outcome 6 muscles Flashcards by ruben abimanan

a child ingested an organophosphate poison used to kill insects. soon the child’s muscles began spastic contractions. predict what occurred at the synaptic cleft.
a. decreased release of acetylcholine from presynaptic neuron
b.increased accumulation of acetylcholine in the synapse
c.increased breakdwn of acetylcholine in the synaptic cleft
d. binding of the poison o acetylscholine receptors leading to inhibition of stimulation
e. both inccreaed accumulation of acetylcholine in the synapse and increased breakdown of acetylcholine in the synaptic cleft are correct

increased accumulation of acetylcholine in the synapse

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what is a fasicle

a fasicle is surrounded by permysium

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a lack of glycotyic enzymes within skeletal muscle fibers would impair which type of atp yielding process

anaerobic and aerobic respiration

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a lack of mitochondira within skeletal muscle fibers would impair which atp yielding chemical process

aerobic respiration

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a muscle fiber will respond to stimulus when that stimulus reaaches the ____ level

a. relaxation
b.threshold
c.recruitment
d.rigor morrtis
e.resting

threshold

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a myofibril is the

a. protein strand composed of actin
b.plasma membrane of a muscle fiber
c.structural and fuctional unit of the skeletal muscle fiber
d. contractile thread that extends the length of the muscle fiber
e.cytoplasm of a muscle fiber

d. contractile thread that extends the length of the muscle fiber

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a myofilament is the
a. cytoplasm of the muscle fiber
b.protein strand composed of actin or myosin
c.plasma membrane of a muscle fiber
d. contractile thread that extends the length of the muscle fiber
e. structural and functional unit of the skeletal muscle fiber

b. protein strand composed of actin or myosin

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a prper definition of muscle tone is
a. a feeling of wellbeing following exercise
b.muscles contracting together
c.constant tension produces by muscles for long periods of tiems
d.warm up of muscle tissue
e.the ability of a muscle to maintain a contraction against an outside froce

c. constant tension produced by muscles for long periods of time

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a sarcomere extends from
a.the middle of the I band to the middle of the A band
b. one z disk to an adjacent z disk
c. one t tubule to the next t tubule
d. the h zone to the i band
e. the m line to the next m line

b. one z disk to an adjacent z disk

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a sarcomere is the
a. plasma membrane of a muscle fiber
b. protein strand composed of actin or myosin
c.structural and fucntional unit of the skeletal muscle fiber
d.contractile thread that extends the length of the muscle fiber
e.cytoplasm of a muscle fiber

c. structural and functional unit of the skeletal muscle fiber

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a skeletal muscle generates the greatest tesnsion when it is
a. well rested and low in creatine phosphate
b.high in lactate concentration
c.fully realxd before being stimulated
d. greatly stretched before being stimulated
e. partially stretched before being stimulated

e. partially stretched before being stimulated

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a sustained muscle contraction is known as ___
a. tetanus
b.treppe
c.tone
d.paralysis
e. twitch

a. tetanus

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a volleyball plater depends on the gastrocnemius muscles for plantar flexion whereas a marathon runner depends more on the soleus muscles for the same action. what characterstic of the soleus muscles makes this so
a. the break atp down to adp and p faster
b. they make more use of aerobic respiration
c.they have more glycogen in them
d. they don’t have as many blood capjilaries per gram of tissue
e. they have smaller mitochondria

b. they make more use of aerobic respiration

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acetylcholine binds to a membrane bound receptor and causes ligand gated sodium channels to open and result ins
a. hyperpolarization
b.there is not enough information to predict the outcome
c.hypopolarization
d.depolarization
e.no change in membrane potential

d. depolarization

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acetylcholine is released from the presynaptic terminal by the process of
a. phagocytosis
b. active transport
c. diffusion
d.endocytosis
e.exocytosis

e. exocytosis

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actin myofilaments
a. are the thickest proteins in muscles
b. contain both myosin and tropomyosin
c. resemble bundles of minute golf clubs
d.contain strands of fibrous actin
e. are heald in place by the m line

b. contain both myosin and tropomyosin

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aerobic exercise
a. can increase the number of itochondria in muscle fibers
b. can increase the efficiency of slow twitch fibers
c. develops fatigue resistance fast twitch fibers
d. all of these choices are correct
e. increase vascularity of muscle

d. all of these choices are correct

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aerobic respiration
a. occurs whether oxygen is present or not
b.yields as many as 36 atp per glucose molecule metabolized
c.produces atp molecule faster than anaerobic respiration
d.occus in the ribosomes
e.occurs entirely in the cytoplasm

b. yields as many as 36 atp per glucose molecule metabolized

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after contraction has occured the ca are
a. chemically bound to the cross bridges
b.returned to the sarcolemma
c.released from troponin
d. destroyedd by cholinesterase
e. secreted by the golgi apparatus to the outside of the cell

c. released from troponin

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an action potential
a. can be of varyin strengths depending on strength of the stimulus
b.occurs when the local potential reaches threshold level
c.is an example of negative feedback
d. has no repolarization phase
e. is not propogated

b. occurs when the local potential reaches threshold level

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an eccentric contraction is described as
a.action potential frequency is highg enough that no relaxation of muscle fibers occurs
b. a muscle produces an increasing tension during contraction
c.a muscle produces increasing tension as it shortens
d. a muscle produces constant tension during contraction
e. a muscle produces tension but the length of the muscle is increasing

e. a muscle produces tension but the length of the muscle is increasing

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an isometric contraction is described as
a. a muscle produces tension but the length of the muscles is increasing
b. a muscle produces contesetan tension during contraction
c. a muscles produces increasing tension as it shortens
d.action potential frequency i high enough taht no relaxation of muscle fibers occurs
e.a muscle produces an increasing tension as the length remains constant

e. a muscles produces increasing tension as the length remains constant

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an isotonic contraction is described as
a. a muscle produces increasing tension as it shortens
b. a muscle produces tension but the length of the muscles is increasing
c.a muscles produces constant tension during contraction
d. a muscles produces an increasing tension during contractions
e. action potential frequency is high enough that no relaxation of muscle fibers

