Muscles Flashcards
1
Q
what do muscles do
A
generate force and movement
2
Q
Name the three types of muscle
A
smooth, skeletal and cardiac
3
Q
what muscle is striated
A
skeletal and cardiac
4
Q
smooth muscle is not a striated but arrangement is
A
single unit cells, in a much more random arrangement
5
Q
What muscle can divide and repair itself
A
smooth
6
Q
Striated muscle is arranged in
A
Highly organised geometrical fashion of triangular and hexagons
7
Q
striated muscle is highly packed so
A
squeezes out nucleus
8
Q
cardiac muscle cells have what
A
intercalating disc
9
Q
what does an intercalating disc do
A
allows electrical conductivity
10
Q
Hard to depolarise heart due to
A
Multi connected heart providing alternative pathway due to the intercalating discs
11
Q
What are striated muscle
A
arranged large protein filaments
12
Q
what are muscles incased in
A
connective tissue sheaths
13
Q
what are myoblasts
A
precursors for muscle
14
Q
true or false myoblasts replace cells if damaged
A
false
15
Q
what are damaged muscles replaced with
A
scar tissue
16
Q
what happens if neighbouring cells die around muscle
A
makes it harder to contract
17
Q
What are muscles attached to
A
Bones by tendons
18
Q
what differentiates to form new muscle fibres when its damaged
A
satellite cells
19
Q
Muscle cells never completely recover due to
A
limited stock of satellite cells
20
Q
what do satellite cells move directly to
A
injury
21
Q
What supplies muscles with oxygen for contractions
A
very deeply penetrating blood vessels
22
Q
To much compression on blood vessels restricts muscles
A
oxygen levels, as can cut of supply
23
Q
repeating units in striations are
A
sacromere
24
Q
what lies between repeating units of sacromeres
A
Z line border
25
Do myosin fibres or actin fibres change in length
No
26
What causes contractions
Filaments slidding over each other and distance between them decreases
27
Thin filament and thick filament is
actin and myosin
28
What is the arrangement of actin
looks like a double helix
29
what is attached to actin
titin filament
30
cross head bridge is attached to what
Myosin filament
31
What generates the greatest force in muscle contraction
crosshead bridge moving actin
32
where does myosin cross head bridge head bind and latch on to
the binding site space on the double helix actin
33
what does the cross bridge head require to flip and detach itself from actin
ATP
34
Hydrolysis of ATP does what to cross bridge head
energises cross bridge attaching itself to actin
35
accumulation of ADP can cause what in contraction
muscle fatigue
36
what triggers contractions
fired AP causing an increase concentration of calcium ions
37
what does muscle do when relaxing
rid itself of calcium ions
38
what partially covers myosin binding site
Tropomyosin
39
Tropomyosin held in position by
troponin
40
Tropomyosin and troponin are an example of
cooperative bonding
41
What happens when calcium binds to troponin
pulls away Tropomyosin opening biding site for cross bridge head on myosin
42
Where is calcium ions stored
sacroplasm reticulum
43
what do transverse tubules deeply invaginated in the sarcolemma allow
depolarisation, conducting signal to release calcium ions
44
Depolarisation across cell membrane triggers
DHP to open calcium channel on sarcoplasmic reticulum
45
Why is relaxation powered
as ATP needed to remove calcium ions back into sarcoplasmic reticulum
46
How is paralysis prevented
muscle fibres within a motor unit may be scattered throughout muscle therefore hard to loose muscle activation
47
What is a motor unit
motor neurons and muscle fibres
48
Define Tension
force exerted by muscle
49
Load
force exerted on muscle
50
isometric
generates contraction without shortening muscle fibres
51
isotonic
shortens lengths of muscle fibres but tone of contraction kept consistent
52
lengthening
contractions with increasing lengths
53
Latent period
the time before excitation contraction starts
54
Contraction time
start of tension and time when we have peak tension
55
what is contraction time dependent on
calcium ion concentration
56
what has shorter latent period, but longer contraction event
Isometric contractions
57
what happens as load increases
contraction velocity and distance shortened decreases
58
What is a twitch
contraction of muscle fibre due to single AP being fired
59
Tetanus/ tetanic contraction
sustained level of contraction lev in any muscle fibre
60
what is an unfused tetanus?
stimulus not frequent enough, so cell can repolarise and depolarise again
61
If action potential is fired rapidly in the muscle what is it called
fused tension
62
why is a tetanic contraction better than a twitch tension
Calcium ions never get low for troponin to roebuck myosin biding sites
63
Less overlap over filaments means what about tension
there is less
64
Why cant we sustain titanic contraction for long
high calcium contraction for to long can cause cellular degradation
65
What happens if you overstretch muscle
Filaments interfere with each other to much and muscle does not contract
66
Optimal length for isometric tension is when?
