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PHYSIOLOGY > Muscle Physiology Part 1 > Flashcards

Muscle Physiology Part 1 Flashcards

1
Q

They are highly specialized for the 💡conversion of chemical energy to mechanical energy by using 💡ATP (adenosine triphosphate).

These are 💡excitable cells, which have the 💡capability to produce response.

A

MUSCLE CELLS

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2
Q

The capability of muscle cells to convert 💡chemical energy to mechanical.

NOTE: - It is a characteristic of 💡skeletal muscles which differs from nerve cells.

A

Contraction

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3
Q

MUSCLE CELLS has the capacity to transmit __ along the cell membrane.

A

Action potential

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4
Q

In muscle cells, force is generated by the interaction of (1) __, a process that requires transient elevation of __.

A

(1) actin and myosin molecules

2) intracellular Calcium (Ca++

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5
Q

Skeletal muscles will not contract unless __.

A

Stimulated by neurons

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6
Q

Smooth & cardiac muscle will contract without __ but their contraction can be influenced by the nervous system.

A

Nervous stimulation

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7
Q

PHYSIOLOGIC PROPERTIES OF SKELETAL MUSCLES

A 
Irritability / Excitability
Conductivity
Contractility
Authomaticity
Rythmicity
Unitary
Multi-unit
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8
Q

It is the ability to 💡generate an action potential.

A

Irritability / Excitability

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9
Q

It is the ability to 💡transmit action potential along the cell membrane.

A

Conductivity

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10
Q

It is the ability to convert 💡chemical energy into a mechanical response.

A

Contractility

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11
Q

THREE MAJOR TYPES OF MUSCLES:

A

Skeletal
Cardiac
Smooth

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12
Q

It is the only type of muscle that is 💡not striated.

A

Smooth muscle

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13
Q

Location of skeletal muscle.

A

Begins and ends in a tendon

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14
Q

Location of cardiac muscle.

A

Heart

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15
Q

Location of smooth muscle.

A

Hollow organs, blood vessels, eyes

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16
Q

What is the shape of skeletal muscle?

A

Long, unbranched, cylindrical, multinucleated (nucleus located peripherally)

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17
Q

What is the shape of cardiac muscle?

A

Cylindrical, branched/bifurcation nucleated/ mononucleated (centrally)

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18
Q

What is the shape of smooth muscle?

A

Spindle-shape, mononucleated (usually centrally located)

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19
Q

Gap junction/ syncytial connections is 💡only absent with what type of muscle?

A

Skeletal muscle

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20
Q

💡Innervation for the muscle cells.

A

Skeletal muscle: Voluntary (CNS)

Smooth and cardiac muscles: Involuntary (ANS)

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21
Q

What is the function of skeletal muscle?

A

Locomotion, Work production, breathing

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22
Q

What is the function of cardiac muscle?

A

Biomechanical pump

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23
Q

What is the function of smooth muscle?

A

Peristalsis, GIT, GUT, Respiratory

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24
Q

Pace maker cells is 💡only absent with what type of muscle?

A

Skeletal muscle

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25
Q

It has the ability to 💡generate impulses even without stimulation.

A

Pacemaker Cells

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26
Q

Syncytial function once stimulates one cardiac muscle cell all will contract, function as one. (once the heart is formed during fetal life, it starts its activity all throughout life, doesn’t need stimulation because
of their pace makers)

A

True

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27
Q

Pacemaker cells syncytial function (unitary smooth muscle cells present in hollow organs)

A

True

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28
Q

Sarcomere is 💡only absent with what type of muscle?

A

Smooth Muscle

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29
Q

Z-line is 💡only absent with what type of muscle?

A

Smooth Muscle (Dense body)

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30
Q

Intermediate Filaments is 💡only present with what type of muscle?

A

Smooth Muscle (desmin and vimentin)

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31
Q

Regulation of Contraction in Skeletal Muscle

A

Thin filament regulated

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32
Q

Regulation of Contraction in Cardiac Muscle

A

Thin filament regulated

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33
Q

Regulation of Contraction in Smooth Muscle

A

Thick filament regulated

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34
Q

What is the 💡Source of Calcium in Skeletal Muscle

A

Sarcoplasmic Reticulum

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35
Q

What is the 💡Source of Calcium in Cardiac and Smooth Muscle

A

Sarcoplasmic Reticulum and ECF

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36
Q

Troponin is 💡only absent with what type of muscle?