c. a muscle produces constant tension during contraction

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callie is a world class marathon runner. which of the descriptions about her dominant type of skeletal is false
a. they are well adapted to anaerobic activity
b. they have low glycogen stores
c. they have large deposits of myoglobin
d. they have a well developed blood supply
e. they split atp slowly

a. they are well adapted to anaerobic activity

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channels that open or close in response to changes in the elctrical charge or voltage across the plasma membrane are called a. voltage gated ion channels b.relegated ion channels c.obligated ion channels d. ligand gated ion channels e. leak ion channels

a. voltage gated ion channels

concentric contraction occur when a. the muscle produces increasing tension as it shortens b. tension in a muscle is maintained while the muscle increases in length c. the muscle produces tension while the length of the muscle increases d. the tension and length of the muscle remain constant during a contraction e. isometric contraction occur

a. the muscle produces increasing tension as it shortens

consider a chemical that blocks the action of acetylcholinesterase what effect does this have on muscles a. the axons of the motor neurons would atrophy and the muscle would weaken b. the muscle would have no way to relax and spastic contractions would result c. it would cause action potentials to be inhibited thereby rendering the muscles useless d. t would cause paralysis e. the body would increase its production of acetylcholine to compensate

b. the muscle would have no way to relax and spastic contractions would result

depolarization of the plasma membrane occurs when here is a rapid influx (inflow) of a. calcium ions b. amino acids c. sodium ions d. chloride ions e. potassium ions

c. sodium ions

disease that affect the ability of skeletal muscle to contract are considered life threatening because a. respiratory movements depend on skeletal muscle contractions b. all of the choices are correct c. the movement of blood through the blood vessels of the body depends solely on skeletal muscles contractions ed. movement of food through the digestive tract depends on skeletal muscle contractions

a. respiratory movements depend on skeletal muscles contractions

drugs called calcium channel blockers may be used to lower blood pressure by causing arteries to vasodilate. how do you suppose these drugs works a. they prevent calcium from exiting the sarcoplasmic reticulum in skeletal muscle. b. they prevent calcium from entering cardia muscle thus slowing down the heart rate c. they prevent calcium from entering the sarcoplasmic reticulum of smooth muscle d. they prevent calcium from entering smooth muscle thus allowing the muscle to relax e. they stimulate the calcium pump in smooth muscle, thus removing calcium from the calmodulin

d. they prevent calcium from entering the smooth muscles thus allowing the muscle to relax

due to the patter of innervation of skeletal muscle one would expect that a. there are fewer muscle fibers that motor neuron b. the number of muscle fibers and motor neurons is equal c. there are fewer motor neurons than skeletal muscle fibers

a. there are fewer muscle fibers than motor neurons

during muscle fiber contraction which of the following decrease in size {check all that apply} a. entire sarcomere b. a-band c. I-band d. h-zone

a. entire sarcomere d. h-zone c. I-band

during resting conditions ______ is synthesized to store energy a. lactate b. ca 2+ c. creatine phosphate d. creatinine e. pyruvate

c. creatine phosphate

during the contraction phase of a muscle twitch a. acetylcholine stimulates he pre-synaptic terminal b. actin-myosin cross-bridges form c. the action potential travels down the t-tubule d. ca2+ are transported back to the sarcoplasmic reticulum e. Na+ diffuse into the muscle fiber

b. actin myosin cross-bridges form

each ____ includes a z disc and extends from each side of the z disc to the ends of the myosin filaments a. anisotropic band or A-band b. isotropic band or I-band c. sarcomere d. muscle fiber

b. isotropic band or I-band

endomysium is a delicate network of loose connective tissue that a. penetrates muscle fibers b. separates individual muscles c. surrounds each muscle fiber. d. is composed of elastic fibers e. forms a sheath around a fascicle

c. surrounds each muscle fiber

epimysium a. is a type of nerve tissue b. is a type of muscle tissue c. separates muscle fibers d. surrounds individual muscles e. connects muscles to bone

d. surrounds individual muscles

excitation-contraction coupling begins with a. the release of the cross bridge b. the production of an action potential in the sarcolemma c. the release of Ca2+ from the sarcoplasmic reticulum d. the depolarization at the T-tubules

b. the production of an action potential in the sarcolemma

hypertrophy of skeletal muscles from weight lifting is cause by an increase in the a. number of nuclei within muscle fibers b. number striations c. size of muscle fibers d. number of muscle fibers e. number of muscle cells

c. size of muscle fibers

identify the statement concerning general functional characteristics of muscle that is true a. none of the statements are true b. muscle tissue shortens passively but lengthens forcefully c. muscle tissue can get longer but cannot get shorter d. muscle tissue can get shortens but cannot get longer e. muscle tissue shortens forcefully but lengthens passively

e. muscle tissue shortens forcefully but lengthens passively

if all the ca2+ within a muscle fiber was removed which of teh following could still occur a. the troponin molecules boud to g actin molecules would be released causing tropomysoin to move b. the headas of the mysoin myofilaments would bind to g actin to form cross bridges c. an action potential that was produces at the neuro-muscular junction would be propagated along the sarcolemma c. the heads of the myosin molecules would return to their resting position and the recovery stroke would occur

d. the heads of the myosin molecules would returns to their resting position and the recovery stroke would occur

if na+ cannot enter a muscle fiber in response to a stimulus a. na+ will be released from the sarcoplasmic reticulum instead b. contraction cannot occur c. the active sites are left exposed d. relaxation cannot occur e. the action potential travels into the muscle anyway

b. contraction cannot occur

in a laboratory expermient the resting membrane potential of a muscle is measured and is found to be more negative. which of the following has occurred a. hyperpolarization b. depolarization c. repolarization d. Iso-polarization e. hypo-polarization

e. hypopolarization

in excitation-contraction coupling a. ca2_ must bind with yosin to expose actiev sites on actin b. mysoin heads bind to exposed actiev sites on actin c. movement of the troponing-tropomyosin complex causes actin myofilaments to slide d. cross-bridges form between mysoin heads and ca2+ e. atp bind to actin myofilaments

b. myosin heads bind to exposed active sites on actin

in order for excitation-contraction coupling to occur, the production of an action potential must occur within the ____ of a muscle fiber

a. sarcolemma

in order for muscle relaxation to occur a. na+ must be actively transported to troponin b. power strokes slow down c. the active sistes on myosin myust be uncovered d. the active sites on actin must be blocked e. ca2+ must be transported to troponin

