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NCSF > 2 ' Muscle Physiology > Flashcards

2 ' Muscle Physiology Flashcards

1
Q

Muscular system is comprised of three types of muscle tissue:

A

Skeletal, cardiac, and smooth

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2
Q

Skeletal

A

Striated muscle attached to the skeleton used to facilitate movement by applying force to bones and joints via contractions

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3
Q

Cardiac

A

Involuntary, mononucleated, striated muscle found exclusively within the heart

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4
Q

Smooth

A

Non-striated muscle found within the “walls” of hollow organs such as the bladder, uterus, and GI tract

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5
Q

Signals initiated in the brain stimulate the nervous system, causing muscles to contract and produce tension

A

True

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6
Q

Motor information is carried via actin potentials from the central nervous system (CNS)

A

True

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7
Q

Action potential

A

Wave-like change in the electrical properties of a cell membrane that results from the difference in electrical charge between the inside and outside of the membrane and causes the muscle call to contract

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8
Q

Capillaries

A

Ting blood vessels that connect arteries and veins, forming an intricate network around body tissues in order to distribute oxygen and nutrients to the cells and remove waste substances

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9
Q

Myofibrils

A

Cylindrical structures containing the myofilaments actin (thin filament) and myosin (thick filament)

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10
Q

Surrounding myofibrils are a calcium-housing network called the sarcoplasmic reticulum (SR), tube-like structures that transfer signals called T-tubules, and mitochondria, which are used to produce energy

A

True

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11
Q

SR

A

A tubular network that surrounds each individual myofibril and acts as a storage site for calcium within the skeletal muscle

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12
Q

T-tubules

A

Tubules that pass in a transverse manner from the sarcolemma across a myofibril of striated muscle passing signals within the cell

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13
Q

Tension is created in a group of muscle fibers by initiation of the action potential

A

True

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14
Q

The action potential travels via an electrical current through the spinal cord and is transferred to the peripheral nervous system (PNS)

A

True

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15
Q

The current runs through outer levels of muscle tissue to very small nerve fibers called motor neurons which connect to the particular fibers to be contracted

A

True

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16
Q

Motor unit

A

Motor neuron and all the muscle fibers it innervates

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17
Q

Inside the muscle fiber, the following must occur to allow for a contraction (sliding filament theory):

A

5 actions

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18
Q

Action potent ion travels down the T-tubules and stimulates the SR

A

True

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19
Q

Calcium is released from the SR, acting as a key to unlock the bond between the thin contractile filament and troponin

A

True

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20
Q

Troponin molecule moves, rotating the tropomyosin molecule away from binding site

A

True

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21
Q

Myosin is free to attach to actin for in a cross-bridge

A

True

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22
Q

Adenosine triphosphate (ATP) is split at the myosin/actin attachment site and energy is released, allowing the muscle fiber to contract and produce force

A

True

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23
Q

A muscle fiber is either in a state of producing maximum tension or not productive any tension at all; this is known as the “all of none” principle

A

True

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24
Q

Motor units are stimulated within the desired muscle to produce movement

A

True

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25
Q

The greater the number of motor units stimulated, the more fibers recruited, producing more tension

A

True

26
Q

Total skeletal muscle force dictates how many muscle fibers are recruited for the concentration

A

True

27
Q

Two type of motor unit firing patterns:

A

Synchronized firing and Asynchronous firing

28
Q

Synchronized firing

A

Employed during high-output demands involving fast-twitch fibers and warranting significant fiber recruitment m

29
Q

Asynchronous firing

A

Employed during endurance activities involving slow-twitch fibers which conserve motor unit potential, allowing prolonged work

30
Q

The ability to increase force production within a muscle through training is dependent on adaptations that occur to both:

A

Muscle fibers (size) and the nervous system (recruitment, firing rate, firing synchronicity)

31
Q

Force production improvements can occur without the addition of new muscle due to efficiency changes related to motor unit recruitment

A

True

32
Q

Inability to produce force, most notably due to intensity of exercise occurs in the CNS and PNS

