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Anatomy and Physiology 1 > Muscular Tissue Chp. 11 > Flashcards

Muscular Tissue Chp. 11 Flashcards

(77 cards)

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1
Q

Universal characteristics of muscle

A

excitability, conductivity, contractility, extensibility, elasticity

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2
Q

Skeletal muscle is _____ and ______

A

voluntary; striated

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3
Q

The skeletal muscle cell is also called

A

muscle fiber or myofiber

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4
Q

Sarcolemma

A

plasma membrane

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5
Q

Sarcoplasm

A

cytoplasm

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6
Q

Myofibrils

A

long protein bundles occupying most of sarcoplasm

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7
Q

Multiple nuclei

A

flattened and pressed against inside of sarcolemma

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8
Q

Mitochondria

A

packed into spaces between myfibrils

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9
Q

Sarcoplasmic reticulum (SR)

A

smooth ER that forms a network around each myofibril; calcium reservoir

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10
Q

Terminal cisternae

A

dilated end-sacs of SR; cross muscle fiber from o side to other

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11
Q

T tubules

A

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on other side
*signal SR when to release calcium which causes muscles contraction

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12
Q

Thick filaments are made of ______ molecules

A

myosin

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13
Q

Thick filaments are shaped like a ______ ______

A

golf club; 2 chains intertwined to form a shaftlike tail

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14
Q

Thick filaments have a _______ _______ myosin head

A

double gobular

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15
Q

Space where there are no myosin heads on thick filament is called _______ ______

A

bare zone

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16
Q

Thin filaments are made of _____

A

actin

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17
Q

Fibrous (F) actin

A

two intertwined strands that make up thin filament

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18
Q

Globular (G) actin subunits

A

each have an active site that can bind to head of myosin molecule

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19
Q

Tropomyosin molecules

A

blocks active site on G actin when the muscle is relaxed; prevents myosin from binding

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20
Q

Troponin molecule

A

small, calcium-binding protein on each tropomyosin molecule

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21
Q

Elastic filaments are made of ______

A

titin

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22
Q

Purpose of titin in elastic filaments

A

anchor thin filament to Z disc & M line
help stabilize & position thick filament
prevent overstretching & provide recoil

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23
Q

Contractile proteins

A

myosin & actin; shorten the muscle

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24
Q

Regulatory proteins

A

troponin & tropomyosin; determine when muscle fiber can/cannot contract

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25
Sarcomere
segment of a myofibril from Z disc to Z disc; functional contractile unit of muscle fiber
26
Muscle cells shorten because their _________ shorten
sarcomeres
27
______ are pulled closer together as thick & thin filaments slide past each other
z discs
28
Neither thick nor thin filaments change length during shortening
only amount of overlap changes
29
During shortening, _______ & _______ proteins also pull on extracellular proteins
dystrophin; linking (transfers pull to extracellular tissue)
30
Structural hierarchy of skeletal muscle (largest to smallest)
muscle, fascicle, muscle fiber, myofibril, sarcomere, myofilament
31
Dystrophin
protein which is located between sarcolemma & outermost myofilaments
32
Dystrophin ______ forces of muscle ______ to CT ultimately leading to tendon
transfers; contraction
33
Muscular dystrophy
a disabling disease which is caused by genetic defects in dystrophin
34
A band
dark; thick (myosin) filaments
35
H band
lighter region in middle of A band; thick filaments only
36
M line
middle of H band; transverse protein complex that links thick filaments
37
I band
light; thin (actin) filaments
38
Z disc
provides anchorage for thin and elastic filaments; bisects I band
39
Skeletal muscle _______ contracts unless stimulated by a _____
never; nerve
40
Somatic motor neurons
nerve cells with cell bodies in brainstem & spinal cord; serve skeletal muscles
41
Somatic motor fibers
axons of somatic motor neurons that lead to skeletal muscle
42
Each ______ ______ branches out to a number of muscle fibers
nerve fiber
43
Each muscle fiber is supplied by only ______ motor neuron
one
44
Motor unit
one nerve fiber and all the muscle fibers innervated by it
45
Muscle fibers of one motor unit are
dispersed throughout the muscle; contract in unison; produce weak contraction over wide area
46
Postural control
motor units take turns contracting to provide long-term contraction
47
The average motor unit has
200 muscle fibers
48
Small motor units
used for a fine degree of control such as eye and hand muscles; 3-6 muscle fibers per neuron
49
Large motor units
used for more strength than control; powerful contractions supplied by large motor units with hundreds of fibers; ex. gastrocnemius has 1,000 muscle fibers per neuron
50
Synapse
point where a nerve fiber meets its target cell
51
Neuromuscular junction (NMJ)/motor end plate
when the target cell is a muscle fiber
52
Each terminal branch of the nerve fiber within NMJ forms
separate synapse with muscle fiber
53
_______ nerve fiber stimulates the _______ ______ at several points within NMJ
one; muscle fiber
54
Synaptic knob
swollen end of nerve fiber; one per synapse; contains synaptic vesicles filled with ACh
55
Synaptic cleft
tiny gap between synaptic knob & muscle sarcolemma
56
Schwann cell
envelopes & isolates all of NMJ from surrounding tissue fluid
57
Junctional folds
beneath synaptic knob; increase surface area holding ACh receptors
58
Basal lamina
thin layer separating Schwann cell & entire muscle cell from surrounding tissues; contains AChE
59
AChE
breaks down ACh after contraction allowing relaxation
60
Muscle fibers and neurons
plasma membranes exhibit voltage changes in response to stimulation
61
Voltage (electrical potential)
a difference in electrical change from one side of the membrane to the other
62
Resting membrane potential
is about -90mV; maintained by the sodium-potassium pump
63
Action potential (AP)
quick up-and-down voltage shift from the negative RMP to a positive value, and back to the negative value again (depolarization & repolarization)
64
Excitation
process in which nerve action potentials lead to muscle action
65
Excitation-contraction coupling
events that link the action potentials on the sarcolemma to activation of the myofilaments, thereby preparing them to contract
66
Contraction
step in which the muscle fiber develops tension and may shorten
67
Relaxation
when stimulation ends, a muscle fiber relaxes and returns to its resting length
68
Length - tension relationship
the amount of tension generated by a muscle depends on how stretched or shortened (contracted) it was before it was stimulated
69
If overly shortened (contracted) at rest, a weak contraction results. why?
thick filaments are too close to z discs and cannot slide
70
If too stretched before stimulated, a weak contraction results. why?
little overlap of thin & thick does not allow for very many cross-bridges to form
71
______ ______ ______ produces greatest force when muscle contracts
optimum resting length
72
The _____ _____ maintains muscle tone (partial contraction) to ensure that resting muscles are near this length
nervous system
73
Rigor mortis
hardening of muscles and stiffening of body beginning 30-4 hours after death
74
Myogram
a chart of timing and strength of a muscle's contraction
75
Weak electrical stimulus causes ___ contraction
no
76
Threshold
minimum voltage necessary to generate an action potential in the muscle fiber & produce a contraction
77
Twitch
a quick cycle of contraction & relaxation when stimulus is at threshold or higher

Anatomy and Physiology 1 (2 decks)

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