AP Chapter 10 - Muscles

Skeletal muscle fiber has only __ NMJ near its midpoint

1

1. nerve impulse arrival stimulate synaptic vesicles ___cytosis to fuse with motor neuron plasma membrane releasing _____ into synaptic cleft 2.____ binds to _________ end plate, opens __+ channel so it can flow across membrane 3. Inflow of __+ increases muscle fiber charge triggering muscle ___________ potential 4. ___ rapidly broken down by ______

1. exocytosis, Ach 2. Ach, motor, Na+ 3. Na+, action 4. Ach, AchE

__ band = darker, middle part of sarcomere

A band

excess ____ is used to synthesize creatine phosphate

ATP

Contraction cycle: 1. _____ hydrolysis - Muscle energized 2. Myosin ___________ Actin - releases hydrolyzed phosphate - forms cross __________ 3. _________ ____________ - myosin head pivots pulling thin filaments past thick towards sarcomere center generating tension ( 4. Myosin ___________ from Actin

ATP Attaches cross bridge Power Stroke detaches

Sarcoplasm includes more glycogen for ____ synthesis; also ______________ to bind O2 from interstitial fluid so can be released by mitochondria fro ____ production

ATP Myoglobin ATP

muscle fiber speed (slow of fast) is dependent on how fast _______ in myosin heads can hydrolyze ATP

ATPase

__________________ neurotransmitter responsible for all skeletal muscle contraction, stored in synaptic terminal, when the nerve impulse arrives vesicles with it pop to outside to release it into synaptic cleft, binds to receptors

Acetylcholine

Main component of thin filaments =

Actin

___ catalyzes phosphate from creatine back to ADP to generate ATP

CK

aA lot of _____ is stored in Sarcoplasmic Reticulum

Ca2+

____________ - dense sheet that lines body walls / limbs and supports - surrounds muscles ?/ organs

Fascia

__________ - muscle fiber bundles

Fascicles

Muscle enlargement due to hypertrophy is from these skeletal muscle fibers

Fast Glycolytic

__ zone = center of A bands, narrow, thick filaments only

H

___________ contraction - tension without muscle length change

Isometric

__ discs separate 1 sarcomere from the next

Z discs

Main component of thick filaments with motor protein function that converts ATP to motion =

Myosin

_________ heads move along thin filaments at both sarcomere ends __________ thin filaments toward M line --> mov inward to meet @ center sarcomere

Myosin pulling

___mysium - surrounds fascicles

Perimysium

1. Ach ______________ 2. Ach receptor __________ 3. Muscle _________ __________ triggered 4. Ach activity _____________

Released Activated Action Potential Terminated

Fluid filled sacs that encircle each myofibril =

Sarcoplasmic Reticulum

_____________ Muscle Functions: movement, posture, guard ECPs, Body Temp, store nutrients,

Skeletal

Thin filaments of myofibrils =

actin

Four special properties of Muscle: 1. generate _____________ potentials 2. __________ forcefully 3. _________ within limits without damage 4. ________ return to original shape after contraction

action potentials contract stretch return

Structural myofibrils keep thick / thin filaments ____________ ; link myofibrils to _____________ and ECM

aligned sarcolemma

Aerobic respiration is slower than _____________ glycolysis, but AR has higher ____ yield

anaerobic ATP

Connective tissue that extends as broad, flat sheet =

aponeurosis

Ca2+ enters sarcoplasm from SR and interstitial fluid of _________ muscle

cardiac

__________ muscle - striated, involuntary

cardiac

Feeling of tiredness / desire to cease activity prior to muscle fatigue is caused by changes in CNS and called _________ fatigue

central

At rest Terminal Cisterns are blocked by T tubule ___________

clusters

Isotonic muscle contractions are _____________ and ___________

concentric and eccentric

3 kinds of myofibril proteins

contractile, regulatory, structural

During this phase of muscle contraction Ca2+ binds to troponin, myosin binding sites on actin exposed, cross bridges form, and peak tension reached =

contraction

Regulatory myofibrils turn _______________ on / off

contraction

When muscle fibers contract the Ca2+ released from the terminal cisterns trigger muscle ____________

contraction

3 ways muscle makes ATP =

creatine phosphate anaerobic glycolysis aerobic respiration

Stretched muscles have decreased overlap and ____________ ability to contract

decreased

___________ hold cardiac muscle together

desmosomes

Thick and thin filaments ______ extend entire length of muscle fiber

don't

Botox blocks _________ of synaptic vesicles at NMJ

exocytosis

this muscle fiber is white, has large amounts of glycogen, generates ATP form glycolysis, strong / quick contraction, fast twitch, intense anaerobic movements of short duration and fatigue fast ; weight lifting

fast glycolytic

This muscle fiber is dry red, generates ATP from AR & anaerobic glycolysis, moderate to high fatigue resistance, high intracellular glycogen, fast contraction; walking / sprinting =

fast oxidative

Depletion of CP causes _____________

fatigue

Contractile myofibrils generate ________

force

number of impulses per second = __________ of stimulation

frequency

Sustained contraction, can't detect individual twitches with no relaxation = ___________ ________________

fused tetanus

____ junctions allow action potentials to spread in cardiac muscle

gap

When creatine phosphate supply depleted _______ catabolized to make ATP

glucose

__________ = glucose molecule breaks down into 2 pyretic acid molecules in cytosol producing net gain of 2 ATP, and doesn't require O2

glycolysis

Total number of skeletal muscle fibers does not __________ with exercise, but characteristics can change

