Muscles Flashcards
(107 cards)
1
Q
What is required for muscle function
A
interaction of protein filaments
2
Q
is muscular activity a related to the nervous system
A
yes it is a response to input from the nervous system
3
Q
What composes the thin filaments
A
composed mainly of actin
4
Q
what composes the thick filaments
A
composed mainly of myosin
5
Q
what do muscle cell contractions rely on
A
interactions between thin and thick filaments
6
Q
how do contractions occur
A
thick and thin filaments overlap which increases during the contraction, after contraction everything slides
7
Q
what powers contractions
A
powered by ATP
8
Q
what are the three types of muscles in vertebrates
A
skeletal, cardiac, and smooth
9
Q
what does skeletal muscle control/ involve
A
voluntary movement and breathing
10
Q
what does cardiac muscle control/ involve
A
beating of the heart
11
Q
what does smooth muscle control/ involve
A
involuntary, movement of internal organs
12
Q
what is the functional unit of a muscle called
A
a sarcomere
13
Q
Does the I band consist of only actin, only myosin, or both.
A
The I band consists of only actin
14
Q
Does the H zone consist of only actin, only myosin, or both.
A
The H zone consists of only myosin
15
Q
how many actin surround a myosin filament
A
each myosin is surrounded by 6 actin
16
Q
what is titan
A
it is the largest protein in the body (spans entire sarcomere)
17
Q
what is the function of titan
A
titan holds myosin in place because the only thing myosin touches is the M band
18
Q
why is skeletal muscle also called striated muscle
A
because the arrangement of the myofilaments create a pattern of light and dark bands
19
Q
What is the structure of myosin
A
each myosin has a long ‘tail” and a globular “head”
20
Q
what is the function of the myosin head
A
The myosin head binds to actin filaments and pull them towards the center of the sarcomere. muscle contractions require the repeated cycle of this
21
Q
What are the regulatory proteins
A
Tropomyosin and troponin complex
22
Q
what are the regulatory proteins
A
tropomyosin and the troponin complex are additional proteins that bind to actin strands on thin filaments
23
Q
what is the purpose of the regulatory proteins
A
they prevent actin and myosin from interacting. for muscle contractions to occur, the myosin binding sites must be exposed
24
Q
What do calcium ions do for muscle contractions
A
they bind to the troponin complex and expose the myosin binding sites
25
how are calcium ions and contractions related
contraction occurs when the concentration of Ca2+ is high; muscle contraction stops when the concentration of Ca2+ is low
26
what is the stimulus that leads to a muscle contraction
an action potential
27
where does the action potential occur
in a motor neuron that synapses with the muscle fiber
28
the neurotransmitter acetylcholine is released by the synaptic terminal what does it do
acetylcholine depolarizes the muscle, causing it to produce an action potential
29
how do action potentials travel inside the muscle fibers
action potentials travel to the interior of the muscle fibers along transverse (t) tubules
30
what do the action potentials cause to be released
the action potentials along T tubules cause the sarcoplasmic reticulum to release Ca2+
31
how does the calcium get out when the contraction is over
transport proteins in the SR pump calcium out of the cytosol
32
where is calcium released from
the sarcoplasmic reticulum
33
what does the calcium bind to
binds to troponin
34
where is the troponin that the calcium binds to
troponin in the actin filaments
35
what does calcium binding to troponin do to the cell
it leads to a conformational change in the tropomyosin
36
what does the conformational change in tropomyosin do
it allows actin-myosin interaction
37
contraction of the muscle is graded. what does this mean
the extent and strength of its contraction can be voluntarily altered
38
how does the nervous system produce the graded contractions
the number of fibers that contract and the rate the fibers are stimulated
39
how many muscle fibers can synapse with each motor neuron
multiple muscle fibers although each fiber is controlled by only one motor neuron
40
what is a motor unit
a single motor neuron and all the muscle fibers it controls
41
what is a twitch/ single twitch
when action potentials are close together in time; tension increases
42
what is tetanus
a state of sustained contraction produced when the rate of stimulation is so high that muscle fibers cannot relax between stimuli
43
what are the three systems for obtaining ATP
immediate system, glycolytic system, oxidative system
44
what is the immediate system
it uses preformed ATP and creatine-phosphate
45
how long does the immediate system last for
can only power muscles for 10 seconds or less
46
where is the energy stored in the immediate system
it stores energy in phosphate bonds which is then transferred to ADP
47
why does the immediate system get exhausted so fast
it gets exhausted within seconds because the muscle can only store very little creatine phosphate and it burns through it fast
48
what is the glycolytic system
metabolizes carbohydrates to pyruvate and lactic acid
49
how is the glycolytic system different from the immediate system
it makes ATP quickly available but doesn't produce a lot of ATP
50
how much ATP is produced from the glycolytic system
1 glucose = 2 ATP
51
where does the glycolytic system occur
it occurs in the cytoplasm (sarcoplasm)
52
is the glycolytic system anaerobic or aerobic
anaerobic it doesn't need oxygen
53
how long does the glycolytic system last for
provides energy for less than one minute
54
why does the glycolytic system last for only a minute
lactic acid accumulates; muscle function decreases as it leads to acidosis
55
what is the oxidative system
it metabolizes carbohydrates and fatty acids to h2o and co2
