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Z Phase 1 Others > Week 6 > Flashcards

Week 6 Flashcards

1
Q

What are the three types of muscle?

A

Skeletal, smooth and cardiac muscle

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2
Q

What type of muscle forms the majority of muscle tissue in the body

A

Skeletal muscle

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3
Q

How is skeletal muscle organised?

A

Parallel bundles of long, multinucleated fibers

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4
Q

What is the power/stamina of skeletal muscle like?

A

Skeletal muscle is capable of powerful contractions but can,however tire quickly

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5
Q

Where is skeletal muscle found?

A

Attached to the skeleton by either tendons or aponeurosis

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6
Q

What is an aponeurosis?

A

A thin sheet of connective tissue

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7
Q

What are the functions of skeletal muscle?

A

Moves bones and other structures
Provides support and gives form to the body

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8
Q

Is skeletal muscle controlled voluntarily or involuntarily?

A

Voluntarily but not always consciously

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9
Q

Where is the muscle belly found?

A

Between the origin and insertion

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10
Q

How many origins, insertions and bellies can muscles have?

A

Muscles can have multiple origins,insertions and bellies

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11
Q

What movements can skeletal muscles carry out?

A

They can contract, stretch beyond its normal length and revert to its original resting length

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12
Q

What are the constituent parts of skeletal muscle?

A

Muscle fascicles, Muscle fibers, myofibrils and myofilaments

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13
Q

What is a muscle fascicle?

A

Bundles of muscle fibers (muscle cells)

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14
Q

What is a muscle fiber?

A

Bundles of myofibrils

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15
Q

What is a myofibril?

A

Bundles of myofilaments

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16
Q

What are myofilaments?

A

The proteins responsible fro muscle contraction

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17
Q

What is the endomysium?

A

A thin layer of connective tissue that surrounds each muscle fiber

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18
Q

What is the perimysium?

A

A thick layer of connective tissue that surrounds each muscle fascicle

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19
Q

What is the function of the permysium?

A

To protect the fascicle from damage. It also contains capillaries and nerve fibers

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20
Q

What is the epimysium?

A

A sheet of thick connective tissue that surrounds the entirety of a skeletal muscle. It may continue at the end of the muscle belly as a tendon and thus become continuous with the periosteum

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21
Q

What is the function of epimysium?

A

To separate the muscle from surrounding tissues and organs.

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22
Q

What does each skeletal muscle fiber contain?

A

A plasma membrane (sarcolemma), cytoplasm (sarcoplasm), nuclei, sarcoplasmic reticulum and is composed of bundles of protein fibers

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23
Q

What is the sarcolemma?

A

The plasma membrane of a muscle fiber. It has invaginations to from the T tubules

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24
Q

What is the function of the sarcolemma?

A

To receive electrical stimuli and conduct an action potential to the internal structure of the muscle fiber (via the T tubules)

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25
Q

What is the sarcoplasmic reticulum?

A

A special type of smooth ER found only in skeletal muscle cells

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26
Q

What is the function of the sarcoplasmic reticulum?

A

Stores large, concentrated stores of calcium

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27
Q

What is the sarcoplasm?

A

The cytoplasm of muscle cells

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28
Q

What is the function of the sarcoplasm?

A

To store large amounts of glycogen and myoglobin.
-Glycogen provides energy during muscle contraction
-Myoglobin contains stored oxygen

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29
Q

What are myofibrils?

A

Thread-like organelles 1-3 micro meters in diameter that extend the length of the muscle fiber

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30
Q

What are the two general types of skeletal muscle fibers?

A

Slow-twitch (type 1) and fast - twitch (type 2)

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31
Q

What is the structure of fast - twitch muscles like?

A

Fast twitch muscles are thicker and quicker to contract than slow twitch muscles.

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32
Q

What is the endurance of slow twitch muscles like?

A

Slow twitch muscles have generally more endurance than fast twitch muscles

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33
Q

Where is cardiac muscle found?

A

The walls of the heart

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34
Q

What is special about cardiac muscle?

A

Cardiac muscle is resistant to fatigue and contracts without any external stimulation

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35
Q

What is the word used to describe the nerves that stimulate cardiac muscle?

A

Autonomic

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36
Q

What does autonomic mean?

A

The control is involuntary

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37
Q

Where is smooth muscle found?

A

The walls of internal organs, such as otrgans of the digestive system, walls of blood vessels and the intrinsic muscles of the eye.

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38
Q

What is the structure of smooth muscle?

