri myosin heads hydorlyzes ATP 3 to 5 times faster than the myosin ATPase in SO fibers, which makes thier spped of contraction faster
slow oxidative fibers
these fibers are very ersistant to fatigue and are capaple of prologned, sustained contractions for many ohours
fast glycotlyrtic fibers
these fibers can generate themost powerful contractions
fast oxidative glycolytic fibers
these fibers contribute to activities such as walking and sprinting.
fast glycolytic fibers
these fibers have low myoglobin content, relativeley few blood capillaries, few mitochondria, and appear white in color
contractile fibers
these fibers have the necessary myofibrils to contract, but do not have the ability to initiate action potentials
fast glycolytic fibers
these fibers of a weightlifter may be 50% larger than those of a sedentary person or an endurance athlete
thin filaments
these filaments contain actin, torponin, and tropomyosin (cardiac muscle)
smooth msucle fiebrs
these fmuscle fibers -- suc as those in the uterus -- retain their capacity for division and thus can grow by hyperplasia
ATP binding site of myosin head
these functiosn as an ATPase (hydrolizes ATP tog enerate energy for muscle contraction)...involved in a contractile protein
smooth msucle fibers
these have thick and thin filaments, but no transverse tubules and only a small amount of sarcoplsamic reticulum
desmosomes
these hold fibers together in cardiac muscle...they are part of the intercalated discs
thick filamnets
these iflaments contain myosin (cardiac muscleP)
multi unit smooth msucle fibers
these muscle fibers lack gap junctions and contract independently smoooth mscule
skeletal muscles
these muscles maintian posture or stabilize body position contract wihtout conscious control
sphincters
these prevent the outflow of the contents of a hollow organ
myomesin
these protein molueclues form the M line
contractile proteins
these proteins generate force during contraction
regulatory proetins
these proteins hellp switchthe contraction prcess on and off
structural proteins
these proteins keep the thick and thin filaments int he proper alignments, giv eth myofibril extensibility and elasticity, and link the myofibrils to the sarcolemma and extracelluarl matrix
contratile fibers of single unit smooth mscule
these specific fiberrs of single unit smooth muscle produce action potentials when they rare depoalrized to threshold by an autoryhtmic singal or certain other sitmuli
autrorhymthic fibers
these spontaneouls ygnerate APs....they are unable to coontract, becase they contain essentially no myofibrils
anaerobic glycolysis and aerobic respiration
these two other energy generating mechanisms in a muscle fiber take more time to produce ATP
cardiac and smoooth muscle
these two types of muscle are regulated by motor neurons that are part of the autonomic nervous system and by hormones released by endocrine glands
contractile smooth msucle fibers
these tyeps of fibers are capable of producing APs these APs can either be a spike potential or an AP wiht a plateua
contractile fibers of multi unit smooth muslce
these type fibers of smooth muscle do not usualyl produce APs, but can respond to some stimlui by forming graded potentials (depolariziaotn or hyper poalrizaiotns)
smooth mucsle fibers
these type of mucsle fibers cna proliferate in certain patholgical condiitions, such as atherosclerosis
L-type voltage-gated Ca2+ channels
these types of channels are in the sarcolemma of a smooth muscle fiber...the open in reepsone to membrane depolarization, allowsing Ca 2+ too move from extracellular fluid into the sarcoplassm
IP3 gated channels
these types of channnels increase the sarcoplasmic Ca 2+ conctntraiotn by activiy a seond messenger pathway that opens these channels , whic end up releaseing 'Ca 2+ conctntra
isotonic contractions
these types of contracitions are used for body movements and for moving objecets
isometric contractions
these types of contractions do not result in body movement, but energy is still expended
more tension generated
thicker muscle fiber diameter, more myofibrils, meaning what can for tension
smooth muscle
thin filaments in this type of muslce are more abundant than in striated msucle fibers
slow wave potentiasl