c. the active sites on myosin must be uncovered

in smooth muscle cross bridging occurs due to a. both ca2+ binding to calmodulin and myosin kinase adding a phosphate to myosin heads b. ca2+ binding to troponin c. both ca2+ binding to troponin and calmodulin d. myosin kinase adding a phosphate to myosin heads e. ca2+ binding to calmodulin

a. both ca2+ binding to calmodulin and myosin kinase adding a phosphate to myosin heads

lack of acetylcholinesterase in the synaptic cleft would result in a. continuous stimulation of the presynaptic membrane b. a decrease in acetylcholine production by the motor neuron c. relaxation of the muscle d. rapid degradation of acetylcholine e. continuous stimulation of the postsynaptic membrane

a. continuous stimulation of the presynaptic membrane

one atp molecule is required for a. release of the cross bridge b. formation of the cross bridge c. formation of the cross bridge and for movement of the cross bridge d. formation of the cross bridge for movement of the cross bridge and for release of the cross bridge e. movement of the cross bridge

d. formation of the crossbridge for movement of the cross bridge adn for release of the cross bridge

physiological contracture a. is condition in which cross bridges cannot release b. occurs when muscles are resting c. results when the neurotransmitter remains in the receptor d. results when muscles are well exercised e. is caused by an abundance of atp in muscle fibers

a. is a condition in which cross bridges cannot release

susan slipped on the ice and was unable to be fully mobile for several days. what disruption to homeostasis would you predict she experienced during her immobile period in terms of her muscular system a. susans uninured muscles overcompensate for the inactive ones by contracting spontaneously b. susan was more col than usual because her inactivity prevented her muscles from helping to regulate her body temperature c. susans metabolic rate was rasied and it initiated sweating

b. susan was more cold than usual because her inactivity prevented her muscles from helping to regulate her body temperature

synaptic vesicles in the neuromscular junction contain a. atp b. acetylcholinesterase c. acetylcholine d. sodium e.calcium

c. acetylcholine

t-tubules a. generate new muscle fibers b. conduct action potentials deep into the muscle fiber c. store calcium ions d. provide nutrients to the muscle fiber e. release acetylcholine

b. conduct action potentials deep into the muscle fiber

t-tubulues are invaginations of the a. myofibril b. sarcoplasmic reticulum c. sarcomere d. sarcolemma e. sarco plasm

d. sarcolemma

the active sites to which crossbridges attach are found on the a. myosin myofilaments b. actin myofilaments c. z-disks d. t-tubules e. sarcoplasmic reticulum

b. actin myofilaments

the capacity ofa muscle to shorten forcefully is known as a. elasticity b. exciteablity c. flexibility d. contractility e.extensibility

d. contractility

the elctical poroperties of cells are the result of a. none of these choices are correct b. receptor sites that are present on the plasma membranes c. phosphorylation reactions within the cytoplasm d. ion concentration differences across the plasma membrane e. phospholipids in the plasma membrane

d. ion concentration differences across the plasma membrane

the h-zone a. contains both myosin and actin myofilaments b. contains only actin myofilaments c. contains only myosin myofilaments

c. contains only myosin myofilaments

the length of the resting sarcomere is a. the same length as the muscle fibers b. the same length as the myofibrils c. the same length as a contracted sarcomere d. shorter than the length of a contracted sarcomere e. longer than the length of a contracted sarcomere

e. longer than the length of a contracted sarcomere

the model that describes the contraction of the muscle is called the a. paddle model b. slipping fibril mechanism c. power stroke d. contraction cycle e. sliding filament model

e. sliding filament model

the outside of the resting plasma membrane is ___ relative to the inside of the resting plasma membrane a. electrically neutral b. positively charged c. negatively charged d. recharged e. none of these choices are correct

b. positively charges

the plasma membrane of an excitable cell is more permeable to k+ because a. there are more gated channels for k+ b. protein molecules cannot exit trhough the plasma membrane c. of it's positive electrical charge d. there are more leak ionchannels for k+ than na+ e. clacium ions block na+ and cl- channels

d. there are more leakd ion channels for k+ than na+

the region of the sarcomere that contains bot hactin and myosin myofilaments is called the a. m-line b. h-zone c. z-disk d. a-band e. I-band

d. a-band

the sarcolemma si the a. structural and functional unit of the skeeltal muscle fiber b. plasma membrane of a muscle fiber c. cytoplasm of a muscle fiber d. protein strand composed of actin \ e. contractile thread that extends the length of the muscle fiber

b. plasma membrane of a muscle fiber

the sarcoplasmic reticulum a. covers the muscle fiber b. stores ca2+ c. transmits nerve impulses to the myofibrils d. connects adjacent sarcomeres e. shortens during muscle contractions

b. stores ca2+

the sites where a chemical substance is transmittted from the presynaptic terminal of an axon to the postynsaptic membrane of a muscle fiber are called a. cell bodies ofneurons b. neuromuscular junctions c. sarcomeres d. z-disks e. myofilaments

b. neuromuscular junctions

too much acetylcholinesterase causes a. an increase in na+ uptake by the muscle fiber. b. exocytosis of synaptic vesicles c. voltage gated ca2+ channels opening in the presynaptic terminal d. continuous stimulation of the muscle fiber e. rapid degradation of acetylcholine

e. rapid degradation of acetylcholine

treppe a. contribute to improved muscle deficiency b. is achieved during warm up exercises c. all of these choices are correct d. is an example of graded response e. may be due to an increase in the level of ca2+ around the myofibril

c. all of these choices are correct

Troponin a. has two subunits b. has calcium binding site c. is a long flexible protein d. is part of the myosin myofilament e. binds to atp

b. has a clacium binding site

what are caveolae a. parts of the intracellular cytoskeelton b. shallow invaginations of plasma membrane c. structures that allow for relatively constant tension maintained for a period of time

b. shallow invaginations of plasma membrane

what is a cross bridge a. the movement of myosin head while attached to actin myofilament b the combinations of myosin heads with active sites on actin molecule c. a t tubule and two adjacent terminal cisternae d. a protein found along