A

Smooth muscle is non-striated. It consists of elongated or spindle-shaped fibres.

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39
Q

What type of contractions are smooth muscles capable of?

A

slow, sustained contractions

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40
Q

How is smooth muscle controlled?

A

Smooth muscle is able to contract without external stimulation, and is modified by the autonomic nervous system. It is under involuntary control and doesn’t fatigue

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41
Q

What is the electrical excitability of a muscle?

A

The ability of a muscle to respond to stimuli

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42
Q

What is the contractility of a muscle?

A

The ability of a muscle to shorten in response to an action potential

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43
Q

What is the extensibility of a muscle?

A

the ability of a muscle to stretch

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44
Q

What is the elasticity of a muscle?

A

the ability of a muscle to recover its original shape after contraction or extension

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45
Q

How does muscle contribute to body movement?

A

The contraction and relaxation of muscles produce movement around various joints of the body

46
Q

How does muscle contribute to the stabilisation of joints?

A

Regulates the degree of movement possible at each joint

47
Q

How does muscle contribute to the maintenance of body positions?

A

Continuous or sporadic contraction of skeletal muscles around the body helps us to maintain our posture and position

48
Q

How does muscle contribute to storage of substances?

A

Contraction of smooth and skeletal muscle at specific points within the body enables certain substances to be kept within one place

49
Q

How does muscle contribute to the movement of substances?

A

Relaxtion of cardiac and smooth muscle at specific points within the body controls the movement of substances from one place to another

50
Q

How does muscle contribute to thermogenesis?

A

contracting muscles produce heat as a by-product, and this contributes to the maintenance of normal body temperature

51
Q

How does muscle contribute to communication?

A

Movement of muscles permits both verbal and non-verbal expression

52
Q

What is muscle atrophy?

A

The weakening and shrinking of a muscle

53
Q

What is muscle atrophy caused by?

A

Immobilisation or loss of neural stimulation

54
Q

What is muscle hypertrophy?

A

The enlargement of a muscle (cell size).
The muscle will develop more capillaries and more mitochondria

55
Q

What is muscle hypertrophy caused by?

A

Strenuous exercise or steroid hormones

56
Q

How does muscle hypertrophy occur?

A

When slow twitch muscle fibers become tired, fast twitch fibers take over which is when muscle mass will increase

57
Q

Why do men in general have more hypertrophied muscles than women?

A

They produce more steroid hormones

58
Q

What is muscle hyperplasia?

A

An increase in muscle cell numbers

59
Q

What type of muscle does hyperplasia occur in?

A

Smooth muscle is the only type of muscle capable of cell division

60
Q

Where does excitation-contraction coupling take place?

A

The sarcoplasm of a muscle fiber

61
Q

What is the concentration of calcium ions in the cytosol like in a relaxed muscle fiber?

A

Relatively low

62
Q

Where are a large number of calcium ions stored?

A

The sarcoplasmic reticulum

63
Q

When are the calcium ions released?

A

During contraction to mediate the process by binding to troponin

64
Q

What are the general functions of muscles?

A

movement
heat production
posture

65
Q

What are muscle fibres coated with?

A

endomysium

66
Q

What are fascicles?

A

groups of muscle fibres

67
Q

What are fascicles bound by?

A

perimysium

68
Q

What are muscles covered by?

A

epimysium

69
Q

Describe skeletal muscles

A

long cylindrical cells
many nuclei
striated
voluntary
rapid contractions

70
Q

Describe cardiac muscle

A

branching cells
1 or 2 nuclei
striated
involuntary
medium speed contractions

71
Q

Describe smooth muscle

A

fusiform cells
1 nucleus
non-striated
involuntary
slow, wave-like movement

72
Q

What are some defining features of skeletal muscle?

A

plasma membrane = sarcolemma
cytoplasm = sarcoplasm
Smooth ER = sarcoplasmic reticulum
many more mitochondria
several nuclei
transverse (T) tubules - inward extensions of the sarcolemma
myofibrils made up from microfilaments

73
Q

What is a sarcomere?

A

from Z line to Z line

74
Q

What is the A band?

A

The length of the myosin filament

75
Q

What is the I band?

A

The regions with no myosin

76
Q

What is the H zone?

A

The central region where there is no actin filaments

77
Q

What connects myosin to the Z band?

