Skeletal Muscle Flashcards
(182 cards)
1
Q
Which is the largest organ in the body by mass?
A
skeletal muscle
2
Q
What is skeletal m uscle responsible for?
A
locomotion, metabolic activity
3
Q
What are the three types of muscle?
A
skletal smooth cardiac
4
Q
What are the five different jobs that the three types of muscle perform?
A
movement, stabilization, storage, moving substances, generating heat
5
Q
What is the largest metabolic organ?
A
skletal muscle
6
Q
How do you change metaoblism?
A
stress muscles
7
Q
When heart rate increases, this means muscles are ____
A
activated
8
Q
What controls skeletal muscle contraction?
A
peripheral nerves
9
Q
Where do peripheral nerve axons originate from?
A
motor neuron cell bodies in the spinal cord, somatic
10
Q
Skeletal muscle contraction accounts for all what?
A
all voluntary body movement
11
Q
What are two terms for muscle cells?
A
fibres or myocytes
12
Q
Myocytes are filled with what?
A
myofibrils
13
Q
What are sacromeres in series?
A
myofibrils
14
Q
What are myocybrils?
A
sacromeres in series
15
Q
What is the basic contraction unit of the muscle?
A
sacromere
16
Q
One sacromere is identified?
A
btw 2 z lines
17
Q
Myosin is what
A
thick filament
18
Q
actin is what
A
thin filamenet
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
20
Q
What are fibres wrapped in?
A
endomysium
21
Q
What are fasicles wrapped in?
A
perimysium
22
Q
What are muscles wrapped in?
A
epimysium
23
Q
Order perimysium, endomysium, epimysium
A
endomysium < perimysium < epimysium
24
Q
What is an H zone?
A
space btw thin filaments when muscle is resting
25
What is the 1/2 I band?
space btw 2 lines and thick filament
26
Which spaces get smol during contraction?
H zone and 1/2 I band, therefore sarcomere shortens
27
What shortens in muscle contraction?
sarcomere
28
What is the structure in the middle of a sarcomere?
M line
29
What is an A band?
the width of the thick filament
30
Describe sliding filament theory
Thick filament doesnt move, filaments slide past one another to shorten
31
What decreases in atrophy?
filaments and sarcomeres, therfore fibers
32
Why is there atrophy?
when muscle isnt used it atrophys bc muscles are metabolically demanding and costs too much energy to maintain
33
What causes atrophy?
casts, going to space, denervation
34
Give an example of denervation
spinal cord injury
35
In sliding filament theory, how many actins does myosin interact with?
6
36
In sliding filament theory, how many myosins does actin interact with?
3
37
The three types of muscle differ in: (4 items)
morphology, location, function, method of activation
38
Skeletal muscle is wrapped in what type of tissue?
connective tissue
39
What are the three types of connective tissue involved in skeletal muscles?
endomysium, perimysium, epimysium
40
Endomysium surrounds what
individual muscle fibres
41
perimysium surrounds what
bundle of muscle fibres
42
epimysium surrounds what
entire muscles
43
What is the periosteum of the bone
lining of the bone
44
what is continous with the periosteum of the bone
tendon
45
What is aponeurosis?
broad flat tendon
46
What do you call a broad flat tendon
aponeurosis
47
How is the muscle connected tot he bone?
through the matrix around it which joins together to form a tendon and the tendon attches to the bone
48
Define muscle dystrophy
erros in the interface btw connective tissue and tendons
49
Examples of muscle dystrophy?
mutation in matrix protein or in muscle (where proteins connect to matrix) which causes rip in muscles
50
Pathology of muscle dystrophy? Who is affected?
duchenne syndrome, lil boys
51
What is hypertrophy
increased number of filaments (actin and myosin), more sarcomeres expands fibres which causes muscle enlargement and efinition
52
What happens to the # of muscle cells is muscle hypertrophY?
of myocytes font increase, rather the fibre diameter gets bigger which means stronger
53
What features of myosin allow it to cross bridge?
2 globular heads and long hinged tail
54
What is a thick filament
lots of myosin
55
What does myosin atpase do? What does this allow myosin to do?
breaks atp to harness energy which allows myosin to pull actin
56
What are the diff features of myosin
tail, hinge, myosin heads (2), actin binding sites, myosin ATPase
57
describe architecture of thin filament
actin molecules form 2 coiled chains
58
Describe actin
a series of lil globuals with binding sites
59
What does tropomyosin do
tropomyosin molecules run along actin and block cross bridge binding sites
60
What substance blocks cross bridge binding sites?
tropomyosin
61
What substance holds tropomyosin in place?
troponin
62
What does troponin do?
hold tropomyosin in place
63
What can bind to troponin? What happens when this substance binds?
