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BIO-168-1903 > Muscular System > Flashcards

Muscular System Flashcards

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1
Q

What are the seven major functions of muscles?

A
  1. Movement of the body .
  2. Posture
  3. Respiration
  4. Body heat
  5. Communication
  6. Constriction of organs and vessels
  7. Contraction of heart
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2
Q

Four major functional properties of Muscles?

A
  1. Contractility
  2. Excitability
  3. Extensibility
  4. Elasticity
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3
Q

Contractility

A

Muscle shortens forcibly and opposing muscle lengthening is passive.

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4
Q

Excitability

A

The capacity of a muscle to respond to a muscle stimulus.

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5
Q

Extensibility

A

Muscle is able to extend beyond its normal resting state and still be able to contract.

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6
Q

Elasticity

A

Muscle springs back to its original resting length after it has been stretched.

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7
Q

Two main elements of muscle contractions?

A
  1. Electrical component
  2. Mechanical component
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8
Q

Three muscle fibers that respond to and transmit electrical signals?

A
  1. Sarcolemma
  2. Transverse Tubules
  3. Sarcoplasmic reticulum
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9
Q

Sarcolemma is a?

A

Plasma membrane of muscle fibers

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10
Q

Transverse Tubules are

A

Tube like inward folds of the sarcolemma

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11
Q

Sarcoplasmic reticulum

A

Highly specialized smooth endoplasmic reticulum in skeletal muscle fibers that stores high levels of Ca2+

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12
Q

Mitochondria and energy-storing glycogen granules constitute the cytoplasm, called the _____?

A

Sarcoplasm

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13
Q

Bundles of protein filaments are called?

A

Myofibrils

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14
Q

Muscle property of contractility is due to two main structures in muscle fibers called?

A
  1. Myofibrils
  2. Myofilaments (2 types)
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15
Q

The protein filaments in the myofibrils interact to ____ the muscle fiber during contraction?

A

Shorten

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16
Q

The ____ are threadlike structures that extend the entire length of the muscle fiber.

A

Myofibrils

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17
Q

There are two types of myofilaments?

A
  1. Actin myofilaments
  2. Myosin myofilaments
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18
Q

Actin myofilaments are Thin/Thick?

A

Thin filaments

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19
Q

Myosin myofilaments are thin/thick

A

Thick filaments

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20
Q

The ______ are the structural and functional units of the skeletal muscle.

A

Sacromeres

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21
Q

The _____ in the sarcomere provides the mechanical aspect of muscle contraction.

A

Myofilaments

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22
Q

The ____ is the smallest portion of the muscle that contracts.

A

Sarcomere

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23
Q

What is the neuromuscular junction?

A

It is the site where the nerve fiber innervates the muscle fiber.

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24
Q

When the membrane potential of a cell becomes more positive than its resting potential, the cell is

A

depolarized

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25
Q

Which statement explains how the shortening of the sarcomere leads to contraction of the whole muscle?

A

Whole muscle is made up of subunits whose smallest functional unit is the sarcomere. When one shortens, the other units by default have shortened.

When sarcomeres shorten, myofibrils which make up the muscle fiber also shorten because the myofibrils consist of sarcomeres joined end to end.

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26
Q

Hyperpolarization occurs because voltage-gated Blank______ channels stay open longer than required to reach resting membrane potential.

A

potassium

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27
Q

Describe myoglobin.

A

A molecule that stores oxygen in muscles

28
Q

A neuromuscular junction is also called a

A

synapse

29
Q

A shift in the membrane potential towards a less negative value is called a

A

depolarization

30
Q

During muscle contraction, the muscle shortens when

A

sarcomeres and muscle fascicles shorten

31
Q

What does the sliding filament theory of muscle contraction predict about myofilaments and sarcomere length?

A

During contraction, the thin myofilaments slide past the thick myofilaments.

During contraction, the total length of the sarcomere decreases.

32
Q

Which factors contribute to the generation of the resting membrane potential? (select all that apply)

A

Diffusion of ions down their concentration gradients through the membrane

The electrical attraction of cations and anions to each other

Selective permeability of the membrane, allowing some ions to pass more easily than others

33
Q

Myoglobin would be most abundant in what type of muscle fiber?

A

Oxidative (slow) fibers

34
Q

Hypertrophy of muscles results from an increase in the

A

size of muscle fibers

35
Q

Acetylcholine diffuses across a synaptic cleft and binds to ligand-gated Blank______ channels.

