Chapter 10: Muscle Tissue Flashcards
(93 cards)
1
Q
acetylcholine (ACh)
A
neurotransmitter that binds at a motor end-plate to trigger depolarization
2
Q
actin
A
protein that makes up most of the thin myofilaments in a sarcomere muscle fiber
3
Q
action potential
A
change in voltage of a cell membrane in response to a stimulus that results in transmission of an electrical signal; unique to neurons and muscle fibers
4
Q
aerobic respiration
A
production of ATP in the presence of oxygen
5
Q
angiogenesis
A
formation of blood capillary networks
6
Q
aponeurosis
A
broad, tendon-like sheet of connective tissue that attaches a skeletal muscle to another skeletal muscle or to a bone
7
Q
ATPase
A
enzyme that hydrolyzes ATP to ADP
8
Q
atrophy
A
loss of structural proteins from muscle fibers
9
Q
authorhymicity
A
heart’s ability to control its own contractions
10
Q
calmodulin
A
regulatory protein that facilitates contraction in smooth muscles
11
Q
cardiac muscle
A
striated muscle found in the heart; joined to one another at intercalated discs and under the regulation of pacemaker cells, which contract as one unit to pump blood through the circulatory system. Cardiac muscle is under involuntary control.
12
Q
concentric contraction
A
muscle contraction that shortens the muscle to move a load
13
Q
contractility
A
ability to shorten (contract) forcibly
14
Q
contraction phase
A
twitch contraction phase when tension increases
15
Q
creatine phosphate
A
phosphagen used to store energy from ATP and transfer it to muscle
16
Q
dense body
A
sarcoplasmic structure that attaches to the sarcolemma and shortens the muscle as thin filaments slide past thick filaments
17
Q
depolarize
A
to reduce the voltage difference between the inside and outside of a cell’s plasma membrane (the sarcolemma for a muscle fiber), making the inside less negative than at rest
18
Q
desmosome
A
cell structure that anchors the ends of cardiac muscle fibers to allow contraction to occur
19
Q
eccentric contraction
A
muscle contraction that lengthens the muscle as the tension is diminished
20
Q
elasticity
A
ability to stretch and rebound
21
Q
endomysium
A
loose, and well-hydrated connective tissue covering each muscle fiber in a skeletal muscle
22
Q
epimysium
A
outer layer of connective tissue around a skeletal muscle
23
Q
excitability
A
ability to undergo neural stimulation
24
Q
extensibility
A
ability to lengthen (extend)
25
fascicle
bundle of muscle fibers within a skeletal muscle
26
fast glycolytic (FG)
muscle fiber that primarily uses anaerobic glycolysis
27
fast oxidative (FO)
intermediate muscle fiber that is between slow oxidative and fast glycolytic fibers
28
fibrosis
replacement of muscle fibers by scar tissue
29
glycolysis
anaerobic breakdown of glucose to ATP
30
graded muscle response
modification of contraction strength
31
hyperplasia
process in which one cell splits to produce new cells
32
hypertonia
abnormally high muscle tone
32
hypertrophy
addition of structural proteins to muscle fibers
33
hypotonia
abnormally low muscle tone caused by the absence of low-level contractions
34
intercalated disc
part of the sarcolemma that connects cardiac tissue, and contains gap junctions and desmosomes
35
isometric contraction
muscle contraction that occurs with no change in muscle length
36
isotonic contraction
muscle contraction that involves changes in muscle length
37
lactic acid
product of anaerobic glycolysis
38
latch-bridges
subset of a cross-bridge in which actin and myosin remain locked together
39
latent period
the time when a twitch does not produce contraction
40
motor end-plate
sarcolemma of muscle fiber at the neuromuscular junction, with receptors for the neurotransmitter acetylcholine
41
motor unit
motor neuron and the group of muscle fibers it innervates
42
muscle tension
force generated by the contraction of the muscle; tension generated during isotonic contractions and isometric contractions
43
muscle tone
low levels of muscle contraction that occur when a muscle is not producing movement
44
myoblast
muscle-forming stem cell
45
myofibril
long, cylindrical organelle that runs parallel within the muscle fiber and contains the sarcomeres
46
myogram
instrument used to measure twitch tension
47
myosin
protein that makes up most of the thick cylindrical myofilament within a sarcomere muscle fiber
48
myotube
fusion of many myoblast cells
49
neuromuscular junction (NMJ)
synapse between the axon terminal of a motor neuron and the section of the membrane of a muscle fiber with receptors for the acetylcholine released by the terminal
50
neurotransmitter
signaling chemical released by nerve terminals that bind to and activate receptors on target cells
51
oxygen debt
amount of oxygen needed to compensate for ATP produced without oxygen during muscle contraction
52
pacesetter cell
cell that triggers action potentials in smooth muscle
53
pericyte
stem cell that regenerates smooth muscle cells
54
perimysium
connective tissue that bundles skeletal muscle fibers into fascicles within a skeletal muscle
55
power stroke
action of myosin pulling actin inward (toward the M line)
56
pyruvic acid
product of glycolysis that can be used in aerobic respiration or converted to lactic acid
57
recruitment
increase in the number of motor units involved in contraction
58
relaxation phase
period after twitch contraction when tension decreases
59
sarcolemma
plasma membrane of a skeletal muscle fiber