increase

Cardiac muscle has ____________ discs

intercalated

T-Tubules are filled with ____________ fluid so ___________ potentials travel along sarcolemma quickly spreading to excite all parts of _________ fiber at same time

interstitial action muscle

During heavy exercise where O2 is lacking, pyruvic acid is converted to ______ acid in process called anaerobic __________

lactic glycolysis

O2 used to restore metabolic condition to resting levels in 3 ways 1. convert ________ acid back to ________ stored in liver 2. replenish CP + ATP in _____________ 3. replace ____ removed from myoglobin

lactic, glycogen muscle O2

large motor units = __________ movements

large

during this phase of muscle contraction action potential sweeps over sarcolemma causing Ca2+ release form SR =

latent

resting --> ____________ --> contraction --> _______________ --> ______________

latent relaxation refractory

Cardiac muscle has a ___________ refractory time

long

Relaxed muscle = ______ Ca2+

low

Subcutaneous layer also known as hypodermis separates ________ from skin

muscle

The use of creatine phosphate is unique to __________

muscles

____________ give skeletal muscle striped look

myofibril

contractile organelle of skeletal muscle =

myofibril

Thick filaments of myofibrils =

myosin

___________________. _______________ = synapse between somatic motor neuron and skeletal muscle fibers

neuromuscular junction

Chemical messenger =

neurotransmitter

End of A band is the _______ zone, where thick and thin filaments are side by side

overlap

small motor units = __________ movements

precise

total force depends on ________ of impulses arriving at NMJ

rate

Muscle fibers with high myoglobin are the color __________ equivalent of ________ meat

red dark

During this phase of muscle contraction Ca2+ actively transported back into SR, myosin binding sites covered by tropomyosin, myosin heads detach from actin, and tension decreases =

relaxation

muscle fibers when ___________ produce > ATP than needed

relaxed

Increased muscle tone without tendon reflexes =

rigidity

motor unit recruitment are not stimulated to contract at _____ time; the ___________ motor units are recruited first; this is why contraction is smooth and not jerky

same weakest

______________ = muscle cell plasma membrane

sarcolemma

Filaments are arranged in compartments called

sarcomeres

_______________ = muscle fiber cytoplasm

sarcoplasm

Skeletal muscle has a ___________ refractory time

short

if tension generated by muscle is > resistance of object a muscle will be ______________ and movement occurs

shortened

Action potential are always the same ________

size

total strength of contraction depends on _____ of motor units and ___________ activated at given time

size number

____________ muscle - striated / voluntary

skeletal

Skeletal muscle shortens during contraction, thick / thin filaments _______ past each other

slide

this muscle fiber is dark red, generates ATP from AR, slow contraction speed, fatigue resistant; associated with posture / endurance =

slow oxidative

3 types of skeletal muscle fibers are

slow oxidative, fast oxidative, fast glycolytic

_______ muscle can stretch considerably and still maintain contraction function

smooth

__________ muscle - not striated, involuntary

smooth

__________ muscle contracts in twisting pattern and relaxes in opposite

smooth

____________ muscle has the greatest amount of stretching

smooth

Neurons that stimulate skeletal muscle to contract are __________ motor neurons

somatic

Increased muscle tone with increased tendon reflexes =

spasm

Increase in Ca2+ concentration in sarcoplasm _____________ contraction

starts

Decrease in Ca2+ concentration in sarcoplasm _____________ contraction

stops

When muscle fibers are relaxed the SR ________ Ca2+

stores

A 2nd stimulus after refractory period of 1st but before skeletal muscle fiber relaxed will cause the 2nd contraction to be ________ than the 1st; this is called _________ ______________

stronger wave summation

Dilated ends sac on sarcoplasmic reticulum =

terminal cisterns

A bands extend the entire length of _______ filaments

thick

I band contains only _____ filaments

thin

to sustain muscle _________ motor units alternate on / off

tone

Terminal cisterns butt against T-tubules on both sides to form a _______

triad

When a muscle is relaxed myosin is blocked from binding to actin by ________________ the covers the myosin binding sites on actin

tropomyosin

When Ca2+ binds ___________ it causes shape change which moves tropomyosin so contraction can begin

troponin

tropomyosin is held in place by

troponin

2 regulatory proteins that are part of thin filaments are

troponin tropmyosin

VGC-Na+ channels are located on T ____________ ; main role is to trigger opening of Ca2+ release channels in ______________ ____________ of SR,

tubules terminal cisterns

_________ contraction = brief contraction

twitch

Sustained but wavering contraction with partial relaxation = __________ ___________________

unfused tetanus

The force of muscle contractions _________

varies

Muscle fibers with low myoglobin are the color __________ equivalent of ________ meat

white white

___________ contraction = muscle shortens and pulls on structure to produce movement

Concentric

ATP formation from CP occurs rapidly, therefore, it is the ____ source of energy when muscle contraction begins

1st

If 2 stimuli applied, 1 after another, muscle respond to only _____

1st

Ration of thin : thick filaments

2:1

___________ contraction - causes more muscle damage

Eccentric

___________ contraction - muscle lengthens, tension exerted by myosin cross-bridges to resist movement load slowing lengthening

Eccentric

______mysium - surrounds muscle fiber cells; contains muscle stem cells; mostly reticular fibers

Endomysium

____mysium - separates muscle from surrounding tissues

Epimysium

Z discs pass through center of __ band

I

__ Band is lighter and less dense

I

__ zone = middle sarcomere, holds thick filaments together in center of H zone

M

__________________ of muscle is in rows near contractile muscle proteins so ATP can be produced fast

Mitochondria