think smootht muscle these are cycles of alternating depolarizaiotn and repolariziaton tha do not necessarily reach threshold
mehcanical disadvantgae
this arragnemnet favors speed and range of motion over force
mechanical advantgae
this arrangmenet sacrifices speed and range of motion for force
A band
this band is named so because it is anisotropic to polarized light (refracts it unevenly in difffernet directions)
myosin phophatase
this enzyme depohsophorylates myosin heads...it is present in the sarcoplasm of the smooth msuclee fiber
twitch
this is a brief contraction of a group of muscle fibers within a msucle in response to a single action potential
dystrophin
this is a cytoskeletal protein that linkes thin filaments of the sarcomere to integral membrnae proteins of the ssarcolemma, whic are ttached in turn to proteni in the connnective tissue extracelllular matrix that surroudn msuscle fibers
nebulin
this is a long, nonelastic protein wrapped around the entire length fo each thin filament,,,it helps anchor tht thin filaments to the z discs and egulates te length of thin filaments duering devleopment
autorhythmicity
this is a major physiological differcent between cardiac muscle and skeletal msucle: Contractions occur because action potentials within cardiac muscle itself are spontaneously generated on a periodic basis what concept does this decsribe
creatine
this is a small, amino acid like molecule that is synthesiced in the liver, kidneys, and pacreas and the transported to muscle fibers
spike potential
this is an action potential that is shaped like a psike (generlaly occurs in neurons and skeletal muscle fibers)
action
this is the type of movement that occurs whn the muscle contracts
creatine phosphate
this is three to six times more plentiful than ATP in the sarcoplasm of a relaxed muscle fiber
central fatigure
this is when a person may have feelings of tiredness and the desire to ceases acivit thsi resposne is caused by changes in the CNS
muslce tone
this keeps skeletal msucles firm, but it does nto resutl in a force beign strong enoug to produce movemnt
myosin
this molecule consists of six polypeptide chians: two large heavy cians and 4 small light chains
cardiac muscle
this muscle is only contained in the heart forms the heart wall striated
cardiac muscle
this muscle, unlike skeletal muscle, is involuntary: Its contractions are not under conscious control. Instead, the heart beats because it has a pacemaker that initiates each contraction.
aerobic respoiration
this overall process includes the Krebs cycl and the ETC
I band
this part refeact polarized light uniforomatly in all directions
relaxation period
this periood lasts about 10-100 msec....it is when Ca 2_ is activty transported back into the SR, myosin binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases
Ca 2+ induced Ca 2_ rlease
this phenomenon was present in cardiac muscle (now smooht), wher eit provides the majority of Ca 2_ needed for contractio since cardiac muscle fibers have a modertaley extensive SR witha large itracellualr reserve of Ca 2+
extensibility
this preoperty of a muscle allos muscle to contract forefully even if it is already stretched
pyruvic acid
this product formed by glycolysis in the cytosol ordinarilly enters the mitochondriam, where it undergoes a series of oxygen reuqurieing reactions called aerobic respiration to gneerate a large amount of aTP
dystrophin
this proetin and its associated proeitns ar thought to reinforce the sarcolemma and help transmit= the tension generated by the sarcomere to the tendons
hinge region
this region allows the myosin head to pivot during the contraction process
load velocity relationship
this relationship works as follows (1) when the load is
fatigure
this resutls mainly form changes within msucle fibers
glycogen
this serves as a storgaae form of glucose the number of skeletal muscle fibers is set before you are born, and most of these cells will last you a lifetime.
functional synctium
this term descries the idea of how cardiac muscle fibers are electrically coupled by gap junctions, when an action potential is generated in a mass of cardiac muscle fibers, it quickly spreads to all of the muscle fibers in that mass and then the muscle fibers contract together.