b. the combination of myosin heads with active sites on actin molecules

what is a cross bridge a. the movement of myosin head while attached to actin myofilament b. the combination of myosin heads with active sites on actin molecule c. a t tubule and two adjacent terminal cisternae d. a protein found along the groove of the f-actin double helix e. after exercise the o2 taken in that exceeds the o2 required for resting metabolism

b. the combination of mysoin heads with active sites on actin molecules

what is the power stroke a. the combination of myosin heads with active sites on actin molecules b. the movement of mysoin head while attached to actin myofilament c. after exercise the o2 take in that exceeds the o2 required for resting metabolism d. a t tubule and two adjacent terminal cisternae e. a protein found along the groove of the f-actin double helix

b. the movement of myosin head while attached to actin myofilament

what is tropomyosin a. after exercise the o2 taken in that exceeds the o2 required for resting metabolism b. the combination of myosin heads with active sites on actin molecules c. a t tubule and two adjacent terminal cisternae d. the movement of myosin head while attached to actin myofilament e. a protein found along the groove of the f-actin double helix

e. a protein found along the groove of the f-actin double helis

what would result from a lack of extracellular ca2_ at the neruomuscular junction a. the neuron must use it's intracellular ca2+ to make the vesicles fuse b. synaptic vesicles would fail to fuse and ach would not be released c. potassium ions are used in place of ca2+ to ensure the vesicles fuse d. nothing would happen because extracellular ca2+ does not play a role in muscle stimulation e. excessive synaptic vesicles would fuse and release too much ach, overstimulating the myofiber

b. synaptic vessicles would fail to fuse and ach would not be released

whe nrepolarization of the plasma membrane is complete teh a. cell no longer has a potential difference acrosss its membrane b. original polarity of the cell is resotred c. cell regenerates d. cell is no longer responsive e. cell dies

b. original polarity of the cell is restored

when skeltal muscles is producing co2 and water while making atp which chemical processes could be active at this time a. aerobic respiration b. both anaerobic respiration and aerobic respiration are correct c.anaerobic respiration

a. aerobic respiration

when the myosin head flexes into a bed pullling the actin filamen along with it this is called the a. muscle tone b.power stroke c. action potential d. recovery stroke e. action reaction

b. power stroke

which of the following correctly describes myogolobins special function in muscle tissue a. acts as a resrvoir for o2 b. produces action potentials c. stores glucose d. breaks down glycogen e. synthesizes atp

a. acts as a rervoir for o2

which of the following descriptions best represents the appearance of the sarcomere during peak contraction a. the width of the a-band is slightly less than the width of the I-band b. the i bands and a bands are of equal widths c. the h zone is equivalent t oone third of the length of the a band d. the h zone is eliminated and the i bands are very thin

d. the h zone is eliminated and the I-bands are very thin

which of the followin events occurs on the pstsynaptic membrane a. release of neurotransmitter b. neurotransmitter combines with a receptor molecule c. release of ca2+ d. rapid degradation of acetylcholine e. acetylcholine production

b. neurotransmitter combines with a receptor molecule

which of the following individuals would have more mitochondira in her skeletal muscle a. a 22 year old soccer player b. a newborn c. a 50 year old sedentary computer programmer d. a model on a reduced calorie deficit e. a long termhospice patient

a. 22 year old soccer player

which of the followin is composed of mysoin molecules a. sarcolemma b. i-bands c. thick myofilaments d. z-disks e. tropomyosin

c. thick myofilaments

which of the following is mismatched a. i-band - contains only actin b. myosin myofilaments - thin myofilaments c. z- deisk structure between adjacent sarcomeres d. actin myofilaments - thin myofiliaments e. m-line - middle of the h zone

b. myosin myofilament - thin myofilaments

which of the following a part of a thin myofilament a. globular g actin b. sarcolemma c. atp binding site d. calcium e. myosin

a. globular g actin

which of the following statements concerning fast twitch muscle fibers is true a. they are well adapted to aerobic metabolism b. they have large deposits of myoglobin c. they split atp rapidly d. they have many mitochondria e. they have a well-developed blood supply

c. they split atp rapidly

As soon as an individual flexes trunk to reach a dropped object, skeletal muscles are stretched to retrieve the object. Aforementioned scenario exhibits functional property of skeletal muscle fibers known as a. extensibility b. elasticity c. contractiity d. excitability

a. extensibility

which of the following exampes represent elasticity of muscle tissue a. retrieving a dropped pen b. passive expiration c. inspiration through excitement of muscles of inspiration d. firing of skeletal muscles by motor nerves in order for them to respond to electrical stimulus

b. passive expiration

the dens irregular connective tissue that surrounds the entire skeletal muscles and blends together with the muscullar fascia is called a. epimyseum b. perimyseum c.endomyseum d. endomyseum

a. epimyseum

identify connetive tissue converings which subdvides muscles in a whole muscle into fascicles or bundles a. epimysuem b. perimysuem c. endomyseum d. fasciae

b. perimysuem

interwoven fibers of epimyseum, perimyseum and endomysuem blend together to give rise to _____ to aiat attachment to bones a. ligaments b. cartialge c. muscles d. tendons

d. tendons

motor or efferent neurons originate in the _____ and extend via ____ to skeletal muscle fibers a. nerves, brain/ spinal cord b. brain/ spinal cord, blood vessels c. brain/ spinal cord, connective tissue d. brain/ spinal cord nerves

d. brain/ spinal cord nerves

deoxygenated blood is carried away from adn extensive network of capillaries by branches of ____ a. nerves b. arteries c. veins

c. veins

idnetify the connective tissue layer at which motor nuerons branch their axons extensively to supply muscle fibers in their respective bundles or fascicles a. epimyseum b. endomyseum c. perimysuem

c. perimyseum

the sarcoplasmic reticulum is a highly speicialised ____- a. golgi apparatus b. rough endoplsmicreticulum c. smooth endoplasmic reticulum d. ribosome

c. smooth endoplasmic reticulum

sarcoplasmic reticulum serves as a storage site for a. sodium b. calcium c. poteins d. potassium

b. calcium

which of the following are not conisdered electrical component of an individual muscle fiber a. actin and myosin myofilaments b. transverse t tubules c. sarcolemma d. sarcoplasmic reticulum