60
sarcomere
longitudinally, repeating functional unit of skeletal muscle, with all of the contractile and associated proteins involved in contraction
61
sarcopenia
age-related muscle atrophy
62
sarcoplasm
cytoplasm of a muscle cell
63
sarcoplasmic reticulum (SR)
specialized smooth endoplasmic reticulum, which stores, releases, and retrieves Ca++
64
satellite cell
stem cell that helps to repair muscle cells
65
skeletal muscle
striated, multinucleated muscle that requires signaling from the nervous system to trigger contraction; most skeletal muscles are referred to as voluntary muscles that move bones and produce movement
66
slow oxidative (SO)
muscle fiber that primarily uses aerobic respiration
67
smooth muscle
nonstriated, mononucleated muscle in the skin that is associated with hair follicles; assists in moving materials in the walls of internal organs, blood vessels, and internal passageways
68
somites
blocks of paraxial mesoderm cells
69
stress-relaxation response
relaxation of smooth muscle tissue after being stretched
70
synaptic cleft
space between a nerve (axon) terminal and a motor end-plate
71
T-tubule
projection of the sarcolemma into the interior of the cell
72
tetanus
a continuous fused contraction
73
thick filament
the thick myosin strands and their multiple heads projecting from the center of the sarcomere toward, but not all to way to, the Z-discs
74
thin filament
thin strands of actin and its troponin-tropomyosin complex projecting from the Z-discs toward the center of the sarcomere
75
treppe
stepwise increase in contraction tension
76
triad
the grouping of one T-tubule and two terminal cisternae
77
tropomyosin
regulatory protein that covers myosin-binding sites to prevent actin from binding to myosin
78
troponin
regulatory protein that binds to actin, tropomyosin, and calcium
79
twitch
single contraction produced by one action potential
80
varicosity
enlargement of neurons that release neurotransmitters into synaptic clefts
81
visceral muscle
smooth muscle found in the walls of visceral organs
82
voltage-gated sodium channels
membrane proteins that open sodium channels in response to a sufficient voltage change, and initiate and transmit the action potential as Na+ enters through the channel
83
wave summation
addition of successive neural stimuli to produce greater contraction
84
4 properties of muscle
excitability
contractibility
extensibility
elasticity
85
skeletal muscle characteristics
- muscle fibers multinucleated
- striated
- voluntary
- essential for movement
86
smooth muscle characteristics
- uniform non-striated cytoplasm
- uninucleated
- involuntary
- essential for visceral organs and circulation
- spindle shape fibers
- endomysium CT
- actin and myosin contracile proteins
- dense bodies
- calcium supplied by calveoli
- stress relaxation response
87
cardiac muscle
- 2 nuclei in each fiber
- fibers physically and electrically connected
- involuntary
- intercalated discs allows muscles to contract
- possess mitochondria and myoglobin
- gap junctions & desmosomes
- autorhythmicity
- branched fibers
88
6 functions of skeletal muscle
- contract and cause movement and stop movement
- resisting gravity to maintain posture
- maintain skeletal stability and prevent skeletal structure damage
- allows for basic voluntary movements such as urination or swallowing
- protect internal organs
- maintenance of homeostasis through heat generation and shivering
89
layers of skeletal muscle
1. epimysium- surrounds skeletal muscle
2. perimysium- surrounds muscle fascicle
3. endomysium- surrounds muscle fiber
4. muscle fibre
5. myofibril
6. microfilaments
90
signaling steps
- neuronal action potential travels along axon of motor neuron
- at neuromuscular junction, axon terminal releases acetylcholine
- ACh diffuses across synaptic cleft
- ACh binds to receptors in the motor end plate on sarcolemma on other side of synapse
- ACh receptor opens up for a channel for positive ions to pass
- muscle fibers depolarize and membrane potential becomes less negative
- voltage-gated sodium channels triggered to open
- sodium ions enter muscle fiber
- action potential fires and initiates excitation-contraction coupling
91
excitation-contraction coupling
- signals from the somatic motor division of the nervous system; motor neurons originate from spinal cord
- muscle fiber action potential sweeps across sarcolemma as a wave
- AP is coupled to the actual contraction through the release of calcium ions from sarcoplasmic reticulum
- calcium interacts with shield proteins forcing them to move aside so actin-binding sites are available
- myosin pulls actin filaments towards center
- muscle fiber shortened
92
muscle contraction steps
- Action potential in a motor neuron triggers the release of Ca2+ ions from the sarcoplasmic reticulum
- Calcium ions bind to troponin (on actin) and cause tropomyosin to move, exposing binding sites for the myosin heads
- The actin filaments and myosin heads form a cross-bridge that is broken by ATP
- ATP hydrolysis causes the myosin heads to swivel and change orientation
- Swiveled myosin heads bind to the actin filament before returning to their original conformation (releasing ADP + Pi)
- The repositioning of the myosin heads move the actin filaments towards the centre of the sarcomere
- The sliding of actin along myosin therefore shortens the sarcomere, causing muscle contraction