A

Smooth Muscle (Calmodulin)

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37
Q

T-tubule (Sarcotubular system) is 💡only absent with what type of muscle?

A

Smooth Muscle (calveolae)

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38
Q

T-tubule of Skeletal muscle

A

Triad (A and I band) less developed

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39
Q

T-tubule of Cardiac Muscle

A

Diad (Z line) well

developed

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40
Q

💡Excitation Contraction Coupling of Skeletal muscle and Cardiac Muscle

A

Electrochemical Coupling

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41
Q

💡Excitation Contraction Coupling of Smooth Muscle

A

Pharmaco-mechanical Coupling

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42
Q

It is the ability to 💡produce an action potential even without stimulus

A

Authomaticity

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43
Q

It refers to the 💡regularity of impulse

A

Rythmicity

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44
Q

The only 💡one nerve but supplies several muscle fibers through gap junctions

A

Unitary

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45
Q

MUSCLES PRIMARY FUNCTIONS

A

Generate a 💡force or 💡movement in response to a physiologic stimulus by transducing 💡chemical or electrical stimuli into a 💡mechanical response triggered by a 💡rise in free cytosolic Ca++ concentration.

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46
Q

It surrounds the 💡whole skeletal muscle

A

Epimysium

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47
Q

It is a several 💡bundle inside the whole skeletal muscle

A

Fasciculus

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48
Q

It is a connective tissue that 💡covers fasciculi

A

Perimysium

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49
Q

These are 💡structures inside one fasciculus, 💡building block of skeletal muscle (💡structural and functional unit); innervated by the nerve.

A

Muscle fibers

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50
Q

It is connective tissue that 💡covers muscle fiber

A

Endomysium

51
Q

It is is a specialized region of the tendon where the ends of the muscle fibers interdigitate with the tendon for the transmission of the force of contraction of the muscle to the tendon to effect movement of the skeleton (discussed later in this section).

A

Myotendinous junction

52
Q

What will happen if epimysium, perimysium, and endomysium go out of the muscle.

A

It’ll thicken and become a tendon.

53
Q

ORGANIZATIONS of Skeletal Muscle

A 
 Origin
 Insertion
 Point of attachment on the far side
 Distal
 Tendons (connective tissue)
 Connects muscle to a bone
 Flexor muscle
 Contraction decreases the angle of joint
 Extensor muscle
 Contraction increases the angle of joint
54
Q
  • 💡Point of attachment closest to the spine

- More proximal

A

Origin

55
Q

At the ends of the muscle, the connective tissue layers come together to form a __, which 💡attaches the muscle to the skeleton.

A

Tendon

56
Q

The connective tissue layers of the tendon are composed mainly of __, and they serve to 💡transmit movement of the actin and myosin molecules to the skeleton to effect movement.

The connective tissue layers also contribute to 💡passive tension of muscle and 💡prevent damage to the muscle fibers as a result of overstretching or contraction (or both).

A

Elastin and collagen

fibers

57
Q

These are 💡structures inside a muscle fiber made up of 💡alternating actin and myosin filaments (thick and thin filaments).

They are 💡subdivided longitudinally into sarcomeres (2 um)

A

Myofibrils

58
Q

💡Actin and myosin filaments in muscle fiber are collectively called?

They are 💡key molecular regulators of the contraction in cardiac and skeletal muscles.

A

Myofilaments

59
Q

They are demarcated by 💡2 dark lines (Z lines) and represents a 💡repeating contractile unit in skeletal muscle.

A

Sarcomere

60
Q

It contains 💡thin filaments composed of actin.

Located on 💡either side of the Z line

Light band

A

I band

61
Q

It contains 💡thick filaments composed of myosin.

Located 💡between two I bands within a sarcomere.

There is an 💡overlapping of thick and thin filaments (dark area at the end)

A

A band

62
Q

It 💡light area in the center of sarcomere (💡inside A band) that contains 💡myosin (thick) but no actin (thin) and is 💡divided centrally by M band.

