Chapter 10 part 2` Flashcards
(118 cards)
1
Q
a twitch
A
is a single stimulus-contraction-relaxtion sequence of a muscle fiber
2
Q
how many phases in a muscle twitch?
A
3
3
Q
latent period
A
is the lag period between the arrival of the stimulus before contraction starts where no tension is produced
4
Q
how long does the latent period last?
A
3 milliseconds
5
Q
The events of latent period are?
A
- ach binds with receptors(stimulus)
- chemically gated ion channels open
- sodium ions enters fiber and depolarizes it to threshold
- action potential spreads through sarcolemma and transverse tubules
- sarcoplasmic reticulum releases calcium ions
- calcium ions bind to troponin
- troponin changes shape and moves tropomyosin
- myosin binding sites on actin are exposed
- some cross bridges form
6
Q
contraction period
A
repetative power strokes pull thin filaments past thick filaments shortening the sarcomere increasing tension to a peak
7
Q
how long does contrition period last?
A
it varies
8
Q
what are the steps for contract period?
A
1.power stroke occurs
2. crossbridge cycling: multiple repetitions of attach, pull, release and reset
3, the sarcomere fully contracts
9
Q
relaxtion phase
A
is where the tension returns to resting levels, lasts 25 milliseconds
10
Q
the events of the relaxation phase are
A
- myosin heads release actin
- calcium ion levels in sarcoplasm decrease
3 tropomyosin covers myosin binding sites
11
Q
Why does calcium ion levels decrease during the relaxation phase?
A
the ion pumps return calcium ions into the sarcoplasmic reticulum and the gated ion channels close
12
Q
muscle tension is?
A
the force generated when a skeletal muscle is stimulated to contract based on the frequency of stimulation
13
Q
at a low frequency
A
a full twitch cycle where muscle is able to completely relax
14
Q
at a low frequency each twitch is producing what?
A
the same tension
15
Q
treppe
A
stimulus directly follows relaxation phase of previous contraction resulting in stepwise increase in strength of contraction
16
Q
Sequential contractions have higher maximum tension over the first ____ minutes
A
30-50
17
Q
Why is tension rising with each twitch?
A
not all calcium was put back into the SR from previous contraction
18
Q
more calcium ions means?
A
more cross bridges can be formed
19
Q
the warming up effect
A
prior contraction produces heat which increases efficiency of molecular interaction
20
Q
wave(temporal) summation
A
second stimulus arrives before relaxation period causing twitches to combine and produce greater tension
21
Q
Muscle contraction is sustained as, each new wave is added to?
A
the previous
22
Q
Incomplete tetany
A
stimulus frequency increased resulting in rapid cycles of contraction relaxation near max tension
23
Q
muscle contraction is sustained at max tension with?
A
no rest at all
24
Q
tetany
A
stimulus frequency so high that relaxation period is eliminated
25
if incomplete tetany continued?
the muscle would fatigue
26
incomplete tetany is
only observed in lab experiments
27
increasing number of active motor units
recruitment
28
motor unit
all muscle fibers innervated by a single motor neuron
29
Muscle fibers of motor units are intermingled so the:
direction of force on tendon does not change with activation of different motor units
30
More motor units activated =
greater force generated by muscle
31
motor units want to
generate proper amount of force to overcome the load
32
muscle tone
Variable number of motor units are always active even when not contracting
33
more muscle tone means
greater resting rate of metabolism
34
muscle tone is
subconsciously controlled
35
different motor units
are activated and relaxed all of the time
36
during Normal resting length of a sarcomere, it is at its
optimal range, max # of cross bridges can form
37
when does sarcomere generate greatest amount of tension?
ormal resting length
38
stretched sarcomeres
zone of overlap decreases when stretched
39
stretched sarcomeres make it so less...