a. actin and myosin myofilaments

sarcoplasm contains contractile proteins like actin and myosin myofilaments and a stored form of glucose called a. cellulose b. starch c. sucrose d. glycogen

d. glycogen

glycogen phosporylase is a powerful enzyme in the sarcoplasm of muscle fibers which breaks down glycogen to release a.amino acids b. glucose molecules c.cholesterol d. fatty acids

b. glucose molecules

mechanical spect of muscle contraction is provided by a. transverse t tubules b. sarcolemma c. actin and myosin myofilaments d. sarcoplasmic reticulum

c. actin and myosin myofilaments

lighter i-bands in asingle skeletal muscle fiber contains a. only actin myofilaments b. overlapping section of actin and myosin myofilaments c. m-line d. only myosin myofilaments

a. only actin myofilaments

the very centre of darker a band in a sarcomere contains only a. myosin myofilaments b. actin filaments c. titin d. z-disks

a. myosin myofilaments

the type of protein in sarcomere which gives muscle fibers properties of extensibility and elasticity a. troponini b. actin c. myosin d. titin

d. titin

actin myofilaments are composed of all of the following components except a. troponinig complex b. tropomyosin c.mysoin heads d. f-actin strand

c. myosin heads

it is the relationship between ___ and ____ that dictates when skeletal muscle will contract a. f actin strand, myosin b. troponin, tropomyosin c. troponin, f actin strand d. calcium, troponin

b. troponin, tropomyosin

skeletal muscle fiber can not form cross bridges in order to contract unless ___ moves away from active sites of g actin molecules a. troponin-I b. tropomyosin c. myosin d. troponin-c

b. tropomysoin

presynaptic cell in neuromuscular junction will be a. terimnal foot process of boutons of motor neurons b. terminal foot process of sensory neurons c.motor end plate or sarcolemma of muscle fiber

a. terminal foot process of boutons of motor neurons

sarcolemma or motor end plate will act as a a. presynaptic terminal b. postsynaptic terminal

b. postsynaptic terminal

Action potentials or electrical signals start in the cell bodies of motor neurons in the brain and travel through axons ———————to connect with the sarcolemma or motor end plate of muscle fibers. a. veins b. nerves c. arteries

b. nerves

Ligand gated sodium ion channels in a typical neuromuscular junction of skeletal muscle fiber are located in a. transverse t tubules b. sarcoplasmic reticulum c. sarcolemma or postsynaptic membrane or postsynaptic terminal d. presynaptic terminal of motor neuron

c. sarcolemma or postsynaptic membrane or postsynaptic terminal

In a neuromuscular junction, When an action potential arrives at the terminal foot process of a motor neuron otherwise called presynaptic terminal, it would immediately result in a. diffusion oc clacium ions from cytoplasm of motor neuron to extracellular fluid via n-type voltage gated calcium ion channels b. diffusion of clacium ions from extracellular fluid into the cytoplas of motor neuron via n-type voltage gate calcium ion channels c. attachment of acetylcholine to nicotinc receptor situated on ligand gated osdium ion channels anchoered in motor end plate (post synaptic terminal) d. the relaese of calcium ion stored in the sarcoplasmic reticulum of a muscle fiber

b.diffusion of clacium ions from extracellular fluid into the cytoplas of motor neuron via n-type voltage gate calcium ion channels

Upon the binding of calcium ions to synaptic vesicles in the presynaptic terminal of a motor neuron in a neuromuscular junction, what will be the immediate subsequent action? a. synaptic vesicles willliberate stored neurotransmitter through exocytosis into the blood b.action potential will quickly propogate along the sarcolemma of muslce fiber (post synaptic cell) to finally resaerch transverse t-tubules c.the union of neurotransmitter with nicotinic receptors on ligand-gated sodium ion channels intiriates the influx of sodium ions into muscle fiber sarcoplasm d. synaptic vesicle will liberate store nuerotransmitter through exocytosis into the synaptic cleft

d. synaptic vesicle will liberate store nuerotransmitter through exocytosis into the synaptic cleft

excluislvely found in the synaptic vesicles of motor neuron within neuromuscular junctions of skeletal muscle fibers___ serves as the main neurotransmitter a.norepinephrine b. dopamine c. acetylcholine d. serotonin

c.acetylcholine

the intionat of graded anction potential (electrci impulses) occurs iun the motor end plate or sarcolemma of a muscle fiber (postynaptic terminal) at the neuromuscular junction upon the binding of acetylchoine to a. ligand gated sodium ion channels b. voltage gated calcium ion channels c.ryr-1 or ryanoodine recepetors d. voltage gated sodium ion channels

a. ligand gated sodium ion channels

excitation events in excitation contraction couplin inclue all of the following excep a.binding of calcium to synaptic vessicles in presynaptic terminals to release neurotransmitter b. power and recover stroke of cross bridge stclin c. release of neurotransmitter such as acetylcholine into the synaptic cleft via exocytosis d. propogation of action potential along the plasma membrane of motor neurons until opening of voltatge gated clacium ion channels

b. power and recover stroke of cross bridge actin

The activation of DHPR or Dihydropyridine receptors, interchangeably referred to as L-type voltage-gated calcium ion channels anchored in transverse T-tubules of sarcolemma, by stimulation with action potentials or electric impulses will result in the a. opening of ligand gated sodium ion channels in sarcolemma at the neuromuscular junction b. opening of ryanodine receptors or ryr-1 located the cisternae of sarcoplasmic reticulum c. closure of voltage gated sodium ion channels located in transverse tubules of sarcolemma d. closure of ryanodie receptors or ryur-1 situated on the cisternae of sarcoplasmic reticulum

a. opening of ligand gates osdium ion channels in sarcolemma at the neuromuscular juncion

as soon as ryanodine receptors ryr-1 are discloacted from the cisternae of sarcoplasmiic reticulu ____ will efflux into the sarcoplasm of muscle fiber a. magnesium mg b. sodium na c. potassium k d. calcium ca 2

d. calcium ca2

all of the following options include mechancical events to induce dkeletal muscle contraction except a. binding of calcium to troponin- c in a muscle fibre b. interaction of myosin heads with g-actin active sites to form cross bridges to produce adequate tension c. release of a neurotransmitter from its synaptic vesicles into the synaptic cleft of a neuromuscular junction d. removal or sisplacement of tropomyosin molecules from g actin active sites with the traction applied by troponin-t

c. release of a neurotransmitter from its synaptic vesicles into the synaptic cleft of a neuromuscular junction

