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anatomy > Skeletal Muscle > Flashcards

Skeletal Muscle Flashcards

1
Q

Which is the largest organ in the body by mass?

A

skeletal muscle

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2
Q

What is skeletal m uscle responsible for?

A

locomotion, metabolic activity

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3
Q

What are the three types of muscle?

A

skletal smooth cardiac

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4
Q

What are the five different jobs that the three types of muscle perform?

A

movement, stabilization, storage, moving substances, generating heat

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5
Q

What is the largest metabolic organ?

A

skletal muscle

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6
Q

How do you change metaoblism?

A

stress muscles

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7
Q

When heart rate increases, this means muscles are ____

A

activated

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8
Q

What controls skeletal muscle contraction?

A

peripheral nerves

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9
Q

Where do peripheral nerve axons originate from?

A

motor neuron cell bodies in the spinal cord, somatic

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10
Q

Skeletal muscle contraction accounts for all what?

A

all voluntary body movement

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11
Q

What are two terms for muscle cells?

A

fibres or myocytes

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12
Q

Myocytes are filled with what?

A

myofibrils

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13
Q

What are sacromeres in series?

A

myofibrils

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14
Q

What are myocybrils?

A

sacromeres in series

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15
Q

What is the basic contraction unit of the muscle?

A

sacromere

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16
Q

One sacromere is identified?

A

btw 2 z lines

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17
Q

Myosin is what

A

thick filament

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18
Q

actin is what

A

thin filamenet

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19
Q

Order muscle components from smallest to largest

A

actin and myosin < sacromere < series of sacromeres = myofibrils , fibres/myocytes (wrapped in edomysium) , fasicle wrapped in perimysium < muscle wrapped in epimysium FORMs tendon ATTACHES to bone

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20
Q

What are fibres wrapped in?

A

endomysium

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21
Q

What are fasicles wrapped in?

A

perimysium

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22
Q

What are muscles wrapped in?

A

epimysium

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23
Q

Order perimysium, endomysium, epimysium

A

endomysium < perimysium < epimysium

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24
Q

What is an H zone?

A

space btw thin filaments when muscle is resting

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25
Q

What is the 1/2 I band?

A

space btw 2 lines and thick filament

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26
Q

Which spaces get smol during contraction?

A

H zone and 1/2 I band, therefore sarcomere shortens

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27
Q

What shortens in muscle contraction?

A

sarcomere

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28
Q

What is the structure in the middle of a sarcomere?

A

M line

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29
Q

What is an A band?

A

the width of the thick filament

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30
Q

Describe sliding filament theory

A

Thick filament doesnt move, filaments slide past one another to shorten

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31
Q

What decreases in atrophy?

A

filaments and sarcomeres, therfore fibers

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32
Q

Why is there atrophy?

A

when muscle isnt used it atrophys bc muscles are metabolically demanding and costs too much energy to maintain

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33
Q

What causes atrophy?

A

casts, going to space, denervation

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34
Q

Give an example of denervation

A

spinal cord injury

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35
Q

In sliding filament theory, how many actins does myosin interact with?

A

6

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36
Q

In sliding filament theory, how many myosins does actin interact with?

A

3

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37
Q

The three types of muscle differ in: (4 items)

A

morphology, location, function, method of activation

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38
Q

Skeletal muscle is wrapped in what type of tissue?

A

connective tissue

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39
Q

What are the three types of connective tissue involved in skeletal muscles?

A

endomysium, perimysium, epimysium

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40
Q

Endomysium surrounds what

A

individual muscle fibres

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41
Q

perimysium surrounds what

A

bundle of muscle fibres

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42
Q

epimysium surrounds what

A

entire muscles

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43
Q

What is the periosteum of the bone

A

lining of the bone

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44
Q

what is continous with the periosteum of the bone

A

tendon

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45
Q

What is aponeurosis?

A

broad flat tendon

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46
Q

What do you call a broad flat tendon

A

aponeurosis

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47
Q

How is the muscle connected tot he bone?

A

through the matrix around it which joins together to form a tendon and the tendon attches to the bone

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48
Q

Define muscle dystrophy

A

erros in the interface btw connective tissue and tendons

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49
Q

Examples of muscle dystrophy?