cross bridges can form
40
stretched sarcomeres ____the amount of tension it can produce
decrease
41
thin filaments overlap portion of myosin tails
compressed sarcomeres
42
sarcomeres have ____ before thick filaments run into Z line
less distance to shorten
43
compressed sarcomeres decrease the amount of
tension it can produce
44
same length; different tension
isometric concentration
45
an isometric contraction, Muscle maintains same length even as:
the amount of tension changes
46
in isometric contraction, muscle fibers shorten and
muscle fibers stretch
47
in isometric contraction, tension doesn't overcome the load equalling
no movement
48
isotonic contraction
same tension, different length
49
muscle maintains tension as it changes length to cause
movement
50
concentric contraction
muscle shortens, tension is greater than the load
51
eccentric contraction
muscle elongates, tension is less than the peak tension so the muscle lengthens
52
example of isotonic contraction
tension in the biceps bracii while raising a barbell during biceps curls
53
example of eccentric contraction
tension in biceps brachia while lowering your coffee
54
muscle contraction requires ATP to
recock myosin heads
| pump calcium ions into the sarcoplasmic reticulum
55
Energy Sources Stored in Typical Muscle Fiber
ATP
Creatine Phosphate (CP)
Glycogen
56
ultimate energy source for cells
ATP
57
ATP stores energy in bonds between:
phosphate groups
58
only enough in muscle fiber to produce about
5-6 seconds of work
59
creatine phosphate
high energy compound produced within skeletal muscles composed of amino acids
60
only enough to produce about
130 seconds of work
61
glycogen is
stored glucose
62
if broken down through anaerobic respiration, will be able to produce
130 seconds of work
63
if broken down through aerobic respiration it will be able to produce
40 minutes of work
64
anerobic respiration
doesn't require oxygen
located in the cytosol
also known as glycolosis
65
in anerobic respiration, breaks down a glucose molecule to produce
```
4 ATP( net gain of 2)
2 pyruvate molecules
```
66
aerobic respiration
requires oxygen and located in mitochondria
67
aerobic respiration breaks down 2 glucose molecules and produces
co2
H2O
ATP
68
the citric acid cycle
removes hydrogen ions and electrons to be used by the electron transport system
69
The citric acid cycle produces
2CO2 and 1 ATP per cycle
70
The electron transport system
is a series of inner mitochondrial membrane protien pass along electrons and pump across hydrogen ion channels to create an hydrogen ion gradient which is used to create ATP with the help of ATP synthase
71
What does the electron transport system create
6 H2O and 34 ATP
72
Muscle at rest
demand for ATP is low and it produces ATp
73
Extra ATP is used to build up preserves of
creatine phosphate and glycogen
74
muscles at moderate activity levels
demand for ATP increases, uses aerobic respiration and anaerobic respiration to break down glucose
75
muscles at peak activity levels
not enough oxygen present for aerobic respiration to keep up with demands
76
in Muscles at Peak Activity Levels dont have enough oxygen present for aerobic respiration to occur remaining pyruvate will be:
converted to lactic acid
77
lactic acid dissociates into
lactate and a hydrogen ion
78
lactic acid lowers?
Ph
79
lactate can be converted back into what when oxygen is present?
pyruvate and broken down into mitochondria
80
lactate is put back into blood and
sent to the heart to be broken down to make ATP and liver to be converted back into glucose(cori cycle)
81
muscle fatigue is
when muscles can no longer continue to perform at the required level of activity
82
Factors attributing to fatigue: (4)
1. Depletion of metabolic reserves
2. Less Ca+ available
3. Change in [Na+]/[K+] interfering with ability to conduct AP
4. Elevated [P] slowing rate of cross bridge`
83
WHat does Ca+ do in muscles
1. Trigger exocytosis from synaptic knob
| 2. Bind with troponin
84
Effects are cumulative; the more fibers /neurons effected the greater the reduction in performance
gradual onset
85
muscles still have some ATP otherwise
cross bridges would remain intact and muscles would stay contracted
86
recovery from fatigue
oxygen debt, excess post exercise oxygen consumption(EPOC)
87
Excess Post Exercise Oxygen Consumption is:
Amount of O2 required to restore the fiber back to pre exercise conditions
88
while oxygen debt is being replaced
breathing rate and depth increases
89
with endurance exercise enhance ability to produce ATP by increasing
Capillary network
mitochondria
myoglobin
90
with resistance exercise enhance peak tension by increasing
the number of myofilaments
91
types of skeletal muscle fibers
fast
slow
intermediate
92
```
fast fibers are:
____ in diameter
appear __(color)__
reach peak twitch tension @ __(time)__
powered by _____ respiration
```
large
white
.1 sec or less
anaerobic
93
fast fibers:
____ in capillary beds
____ mitochondria
____ amount of myoglobin
sparse
few
small
94
fast fibers ___ rapidly
fatigue
95
muscle with large % of fast fibers are in:
upper limbs
96
```
slow fibers are:
____ in diameter
appear __(color)__
reach peak twitch tension @ __(time)__
powered by _____ respiration
```
half the size of fast fibers
red
slow to reach peak tension
aerobic
97
slow fibers are:
____ in capillary networks
____ mitochondria
____ amount of myoglobin
extensive
many
large
98
slow fibers are ___ to fatigue
slow
99
Muscle with large % of slow fibers are in the
trunk and lower limbs
100
```
intermidate fibers are:
____ in diameter
appear __(color)__
reach peak twitch tension @ __(time)__
powered by _____ respiration
```
between slow and fast
pink
between slow and fast
aerobic
101
intermediate fibers are:
____ in capillary networks
____ mitochondria
____ amount of myoglobin
moderately extensive
many
medium
102
intermidiate fibers resist
fatigue
103
Muscle with large % of intermediate fibers are in the
legs
104
Most muscles in human contain a
mixture
105
% of fast v. slow fibers are ____ determined
genetically
106
Ratio of intermediate to fast however can be altered through
athletic training
107
enlargement of stimulated muscles
hypertrophy
108
do you create more muscle fibers?
no
109
Increase in muscle diameter is due to:
increase in muscle fiber diameter
110
muscle is stronger to produce
a greater peak tension
111
atrophy
reduction of muscle tone, size and power
112
atrophy is a result from?
muscles not being used frequently
weaker muscle
aging
113
rigor mortis
generalized skeletal muscle contraction following death throughout body
114
rigor mortis is caused by
deterioration of sarcoplasmic reticulum
| lack of ATP
115
Deteratiion of Sarcoplasmic reticulum
calcium binds with troponin allowing contraction
116
without ATP
myosin heads can't be reset
| calcium ions can't be pumped out of sarcolemma
117
when does rigor mortis begin?
2-7 hours after death
118
when does rigor mortis disappear?
1-6 days when decomposition begins