What will be the subsequent action once a calcium spark is observed in the sarcoplasm of a skeletal muscle fiber? A. calcium moves on to bind ryanodine receptor ryr-1 b. calcium moves on to bind to troponin-c c. calcium moves on to bind to calmodulin complex d. calcium immediately binds to myosin heads

b. calcium moves on to bind troponin-c

in malginant hyperthemia a genetic mutation will result in a. malfunctioninig of n-type voltage gated clacium channels found in potsymatic neuron terminals in neuromuscular junction b. malfunctioning of dihydropyridine receptor alternatively called l type voltage gated calcium ion ca+2 channels c. malfunctioning of ligand gated sodium ion channels in postsynaptic terminal of sarcolemma in neuromsucular junction d. malfunctioning of rynaodine receptors or ryr-1 receptor

d. malfunctioning of rynaodine receptors or ryr-1 receptor

In a neuromuscular junction, When an action potential arrives at the terminal foot process of a motor neuron otherwise called presynaptic terminal, it would immediately result in a. attachment of acetylcholine to nicotinic receptors situated on ligand gated sodium ion channels anchored in motor end plate b. the releasele of calcium ions stored in the sarcoplasmic reticulum of a muscle fiber c.diffusion of clacium ions from extracellular fluid into the cytoplasm of motor neuron via n-type voltage gated calcium ion channels d.diffucion of caclcium ions from cytoplasm of motor neuron to extracellular fluid via n-type voltage gated calcium ion channels

c.diffusion of clacium ions from extracellular fluid into the cytoplasm of motor neuron via n-type voltage gated calcium ion channels

Upon the binding of calcium ions to synaptic vesicles in the presynaptic terminal of a motor neuron in a neuromuscular junction, what will be the immediate subsequent action? a. synaptic vesicles will liberate stores neurotransmitter through exocytosis into the synaptic cleft b. the union of neurotransmitter with nicotinic receptors on ligand gated sodium ion channels initiates the influx of sodium ions into muscle fiber sarcoplasm c. action potential will quickly propogate along the sarcolemma of muscle fiber (postsynaptic cell) to finall reach the transverse t tubule d. synaptic vesicles will liberate stored neurotransmitter through exocytosis into the blood

d. synaptic vesicles will liberate stored neurotransmitter through exocytosis into the blood

what ion is necessary for the movement of troponin-tropomyosin complex a. calcium b. chloride c.potassium d. sodium

a. calcium

as soon as g-actin active sites are exposed, myosin heads attach to g actin active sites to establish cross bridges and triggers a. power stroke b. recovery stroke

a. power stroke

what happens during the power sroke of skeletal muscle contractions a. atp binds to the myosin head b. the myosin head goes back into a high-energy state c. the myosin head pulls the actin filament toward the center of h-zone in the sarcomere d. calcium ion are pumped back into the sarcoplasmic reticulum

c.the myosin pulls the actin filament toward the centre of h-zone in the sarcomere

which of the following evens occurs during the recovery stroke a. actin filaments slide back to their original position b.myosin head detaches from actin c. adp is released from the myosin head d. the mysoin head binds to a new atp molecule

b. mysoin head detaches from actin

what role does atp play in the recovery stroke a. it binds to the myosin head causing it to release from acin b. it causes acting to change shape c. it provides enerygy for the power stroke d. it removes calcium from the sarcoemere

a. it binds to the myosin head causing it to release from actin

what is the final step in the recovery stroke before the next power stroke begins a. myosin head detaches from actin b. myosin head binds to a new actin site c. atp is hydrolyzed to adp and pi d. calcium binds to troponin

c. atp is hydrolyzed to adp and pi

which molecule binds to the moyosin head to cause detachment from actin during the recovery stroke a. adp b. atp c. phosphate d. calciumq

b. atp

what enzyme is primarily inhibited by organophosphate compounds a.monomine oxidase b. cytochrome p450 c. acetylcholinesterase d. catechol-0-methyltransferase

c. acetylcholinesterase

inhibition of acetylcholinesterase by organophosphates leads to the accumulation of which neurotransmitter in the synaptic cleft of neuromuscular junction a. dopamine b. acetylcholine c. serotonin d. glycine

b. acetylcholine

which of the following receptors is overstimulated due to acetylcholine accumulation in organophosphate poisoning a. nicotinc receptors of ligand gated sodium ion channels and muscarinic receptors b. gaba receptors c. glutamate receptors d. dopamine receptors

a. nicotinic recepors of ligand gates sodium ion channels and muscarinic receptors

what is the priary result of excessive acetylcholine buildup in organophosphate poisoning a. decreased salivation and sweating b. muscle paralysis and respiratory failure c. increased heart rate and vasoconstriction d. reduced gastrointestinal mobility

b. muscle paralysis and respiratory failure

organophosphate poisoning usually ______ the transmission of action potentials across the neuromuscular junction whereby causing spastic paralysis a. attentuates b. neither exaggerates nor attentuates c. exaggerates

c. exaggerates

what is the primary cause of myasthenia gravis a. the phenomenon commonly known as an autoimmune attack on nicotinic receptors also referred to as cholinergic or acetylcholine receptors, AChRs of ligand gated sodium ion channels b. deficiency of neurotransmittter acetylcholine in the presynaptic terminal c. genetic mutation of cholinergic or actylsholine receptors achrs of ligand gated sodium ion channels d. viral infection of achrs

a. the phenomenon commonly known as an autoimmune attack on nicotinic receptors also referred to as cholinergic or acetylcholine receptors, AChRs of ligand gated sodium ion channels

which of the following symptoms is most commonly associated with myasthenia gravis a. joint pain b. muscle weakness that worsens with activity c. numbness and tingling

b. muscle weakness that worsens with activity

which symptom is most commonly associated with myasthenia gravis a. muscle cramps b. numbness in the limbs c. severe headaches d. ptosis (drooping of the eyelids)

c. severe headaches

in myasthenia gravis muscle weakness typically a. worsens with rest b. sorsens with activity and improves with rest c. improves activiy d. is constant and does not fluctuate

