nucleus muscle fiber endomysium...
TRANSCRIPT
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Fig. 11.1
Endomysium
©Ed Reschke
Nucleus
Muscle fiber
Striations
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Openings intotransverse tubules
Sarcoplasmicreticulum
Musclefiber
Nucleus
A band
I band
Z disc
Mitochondria
Myofibrils
Myofilaments
SarcoplasmSarcolemma
Transverse tubuleTerminal cisternae
Triad:
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Fig. 11.2
3
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TailHead
(a) Myosin molecule
Myosin head
Tropomyosin Troponin complex G actin
Thick filamentThin filament
(c) Thin filament
Bare zone
(b) Thick filament
(d) Portion of a sarcomere showing the overlap of thick and thin filaments
Fig. 11.3
4
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Endomysium
Linking proteins
Basal lamina
Sarcolemma
Dystrophin
Thin filament
Thick filament
Elastic filament
Fig. 11.4
5
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a: ©Donald Fawcett/Visuals Unlimited
Nucleus
Sarcomere
Z disc M line
H band
I band A band I band Indi
vidu
al m
yofib
rils
12
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5
(a)
I bandSarcomere
H bandA band
Thick filamentThin filament
Elastic filamentZ disc(b)M line
Z disc
I band
Fig. 11.5
6
Table 11.1
7
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Neuromuscularjunction
Skeletalmusclefibers
Spinal cord
Motorneuron 1Motorneuron 2
Fig. 11.6
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(b)
Nucleus
Nucleus
Motor nervefibers
Neuromuscularjunction
Muscle fibers
100 µm
Motor nerve fiberMyelin
Schwann cell
Basal lamina
Synaptic cleftSarcolemma
Sarcoplasm
Synaptic knob(a)
Synaptic vesicles(containing ACh)
Ach receptor
Junctional folds
MitochondriaMyofilaments
a: ©Victor B. Eichler
Fig. 11.7
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Table 11.2
10
K+
Binding of ACh to receptor Opening of ligand-regulated ion gate;creation of end-plate potential
4
Opening of voltage-regulated ion gates;creation of action potentials
5
3
ACh receptor
Plasmamembraneof synapticknob
Na+
Sarcolemma
MotornervefiberSarcolemma
ACh
Sarcolemma
K+
Synapticcleft
Na+
Acetylcholine (ACh) release2Arrival of nerve signal
ACh
Ca2+ enterssynaptic knob
Synapticknob
Synapticvesicles
AChreceptors
Voltage-regulatedion gates
ACh
1
Fig. 11.8
Nerve signal
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11
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Binding of calciumto troponin
8 Shifting of tropomyosin;exposure of active siteson actin
9
Calcium released fromterminal cisternaeAction potentials propagated
down T tubules6 7
Ca2+
Ca2+
Ca2+
T tubuleTerminalcisternaof SR
Myosin
Ca2+Troponin
Active sites
Tropomyosin Actin Thin filament
Sarcoplasmic reticulum
T tubule
Fig. 11.9
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Troponin Tropomyosin
ADP
Myosin
10
ATP
13
Cross-bridge:ActinMyosin
ADP
11
ADPPi
12
Z
I A I
Z
Appearance of contracting sarcomere
Pi
Pi
Fig. 11.10
Myosin
Hydrolysis of ATP to ADP + Pi;activation and cocking of myosin head
Binding of new ATP;breaking of cross-bridge
Power stroke; sliding of thinfilament over thick filament
Formation of myosin–actin cross-bridge
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Cessation of nervous stimulationand ACh release
AChE
ACh
ACh breakdown byacetylcholinesterase (AChE)
Terminal cisternaof SR
Reabsorption of calcium ions bysarcoplasmic reticulum
Return of tropomyosin to positionblocking active sites of actin
Tropomyosin
Loss of calcium ions from troponin
Ca2+
Ca2+
Ca2+ Ca2+
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16
15
17
18
ADP
ATP
Pi
Fig. 11.11Copyright © McGraw-Hill Education. Permission required for reproduction or display.