smooth muscle fiber
this tyope of msucle fiber can contract in response to an AP, and can also contract in response to a subthreshold depolarizaiotn that never gives rise to an action poteintal; and it cna even contract when there is no change in membrnae potential at all
cardiac muscle
this type of msucle does not require any external sitmulation to contract
smooth muscle
this type of muscle has no striations
skeletal muscle
this type of muscle is attached to bones and moves parts of the skeletal it is striated
smooth muscle
this type of muscle is located int he walls of hollow internal organs, such as blood vessels, the airways, stomacch, intesteines, and uterus
smooth muscle
this type of muscle is mainly found in the walls of hollow organs and tubes, where it contracts to move substances through the interior spaces of these structures
cardiac muscle
this type of muscle is onyl found in the heart, where it fomrs the bulk of the heart wall
smooth muscle
this type of muscle is spindle-shaped (thickest in the middle and tapered at each end) and has a single, centrally located nucleus
skeletal muscle
this type of muscle works mainly in a voluntary manner: its activity can be consciously controlled by motor neurons that are part of the somatic nerucos system
cardiac muscle fibers
this type of muscles is has individual fibers that are branched and usually have only one centrally located nucleus
somatic neuron
this type of neuron is resonsible for skeletal muscle contraction
plateau potential
this type of potential /action potential is similar to the AP that occurs in contractile cardiac muscle fibers...
multi unit smooth msucle
this type of smooth msucle consist of fibers that act independently of each other as multiple units
multi unit smooth muscle
this type of smooth muscle is found inthe airways to the lungs, the iris and cilliary body of the eye, the arrector pili muscles of the skin, and some blood vessels
transver (T) tubules
tiny invaginations of the sarcolemma... thousands of these tunnel in form the surfcae toward the center of each muscle fiber
troponin
tropomysoin strands are held in place by these molecules
tropomysoin
troponin, after gettting with calcium, moves ____ away orm the myosin binidingn sites on actin
T tubules
tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side
fast oxidative glycolytic fibers
twitches of these fibers reach peak tension more quickly than those of SO fibers but are briefer in duration—less than 100 msec.
lactic acid
under anaerobic conditions, the pyruvic acid generated form glycolysis is converted to this
contractile fibers of smooth muscle
unlike autorhymic fibers of smooth muscle, these fibers have a stable resting membrane poteintal of about -50mV
smooth msucle fibers
unlike stratied muscle fibers, this type of muscle fibers can strethc considerably and still maintain their contractile funcion
intermediate filaments
uring contraction, the sliding filament mechanism involving thick and thin filaments generates tension that is transmitted to ______ ______. These in turn pull on the dense bodies attached to the sarcolemma, causing a lengthwise shortening of the muscle fiber
dense bodies
uring contraction, the sliding filament mechanism involving thick and thin filaments generates tension that is transmitted to intermediate filaments. These in turn pull on the ____ _____ attached to the sarcolemma, causing a lengthwise shortening of the muscle fiber
oxygen
uring heavy exercise, however, not enough ____ is available to skeletal muscle fibers
producing body movments
walking, runninng, grasping pencils, nodding head, rely on skeletal muscles, bons, and joints this descirbes what fucntion of the msucles
muscular atrophy
wasting away of msucles...muscle fibers decrease in size because fo progressive loss of myofirils
(1) producing body movements (2) stabilizing body positions (3) stroing and moving substances within the body (4) generating heat
what are the 4 main functions of mucsle
titin, alpha actinin, myomesin, nebulin, and dystrophin
what are the 5 main structural proteins
(1) voltage gated channels (2)CA 2+ relase channels (3) receptor activated channels (4) IP3 gated channels (5)store operatied channels (6) mechanically gated channels
what are the 6 channels that can cause the icnrease of sarcoplasmic CA 2+ in smooth muscle that causes contation
(1) electrical exciteability (2) contractility (3) extensibility (4) elasticity
what are the four proeprties of muscles
(1) no T tubules , so it takes longer for Ca 2+ to reach the filaments int eh center of the fiber and trigger the contraction process (2) MLCK is sloq (3) ATPase activity of myosine heads in smooth msucle is slower than stratied msucle (4) myosin heads in smooth mscle can enter a latch state, in which they staty attahced to actin for longer portion of the crossbridge cycle compared to myosin heads int he stratited muscle
what are the four reasons why smooth muscle generally has a slow start and longer duraction of contraction
(1) ATP hydrolysis (2) attachment of myosin to actin (3) power stroke (4) detachment of myosin form actin
what are the four steps to the contraction cycle
(1) the synaptic end bulbs of a terminal branch of the somatic motor neuron (2) a synaptic cleft (3) the motor end plate, teh region of muscle fiber membrane opposite the synaptic end bulbs
what are the three components of an NMJ
(1) slow oxidative fibers (2) fast oxidative-glycolytic fibers (3) fast glycolytic fibers
what are the three main types of skeletal muscle fibers
(1) latent period (2) contraction periodi (3) relaxation period
what are the three sequentail phases of a muscle twitch
skeletal, cardiac and smooth
what are the three tyeps of muscle
(1) contractile protenins (2) regulatory protins (3) sturcuteral proteins
what are the three types of protiens that make myofibrils
1. an actin binding site 2. atp binding site
what are the two binding sites of myosoin head
myosin and actin
what are the two contactile proteins in muscle
(1) chemical stimuli such as neurotransmitters, hormones (2) autorhythmic electrical signals arising in the muscle tissue itself (as in the hearts pacemaker)
what are the two main types of stimuli that trigger AP in muscle cells?