Calcium can bind to troponin and change its conformation, therefore pulling tropomyosin away from cross bridge binding site
64
Calcium is considered what?
regulator of cross bridge cycling
65
what is the regulator of crossbridge cycling
calcium
66
what allows actin myosin interactions to occur
calcium
67
what happens when calcium is removed
tropomyosin moves back and blocks cross bridge binding sites again
68
What is malignant hypothermia
calcium is released uncontrollably and there are painful contractions
69
what pathology causes calcium to be released uncontrollably?
malignant hypothermia
70
What type of movement is excitation-contraction coupling
voluntary
71
What is the excitation part of excitation-contraction coupling?
electrical signals from brbain
72
what is the contraction part of excitation-contraction coupling?
muscle contraction
73
An _________ signal causes release of Ca
excitatory
74
what type of signal causes Calcium relase
excitatory
75
Define excitation
AP travels to axon terminal, i.e. neuromuscular junction
76
AP in neuron causes release of what NT at neuromuscular junction?
ACH
77
ACH-R at neuromuscular junction is classified as what
nicotinic
78
ACH-R at motor end plate is classified as what
nicotinic
79
what is a motor end plate
area on muscle fibre
80
Describe excitation process
Neurotransmission -> AP -> t-tubules -> sarcoplasmic reticulum (spec. terminal cisternae) -> release of Calcium -> contraction
81
what is a triad
1 tubule and 2 terminal cisternae
82
T tubules stand for what
transverse
83
sarcoplasm contain what
myoglobin and glycogen
84
define sarcolemma
tubular sheath surrounding skeletal muscles fibres
85
define sarcoplasmic reticulum
a type of endoplasmic reticulum that stores and releases calcium
86
sarcoplasmic reticulum can be found where?
cardiac muscle and skeletal striated muscle
87
what are terminal cisternae
enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules
88
what are t tubulues
invaginations of the membrane
89
t tubulues are what
membrane
90
what are the two reeptors in t tubulues
dihydropyridine and ryanodine
91
Describe process of Ca influx to T tubulues
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
how are muscles relaxed in terms of ca
ca is taken up by enzyme calcium atpase
93
how is ca reuptaked?
enzyme calcium atpase
94
which is slower atpase ca reuptake or channel release of ca?
atpase reuptake
95
what two molecules are needed for cross bridge cycling
ATP and Ca
96
what are the four steps of cross bridge cycling
1. energize myosin 2. actin-myosin binding 3. cross bridge movement (power stroke) 4. breaking the cross bridge
97
what step does power stroke occur
cross bridge movement
98
what happens in energizing myosin
atp already bound to myosin so myosin atpase dephosphorylates ATP and this energizes myosin
99
what happens in actin myosin binding
actin will bind to myosin when Ca is available
100
what is tehr egulator of cross bridge cyclin
ca
101
what happens in cross bridge movement
energy stored in myosin is used to make the cross bridge move, therefore shorteining the sarcomere and adp&pi is released
102
What happens in cross bridge breaking
atp binds ot myosin and this breaks the bond btw actin and myosin
103
what is rigor mortis
dont have atp to let myosin release actin so it looks contracted
104
why do u look contracted when u die
dont have atp to let myosin release actin
105
Describe the process of calcium influx into the t tubules
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
out of DHP and ryanodine receptor which is voltage sensitive
DHP
107
out of DHP and ryanodine receptor which is the plug
ryanodine receptor
108
what is the function of terminal cisternae
ensure rapid release of ca
109
where is the ryanodine receptor
in the sarcoplasmic reticulum
110
How do the muscles relax in terms of Calcium?
calcium is taken up by enzymatic calcium atpase
111
when can twitch contraction occur
due to difference in speed of ca efflux vs influx
112
what type of contraction do we do?
tetanic contraction
113
why is max tetanic contraction force 3-5x greater than max twitch contraction force?
max tetanic contraction is so great bc each subsequent AP releases more calcium
114
what are the three factors regulating force production
muscle length, AP frequency, # of fibres per motor unit and the cross sectional area (SIZE!) of those muscle fibres
115
define motor unit
one motor neuron and all the muscle fibres it innervates
116
what is ratio btw neurons and muscle fibres?