A

titan

78
Q

Give a summary of muscle excitation and contraction

A

Nerve impulses reach neuromuscular junction
Acetylcholine is released from the motor neuron
Acetylcholine binds with receptors of the muscle membrane and allow Na+ entry
Na+ influx will generate an action potential in the sarcolemma
Action potential travels down the T-tubule
Sarcoplasmic reticulum releases Ca2+
Ca2+ binds with troponin and moves the troponin-tropomyosin complex
Binding sites on the actin filament are exposed
Myosin heads attach to binding sites and create a power stroke
ATP detaches myosin heads and energises them for another contraction
When action potentials cease the muscles stop contracting

79
Q

What is a motor unit?

A

All the muscle cells that are controlled by one nerve cell

80
Q

Give examples of some motor unit ratios

A

back muscles 1:100
finger muscles 1:10
eye muscles 1:1

81
Q

What is muscle tonus?

A

tightness of a muscle
some fibres always contracted

82
Q

What is tetany?

A

sustained contraction of a muscle
result of rapid succession of nerve impulses

83
Q

What is the refractory period?

A

brief period of time in which muscle cells will not respond to stimulus

84
Q

What is muscle atrophy?

A

weakening and shrinking of a muscle
may be caused by immobilisation or loss of neural stimulation

85
Q

What is muscle hypertrophy?

A

enlargement of a muscle
more capillaries
more mitochondria
caused by strenuous exercise and steroid hormones

86
Q

What is isometric contraction?

A

produces no movement
used in sitting, standing, posture

87
Q

What is isotonic contraction?

A

produces movement
used in walking, moving any part of the body

88
Q

Describe electrochemical gradient

A

the input of energy to transport ions across a membrane has created an electrical gradient
The active transport of positive ions out of a cell has created a chemical gradient
the combination of an electrical and chemical gradient is called an electrochemical gradient
However, the cells remain in osmotic equilibrium
The negative ion will try to move down the electrochemical gradient and follow the positive ion out of the cell, but the membrane inhibits its flow

89
Q

What is resting membrane potential?

A

The electrical gradient across the cell membrane

90
Q

What is the resting membrane potential in nerve and muscle cells?

A

between -40 to -90mV

91
Q

Describe how K+ ions contribute to resting membrane potential

A

The membrane is more permeable to K+ ions
K+ leaks out of the cell down its concentration gradient
Excess negative charge build up inside as Pr- cannot cross the plasma membrane
An electrical gradient is formed
The negative charges attract K+ ions back into the cell down the electrical gradient
net movement of K+ stops at the equilibrium potential (E)

92
Q

What is equilibrium potential?

A

the point at which the electrical gradient opposes the chemical gradient

93
Q

What is the E of K+?

A

-90mV

94
Q

How do Na+ ions contribute to resting membrane potential?

A

membrane permeable to Na+ only
same principles hold as in K+ movement

95
Q

What is the equilibrium potential of Na+?

A

+60mV

96
Q

Describe the resting membrane potential in real cells

A

most cells are 40 times more permeable to K+ than Na+
The resting potential is closer to -70mV because a small amount of Na+ leaks into the cell
The 3Na+ ions are pumped out and 2K+ ions are pumped in by Na+/K+-ATPase
This is also known as an electrogenic pump because it helps maintain an electrical gradient

97
Q

What types of collagen are found in tendon?

A

mainly type I
small amounts of types III and IV

98
Q

What are tendon fascicles held together by?

A

endotenon

99
Q

what surrounds some tendons?

A

paratenon

100
Q

What is synovium that surrounds tendons called?

A

tenosynovium

101
Q

what surrounds endotenon?

A

epitenon

102
Q

what is endotenon continuous with?

A

the periosteum at the tendon-bone interface where collagen fibres enter the bone as Sharpey fibres

103
Q

What is the function of paratenon?

A

an elastic sheath allowing free gliding of the tendon against surrounding tissues

104
Q

which tendons are vascular?

A

those surrounded by paratenon

105
Q

which tendons are avascular?

A

those surrounded by synovial sheaths

106
Q

what is the key property of tendons?

A

high tensile strength

107
Q

what are the functions of tendons?

A

either generate joint motion during concentric contractions or resist joint motion during eccentric contractions

108
Q

What are satellite cells?

A

myoblasts that remain unfused after embryonic development

109
Q

why can satellite cells aid in the minor regeneration if damaged muscle?

A

they can still undergo mitosis

110
Q

What are the three stages of muscle regeneration?

A

Inflammatory response
activation, differentiation and fusion of satellite cells
maturation and remodelling of newly formed myocytes

Z Phase 1 Others (11 decks)

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