A

sodium

36
Q

The portion of the sarcomere that binds Blank______ is troponin.

A

calcium

37
Q

Choose characteristics of the sodium-potassium ion pump.

A

Pumps sodium out of the cell against its concentration gradient

Uses ATP

38
Q

Which of the following ionic movements causes the repolarization phase of the action potential?

A

The movement of a large number of potassium ions out of the cell.

39
Q

Acetylcholine released into the synaptic cleft is rapidly broken down to acetic acid and choline by

A

an enzyme

acetylcholinesterase

40
Q

Describe what must occur before tropomyosin can move away from the myosin binding sites.

A

Calcium must bind to troponin

41
Q

Within a myofibril, calcium-binding sites are found on

A

troponin

42
Q

Acetylcholinesterase prevents Blank______ from accumulating within the synaptic cleft.

A

acetylcholine

43
Q

When an action potential reaches the axon terminal of a motor neuron, which substance diffuses into the axon terminal?

A

Calcium

44
Q

Choose characteristics of the sodium-potassium ion pump.

A

Pumps sodium out of the cell against its concentration gradient

Uses ATP

45
Q

Which of the following ionic movements causes the repolarization phase of the action potential?

A

The movement of a large number of potassium ions out of the cell.

46
Q

Acetylcholine released into the synaptic cleft is rapidly broken down to acetic acid and choline by

A

acetylcholinesterase

an enzyme

47
Q

When calcium enters an axon terminal,

A

acetylcholine is released from synaptic vesicles

48
Q

During relaxation, calcium levels in the sarcoplasm

A

fall

49
Q

When an action potential reaches the axon terminal of a motor neuron, which substance diffuses into the axon terminal?

A

Calcium

50
Q

When the muscle is no longer actively contracting, ATP is used to

A

break the bond between actin and myosin

re-energize the myosin head

move calcium back into the sarcoplasmic reticulum

51
Q

Which of the following molecules covers the active sites on the G-Actin molecule when the muscle fiber is relaxed?

A

Tropomyosin

52
Q

Slow twitch or Type I muscle fibers

A

have well developed blood supplies

have high aerobic capacity but low anaerobic capacity

have the highest resistance to muscle fatigue

53
Q

When a muscle fiber relaxes, ATP is used

A

to transport of Ca 2+ into the sarcoplasmic reticulum

to maintain the normal concentrations of Na+ and K + across the sarcolemma

to detach the myosin head from actin

54
Q

The molecule that inhibits the binding of myosin to actin by blocking the binding site is

A

tropomyosin

55
Q

Both fast-twitch and slow-twitch muscle fibers can increase in Blank______ as a result of exercise and training.

A

size

capacity

strength

56
Q

Fast twitch or Type II muscle fibers

A

have a fast form of myosin ATPase, which allows them to break down ATP more rapidly than other muscle fiber types

respond rapidly to nervous stimulation

57
Q

Identify the effects of exercise on skeletal muscles. Exercise can

A

Increase the number of myofibrils

Increase the number of mitochondria within a myofiber

Increase the concentration of metabolic enzymes

58
Q

Describe what is meant by the threshold. It is

A

the minimum voltage that must be reached in order to cause the opening of the voltage gated ion channels of the axon hillock

59
Q

Which are effects of exercise on skeletal muscles?

A

Increase in the number of myofibrils

Interconversion of type IIa and type IIb fibers

Increase in the vascularity of muscle

Increase in the number of mitochondria within a myofiber

60
Q

The depolarization phase is due to the opening a closing of Blank______ ion channels.

A

voltage-gated

61
Q

Each myosin molecule is composed of Blank______ heavy chains and Blank______ myosin heads.

A

2, 2

62
Q

Cardiac muscle cells are Blank______, which allows them to contract spontaneously and rhythmically.

A

autorhythmic

63
Q

Enlargement of muscles in children and adults that results from an increase in the size of each muscle fiber is called

A

hypertrophy

64
Q

The structure that is a modified form of smooth endoplasmic reticulum located in muscle cells is called__________ reticulum.

A

sarcoplasmic

65
Q

Which of the following are characteristics used in the naming of individual muscles?

A

Bone attachment sites

Number of heads

Function

66
Q

Which are characteristics used in the naming of muscles?

A

Origin and insertion

Size and shape

Region of the body

BIO-168-1903 (11 decks)

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