A

H zone/band

63
Q

It is evident in the 💡center of sarcomere; critical for 💡organization and alignment of thick filaments

It signifies the 💡polarity of arrangement of myosin molecule.

A

M line

64
Q

It is the 💡division in between myofibrils

It is a two dark lines that demarcates sarcomere.

A

Z line

65
Q

It 💡surrounds myofibril; 💡storage and release of Calcium.

A

Sarcoplasmic reticulum (smooth ER)

66
Q

It is the 💡cell membrane in muscle fiber.

A

Sarcolemma

67
Q

These are 💡invaginations of sarcolemma; extracellular network.

A

T tubules

68
Q

These are 💡portion of SR nearest the T tubules; 💡site of Ca++ release; 💡critical for contraction of skeletal muscle.

A

Terminal cisternae

69
Q

It is critical for 💡reaccumulating of Ca++ in the SR; for 💡relaxation of muscle.

A

SERCA (Sarcoplasmic Endoplasmic Reticulum Ca++ ATPase)

70
Q

The thick myosin filaments are 💡tethered to the Z line by cytoskeletal protein called __.

It may also serve as a 💡mechanosensory and influence 💡gene expression and 💡protein degradation in a mechanical activity–dependent manner.

A

Titin

71
Q

Different structure associated with cell membrane of muscle:

A

Muscle end plate
T-tubule
Synaptic fold in motor end plate
Terminal cistern.

72
Q

It is an 💡area of sarcolemma in 💡contact with nerve that thickens.

A

Muscle end plate

73
Q

An area where there is 💡invagination of sarcolemma; 💡transmission of action potential from membrane to fiber (in cardiac muscle this is where it transmits action potential)

A

T-tubule

74
Q

It is important because on top of it is where 💡acetylcholine receptor is located which is a 💡ligand gated channel and on the folds is where 💡voltage gated channel is located.

A

Synaptic fold in motor end plate

75
Q

As Sarcoplasmic Reticulum approaches T tubule, it enlarges/ dilates and forms the __.

A

Terminal cistern

76
Q

SARCOTUBULAR SYSTEM is made up of?

A

T System and a Sarcoplasmic Reticulum

77
Q

SARCOTUBULAR SYSTEM of Skeletal Muscle

A

It is made up of 1 T tubule & 2 terminal cisterns = TRIAD

78
Q

SARCOTUBULAR SYSTEM of Cardiac Muscle

A

It has also sarcotubular system but only 1 T tubule and 1 Terminal cistern = DIAD

79
Q

Why does Smooth Muscle do not contain SARCOTUBULAR SYSTEM?

A

Because it does not have T tubule (caveolae)

80
Q
  • Present in 💡T tubule
  • In skeletal it acts as 💡voltage sensor which is activated by voltage changes like 💡depolarization, 💡action potential, and 💡local potential. (DHP is a 💡Calcium channel except in skeletal)
  • In cardiac it acts as 💡Calcium channel, if activated (during action potential) it opens and Calcium gets inside.
  • L-type voltage-gated Ca++ channel
A

DHPR (Dihydropyridine receptor)

81
Q
  • Present in 💡sarcoplasmic reticulum
  • Between 💡terminal cisternae and T tubule
  • Responsible for 💡calcium release from muscle contraction

**Both cardiac and skeletal, have this receptor and serves as 💡voltage-gated Calcium channel

A

RYR (Ryanodine receptor)

82
Q

Muscle Relaxation:
Relaxation of smooth muscle occurs when (1)__ below a critical level as Ca++ is pumped out of the cell or into the sarcoplasmic reticulum. Ca++ is then released from (2)__ and (3)__ removes phosphate from the myosin light chain, causing (4)__ of the myosin head from the actin filament and (5)__ of the smooth muscle.

ADP, adenosine diphosphate; ATP, adenosine triphosphate; Na+, sodium; P, phosphate.

A

(1) calcium ion (Ca++) concentration decreases
(2) calmodulin (CaM)
(3) myosin phosphatase
(4) detachment
(5) relaxation

83
Q
  • Located in 💡lumen of cisternae
  • 💡Regulates calcium release
  • Allows Calcium to be stored at 💡high concentration to establish a favorable efflux when stimulated
  • 💡Calcium buffer
A

Calsequestrin

84
Q

It is a 💡SH3-cysteine rich domain 3 that 💡critical for coupling of the DHPR to the RYR during excitation contraction coupling in skeletal muscle SR.

