Skeletal Muscle Physiology Flashcards

1
Q

Contractility

A

ability of a muscle to shorten. bring bones together, role in movement and posture

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2
Q

Excitability

A

caapcity of a muscle to respond to a chemical or electrical stimulus

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3
Q

Extensibility

A

unstimulated muscle passively stretch to and beyond resting length

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4
Q

Elasticity

A

ability of muscle to recoil to orginal resting length

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5
Q

Series Elastic components

A

tendons become taut during contraction of muscle

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6
Q

Parallel elastic components

A

cell membranes

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7
Q

Skeletal

A

attached to bones. multiple nuclei per cell, located on outer edges. Striated under voluntary and involuntary reflex control

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8
Q

cardiac

A

heart. single nucleus at the center.Striated, involuntary and intercalated disks

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9
Q

Smooth

A

walls of hollow organs, blood vessels, eyes, glands, skin. single nucleus located at center. Not striated, involuntary, gap junstions

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10
Q

Tendons

A

fibrous connective tissue muscle and bone. Elastic anchors

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11
Q

Muscle head

A

Muscles end attached to more stationary of two bones

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12
Q

Muscle insertion

A

muscle end attached to bone with greatest movement

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13
Q

Muscle Belly

A

largest portion of muscle between head and insertion

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14
Q

Synergist

A

seperate muscles that work together to cause movements

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15
Q

Agonist

A

muscle causing action when its contracted

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16
Q

antagonist

A

opposite of agonist. relaxes during agonist contraction

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17
Q

Parallel fiber architecture

A

parallel to the longitudinal axis of the muscle

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18
Q

Pennate

A

fibers are at an angle to longitudinal axis. generate greater for per mass but have shorter range

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19
Q

Multinucleated syncytium

A

developmental origin as fusion of mononucleated cells. Elongated nuclei, cylinderical with tapered ends

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20
Q

Myoblasts

A

lack of myofibrils. fused together to become myotubes

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21
Q

Myotubes

A

develop myofibrils and specialized organelles for contraction

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22
Q

Sarcomere

A

fundamental contractile unit muscle fibers. Contains family of proteins that is anchoring framework and contractile apparatus. causes sarcomere length to shorted. The distance between striations

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23
Q

Sarcolemma

A

outer membrane that envelops skeletal muscles

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24
Q

Axon of motor neuron

A

connecting to send signals

25
Q

Transverse Tubule

A

invagination of external membrane of skeletal muscle. Allow spreading action potential to pass into depths of fiber allow coordination of Ca moblization from sarcoplasmic reticulum

26
Q

Sarcoplasmic reticulum

A

main calcium channel and storage unit

27
Q

Sarcoplasm

A

cytoplasm of striated muscle cells, where Ca2+ is sensed

28
Q

Actin

A

thin filament. anchored to z-disks

29
Q

Myosin

A

thick filament. overlap adjacent sets of thin filament

30
Q

H-zone

A

length between actin filaments

31
Q

A-band

A

length of myosin filiment

32
Q

Tropomyosin

A

protein that prevents interaction between actin and myosin

33
Q

Crossbridge Cycling

A

Resting fiber, crossbridge, powerstroke, release of crossbridge, reset for next binding

34
Q

Crossbridge cycling
Resting Fiber

A

Myosin head group not attached to actin. ADP and Pi remain bound to myosin ATPase

35
Q

Crossbridge cycling
Crossbridge

A

increase of Ca2+ in the sarcoplasam promotes the binding of the myosin to actin myofilament

36
Q

Crossbridge Cycling
Powerstroke

A

ADP and Pi release. Myosin head crossbridge orientation changes. Thick and thin filaments slide in opposite directions

37
Q

CrossBridge cycling
release cross bridge

A

a new molecule of ATP binds to the myosin head

38
Q

Crossbridge cycling
resent for next binding

A

ATP hydrolysis yields energy facilitating the myosin head to return to its orginal orientation. Myosin pulls z-disks closer together,ATP had byproduct ADP and Pi, energy neede to change conformation of myosin head,Ca2+ provides structure

39
Q

Action potential

A

Transmission of electrical signals along length of motor neuros. Rapid re-distribution of ions across plasma membrane driven by concentration gradients which depolarizes the membrane

40
Q

T tubules

A

enhance polarization signals

41
Q

Axon

A

along plasma membrane where action potential can propagate

42
Q

Axon terminals

A

form synapses with muscle fibers part of the same motor unit

43
Q

excitable cells

A

with stimulus, series changes in electrical characteristics of membrane causes propagation of message beginning outside cell

44
Q

Resting Potential

A

governed by Na+ and K+ gradients. high resting permeability to K+ and interior cell negative compared to K+

45
Q

Depolarization

A

above threshold value, Na+ channels open. allows influx of Na+ temporary overshoot into interior positive state

46
Q

Repolarization

A

voltage gated K+ channels open. allows influx of K+ and reestablish resting potential

47
Q

Resting Membrane Potential

A

energy gradient dependent on relative concentration, permeability of the membrane, driven by ion pumps to create ion gradient

48
Q

Ion channels

A

Membrane bound proteins that act as channel allow rapid movement of ions across excitable membranes

49
Q

Ion channel gating

A

opening and closing of ion channel pore in response to electrical or chemical signal

50
Q

selective permeability

A

each class of ion channel typically only accept one or several types of ions

51
Q

Dihydropyridine receptor(DHPR)

A

resides in the sarcolemma. voltage-sensitive channel, allows slow influx of ca. Interacts and activates the RyR

52
Q

Ryanodine Receptor(RyR)

A

Resides in sarcoplasmic reticulum membrane. Opens directly by activated DHPR. Allows stored Ca+ from SR to sacroplasm to activate contraction

53
Q

Motor Unit

A

motor neuron plus all muscle fibers to which it connects

54
Q

Innervation ratio

A

fibers per neuron, vary based functional requirements of muscle

55
Q

Increase # motor units

A

more motor units + greater force

56
Q

rate of stumuli

A

summation of twitches. More frequency=greater force

57
Q

Starting length of muscle fibers

A

near resting length = greatest force

58
Q

Density/number of Filaments

A

Greater #=more crossbridges =more force