deplarizing phase and repolarizng phase
what are the two phases that a skeletal muscle AP consists of
(1) oxygen that diffuses into muscle fibers form the blood (2) oxygen released by myoglobin withn muscle fibers
what are the two sources of oxygen for msucle tissue
concentric and eccentric
what are the two tpes of isotonic contractions
spike or plateua
what are the two types of APs that a contractile smooht muscule fiber can prodcue
(1) CA 2+ ATPase pumps in the SR membrane actively transport a 2+ form teh sarcoplasm into the SR (2) Na+ Ca 2+ exchagners in the sarcolemma activtely trannsport Ca 2+ out of the celll in exchange for Na+ movmeent inot the cell
what are the two ways that Ca 2+ concentiaration in a cardiac msucle fiber is brought back to normal/resting levels
(1) from creatine phosphate (2) anaerobic glycolysis (3) aerobic respiration
what are thre three ways
prolonged opening of L-type voltage-gated Ca2+ channels, along with the partial opening of voltage-gated K+ channels
what cuases the plateua phase in a plataue potential regarding the channels invovled
it alters the rate and sterngth of cardiac mucsle contractions
what does the autonomonic nervous system do to the heart ? I.e. what are the two ways that the ANS affects the heart
Ca 2+
what ever the facor is, the ultimate affct sit must have to affect smooth msulce acivitt is to modify the concentratoin of ___ in the sarcoplasm of the smooth msucle fiber
the gene that codes for the proteion dystropihin is mutated, so little to no dystrophin is produce
what exactly is the problem in ducheene muscular dystrophy
cardiac muscle itself....occur because APs within cardiacl muscle itself are spontaneously generated on a periodic bases
what generates contractions in cardiac muscle
Considerable, via pericytes (compared with other muscle tissues, but limited compared with epithelium
what is capcity for regeneratio for smooth muscle
limited, via stellite cells
what is teh capccity for regeneration of skeletal mucsle
limtied, under certain conditions
what is the apacity for regeneration of cardiac muscule
creatine phosphate
what is the first source of energy when muslce contraction beigns
hypertrophy
what is the main way that skeletal muscle grow
all of the cells in multi unit smooth msucle are contractile fibers that act as independednt units
what is the makeu pof multi unit smooth msucle : how much of contractile fibers, and how much of autorhymic fibers
2 molecules of ATP
what is the net gain of energy from glycolysis?
aerobic respiration
what is the principle method of ATP rpoduction ni smooht muscle finbers
myosin molecules in smooth muscle can bind to actin only after phosphate groups are added to light chains in the myosin head
what needs to happenn for myosin molecules in smooth muscles to bind to actin ?
contraction period
what period of muscle twtich does peak tension occur
eccentric
what produces more msucle damgae: eccentric or concentric contracionts
cardiac msucle
what type of muscle contractss teh second fastest
aerobic repsiration
what type of respiration do cardicc fibers rely almost exclusively on to generate the ATP they need for muscle contraction?
