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Human Structure and Function I > Chapter 5: Muscular system > Flashcards

Chapter 5: Muscular system Flashcards

1
Q

What are the two types of myofilaments are muscle contractions dependent on?

A

Actin and myosin

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2
Q

What is the muscle plasma membrane called?

A

sarcolemma

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3
Q

What is the cytoplasm of a muscle cell called?

A

sarcoplasm

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4
Q

What are the three prefixes that refer to muscle?

A

myo, mys, and sarco

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5
Q

What are the three types of muscle?

A

Skeletal
Cardiac
Smooth

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6
Q

What are the function characteristics of muscle? 4

A

-Excitability or irritability – the ability to receive and respond to stimuli
-Contractility – the ability to shorten forcibly
-Extensibility – the ability to be stretched or extended
-Elasticity – the ability to recoil and resume the original resting length

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7
Q

Which muscle makes up 40% of the body’s weight

A

Skeletal muscle tissue

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8
Q

Which muscle tissue has striations?

A

Skeletal, Cardiac

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9
Q

Which muscle tissue is uninucleated?

A

cardiac and smooth

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10
Q

What is the origin of the skeletal muscle?

A

Where the short connective tissue fibers attach to the less movable attachment

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11
Q

What is the insertion of the skeletal muscle?

A

Where the connective tissue of the muscle forms a tendon in the more movable attachment

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12
Q

What is the function of the skeletal muscle?

A

 Force production for locomotion and breathing (diaphragm).
 Force production for postural support.
 Heat production during cold stress.

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13
Q

What is the endomysium? 3 points

A

fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber

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14
Q

What is the perimysium? 2 points

A

fibrous connective tissue that surrounds groups of muscle fibers called fascicles

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15
Q

What is the epimysium?

A

an overcoat of dense regular connective tissue that surrounds the entire muscle

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16
Q

How long and thick is one muscle fibril cell?

A

10-100 micrometer in diameter, and up to several cm long

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17
Q

Every muscle cell is a synctium. What does that mean?

A

produced by a fusion of ebryonic cells

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18
Q

What do sarcoplasm contain a lot of? 2

A

glycosomes and myoglobin

Glycosomes are membranes containing glycolytic enzymes.

They break down glucose into two halfs so that it could be converted to ATP

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19
Q

What does it mean to say that muscle fibers act in an all or nothing way?

A

They either all contract or all relax

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20
Q

What do fibers contain? 4

A

Organelles, myofibrils, sarcoplasmic reticulum and T-tubules

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21
Q

What are the dark and light parts of a myofibril called?

A

Dark A bands and light I bands

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22
Q

Which part of the muscles make up most of the muscle mass?

A

myofibrils

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23
Q

What is the smallest contractile unit of as muscle fiber?

A

Sarcomere

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24
Q

What are the two types of myofilaments?

A

Thick-myosin
Thin-actin

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25
Q

Which zone dissapears when a sarcomere contracts?

A

The zone where only myosin is present (H-Zone)

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26
Q

What is the function of the z disc?

A

coin-shaped sheet of proteins (connectins) that
anchors the thin filaments and connects myofibrils to
one another

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27
Q

What protein is present in the M zone?

A

desmin

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28
Q

What is myosin composed of?

A

a rodlike tail and two globular heads

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29
Q

What is the head and the tail of myosin made up of? 4

A

Head - two smaller, light polypeptide chains called bridges
Tail - two interwoven heavy polypeptide chains

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30
Q

What are singular spherical actin subunits called?

A

G actin

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31
Q

What are the regulatory subunits bound to actin called? 2

A

tropomyosin and troponin

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32
Q

Where do T-tubules penetrate the cells?

A

A-band and I-band junction

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33
Q

What is the function of terminal cisternae?

A

regulation of intracellular calcium levels

34
Q

What are triads?

A

T tubules associations with the paired terminal cisternae

35
Q

What is the function of T-Tubules?

A

conduct impulses to the deepest regions of the muscle

36
Q

Which structures provide tightly linked signals for muscle contraction

A

T-Tubules and sarcoplasmic reticulum

37
Q

What part of the muscles act as voltage sensors?

A

T-Tubules protiens

38
Q

What is the function of sarcoplasmic reticulum foot protiens?

A

receptors that regulate Ca2+
release from the SR cisternae

39
Q

Explain the sliding filament model. 4

A
  • In the relaxed state, thin and thick filaments overlap
    only slightly.
  • Upon stimulation, myosin heads bind to actin and sliding begins.
  • Each myosin head binds and detaches several times during contraction, to generate tension and propel the thin filaments to the center of the sarcomere.
  • As this event occurs throughout the sarcomeres, the muscle shortens.
40
Q

State and explain the four sequential events of contraction

A
  • Cross bridge formation – myosin cross bridge attaches to actin filament
  • Working (power) stroke – myosin head pivots and pulls actin filament toward M line
  • Cross bridge detachment – ATP attaches to myosin head and the cross bridge detaches
  • “Cocking” of the myosin head - energy from hydrolysis of ATP cocks the myosin head into the high-energy state
41
Q

What is the excitation contraction coupling?