It is is not present in cardiac muscle, which relies on Ca++ influx through the sarcolemma to initiate Ca++ release from the RYR instead of the direct coupling of the DHPR and the RYR in skeletal muscle.

A

Stac3

85
Q
  • It is located in the terminal cisternae that binds both 💡RYR and 💡calsequestrin
  • 💡Increases buffering capacity at the site of Ca release by anchor calsequestrin near the RYR. (Ca buffer)
A

Triadin, Junctin

86
Q
  • Binds 💡 triadin in a calcium-dependent manner

- It raises the possibility that it has a role more important than serving simply as a Ca++ buffer.

A

Histidine Rich Calcium Binding Protein

87
Q

💡Calcium Pump, responsible for 💡re-sequestration (uptake) of Calcium back to the SR (💡2 Calcium in for 💡1 ATP Hydrolyzed)

A

Sarcoplasmic Endoplasmic Reticulum Calcium ATPase (SERCA)

88
Q

Protein that 💡transfers from sites of Ca++ uptake in the longitudinal tubules to sites of Ca++ release in the terminal cisternae.

!! The portion of the myofibril (or of the whole muscle fiber) that lies between two successive Z disks

A

Sarcolumenin

89
Q

Muscle Contraction:
Intracellular calcium ion (Ca++) concentration increases when (1)__ through calcium channels in the cell membrane or is released from the (2)__. The Ca++ binds to (3)__ to form a Ca++-CaM complex, which then activates (4)__. The active MLCK phosphorylates the (5)__ leading to attachment of the myosin head with the actin filament and contraction of the smooth muscle.

ADP, adenosine diphosphate; ATP, adenosine triphosphate; P, phosphate.

A

(1) Ca++ enters the cell
(2) sarcoplasmic reticulum
(3) calmodulin (CaM)
(4) myosin light chain kinase (MLCK)
(5) myosin light chain

90
Q

Structures inside sarcomere:

A 
A Band (Dark Band)
H Zone
M band
I Band (Light Band)
M line
91
Q

In 💡relax state, H zone is?

A

Wider

92
Q

In 💡contracted state, H zone is?

A

Narrower

93
Q

It is is made up of only one molecule known as 💡myosin (1 long tail and 2 myosin heads, tail to tail).

A

Thick filament

94
Q

It is important because this is where enzyme 💡ATPase (hydrolyze ATP to ADP) is located.

This is also the 💡binding site.

A

Myosin heads aka cross bridges

95
Q

Arrangement of 2 myosin molecule is __ which forms M band

A

Bipolar

96
Q

Myosin heads aka cross bridges is anchored in __ via cytoskeleton protein called titin.

A

Z-line

97
Q

Thin filament is made up of what 3 molecules?

A
  1. Actin
  2. Tropomyosin
  3. Troponin
98
Q

 Made up of 1 molecule of 💡Globular actin (G actin) but get several in the form of filament called 💡Filamentous actin (F actin)]
 Only 💡1 line (G actin), 💡whole filament (F actin)
 2 F actin filaments arrange 💡helically to form 1 filament
 In one filament there is a 💡groove where tropomyosin (relaxing protein) is located

A

Actin

99
Q

 Responsible for 💡inhibition of contraction

 There are 7 binding sites covered by 1 tropomyosin

A

Tropomyosin

100
Q

Where does tropomyosin found?

A

Found in the groove of actin and bound to troponin

101
Q

What is the function of Troponin in the skeletal muscle?

A

Regulatory protein

102
Q

It is a troponin that binds with 💡Calcium

A

Troponin C

in every 💡1 molecule of trop C maximum of 💡4 calcium can bind

103
Q

It is a troponin that binds with 💡Tropomyosin

A

Troponin T

104
Q

It facilitate 💡inhibition of contraction by 💡inhibiting interaction of actin and myosin

A

Troponin I

105
Q

What is the function of 💡Tropomyosin in the skeletal muscle?

A

Relaxing protein

106
Q

What is the function of 💡Actin in the skeletal muscle?