A

mutation in matrix protein or in muscle (where proteins connect to matrix) which causes rip in muscles

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50
Q

Pathology of muscle dystrophy? Who is affected?

A

duchenne syndrome, lil boys

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51
Q

What is hypertrophy

A

increased number of filaments (actin and myosin), more sarcomeres expands fibres which causes muscle enlargement and efinition

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52
Q

What happens to the # of muscle cells is muscle hypertrophY?

A

of myocytes font increase, rather the fibre diameter gets bigger which means stronger

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53
Q

What features of myosin allow it to cross bridge?

A

2 globular heads and long hinged tail

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54
Q

What is a thick filament

A

lots of myosin

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55
Q

What does myosin atpase do? What does this allow myosin to do?

A

breaks atp to harness energy which allows myosin to pull actin

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56
Q

What are the diff features of myosin

A

tail, hinge, myosin heads (2), actin binding sites, myosin ATPase

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57
Q

describe architecture of thin filament

A

actin molecules form 2 coiled chains

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58
Q

Describe actin

A

a series of lil globuals with binding sites

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59
Q

What does tropomyosin do

A

tropomyosin molecules run along actin and block cross bridge binding sites

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60
Q

What substance blocks cross bridge binding sites?

A

tropomyosin

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61
Q

What substance holds tropomyosin in place?

A

troponin

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62
Q

What does troponin do?

A

hold tropomyosin in place

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63
Q

What can bind to troponin? What happens when this substance binds?

A

Calcium can bind to troponin and change its conformation, therefore pulling tropomyosin away from cross bridge binding site

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64
Q

Calcium is considered what?

A

regulator of cross bridge cycling

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65
Q

what is the regulator of crossbridge cycling

A

calcium

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66
Q

what allows actin myosin interactions to occur

A

calcium

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67
Q

what happens when calcium is removed

A

tropomyosin moves back and blocks cross bridge binding sites again

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68
Q

What is malignant hypothermia

A

calcium is released uncontrollably and there are painful contractions

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69
Q

what pathology causes calcium to be released uncontrollably?

A

malignant hypothermia

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70
Q

What type of movement is excitation-contraction coupling

A

voluntary

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71
Q

What is the excitation part of excitation-contraction coupling?

A

electrical signals from brbain

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72
Q

what is the contraction part of excitation-contraction coupling?

A

muscle contraction

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73
Q

An _________ signal causes release of Ca

A

excitatory

74
Q

what type of signal causes Calcium relase

A

excitatory

75
Q

Define excitation

A

AP travels to axon terminal, i.e. neuromuscular junction

76
Q

AP in neuron causes release of what NT at neuromuscular junction?

A

ACH

77
Q

ACH-R at neuromuscular junction is classified as what

A

nicotinic

78
Q

ACH-R at motor end plate is classified as what

A

nicotinic

79
Q

what is a motor end plate

A

area on muscle fibre

80
Q

Describe excitation process

A

Neurotransmission -> AP -> t-tubules -> sarcoplasmic reticulum (spec. terminal cisternae) -> release of Calcium -> contraction

81
Q

what is a triad

A

1 tubule and 2 terminal cisternae

82
Q

T tubules stand for what

A

transverse

83
Q

sarcoplasm contain what

A

myoglobin and glycogen

84
Q

define sarcolemma

A

tubular sheath surrounding skeletal muscles fibres

85
Q

define sarcoplasmic reticulum

A

a type of endoplasmic reticulum that stores and releases calcium

86
Q

sarcoplasmic reticulum can be found where?

A

cardiac muscle and skeletal striated muscle

87
Q

what are terminal cisternae

A

enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules

88
Q

what are t tubulues

A

invaginations of the membrane

89
Q

t tubulues are what

A

membrane

90
Q

what are the two reeptors in t tubulues

A

dihydropyridine and ryanodine

91
Q

Describe process of Ca influx to T tubulues

A

DHP is voltage sensitive and so it changes shape when an AP arrives and pulls ryanodine plug out of sarcoplasmic reticulum allowing ca influx

92
Q

how are muscles relaxed in terms of ca

A

ca is taken up by enzyme calcium atpase

93
Q

how is ca reuptaked?

