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Essentials of Anatomy and Physiology
dr. Arie Nugroho
Gunabangsa 2012
Slide 2.1Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Chapter 7: Muscular System
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The Muscular System
Slide 6.1Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Muscles are responsible for bodymovement
Three types are found in the body
Skeletal muscle**
Cardiac muscle
Smooth muscle
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Types of Muscle
Three types of muscle
Skeletal Cardiac Smooth
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Functions of Skeletal Muscles
Slide 6.1Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Make up flesh of the body Maintain Posture
Voluntary movement
Aid in breathing, eating, speech
Provide facial expression
Generate reflexes Produce body heat
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Characteristics of Skeletal Muscles
Slide 6.2Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Muscle cells are elongated(muscle cel l = muscle fiber)
Muscles are specialized to contract
Terminology:
Prefix myo, mys refer to muscle
Prefix sarco refers to flesh
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Characteristics of Skeletal Muscles
Slide 6.3Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Most are attached by tendons to bones
Cells are multinucleate
Striated have visible banding
Voluntary subject to conscious control
Muscles and their fibers are wrapped byconnective tissue
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Connective Tissue Wrappings ofSkeletal Muscle
Slide 6.4aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Endomysiumaround single
muscle fiber
Perimysiumaround afascicle(bundle) offibers Figure 6.1
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Connective Tissue Wrappings ofSkeletal Muscle
Slide 6.4bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Epimysium covers theentire skeletalmuscle
Fascia on theoutside of theepimysium
Figure 6.1
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Skeletal Muscle Attachments Slide 6.5
Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Epimysium blendsinto a connectivetissue attachment
Tendon cord-likestructure
Aponeurosissheet-like structure
Fig. 7.2abc
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Skeletal Muscle Attachments
Slide 6.5Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sites of muscle attachment
Bones
Cartilages
C. T. coverings
i.e., aponeuroses
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Microscopic Anatomy of SkeletalMuscle
Slide 6.9aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cells are multinucleate
Nuclei are deep to the sarcolemma
Figure 6.3a
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Microscopic Anatomy
Slide 6.9bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sarcolemmaspecialized plasmamembrane
Sarcoplasmic reticulumspecializedsmooth E.R.
Stores Ca++
Required for
contraction
Figure 6.3a
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Microscopic Anatomy
Slide 6.10aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Myofibril: organelleunique to muscleBundles ofmyofilaments
Myofibrils alignment produces distinct bands
I band =light band
A band =
dark band
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Microscopic Anatomy
Slide 6.10aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Banding Pattern depends onarrangement of proteins in myofibrils
Actin: thin
A and I bands
Myosin: thick
A bands
Figure 6.3b
A-bandI-band
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Microscopic Anatomy
Slide 6.10bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sarcomere
Contractile subunit of a muscle fiber
From Z to Z One A band +
Two half Ibands
Figure 6.3b
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Microscopic Anatomy
Slide 6.11aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Organization of the sarcomere
Thick filaments = myosin filaments
Composed of the protein myosinHas ATP-ase enzymes
Figure 6.3c
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Microscopic Anatomy
Slide 6.11bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Organization of the sarcomere, cont
Thin filaments = actin filaments
Composed of the protein actin
Figure 6.3c
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Microscopic Anatomy
Slide 6.12aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Myosin filaments have heads (extensions,or cross bridges)
Myosin andactin overlap
Figure 6.3d
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Microscopic Anatomy
Slide 6.12bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
At rest, there is a bare [H] zone thatlacks actin filaments
Figure 6.3d
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Properties of Skeletal Muscle
Slide 6.13Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Irritability ability to receive and
respond to a stimulus
Contractility ability to shorten when anadequate stimulus is received
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Nerve Stimulus to Muscles
Slide 6.14Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Skeletalmuscles requireinnervation
Motor unitOne motor
neuron +
Muscle cellsinnervated bythat neuron
Figure 6.4a
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Nerve Stimulus to Muscles
Slide 6.15aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Neuromuscularjunction:
communicationsite between amotor neuronand a muscle
fiber
Figure 6.5b
Fig. 7.5a
Motor Neuron
Neuromuscular Junction
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Nerve Stimulus to Muscles
Slide 6.15bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Synaptic cleft :gap betweennerve andmuscle
Nerve andmuscle do notmake direct
contact
Figure 6.5b
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Transmission of Nerve Impulse toMuscle
Slide 6.16aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Neurotransmitter chemical releasedby motor nerve
initiates contraction Causes sarcolemma to depolarize
For skeletal muscle: acetylcholine (Ach)
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Transmission of Nerve Impulse toMuscle
Slide 6.16a
Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Action ofNeurotransmitter
Crosses synapticcleft
Attaches toreceptors on thesarcolemma
Fig. 7.6
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Muscle Contraction
Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
An electrochemical event
Ach is the chemical
Before contraction can occur,
sarcolemma must bepolarizedA polarized membrane is more + outside
and more - inside
Movement of ions creates actionpotential
The ability to do work
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Muscle Contraction
Slide 6.16bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Ach attaches to receptor sites
Sarcolemma becomes permeable tosodium (Na+)
Sodium rushes into the cell
Initiates sliding filament process
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Muscle Contraction
Slide 6.16bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Membrane of sarcoplasmic reticulumalso depolarizes
Ca++ ions are released
Bind to sites on actin
Open attachment sites for myosin
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The Sliding Filament Theory ofMuscle Contraction
Slide 6.17aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Depolarizationallows myosin
heads to attachto binding siteson actin
calledcrossbridges
ATP required
Figure 6.7
Fig. 7.7a
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The Sliding Filament Theory ofMuscle Contraction
Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Actin is pulled pastmyosin by movementof heads
ATP required
Myosin heads detach
ATP required
Then bind to the nextsite on actin
ATP required
Fig. 7.7b
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The Sliding Filament Theory ofMuscle Contraction
Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings
This continuedaction causes asliding of the actinalong the myosin
I band narrows
H zone narrows
A band stays the same
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The Sliding Filament Theory ofMuscle Contraction
Slide 6.17bCopyright 2003 Pearson Education Inc publishing as Benjamin Cummings
Actin slides pastmyosin
Results in shorteningof the sarcomere
Muscle fiber hasthousands of
sarcomeresAll shorten at one time
Muscle contracts
Figure 6.7