A

Contractile protein

107
Q

What is the function of 💡Myosin in the skeletal muscle?

A

Molecular motor protein

108
Q

When skeletal muscle contract, thick filament moves (1)__ and H-zone (2)__, decreases until it disappears

A

(1) medially

(2) narrow

109
Q

There are 6 thin filaments that surround 1 thick filament (HEXAGONAL ARRANGEMENT)

A

True

110
Q

It 💡connects/aligns/anchors 2 tails of Myosin, forming the line at the center called 💡M line

A

Myomesin

111
Q

It binds/anchor actin with Z line

A

Cap Z/ Alpha actinin

112
Q

 💡Largest protein in the body
 💡Anchors thick filament to Z line
 💡Senses changes in muscle tension
 💡Tensor sensing protein
 Made up of folded domains because it provides elasticity to the muscle during stretching.
 Important in organization and alignment of thick filament
 Serves as 💡mechanosensor and influence 💡gene expression and 💡protein degradation in a mechanical activity dependent manner

A

Titin

113
Q

Disorder with Titin

A

Titinopathies

114
Q

 💡Control/regulate the 💡length of actin/thin filament.
 Found along the 💡thin filament
 Aided by 💡tropomodulin
 💡Elongated cytoskeletal protein

A

Nebulin

114
Q

It 💡initiates the length of actin filament

It is located at the end of the thin filament

A

Tropomodulin

115
Q

It is a large protein (≈480 kDa) that consists of six different polypeptides with one pair of large heavy chains (≈200 kDa) and two pairs of light chains (≈20 kDa).

A

Myosin

116
Q

 It 💡covers binding site between myosin and actin

 Each tropomyosin dimer extends across 7 actin molecules

A

Tropomyosin Relaxing Protein

118
Q

It is formed when 💡heavy chains are wound together in an 💡α-helical configuration to form a 💡long rod-like segment, and the 💡N-terminal portions of each heavy chain.

It 💡extends away from the thick filament toward the actin thin filament and is the 💡portion of the molecule that can bind to actin.

It is able to 💡hydrolyze ATP, because the 💡ATPase activity is located here.

It requires the presence of essential light chains

A

Myosin head

119
Q

These are two pairs of light chains are associated with the globular head.

A

Essential light chains

Regulatory light chains

120
Q

It is a light chain that is crucial for the 💡ATPase activity of myosin.

A

Essential light chains

121
Q

It is a light chain that can be phosphorylated by Ca ++/calmodulin-dependent myosin light chain protein kinase, which can influence the interaction of myosin with actin

A

Regulatory light chains

122
Q

This proteins found in the thick filaments may also participate in the bipolar organization or packing of the thick filament (or both).

A

Myomesin and C protein

123
Q

 💡Connects actin filament to 💡dextroglycan which provides 💡strength for the muscle (ex. laminin)
 Provides 💡structural link between subsarcolemmal cytoskeleton of the muscle and extracellular matrix
 💡Stabilizes sarcolemma and hence prevents contraction induced injury

A

DYSTROPHIN GLYCOPROTEIN COMPLEX

124
Q

Cross-Bridge Cycle.

In  the  relaxed  state  (state  a), ATP  is (1)__  (M  •  ADP  •  Pi).  In  the  presence  of  elevated myoplasmic  Ca++  (state  b), (2)__.  Hydrolysis  of (3)__  is  completed  (state  c)  and  causes  a  conformational  change  in  the myosin  molecule  that  pulls  the  actin  filament  toward  the  center  of  the sarcomere.  A  new  ATP  molecule  binds  to  myosin  and  causes  release of  the (5)__  (state  d).  Partial  hydrolysis  of  the  newly  bound  ATP recocks  the  myosin  head,  which  is  now  ready  to  bind  again  and  again. If  myoplasmic  [Ca++]  is  still (6)__,  the  cycle  repeats.  If  myoplasmic [Ca++]  is  low,  (7)__  results. 

A

(1) partially  hydrolyzed
(2) myosin  (M)  binds  to  actin  (A)
(3) ATP
(4) cross-bridge
(5) partial hydrolysis
(6) elevated
(7) relaxation

PHYSIOLOGY (13 decks)

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