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ZOO3600 > Muscles > Flashcards

Muscles Flashcards

1
Q

sarcomere

A

basic unit of a muscle fiber, defined by the area between two Z-discs, containing thick and thin filaments

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2
Q

myofilament

A

protein filaments in muscle fibers; thick filaments (myosin) and thin filaments (actin) that facilitate contraction

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3
Q

cross-bridge

A

the connection formed when a myosin head binds to an actin filament during muscle contraction

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4
Q

excitation-contraction coupling

A

the process that links electrical stimulation of a muscle to its contraction, involving calcium release and interaction between actin and myosin

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5
Q

3 types of muscle

A

skeletal, cardiac, smooth

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6
Q

which muscles are voluntary

A

skeletal muscle

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7
Q

involuntary muscle

A

cardiac and smooth muscle

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8
Q

striated muscle

A

skeletal and cardiac muscle

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9
Q

unstriated muscle

A

smooth muscle

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10
Q

what type of muscle cell is a muscle fiber

A

multinucleated

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11
Q

thin filaments

A

a two-strand actin helix + the filamentous protein tropomyosin + the troponin complex

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12
Q

actin

A

a protein found in all muscle tissues, creates smaller filaments

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13
Q

thick filmanets

A

hundreds of indentical myosin proteins

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14
Q

myosin

A

a protein found in all muscle tissue, creates large filaments

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15
Q

what do the head regions of myosin contain

A

actin and atp-binding sites

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16
Q

what happens to sarcomeres during muscle contraction

A

they shorten; thin filaments actively slide along the thick filaments

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17
Q

what do cross-bridges convert

A

chemical energy into mechanical energy

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18
Q

where does the cross-bridge cycle start

A

binding site

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19
Q

what are the stages of the cross-bridge cycle

A
  1. release - binding of ATP causes myosin to detach from actin
  2. binding - hydrolysis of ATP causes myosin head to extend and attach to actin
  3. power stroke - release of phosphate promotes myosin head rotation
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20
Q

how does rigor mortis occur

A

without ATP, myosin binds irreversibly to actin causing stiffening of muscles

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21
Q

what mineral is myosin movement dependent on

A

calcium

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22
Q

when Ca is low

A

tropomyosin blocks the myosin binding sites on actin, muscles relaxed

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23
Q

when Ca is high

A

troponin pulls tropomyosin out of the way, allowing cross bridges to form

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24
Q

excitation-contraction coupling

A

muscle fibers contract when a postsynaptic end plate potential at the neuromuscular junction causes a propagated AP in the fiber sarcolemma

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25
what type of tubules conduct action potentials into cell interior
transverse
26
what molecules are involved in excitation-contraction coupling
voltage sensitive DHPR and RyR Ca pumps Calsequestrin
27
what is a twitch
a single AP leading to a momentary flood of Ca inside cell, allows cross bridges to form, develops tension (last 5 - 20x longer than action potential)
28
temporal summation
addition of tension due to repeated and rapid stimulation, can result in max tension
29
how many muscle fibers are innervated by one motor neuron
one
30
how to increase muscle tension
- increasing AP frequency (temporal summation) - recruiting more motor units - recruiting higher intensity contraction fibers
31
force-velocity relationship
as load increases, velocity of shortening decreases
32
reason for inverse relationship between load and velocity
cross bridge cycling takes time, when slowed more myosin heads can act at same time leading to greater force potential
33
force transducer
measures tension generated by the muscle fiber when stimulated to contract
34
FG fiber ATP production
glycolysis
35
SO fiber ATP production
oxidative phosphorylation
36
is rate of Ca uptake by SR higher in FG or SO
FG
37
roles of ATP
cross bridge cycling, regulating intracellular Ca levels, maintaining nerve membrane potential
38
what type of movement demands less ATP
high force, low speed
39
what would let an athlete win in a 50 m spring
more FG fibers (unsustained)
40
what would let an athlete win a marathon
more SO fibers (sustained)
41
glycolysis
glucose is broken down into pyruvate, producing energy in the form of ATP in absence or presence of oxygen
42
oxidative phosphorylation
takes place in mitochondria, energy from nutrients is used to produce ATP via electron transport chain and oxygen is final electron acceptor
43
creatine phosphate
high energy molecule stored in muscles that quickly donates a phosphate group to ADP to regenerate ATP during short bursts of high intensity activity
44
how is burst energy ATP made available so quickly
creatine phosphate system and anaerobic glycolysis
45
how does sustained energy have an uninterupted supply of ATP
aerobic respiration and fatty acid oxidation
46
what determines the rate at which a muscle can work
ATP production rate
47
2 definining features of ATP
not transported between cells, not stored
48
what did the mouse experiment demonstratae
mice mutants with full Creatine kinase activity had higher burst activity performance than those with no CK activity, showing that the ability of muscle to perform burst activity is proportional to CK activity
49
what does high-intensity and short term activity produce
lactic acid (indicator of fatigue)
50
what causes fatigue in sustained exercise
inadequate muscle glucose
51
muscle fatigue results from (3 answers)
depletion of energy reserves (ATP, glycogen), ion disturbances, and pH imbalance
52
how can you recover from muscle fatigue
replenishing energy stores (using Cori cycle) reestablishing ion balance (gradients, Ca stores, pH)
53
where does ATP have to come from to recover muscle (recovery metabolism)
aerobic pathways
54
EPOC
Excess post-exercise oxygen recovery
55
why is there an o2 deficit at beginning of exercise
demand of O2 > supply of O2
56
what is the repayment phase
exercise has stopped but oxygen remains high to restore the bodys energy balance
57
what do superfast muscles do
contract synchronously at rates that would put regular muscles into tetanus
58
what is tetanus
sustained contraction with no relaxation
59
what conditions allow superfast muscles to work
1. short Ca transients (rapid cycling between SR and cytoplasm) 2. quick cross-bridge cycling (force generation extremely fast)
60
what does flight require
continuous aerobic high power output at high contraction frequencies
61
adaptations to flying
increasing muscle temperature, skeletal adaptations, increasing mitochondria inner membrane for more ATP production
62
synchronous flight muscles
connect to the wing, one set of muscles raises the wing (elevator muscle) and another lowers them (depressor muscle)
63
what animals have synchronous flight muscles
vertebrates and some insects
64
asynchronous flight muscles
connected to the whole body, vertical muscles contract to make body vertically compressed, longitudinal muscles contract to shorten the body
65
oppositional muscles
when one stretches the other contracts
66
effect of oppositional muscles on Ca
as muscle stretches, Ca increases, triggering contraction
67
AP and contraction relation in asynch flight
single AP initiates series of contractions , frequency of contr is not synched w frequency of AP
68
space distribution in asynch flight muscles
less space for SR and mitochondria, more space for myofibrils
69
what type of muscle is internalized to retain heat in tuna
red muscle
70
what type of muscle is red muscle
slow oxidative muscle, packed with ATP
71
regional heterothermy
parts of the fish are kept warmer than surrounding environment, improving the efficiency of muscles
72
rete mirabile
structure that retains heat in muscle and prevents loss of heat to gill
73
heater organs
specialized eye muscles that keep brain/eye temp stable and warmer than surrounding water
74
what is the carotid rete
collects heat generated by the heater muscle
75
differences between skeletal muscle cells and heater organ muscle cells
increase in mitochondria content (increased ATP production) increased SR content (increase storage and release of Ca) proliferation of T-tubules (increase release of Ca into cell) no contractile apparatus
76
what is responsible for storing and releasing Ca
SR and T tubule
77

ZOO3600 (3 decks)

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