56
why is the oxidative system efficient
it produces large amounts of ATP through oxidative phosphorylation; 1 glucose = 36 ATP
57
is the oxidative system anaerobic or aerobic
aerobic it requires oxygen
58
where does the oxidative system take place
it occurs in the mitochondria
59
why is the oxidative system slower than the other two systems
ATP has to defuse from mitochondria to the myosin in the sarcoplasm
60
what do oxidative fibers have
these fibers have many mitochondria, a rich blood supply, and a large amount of myoglobin
61
what is myoglobin
a protein that bind oxygen more tightly than hemoglobin does. it has a higher affinity to oxygen that hemoglobin. red meat has a lot of myoglobin
62
why is it important that oxidative fibers have a lot of myoglobin and a rich blood supply
oxidative fibers always need oxygen or else it will shut down
63
why do glycolytic fibers tire easily
they cannot replenish ATP fast because they are using glycolysis as their primary source of ATP
64
since glycolytic fibers tire so fast, what are they useful for
they are good for things that need a lot of power but fast; shot term work with maximum strength
65
which fibers do fast twitches occur in
glycolytic fibers
66
which fibers do slow twitches occur in
oxidative fibers
67
what are fast twitches
enable brief, rapid, powerful contractions
68
what are slow twitch fibers
contract more slowly but sustain longer contractions (much longer)
69
do slow fibers have more or less sarcoplasmic reticulum than fast fibers
slow fibers have less than fast fibers
70
do slow fibers pump Ca2+ fast or slow
slow fibers pump Ca2+ slowly
71
do performance endurance athletes have more glycolytic or oxidative fibers
oxidative fibers. they have a higher proportion of slow twitch fibers than normal
72
do sprinters have more glycolytic or oxidative fibers
glycolytic fibers. sprinters have a high proportion of fast twitch fibers than normal
73
can you increase or decrease the amount of fast or slow twitch fibers you have to become a better athlete?
no you are born with it
74
what does tropomyosin do
blocks myosin binding sites on actin
75
what does troponin do
binds calcium
76
what are transverse tubules
infoldings of the plasma membrane
77
does the sarcoplasmic reticulum conduct action potentials in the interior of the muscle cells
no it stores calcium ions
78
cardiac muscle consists of strained cells electrically connected by intercalated disks. what does this allow the cell to do
this allows depolarization to spread quickly
79
can cardiac muscle generate their own action potentials without input from the nervous system
yes
80
why are cardiac muscles branched and interdigitate
to allow them to withstand high pressures
81
why do cardiac muscles have a lot of mitochondria
to continuously produce ATP, because if it doesn't get ATP you are dead
82
what is the junction between two muscle cells (intercalated discs) for
for connectivity for action potentials and strength
83
what is the purpose of t-tubules and the SR in cardiac cells
allows the action potentials to spread quickly
84
what does the pacemaker and conducting cells do
they initiate and coordinate heart contractions
85
what initiates the action potentials in the cardiac muscles
the pacemaker
86
if the pacemaker initials the action potentials, what does the conducting cell do
it spreads the action potentials quickly in order to synchronize contractions
87
do contractions occur with or without input from the nervous system
without input from the nervous system
88
the heartbeat is myogenic, what does this mean
it is generated by the heart muscle itself. the autonomic nervous system modifies the rate of pacemaker cells, but it is not necessary for their function.
89
what do gap junctions do
they connect the cytoplasm of two neighboring cells
90
what is the purpose of having gap junctions in the cardiac muscles
it allows direct electrical communication between cells
91
why is having direct electrical communications important
it allows cardiac and smooth muscle cells to contract simultaneously
92
why are cardiac and smooth muscle cells arranged in sheets
an action potential in once cell can spread to all others in the sheet
93
where are smooth muscle cells found
found mainly in walls of hollow organs like circulatory, digestive and reproductive systems
94
can smooth muscles contract on their own or must they have input from the nervous system
both. contractions may be generated by themselves because they can generate their own action potentials but they can slo be caused by stimulation from neurons
95
why is smooth muscle not striated.
lacks striation because the actin and myosin are not regular arrayed
96
a venom is injected by a wasp causes paralysis to voluntary muscles, while it doesn't affect the myocardium. what is being targeted by the venom
the venom targets acetylcholine receptors
97
which bands/zones shorten in the sarcomere when the muscle contracts
the I band and the H zone
98
EDTA ius a calcium chelator (removes calcium from solution). what is a consequence for having calcium removed from sarcoplasm of muscle fibers
myosin and actin would not be able to bind to each other
99
do fast twitch fibers fatigue slowly
no they fatigue quickly
100
do slow twitch fibers fatigue slowly
yes
101
does cardiac muscle have intercalated discs
yes
102
what is a consequence for having a strong charged disbursed into the body
cross bridges form between actin and myosin
103
you fluorescently tagged antibody that binds to actin. which parts of the sarcomere will show some of the fluorescence
The A and I bands will show the fluorescence.
104
what is the I band
only actin
105
what is the H zone
only myosin
106
what is the A band
myosin and actin
107
after the first 15 mins of a 10-km run, the major energy of the legs is supplied by what
oxidative metabolism