A

True

33
Q

Disrupts the motor units ability to produce force

A

True

34
Q

As the rate of motor unit fatigue increases, performance proportionately declines

A

True

35
Q

Rest interval or rest period

A

Period of time between repeated actions in an exercise; energy system specified and based on physical condition

36
Q

Muscle cell recovery is dependent on the return of intracellular energy supply; circulatory-based, cellular by-product removal; and the delivery of O2

A

True

37
Q

Recovery period is a Period of time between exercise bouts, during which muscle fibers will

A

Replenish their energy reserves, repair any damage resulting from the production of force, and fully return to normal pre-exertion levels

38
Q

Two types of isotonic contractions involve lengthening or shortening of a working muscle

A

Eccentric contraction and Concentric contraction

39
Q

Eccentric contraction

A

Muscle lengthens; negative work is produced; movement is decelerated

40
Q

Concentric concentration

A

Muscle shortens; positive work is produced; movement is accelerated

41
Q

Isometric contractions

A

Mostly used for stability; represent tension in the muscle that helps maintain position but does not cause acceleration or deceleration forces

42
Q

Employed by stabilizing muscles to control movements and prevent undesirable actions

A

True

43
Q

Type of muscle fiber recruited to produce a contraction depends on the amount of force needed

A

True

44
Q

Three types of skeletal muscle fibers

A

Type IIb, type IIa and type I

45
Q

Type IIb

A

High force-producing fibers, or face glycolytic fibers

46
Q

Type IIa

A

Intermediate force-producing fibers, or fast oxidative/glycolytic fibers

47
Q

Type I

A

Low force-producing fibers, or slow oxidative fibers

48
Q

Fast-twitch fiber characteristics

A

Large diameter size, high force output but quick to fatigue (30-50g per motor unit), densely picked myofibrils, large glycogen reserves, preferentially recruited for high-power output activities, increases in size and strength when trained under conditions of short duration and high intensity and preferentially function using anaerobic metabolic systems

49
Q

Slow-twitch fiber characteristics

A

50% smaller than fast-twitch fibers, produce low amounts of force (5g per motor unit), primarily use aerobic metabolic systems, better suited for endurance activities - fatigue-resistant, extensive capillary network and high mitochondrial density and higher amounts of myoglobin, increasing oxygen reserves in cells

50
Q

Myoglobin

A

O2-transporting protein of muscle; resembles blood hemoglobin in function

51
Q

Type IIa intermediate fiber characteristics

A

Used for activities requiring prolonged duration and/or elevated force, composition of both fast- and slow-twitch fiber characteristics, and adaptations support both anaerobic and aerobic activities

52
Q

Genetically predetermined; training will not change concentrations of fibers within segments of the body

A

True

53
Q

Postural muscles maintain a higher concentration of slow- twitch fibers

A

True

54
Q

Soleus, deep muscles of the back, and the rectus abdominis must contract continuously to maintain upright posture and is not designed for rapid, high-force output; experience limited improvements in power/hypertrophh

A

True

55
Q

Slow-twitch fibers do not convert to fast-twitch fibers (or vice versa), but muscle can become better suited to training stimulus due to the following changes:

A

Neural stimulation, capillary and mitochondrial density and enzyme concentration

56
Q

Muscle tone

A

Some motor units in a muscle are always active even when the muscle is not contracting

57
Q

Two primary proprioceptors used to manage the tonicity of muscle tissue

A

Muscle spindles and golgi tendon organs

58
Q

Muscle spindles

A

Intrafusal fibers that lie parallel to normal muscle fibers which relay information to sensory neurons regarding changes in tissue length and tension

59
Q

When rapidly stretched, they respond with a stretch reflex to initiate a concentration that limits an overstretch and potential damage to the muscle

A

True

60
Q

Golgi tendon organs

A

Sensory receptors found within muscle tendons that communicate information to motor neurons regarding the presence of excessive tension that may cause damage

61
Q

If tension in a muscle is too great, they send inhibitory signals to reduce motor neuron activity and thereby reduce the force of muscular contraction

A

True

NCSF (22 decks)

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