A

enzyme calcium atpase

94
Q

which is slower atpase ca reuptake or channel release of ca?

A

atpase reuptake

95
Q

what two molecules are needed for cross bridge cycling

A

ATP and Ca

96
Q

what are the four steps of cross bridge cycling

A
  1. energize myosin 2. actin-myosin binding 3. cross bridge movement (power stroke) 4. breaking the cross bridge
97
Q

what step does power stroke occur

A

cross bridge movement

98
Q

what happens in energizing myosin

A

atp already bound to myosin so myosin atpase dephosphorylates ATP and this energizes myosin

99
Q

what happens in actin myosin binding

A

actin will bind to myosin when Ca is available

100
Q

what is tehr egulator of cross bridge cyclin

A

ca

101
Q

what happens in cross bridge movement

A

energy stored in myosin is used to make the cross bridge move, therefore shorteining the sarcomere and adp&pi is released

102
Q

What happens in cross bridge breaking

A

atp binds ot myosin and this breaks the bond btw actin and myosin

103
Q

what is rigor mortis

A

dont have atp to let myosin release actin so it looks contracted

104
Q

why do u look contracted when u die

A

dont have atp to let myosin release actin

105
Q

Describe the process of calcium influx into the t tubules

A

Ap arrives, DHP which is voltage sensitive changes shape and this pulls out the ryanodine receptor out of the sarcoplasmic reticulum allowing ca influx

106
Q

out of DHP and ryanodine receptor which is voltage sensitive

A

DHP

107
Q

out of DHP and ryanodine receptor which is the plug

A

ryanodine receptor

108
Q

what is the function of terminal cisternae

A

ensure rapid release of ca

109
Q

where is the ryanodine receptor

A

in the sarcoplasmic reticulum

110
Q

How do the muscles relax in terms of Calcium?

A

calcium is taken up by enzymatic calcium atpase

111
Q

when can twitch contraction occur

A

due to difference in speed of ca efflux vs influx

112
Q

what type of contraction do we do?

A

tetanic contraction

113
Q

why is max tetanic contraction force 3-5x greater than max twitch contraction force?

A

max tetanic contraction is so great bc each subsequent AP releases more calcium

114
Q

what are the three factors regulating force production

A

muscle length, AP frequency, # of fibres per motor unit and the cross sectional area (SIZE!) of those muscle fibres

115
Q

define motor unit

A

one motor neuron and all the muscle fibres it innervates

116
Q

what is ratio btw neurons and muscle fibres?

A

one neuron for many muscle fibres

117
Q

what happens if muscle length is too short

A

actin bump into each other and cross bridge cant form efficiently and cross bridge cant form efficiently

118
Q

what happens if muscle length is too stretched

A

number of cross bridges that can form is reduced

119
Q

What can decrease force production in terms of muscle length

A

too stretched or too compressed decreases force production

120
Q

Describe ap frequency in terms of force production

A

summation of AP: send another AP before calcium is reuptaken

121
Q

What are the diff types of AP frequencies

A

single twitch, wave summation, unfused tetanus, fused tetanus

122
Q

describe unfused tetanus

A

some discipation of force

123
Q

describe fused tetanus

A

swamped with AP, no discipation of forcel every possible cross bridge is formed

124
Q

which type of ap summation involves every cross bridge forming

A

fused tetanus

125
Q

Describe the factor of # of fibres per motor unit in terms of fore production

A

3 types of motor units exist based on muscle fibre type

126
Q

how do muscle fibre types differ

A

size and ease of activation

127
Q

how does size of muscle fibres in context of motor units affect force production

A

size of cross sectional area of muscle fibres determines amount of force produced -> if more muscle is innervated by one neuron, more force is produced

128
Q

how are skeletal muscle fibre types classified

A

contraction speed and metabolic profile

129
Q

what are the two types of fibres in terms of contraction speed

A

slow and fast

130
Q

what does contraction speed depend on

A

myosin atpase action rate

131
Q

What are the pros and cons of slow fibres

A

they contract slow (duH) but theyre fatigue resistant

132
Q

what are the two types of fibres in terms of metabolic profile

A

oxidative and glycolytic

133
Q

describe oxidative fibres

A

primarily use oxygen for atp production

134
Q

what type of metabolism do oxidative fibres use

A

aerobic

135
Q

what type of metabolism do glycolytic fibres use

A

anaerobic

136
Q

describe glycolytic fibres

A

high capcity for ATP production with oxygen

137
Q

Which muscle fibre types are fatigue resistant?