(1) decreasing the Ca 2+ caoncentration in the sarcoplasm to resting levels (2) dephosphorylating light chains in the myosin heads
whata re the two ways to get relaxation of msooth muscle
The entering Ca2+ functions as trigger Ca2+ that binds to and opens the Ca2+ release channels in the SR membrane. As a result, additional Ca2+ enters the sarcoplasm from the SR
when L type volrage gaed Ca 2+ channels are opened in the T tublues, what happens with regard to calcium and what is activated?
tension
when a muscle contracts, it generates this while pulling on its attachment points
refractory period
when a muscle fiber recieves enough sitmulation to contract, it temporarily loses its excitability and cannot respond for a time.... this period of lost excitability is called... this is a characteristc of all msucle and nerve cells
sarcolemma
when a region of _____ adjacent to the motor end plate is depolarized to threshold by an EPP, an AP is generated in the skeletal muscle fible
action potential
when a region of sarcolemma adjacent to the motor end plate is depolarized to threshold by an end plate potential, an _____ _____ is generated in the skeletal muscle fiber.
ATP
when contraction begins and the ADP level starts to rise, CK catalyzes the transfer of a high-energy phosphate group from creatine phosphate back to ADP. This direct phosphorylation reaction quickly regenerates new ____ molecules
creatine kinase
when contraction begins and the ADP level starts to rise, ____ catalyzes the transfer of a high-energy phosphate group from creatine phosphate back to ADP. This direct phosphorylation reaction quickly regenerates new ATP molecules
Ca 2+ coencentraiotn in the sarcoplasm decreases to resting levels
when does contraction of cardiac muscle fibers cease? (think Ca 2+ concentration)
store operated channels
when intracellualr reserves of Ca 2+ in the SR are dpeleted, a signal is relayed form the SR to the sarcolemma, where it causes these channels to open (smooth msucle)
acidity
when liver cells convert lactic acid back to glucose, .... in addition to providing new glucose molecules, this conversion reduces the _____ of the blood.
bone
when one skeletal muscle ocntracts, it pulls one ___ toward hte other
stress relaxation response
when smooth mscule fibers are stretched, they initially contact, developing increase tension.. withina minute, the tesnion decreases this phenomenon allos smooth msucle to undergo great changes in legnth while reatingin the ability to contract effectively
contract tension
when smooth muscle fibers are stretched, they initially ____, developing increased ____
eccentric isotonic contraction
when the length of a muscle increases during a contraction
mechanical advantage
when the load is clsoer to the fulcrum than the effort
flaccid
when the motor neurons serving a skeletal muscle are dmaaged or cut, the muscle becomes this, which is a state of limpness in twhich msucle tone is lost
fused (complete) tetanus
when the muscle is stimulated so rapidly that no evidence of relaxation is seen and the contractions are completely smooth and sustained
the tenseion the fiber can produce decreases
when the zone of overlap shortens, which causess fewer myosin heads able to make contact with thin filaments , what happens with tension?
triads of skeletal muscle fiber
where does excitation contraction coupling occur at?
cytosol
where does glycolysis occur?
anaerobiv
which produces less ATP: aerobic or anaerobic glycolysis
skeletal
which type of muscle contracts the fastsest
multi unit smooth mscucle
which type of smooth muscle has a richer supplly of ANS nerve endings: single unit smooth msucle or multi unit smooth msucle
aerobic
which yield more ATP: aerobic or anaarobic
asynchronous recruitment
while some motor units are contracting, others are releaxed this pattern ofmotor activity delays msucle fatigue and allows contraction of a whole muscle to be sustained for lnoger periods of time
FOG fibers are fast because the ATPase in their myosin heads hydrolyzes ATP three to five times faster than the myosin ATPase in SO fibers, which makes their speed of contraction faster.
why are FOG fibers considered fast?
because the ATPase in the myosin heads hydrolyzes ATP relatively slowly and the contraction cycle proceeds at a slower pace than in "fast" fibers
why are slow oxidative fibers said to be "slow"
In all three cases, contraction occurs because the Ca2+ concentration in the sarcoplasm increases. The increase in sarcoplasmic Ca2+ concentration that triggers contraction of a smooth muscle fiber can be caused by the opening of one or more of the following types of channels
why are smooth muscle fibers able to contract in respeonse to an AP, a subthreshold stimuls, or no change in membrane poteinal?