one neuron for many muscle fibres
117
what happens if muscle length is too short
actin bump into each other and cross bridge cant form efficiently and cross bridge cant form efficiently
118
what happens if muscle length is too stretched
number of cross bridges that can form is reduced
119
What can decrease force production in terms of muscle length
too stretched or too compressed decreases force production
120
Describe ap frequency in terms of force production
summation of AP: send another AP before calcium is reuptaken
121
What are the diff types of AP frequencies
single twitch, wave summation, unfused tetanus, fused tetanus
122
describe unfused tetanus
some discipation of force
123
describe fused tetanus
swamped with AP, no discipation of forcel every possible cross bridge is formed
124
which type of ap summation involves every cross bridge forming
fused tetanus
125
Describe the factor of # of fibres per motor unit in terms of fore production
3 types of motor units exist based on muscle fibre type
126
how do muscle fibre types differ
size and ease of activation
127
how does size of muscle fibres in context of motor units affect force production
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
how are skeletal muscle fibre types classified
contraction speed and metabolic profile
129
what are the two types of fibres in terms of contraction speed
slow and fast
130
what does contraction speed depend on
myosin atpase action rate
131
What are the pros and cons of slow fibres
they contract slow (duH) but theyre fatigue resistant
132
what are the two types of fibres in terms of metabolic profile
oxidative and glycolytic
133
describe oxidative fibres
primarily use oxygen for atp production
134
what type of metabolism do oxidative fibres use
aerobic
135
what type of metabolism do glycolytic fibres use
anaerobic
136
describe glycolytic fibres
high capcity for ATP production with oxygen
137
Which muscle fibre types are fatigue resistant?
slow oxidative and fast oxidative glycolytic
138
what are the 3 types of motor units?
slow oxidative, fast oxidative flycolytic, fast glycolytic
139
describe order of reqcruitment of motor units
slow oxidative then fast oxidative flycolytic then fast glycolytic
140
Describe slow oxidative fibres
smol diameter, rich blood supply, aerobic respiration
141
slow oxidative is used for what activity
posture and endurance
142
describe fast oxifative glycolytic
intermediate diameter, rich blood supply, aerobic and anerobic respiration
143
fast oxidative glycolytic is used for what activity
walking and sprinting
144
walking and sprinting requires what motor units
fast oxidative glycolytic and slow oxidative
145
posture and endurance uses what motor units
slow oxidative
146
Which motor unit muscle fibre type has rich blood supply
fast oxidative glycolytic and slow oxidative
147
what is the size principle
the order of requirtment of motor units is SAME for all activities
148
describe fast glycolytic
large diameter, few capillaries, anaerobic respiration
149
what activity uses fast glycolytic
power movements
150
What are the two contraction types
isometric and isotonic
151
describe isometric contraction
no load movement, where muscle force = load
152
describe isotonic contraction
muscle force does not equal load, load is moved
153
what are the two types of isotonic contraction
concentric and eccentric
154
describe force load equation for isotonic concentric movement
force > load; load is up
155
describe force load equation for isotonic eccentric movement
force < load; load is down
156
which muscle types use actin and myosin
smooth and skeletal muscle
157
smooth muscle can be electrically coupled by what
gap junctions
158
actin and myosin are organized how in smooth muscle in comparison to skeltal muscle
less organized
159
which muscle types have striations
cardiac and skeletal
160
why do smooth muscles not have striations
filaments are anchored to desnce bodies on interfilament network in cytosol
161
describe smooth muscle contractions
involvuntary
162
smooth muscle contraction speed?
v slow!
163
how do u get toned muscle
smooth muscle, maintains prolonged tension
164
where do cardiomyocytes connect
intercalated discs
165
what composes intercalated disks
desosomes and gap junctions
166
which muscles contain gap junctions
smooth and cardiac muscle
167
what do desomosomes do
stabilize cell to cell contact
168
what do gap junctions do
allow direct communication btw adjacent cells via ion passage
169
where can smooth muscle be found?
arteries, digestion, reproduction, respiration and urination
170
what is the location of skeletal muscle
MSK system
171
what is the location of smooth muscle
hollow organs
172
relative size of diff muscle types
skeletal -> v large, cardiac -> large, smooth -> smol
173
describe nucleus count in diff muscle types
skeletal is multinucleated, cardiac has 1-2 nuclei, smooth muscle has single nuclei
174
which muscle types are multinucleated
skeletal and cardiac
175
which muscle types are striated
skeletala and cardiac
176
cardiac muscle morphology is
branched
177
smooth muscle morphology is
spindle shapped
178
which muscle type is autorhythymic
cardiac and smooth
179
list contraction speed of muscle types fastest to slowest
skletal is fastest, cardiac is moderate, smooth is slow
180
what regulates skeletal muscle
somatic NS
181
what regultes cardiac muscle
ANS, pacemaker cells, intrinsic conduction system, hormones
182
what regulates smooth muscle
ANS, pacemaker cells, hormones, stretching, nitric oxide