The maximum interaction of myosin heads to maximum number of actin binding
67
Movement of limbs requires what?
two antagonistic groups
68
define antagonistic muscle
muscle that opposes the action of another
69
What are muscle arranged in
Lever system
70
What does lever arrangement allow
Less muscular effort to be given to move a heavier load
71
What allows increased maneuverability
Lever system
72
What does ATP power for contraction
Ca2+ to be pumped back into sacroplasm reticulum
| Binding to myosin hydrolysing Xbridge
73
What is fatigue due to
repeated muscle contraction
74
What is fatigue dependant on
fibre type,
length of contraction,
fitness of individual
75
When does rigor occur in muscles
when muscle uses up vast amount of ATP
76
what causes muscle fatigue during high intensity, short duration exercise
Increased lactic acid from glycolysis
increased ADP inhibiting xbridge
Conduction failure K doesn't depolarise
77
what causes muscle fatigue during long-term, low intensity exercise
decreased muscle glycogen
decreased blood glucose
dehydration
78
What happens in central command fatigue
cerebral cortex cannot excite motor neurons, rest period
79
What are the two ATP forming pathways of skeletal muscle fibres
oxidative or glycotic
80
Skeletal muscle fibres are fast if myosin has
high ATPase activity, so xbridge can be energised quickly
81
what do oxidative fibres contain that glycolytic don't have
myoglobin
| red
82
Why are glycolytic fibres white
dont contain myoglobin pigment
83
What increases oxygen delivery in oxidative fibres
Increased mitochondria
increased vascularisation
low diameters
contain myoglobin
84
what fibres is coloured red
oxidative
85
What diameters do glycolytic fibres have
large
86
What do glycolytic fibres have an increase of compared to oxidative
glycogen
87
What size of neutrons are easiest to exit first and example
small therefore slow oxidative fibres activated first
88
What do slow oxidative resist more of compared to fast glycolytic
fatigue
89
Fast glycolytic fibres are the largest and produce the most force due to
containing the most myofibrils
90
What fibres are last to be activated
Fast glycolytic fibres
91
increasing load results in increasing
number of active motor units
92
when the number of active motor units is increasing its called
recruitment
93
Neural control of muscle tension depends on
Frequency of AP’s
| Recruitment of motor units
94
What do muscles need to be able to survive
base line level of stimulation
95
what is denervation atrophy and what can be the cause
Muscle wastage due to destroyed nerve or NMJ
96
when muscle is not used what happens
Disuse atrophy
97
What is an increase in muscle mass called
Hypertrophy
98
How does exercise cause hypertrophy?
Proteins are taking up to repair muscle damage
99
What is smooth muscle innervated by
autonomic NS
100
Where does smooth muscle exist
in hollow organs
| eg. GI tract, uterus, airways, ducts
101
Structure of smooth muscle
spindled shape
| mononucleate
102
What muscle can divide through life
smooth muscle
103
How are filaments arranged in smooth muscle
diagonally across the cells anchored by dense bodies to cell membrane and cell structures
104
In smooth muscle what does calcium bind to during x bridge activation
calmodulin
105
What activates myosin light chain kinase
calcium calmodulin complex
106
What does activated myosin light chain kinase do in smooth muscle
phosphorylates myosin x bridge with ATP
107
How does smooth muscle relax
dephosphorylation of X-bridges
108
How can persistent stimulation s useful in blood vessels and can be maintained by
decreasing rate of ATP splitting
slow x bridge
Xbridge dephophorylated when still bound to actin
109
What muscle are only some sites activated by Ca2+
smooth muscle
110
In skeletal muscle ca2+ from one action potential saturates how many troponin sites
all
111
What muscle has the greatest range and control
smooth muscle
112
Depending on how many AP reach the cell is how smooth muscle does what
grade the contraction
113
What does it mean than smooth muscle has a tone
basically has a base level of Ca2+ causing constant level of tension
114
What factors affect the activity of contraction
```
Autonomic NT
Hormones
local factors
stretching of muscles
Spontaneous electrical activity in muscle membranes ie pacemakers
```
115
What are the two types of smooth muscle
single unit or multi unit
116
Many cells linked by gap junctions is what kind of smooth muscle type
single unit
117
What muscle type responds to stretch
single unit
118
How do signal travel in single unit and how do cells contract
signals travel between cells
| contract synchronously
119
Smooth muscle sing unit fibres may contain what
pacemakers
120
examples of multiunit fibres
hair, airways, large arteries
121
Small blood vessels, GI tract and uterus are what smooth muscle fibres
single unit