A

slow oxidative and fast oxidative glycolytic

138
Q

what are the 3 types of motor units?

A

slow oxidative, fast oxidative flycolytic, fast glycolytic

139
Q

describe order of reqcruitment of motor units

A

slow oxidative then fast oxidative flycolytic then fast glycolytic

140
Q

Describe slow oxidative fibres

A

smol diameter, rich blood supply, aerobic respiration

141
Q

slow oxidative is used for what activity

A

posture and endurance

142
Q

describe fast oxifative glycolytic

A

intermediate diameter, rich blood supply, aerobic and anerobic respiration

143
Q

fast oxidative glycolytic is used for what activity

A

walking and sprinting

144
Q

walking and sprinting requires what motor units

A

fast oxidative glycolytic and slow oxidative

145
Q

posture and endurance uses what motor units

A

slow oxidative

146
Q

Which motor unit muscle fibre type has rich blood supply

A

fast oxidative glycolytic and slow oxidative

147
Q

what is the size principle

A

the order of requirtment of motor units is SAME for all activities

148
Q

describe fast glycolytic

A

large diameter, few capillaries, anaerobic respiration

149
Q

what activity uses fast glycolytic

A

power movements

150
Q

What are the two contraction types

A

isometric and isotonic

151
Q

describe isometric contraction

A

no load movement, where muscle force = load

152
Q

describe isotonic contraction

A

muscle force does not equal load, load is moved

153
Q

what are the two types of isotonic contraction

A

concentric and eccentric

154
Q

describe force load equation for isotonic concentric movement

A

force > load; load is up

155
Q

describe force load equation for isotonic eccentric movement

A

force < load; load is down

156
Q

which muscle types use actin and myosin

A

smooth and skeletal muscle

157
Q

smooth muscle can be electrically coupled by what

A

gap junctions

158
Q

actin and myosin are organized how in smooth muscle in comparison to skeltal muscle

A

less organized

159
Q

which muscle types have striations

A

cardiac and skeletal

160
Q

why do smooth muscles not have striations

A

filaments are anchored to desnce bodies on interfilament network in cytosol

161
Q

describe smooth muscle contractions

A

involvuntary

162
Q

smooth muscle contraction speed?

A

v slow!

163
Q

how do u get toned muscle

A

smooth muscle, maintains prolonged tension

164
Q

where do cardiomyocytes connect

A

intercalated discs

165
Q

what composes intercalated disks

A

desosomes and gap junctions

166
Q

which muscles contain gap junctions

A

smooth and cardiac muscle

167
Q

what do desomosomes do

A

stabilize cell to cell contact

168
Q

what do gap junctions do

A

allow direct communication btw adjacent cells via ion passage

169
Q

where can smooth muscle be found?

A

arteries, digestion, reproduction, respiration and urination

170
Q

what is the location of skeletal muscle

A

MSK system

171
Q

what is the location of smooth muscle

A

hollow organs

172
Q

relative size of diff muscle types

A

skeletal -> v large, cardiac -> large, smooth -> smol

173
Q

describe nucleus count in diff muscle types

A

skeletal is multinucleated, cardiac has 1-2 nuclei, smooth muscle has single nuclei

174
Q

which muscle types are multinucleated

A

skeletal and cardiac

175
Q

which muscle types are striated

A

skeletala and cardiac

176
Q

cardiac muscle morphology is

A

branched

177
Q

smooth muscle morphology is

A

spindle shapped

178
Q

which muscle type is autorhythymic

A

cardiac and smooth

179
Q

list contraction speed of muscle types fastest to slowest

A

skletal is fastest, cardiac is moderate, smooth is slow

180
Q

what regulates skeletal muscle

A

somatic NS

181
Q

what regultes cardiac muscle

A

ANS, pacemaker cells, intrinsic conduction system, hormones

182
Q

what regulates smooth muscle

A

ANS, pacemaker cells, hormones, stretching, nitric oxide

anatomy (12 decks)

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