b. worsens with activity and improves with rest

what is the mehcanism of action of curare at the neuromuscular junction a. activiation of muscarinic receptors b. inhibition of acetylsholinesterase d. relase of excessive acetylcholine d. competetive blockade of nicotinc acetylcholine receptors achrs of ligand gated sodium ion channels

d. competitive blockade of ligand gated sodium ion channels

which of the following is a common symptom of curare poisoning a. severe abdominal pain b. flaccid muscle paralysis c. elevated blood pressure d. excessive sweatingq

b. flaccid muscle paralysis

what is the primary source of curare in a clinical context a. environmental pollutants b. contaminated food c. natural toxins from plants such as chondrodendron tomentosum d. synthetic chemical compounds

c. natural toxins from plants such as chondrodendron tomentosum

what is the primary clinical use of curare in anaesthesia a. induction of sleep b. control of blood pressure c. neuromuscular blockade for muscular relaxation d. pain relief

c. neuromuscular blockade for muscle relaxation

in which of the following scenarios would curare or a neuromuscular blocker be commonly utilized a. to promote digestion in patients with gastrointestinal disorders b. as a treatment for chronic pain c. for rapid sequence intubation in emergency medicine d. during administration of local anaesthesia

c. for rapid sequence intubation in emergency medicine

what is a muscle twitch a. a relaxation fo a muscle b. a single brief contraction of a muscle fiber c. a continuous contraction of a muscle d. a prolonged contraction of a muscle

b. a single brief contraction of a muscle fiber

which of the following phases occurs first during a muscle twitch a. relaxation phase b. contraction phase c. refractory phase d. latent phase

d. latent phase

during contraction phase of a muscle twitch which event primarily occurs a. muscle fibers lengthen b. myosin heads bind to actin c. atp is produced d. calcium is sequestered

b. myosin heads bind to actin

what is the role of calcium ions in muscle contraction a. it provide energy for contraction b. it initiates the actino potential c. it binds to troponin causing tropomyosin to move away from g-actin active sites on f actin strands d. it deactivates actin

c. it binds to troponin causing tropomyosin to move away from g-actin active sites on f actin strands

which of the following best describes the relaxation phase of a muscle twitch a. calcium is released into the cytoplasm b. calcium is pumped back into the sarcoplasmic reticulum d. atp is consumed rapidly

b. calcium is pumped back into the sarcoplasmic reticulum

which term describes the process of increaseing the number of active motor units to enhance muscle contraction a. recruitment b. synchronisation c. summation d. tetanus

a. recruitment

what is teh effect of motor unit size on muscle control a. large motor units only produce force, not control b. smaller motor units provide more precise control c. motor unit size has no effect on control d. larger motor units provide more precise control

b. smaller motor units provide more precise control

which of the following best describesthe relationship between motor units and muscle strength a. more motor units always equal more strength b. strength is solely determined by muscle fiber type c. muscles strength is influenced by both motor unit recruitment and fiber type d. the size of motor units does not affect strength

c. muscles strength is influenced by both motor unit recruitment and fiber type

what does the length tension curve primarily illustrate a. the relationship between muscle length and the force produced by the muscle a. the relationship between muscle length and force produced by the muscle b. the relationship between muscle length and muscle fiber diameter c. the relationship between muscle length and muscle fatigue d. the relationship between muscle temperature and contraction speed

a. the relationship between muscle length and the force produced by the muscle

active tension in a muscle refers to a. the tension generated during muscle contraction after the propogation of action potentials b. the tension generated by surrounding connective tissues c. the tension present at rest

a. the tension generated during muscle contraction after the propogation of action potentials

passive tension in a muscle is primarily due: a. neural stimulation b. muscle fiber recruitment c. elastic properties of connective tissue d. actin and myosin cross bridging

c. elastic properties of connective tissu

what happens to active tension when a muscle is stretched beyond its optimal length a. active tension increases b. active tension remains unchanged C. active tension decreases

c. active tension decreases

the total tension in a muscle at a given length can be defined as a. the difference between active and passive tension b. only active tension c. the sum of active and passive tension d. only passive tension

c. the sum of active and passive tension

in a typical length-tension curve, what occurs as musclelength decreases from the optimal length a. active tension increases b. active tension decreases rapidly c. passive tension increases d. total tension decreases

b. active tension rapidly decreases

which of the following factors can influence the active tension generated by a muscle a. length of the muscle at the time of the contraction b. all options are true c. muscle fiber type d. rate of neural stimulation

b. all options are true

what does the size principal of motor unit recruitment state a. smaller motor units are recruited before larger ones b. larger motor units are recruited before smaller ones c. motor units are recruited randomly d. all motor units are recruited simultaneously

a. smaller units are recruited before larger ones

which type of muscle fibers are typically associated with smaller motor units a. type 1 slow twitch fibers b. type 2a fast twitch oxidative fibers c. type2b fast twitch glycotic fibers d. type 3 fibers

a. type 1 slow twitch fibers

during maximal effort contraction what happens to motor unit recruitment according to the size principle a. both small and large motor units are recruited, with large units recruited last b. only large motor units are recruited c. smaller units are deactivated d. motor unit recruitment is random

a. both large and small motor units are recruited, with large units recruited last

in which scenario is the size principle particularly important a. activities requiring fine motor skills b. light endurance activities c. all of the options are true

c. all of the options are true

what is a practical application of the size principle in resistance training a. avoiding maximal lifts b. performing low weight, high rep exercises only c. focusing slowly on endurance training d. gradually increasing the weight to recruit larger motor units

d. gradually increasing the weight to recruit larger motor units

what physiological advantage doesthe size principle provide during low intensity activities a. enhanced speed of contraction b. gretaer force production c. reduce energy expenditure d. increased muscle hypertrophy

c. reduced energy expenditure

how does the size principle help to maintain muscle endurance a. by utilizing slow twitch fibers that are less prone to fatigue b. by maximizing force output c. by only recruiting fast twitch fibers d. by alternating between different motor units randomly

a. by utilizing slow twitch fibers that are less prone to fatigue

which of the following best describes the implications of the size principle for rehabilitation exercises a. use unpredictable weights to maximize motor unit recruitment b. only focus on strength training withouth considering endurance c. focus on heavy weights to active all motor units at once d. start with low wieghts to engage smaller motor units and progress gradually

d. start with low weights to engage smaller motor units and progress gradually

What defines an isometric contraction? A. Muscle length changes while tension remains constant. B. Muscle tension increases without changing length. C. Muscle fibers shorten, producing movement. D. Muscle lengthens while producing force.