A

It is the communication between the electrical events and the mechanical events that happen as a response

42
Q

What happens when calcium ions binds troponin?

A

The blocking action of tropomyosin ceases and Actin active binding sites is exposed

43
Q

What is the function of excitation contraction coupling?

A

to transform the electrical stimulation of the sarcolemma into muscle contraction

44
Q

What is the one crucial event that starts muscle contraction?

A

The stimulus by nerve terminal

45
Q

What is the neuromuscular junction?

A

junction between the motor nerve and skeletal muscle fiber

46
Q

What is the axonal terminals

A

the terminal end of the
axon

47
Q

What happens when when a nerve impulse reaches
the end of an axon at the neuromuscular junction?

A
  • Voltage-regulated calcium channels open and allow Ca2+ to enter the axon.
  • Ca2+ inside the axon terminal causes axonal vesicles to fuse with the axonal membrane.
48
Q

What happens after the fusion of axonal vesicles in the membrane?

A

-Releases ACh into the synaptic cleft via
exocytosis.
-ACh diffuses across the synaptic cleft to ACh
receptors on the sarcolemma.
-Binding of ACh to its receptors initiates an action
potential in the muscle.

49
Q

What is the role of acetylcholine at the nerve terminal? 3

A

-ACh binds its receptors at the motor end plate (on
sarcolemma)
-Binding opens chemically (ligand) gated channels
-Na+ diffuses inwards and the interior of the sarcolemma becomes less negative

50
Q

What causes depolarization in the skeletal muscle?

A

The opening of sodium channels, when the sodium enters the cell and potassium leaves it

51
Q

How does depolarization spread? And what are the names given to each stage?

A

-Initially, this is a local electrical event called end plate
potential
-Later, it starts an action potential that spreads in all
directions across the sarcolemma

52
Q

Where does generation of active potential happen?

A

In muscle fiber

53
Q

How can you describe a twitch movement?

A

A single contraction that goes into rest afterwards

54
Q

How can you describe a summing of contractions?

A

A second nerve impulse that is sent before the first is recovered

55
Q

How do you describe an unfused tetanus movement?

A

Severeal impulses sent before first comes to rest

56
Q

How do you describe an fused tetanus movement?

A

when there is no relaxation of the muscle fibers between stimuli

57
Q

When muscles cross a joint anteriorly what movement does it produce?

A

Felxion

58
Q

When muscles cross a joint posteriorly what movement does it produce?

A

Extension

59
Q

When muscles cross a joint medially what movement does it produce?

A

Adduction

60
Q

When muscles cross a joint laterally what movement does it produce?

A

Abduction

61
Q

Muscles located within the same group of muscles share the same what?

A

Action, innervation and blood supply

62
Q

Muscles dorsal to upper limb bones produce which movement?

A

Extension

63
Q

Muscles dorsal to lower limb bones produce which movement?

A

Flexion

64
Q

What are skeletal muscle names based on? (6)

A
  • Direction of fascicles and muscle fibers
  • Location of attachments
  • Number of origins
  • Action
  • Location
  • Shape
  • Relative size
65
Q

What are the functional classification of muscles?

A
  • Prime move
  • Antagonist
  • Synergist (adds extra force or reduces undesirable movements)
  • Fixator
66
Q

What are the types of fascicle arrangements?

A
  • Convergent
  • Parallel:
    Straplike
    Fusiform
67
Q

What is in an example of parallel strap like muscle?

A

Sartorius

68
Q

What is an example of fusiform parallel muscle?

A

Biceps brachii

69
Q

What is an example of a convergent muscle?

A

Pectoralis major

70
Q

What is a type of unipennate muscle?

A

Extensor digitorum longus

71
Q

What is an example of bipennate muscle?

A

Rectus femoris

72
Q

What is an example of multipennate muscle?

A

Deltoid

73
Q

What is another name for circular muscles ?

A

Sphincter

74
Q

What is an example of a circular muscle?

A

Orbicularis Oris/oculi

75
Q

Describe first class lever

A

Effort. Load
|. Fulcrum. |

76
Q

Describe class 2 levers

A

|. Load
Effort. |. Fulcrum

77
Q

Describe third class lever

A

|. Load
Fulcrum. Effort |

78
Q

What is an example of first class lever?

A

Scissors

79
Q

What is an example of second class lever?

A

Wheelbarrow

80
Q

What is an example of third class lever?

A

Tweezers

81
Q

What is the most used lever in body?

A

Third class

82
Q

What is the law of levers?

A

When the effort is farther from the fulcrum than the load, the lever operates at a mechanical advantage

Human Structure and Function I (7 decks)

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