unstable resting membrane potenials
why can autorhythmic fibers of a signle unit smooth muscle able to intiate thier own APs?
sarcoplasm
wihtin this are mitchodria, whic produce large amoutns of ATP
antagonistic muscles
with a given pair of _____ muscles, when one muscle contracts, the other muscle relaxes
filaments
within myfibrils are these smaller structures they can have either a thin or thick diameter
acetylcholine
without ____, end plate potentails are not generated, and the proudciton of muscle APs ends
zone of overlap
zone where the thick and thin filaments overlap... each thick ilament is surroudned by a hexagonal arrrangment of six thin fibers, and each thin filament is surrounded by a triangular arrangement of three thick filaments
regulatory proteins
preotins that help switcht he muscle contraction process on and off
Ca 2+ rleease channels
present in the terminal cisternal memrbane fo the SR each one f these has four projections callled foot processes or junctional feet
rapid, intense movemnets of short duraiton
priamry function of FG fibers
wlaking, sprinting
priamry functions of FOG fibers
maintian posture and aerobic endurance activities
prmary function of SO fibers
electrical excitability
property of both neurons and muscle cells that is the abililty ot respond to certain stimuli by producing action potentials
myoglobin
prsent in the sarcoplasm these are a red colord, oxygen binding protein that is found only in mucsle...stores oxygen until it is needed by mitochondria to generate ATP
fast
rate of ATP hydorlysis by myosin ATPase for FG fibers
slow
rate of ATP hydrolusis by myosinATPase for SO fibers
fasst
rate of ATP hydrolysis by myosin ATPase for FOG fibers
myogram
record(s) of muscle contractions
smooth mucsle movments
recruitment is one factor repsonsible for producing what type of muscle movments rather than a series of jerks
not possible
recruitment of a larger number of muscle fibers to produce graded contractions is (possible/not possible) in single-unit smooth muscle as it is in skeletal muscle because all of the existing fibers in the syncytium contract at the same time
skeletal
recruitment of a larger number of muscle fibers to produce graded contractions is not possible in single-unit smooth muscle as it is in ____ muscle because all of the existing fibers in the syncytium contract at the same time
muscular dystrophy
refers to a group of inherited muscle-destroying diseases that cause progressive degeneration of skeletal muscle fibers
oxygen debt
refers to the added oxygen, over and above the resting xoygen consumption, that is taken iotn the body after exercise
slowly
Compared to striated muscle, relaxation of smooth muscle occurs more ______, mainly because removal of Ca2+ from the sarcoplasm is slower in smooth muscle fibers than in striated muscle fibers
myoglobin hemoglobin
Both _____ (found only in muscle cells) and ____ (found only in erythrocytes) are oxygen-binding proteins. They bind oxygen when it is plentiful and release oxygen when it is scarce
graded
Cardiac muscle fibers can produce ____ contractions (contractions that vary in strength) by increasing the amount of Ca2+ that enters the sarcoplasm, which in turn increases myosin crossbridge formation.
fast glycolytic fibers
Due to their large size and their ability to hydrolyze ATP rapidly, FG fibers contract strongly and quickly. these are what fibers?
Z discs
During a maximal muscle contraction, the distance between two ____ ___ can decrease to half the resting length.
different
Most smooth, sustained voluntary muscle contractions in the body are achieved by out-of-synchrony unfused tetanus in (same/differnet) motor units
myosin
Muscle contraction occurs because ____ heads attach to and "walk" along the thin filaments at both ends of a sarcomere, progressively pulling the thin filaments toward the M line
more
Muscle fibers that have a thicker diameter have more myofibrils and can generate (more/less) tension compared to muscle fibers that have a thinner diameter.