b. muscle tension increases without changing length

During which type of contraction does the muscle shorten while generating force? a. isotonic contraction b. isokinetic contraction c. isometric contraction d. eccentric contraction

a. isotonic contraction

Which of the following is an example of an isotonic contraction? A. Holding a weight in a fixed position B. Performing a bicep curl with a dumbbell C. Pushing against a stationary wall D. Performing a plank exercise

b. performing bicep curl with a dumbbell

During a bicep curl, when lifting the dumbbell upwards, the biceps are undergoing which type of contraction? A. Isometric contraction B. Eccentric contraction C. Concentric isotonic contraction

c. concentric isotonic contraction

Which type of contraction typically produces the highest force output? a. isokinetic contraction b. concenric contraction c. eccentric contraction d. isometric contraction

c. eccentric contraction

In which scenario is an isometric contraction typically utilized a. sprinting on a track b. jumping over a hurdle c. holding a yoga pose d. lifting a heavy box off the ground

c. holding a yoga pose

What is the primary difference between concentric and eccentric contractions? a. concentric contractions shorten the muscle while eccentric contractions lengthen it b. both occur simultaneously c. concentric contractions lengthen the muscle while eccentric contractions shorten it d. there is no difference they are synonymous terms

a. concentric contractions shorten the muscle while eccentric contractions

Which type of muscle fiber is primarily responsible for endurance activities? a. slow tiwtch fibers b. fast twitch fibers c. intermediate fibers d. white muscle fibers

a. slow twitch fibers

Fast-twitch muscle fibers are characterized by a. a low glycolytic capacity b. a high density of mitochondria c. a high rate of fatigue resistance d. a rapid contraction speed

d. a rapid contraction speed

Which of the following statements is true about slow-twitch fibers? a. they contain less myoglobin than fast twitch-fibers b. they are primarily used for shore explosive activities c. they generate a lot of force quickly d. they are more resistant to fatigue than fast twitch fibers

d. they are more resistant to fatigue than fast twitch fibers

What is a key characteristic of Type 2a fibers? a. they can utilize both aerobic and anaerobic metabolism b. they are the most fatigue resistant fiber type c. they have a low oxidative capacity d. they are primarily anaerobic

a. they can utilize both aerobic and anaerobic metabolism

Which muscle fiber type has a higher concentration of myoglobin? a. fast twitch fibers b. slow twitch fibers c. myoglobin concentration is not related to fiber type d. both have the same concentration

b. slow twitch fibers

What type of training is most beneficial for developing fast-twitch muscle fibers? a. high intensity interval training b. aerobic training c. plyometric training d. long distance running

a. high intesntiy interval training

Which of the following is a characteristic of fast-twitch Type IIb fibers? a. low force b. high oxidative capacity c. high glycolytic capacity d. slow contraction speed

c. high glycolytic capacity

What is the primary energy source for slow-twitch muscle fibers during prolonged activity?. A. Phosphocreatine B. Glycogen C. Fatty acids D. ATP-CP

b. fatty acids

what is hypertrophy a. decrease in muscle size b. increase in number of cells c. increase in growth size of existing cells d. abnormal growth of tissue

c. increase in size of existing cells

Which of the following can lead to muscle atrophy? a. regular strength training b. prolonged immobilized c. increased physical activity d. enhanced nutrient intake

b. prolonged immobilization

What does hyperplasia to? a. increase in cell size b. abnormal tissue growth c. decrease in muscle mass d. increase in the number of cells

d. increase in the number of cells

what is muscle fatigue a. a complete recovery of muscle function b. an increase in muscle size c. a temporary decrease in the ability to generate force d. a compete lost of muscle strength

c. a temporary decrease in the ability to generate force

What is the role of creatine phosphate in muscle fatigue? a. it contributes to lactic acid production b. it has not effect on muscle fatigue c. it decreases atp production d. it provides a rapid source of energy for atp resynthesis

d. it provides a rapid source of energy for atp resynthesis

What is physiological contracture? a. a complete lost of muscle tone b. a permanent shortening of muscles c. a temporary state of muscle stifness due to calcium accumulation d. an increase in muscle elasticity

c. a temporary state of muscle stiffness due to calcium accumulation

what cases rigor mortis a. increased blood flow to tissues b. increased atp production c. depletion of atp in muscle cells d. excessive oxygen supply

c. depletion of atp in muscle cells

Which condition can lead to physiological contracture? a. high levels of calcium in the blood b. muscle fatigue c. prolonged inactivity d. dehydration

b. muscle fatigue

What is the primary reason for the stiffness observed in rigor mortis? a. formation of actin-myosin cross bridges without atp b. elevated blood glucose levels c. accumulation of lactic acid d. increased muscle fiber elasticity

a. formation of actin-myosin cross bridges without atp

During physiological contracture, which process is disrupted, leading to sustained muscle tension? A. Calcium reuptake into the sarcoplasmic reticulum B. Cross-bridge cycling between actin and myosin C. ATP synthesis in mitochondria d. glycogen breakdown

A. Calcium reuptake into the sarcoplasmic reticulum

How does the lack of ATP contribute to physiological contracture? a. it promotes muscle relaxation b. it inhibits the formation of actin-myosin cross bridges c. it prevents calcium release from the sarcoplasmic reticulum d. it prevents the detachment of myosin heads from actin

d. it prevents the detachment of myosin heads from actin

How can oxidative stress contribute to muscle fatigue during prolonged exercise? a. by increasing oxygen availability to muscles b. by causing inflammation and imparing muscle contraction c. by enhancing mitochondrial function d. by reducing the need for energy substrates

b. by causing inflammation and imparing muscle contraction

Which type of exercise is most likely to induce oxidative stress in muscle tissue? A. low intensity steady state exercise take B. stretching exercises c. light walking d. high intensity interval training (hiit)

d. high intensity interval training (hiit)