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Optimum resting length(2.0–2.25 µm)
z z
Overly contractedz z Overly stretched
z z
1.0
0.5
0.01.0 2.0 3.0 4.0
Sarcomere length (µm) before stimulation
Rel
ativ
e te
nsio
n ge
nera
ted
upon
stim
ulat
ion
Fig. 11.12
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Contractionphase
Relaxationphase
Latentperiod
Time
Mus
cle
tens
ion
Time ofstimulation
Fig. 11.13
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Stimuli to nerve
Proportion of nerve fibers excited
Responses of muscle
Threshold
1 2 3 4 5 6 7 8 9
987654321
Tens
ion
Stim
ulus
vol
tage
Maximum contraction
Fig. 11.14
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(a) Low stimulus frequency
Muscle twitches
Mus
cle
tens
ion
Temporal summationand incomplete tetanus
Complete (fused) tetanus
Stimuli(b) Physiologicially normal stimulus frequency (c) Unnaturally high stimulus frequency
StimuliStimuli
Fig. 11.15
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Muscle developstension but doesnot shorten
No movement
(a) Isometric contraction
Muscle shortens,tension remainsconstantMovement
(c) Isotonic eccentric contraction(b) Isotonic concentric contraction
Muscle lengthenswhile maintainingtension
Movement
Fig. 11.16
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Leng
th o
r Ten
sion Muscle
tensionMusclelength
Isometricphase
Isotonicphase
Time
Fig. 11.17
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Repayment ofoxygen debt
40 seconds
Mode of ATP synthesis
Duration of exercise10 seconds0
Aerobic respirationusing oxygen frommyoglobin
Phosphagensystem
Glycogen–lactic acidsystem(anaerobicfermentation)
Aerobicrespirationsupported bycardiopulmonaryfunction
Fig. 11.18
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ADP
AMP
Creatinephosphate
Creatine
Myokinase
Pi
ADP
ATP
ADP
Creatinekinase
Pi
ATP
Fig. 11.19
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Table 11.3
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Table 11.4
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Table 11.5
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Single-unitsmooth muscle
Synapticvesicle
Varicosities
Mitochondrion
Neurotransmitterreleased
Autonomicnerve fiber
Fig. 11.21
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Mucosa:
EpitheliumLamina propriaMuscularismucosae
Muscularis externa:Circular layerLongitudinallayer
Fig. 11.22
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Copyright © McGraw-Hill Education. Permission required for reproduction or display.Fig. 11.23
Autonomicnerve fibers
Varicosities
Gap junctions
(a) Multiunitsmooth muscle
(b) Single-unitsmooth muscle
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(a) Relaxed smooth muscle cells
Intermediate filamentsof cytoskeleton
Actin filaments
Dense bodies
Myosin
(b) Contracted smoothmuscle cells
Fig. 11.24
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INTEGUMENTARY SYSTEMFacial expressions result from the action of muscles on the skin.
LYMPHATIC/IMMUNE SYSTEMMuscle contractions aid flow of lymph; exercise elevates levels of immune cells and antibodies in circulation; excessive exercise can inhibit immunity.
RESPIRATORY SYSTEMMuscle contractions ventilate the lungs; muscles of the larynx and pharynx regulate airflow; CO2generated by muscular activity stimulates respiration; abdominal muscles produce pressure bursts of coughing and sneezing and aid in deep breathing.
URINARY SYSTEMA skeletal muscle sphincter retains urine in bladderuntil convenient for release; abdominal and pelvic muscles aid in compressing and emptying bladder; muscles of pelvic floor support bladder; bulbospongios us muscle helps clear urine from male urethra.
DIGESTIVE SYSTEMMuscles enable chewing and swallowing; muscles control voluntary aspect of defecation; abdominal muscles produce vomiting; abdominal and lumbar muscles protect digestive organs.
REPRODUCTIVE SYSTEMMuscles are involved in sexual responses including erection and ejaculation; abdominal and pelvic muscles aid in childbirth.
CIRCULATORY SYSTEMMuscle contractions affect blood flow in many veins; exercise stimulates growth of new blood vessels.
ENDOCRINE SYSTEMSkeletal muscles provide protective cover for some endocrine glands; muscle mass affects insulin sensitivity.
NERVOUS SYSTEMMuscles give expression to thoughts, emotions, and motor commands that arise in the central nervous system.
SKELETAL SYSTEMMuscles move and stabilize joints and produce stresses that affect ossification, bone remodeling, and the shapes ofbones.
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