FG
Muscles of the shoulders and arms, in contrast, are not constantly active but are used briefly now and then to produce large amounts of tension, such as in lifting and throwing. These muscles have a high proportion of ___ fibers
small
Muscles that control precise movements, which involve only small amounts of force, contain (big/small) motor units.
stabilizing body positions
Skeletal muscle contractions stabilize joints and help maintain body positions, such as standing or sitting. Postural muscles contract continuously when you are awake; for example, sustained contractions of your neck muscles hold your head upright this describes what function of muscles
skeletal
So, in cardiac muscle, the Ca2+ required for contraction is derived from two sources: the SR and extracellular fluid. This is contrast to ____ muscle, in which all of the requisite Ca2+ comes from the SR.
SR
So, in cardiac muscle, the Ca2+ required for contraction is derived from two sources: the SR and extracellular fluid. This is contrast to skeletal muscle, in which all of the requisite Ca2+ comes from the ___.
SR and extracellular fluid (SR is 90%)
So, in cardiac muscle, the Ca2+ required for contraction is derived from two sources: what are they?
eyes
Some fibers, such as the fast-twitch fibers that move the ____ (described shortly), have contraction periods as brief as 10 msec and equally brief relaxation periods.
unfused (incomplete) tetanus
Some relaxation occurs between contractions. The results are summed
fast glycolytic fibers
Strength training programs that engage a person in activities requiring great strength for short times increase the size, strength, and glycogen content of these fibers
I band
The lighter, less dense area of the sarcomere that contains the rest of the thin filaments but no thick filaments. A Z disc passes through the center of each I band.
striated
cardiac musclce: strated or not
gap junctions
cardiac muscle fibers are electrically coupled by ___ ______, when an action potential is generated in a mass of cardiac muscle fibers, it quickly spreads to all of the muscle fibers in that mass and then the muscle fibers contract together.
hypertrophY
cardiac muscle fibers can undergo this form of growth in response to icreaed workload, and its why many athletes have enlarged heearts
involuntary (ANS)
cardiac muscle nervous contro (voll or invol)
moderate
cardiac muscle speed of contrcation
(1) autorhytmic fibers (2) contractile fibers
cariac musle consists of two types of cells....
white(pale)
color of FG fibers
red pink
color of FOG fibers
red
color of SO fibers
slower
compared to striated muscle, relaxation of smooth muscle occurs more slowly, mainly because removal of Ca2+ from the sarcoplasm is _____ in smooth muscle fibers than in striated muscle fibers
myosin tail
composed of portions of hte heavy chians that wrap aorund each otoher to form a double stranded helix
conduciton system (of the heart)
consists fo the sinoatrial (SA) node, atrioventricular (AV) node, atrioventricular (AV) bundle or bundle of His, the right and left bundle branches, and the Purkinje fibers.
cross bridge
myosin head attached to actin during contraction cycle
ATPase
myosin head includes an ATP binding site that funcitons as a.n...
energized
myosin head is said to be _____ after energy form ATP hydrolysis occuts
power stroke
mysin crossbridge pivots, moving the thin filament past the thick filament towards the middle of the sarcomere, generating tension in the process
H zone
narrow zone in the ecnter of each A band contained thick filaments but no thin filaments
z discs
narrow, plate shaped regions of dense protein material thse things separate one sarcomere fomr the next
clsoing of L-type voltage-gated Ca2+ channels voltage-gated K+ channels
or both spike potentials and action potentials with a plateau, the depolarizing phase is caused by the opening of L-type voltage-gated Ca2+ channels, and the repolarizing phase is caused by the closure of_________ and the opening of _______
inversely
or concentric isotonic contractions, the load and velocity of shortening are ______ related
antagonistic muscles
or example, during flexion of the forearm, the biceps contracts and the triceps relaxes (Figure 11.19a). However, during extension of the forearm, the triceps contracts and the biceps relaxes (Figure 11.19b). If both muscles of an antagonistic pair contracted at the same time with equal force, there would be no net movement the biceps and triceps are considered ____ muscles
SO
or example, the continually active postural muscles of the neck, back, and legs have a high proportion of ___ fibers
first
order of recruitment for SO fibers
third
order of recrutiment for Fg fibers
refractory period
period of time after an action potential begins when an excitable cell temporarily loses its excitability (occurs in cardiac muscle, neurons, and skeltela muscle up to this piont})
concentric isotonic contraction
picking pu a book off a table invovles this type of contraction in the biceps