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SkeletalSkeletal – striated, multinucleate, voluntary, 10-100 m
SmoothSmooth - found in walls of hollow visceral organs; ex. stomach, bladder, respiratory passages; visceral, nonstriated, involuntary; discuss peristalsis
CardiacCardiac – in heart only, striated, involuntary, intercalcated disks
Muscle function:• produce movement• maintain posture• stabilize joints• generate heat• move substances within the body
Functional Characteristics:• Excitability- respond to a stimulus• Contractility- ability to shorten
forcibly when adequately stimulated • Extensibility- the ability to be
stretched• Elasticity- the ability of a muscle
fiber to resume its resting length after being stretched
Skeletal Muscle Skeletal Muscle TissueTissue
Smooth Muscle Smooth Muscle TissueTissue
Cardiac Muscle Cardiac Muscle TissueTissue
Skeletal MuscleSkeletal MuscleConnective tissue sheaths of skeletal muscle:Connective tissue sheaths of skeletal muscle:
• Epimysium: dense regular connective tissue Epimysium: dense regular connective tissue surrounding entire muscle surrounding entire muscle
• Perimysium: fibrous connective tissue Perimysium: fibrous connective tissue surrounding fascicles (groups of muscle fibers)surrounding fascicles (groups of muscle fibers)
• Endomysium: fine areolar connective tissue Endomysium: fine areolar connective tissue surrounding each muscle fibersurrounding each muscle fiber
Figure 9.1
Bone
Perimysium
Endomysium(between individualmuscle fibers)
Muscle fiber
Fascicle(wrapped by perimysium)
Epimysium
Tendon
Epimysium
Muscle fiberin middle ofa fascicle
Blood vessel
Perimysium
Endomysium
Fascicle(a)
(b)
bundle of muscle fibers
muscle fiber(cell)
myofibril
sarcomere
Muscle Muscle AnatomyAnatomy
Muscle Fiber
Myofibril
SarcomereSarcomere
Z lines
SarcomeSarcomerere A band
SarcomeSarcomerere I bands
SarcomeSarcomerere H zone
Actin and Myosin FilamentsActin and Myosin Filaments
myosinactin
Myosin (Thick) FilamentMyosin (Thick) Filament
Actin (Thin) FilamentActin (Thin) Filament
Sliding Filament HypothesisSliding Filament Hypothesis
A
Z ZH
I I
AI I
Z ZH
Z ZHAI I
Actin (Thin) FilamentActin (Thin) FilamentNo Calcium IonNo Calcium Ion
tropomyosin
troponin
Actin (Thin) FilamentActin (Thin) Filament
Calcium Ion PresentCalcium Ion Present
tropomyosin
myosin binding sites
Actin & Myosin InteractionActin & Myosin Interaction
Biology 100Biology 100Human BiologyHuman Biology
Motor UnitMotor Unit
spinal cord
motor neurons
muscle bundle
muscle fibers
neuromuscular junctions
Neuromuscular Neuromuscular junctionsjunctions
branching axon branching axon to motor unitto motor unit
muscle fibersmuscle fibers
Axon(motor neuron)
sarcolemma
myofibrils
sarcomere
sarcoplasmSarcoplasmic Reticulum
Neuromuscular junction
T tubules
sarcoplasmic reticulum
http://www.blackwellpublishing.com/matthews/myosin.html
Stimulation of Skeletal Muscle
Figure 9.9
Na+
Na+
Open Na+
Channel
Closed Na+
Channel
Closed K+
Channel
Open K+
Channel
Action potential++++++
+++++
+
Axon terminal
Synapticcleft
ACh
ACh
Sarcoplasm of muscle fiber
K+
2 Generation and propagation ofthe action potential (AP)
3 Repolarization
1 Local depolarization: generation of the end plate potential on the sarcolemma
K+
K+Na+
K+Na+
Wave ofde
po
lari
zatio
n
Figure 9.9, step 1
Na+
Na+
Open Na+
ChannelClosed K+
Channel
K+
Na+ K+Action potential
++++++
+++++
+
Axon terminal
Synapticcleft
ACh
ACh
Sarcoplasm of muscle fiber
K+
1 Local depolarization: generation of the end plate potential on the sarcolemma
1
Wave ofde
po
lari
zatio
n
Figure 9.9, step 2
Na+
Na+
Open Na+
ChannelClosed K+
Channel
K+
Na+ K+Action potential
++++++
+++++
+
Axon terminal
Synapticcleft
ACh
ACh
Sarcoplasm of muscle fiber
K+
Generation and propagation of the action potential (AP)
1 Local depolarization: generation of the end plate potential on the sarcolemma
2
1
Wave ofde
po
lari
zatio
n
Figure 9.9, step 3
Na+
Closed Na+
ChannelOpen K+
Channel
K+
Repolarization3
Figure 9.9
Na+
Na+
Open Na+
ChannelClosed K+
Channel
Action potential++++++
+++++
+
Axon terminal
Synapticcleft
ACh
ACh
Sarcoplasm of muscle fiber
K+
2 Generation and propagation ofthe action potential (AP)
3 Repolarization
1 Local depolarization: generation of the end plate potential on the sarcolemma
K+
K+Na+
K+Na+
Wave ofde
po
lari
zatio
n
Closed Na+
ChannelOpen K+
Channel
Figure 9.10
Na+ channelsclose, K+ channelsopen
K+ channelsclose
Repolarizationdue to K+ exit
Threshold
Na+
channelsopen
Depolarizationdue to Na+ entry
Stimulation of Skeletal Muscle
Stimulation of Skeletal Muscle
Stimulation of Skeletal Muscle
Stimulation of Skeletal Muscle
Stimulation of Skeletal Muscle
Stimulation of Skeletal Muscle
Stimulation of Skeletal Muscle
Relaxation of Skeletal Muscle
Stimulation of Skeletal Muscle
Stimulation of Skeletal Muscle
Muscle TwitchMuscle Twitch
Contraction Contraction ResponseResponse
single twitches
wave summation tetanus
action potentials in motor neuron
Isotonic and Isometric ContractionsIsotonic and Isometric Contractions
Isotonic contraction • Contraction with a change in length• The muscle shortens and movement occurs.
Isometric contraction • Contraction without any change in length• The muscle does not shorten and there is no
movement produced even though the muscle contracts.
Isotonic and Isometric ContractionsIsotonic and Isometric Contractions
Isotonic
Isometric
Slow-Twitch Versus Slow-Twitch Versus Fast-TwitchFast-Twitch
Muscle FibersMuscle Fibers
ATP is Generated by:1. creatine phosphate
ADP + creatine phosphatecreatine + ATP
2. lactic acid fermentationFrom stored glycogen via anaerobic glycolysis; glucosepyruvic acid (no O2) lactic acid
O2
3. aerobic respirationKrebsCO2 + H2O + ATP
Energy for muscle contraction:Energy for muscle contraction:ATP is the only energy source ATP(ATPase + H2O) ADP + Pi
Muscle Fiber Types
• Fast glycolitic• Slow oxidative• Fast oxidative-glycolytic
Ratio- red:white (all 3 types in body)
Fast glycolitic:
• white muscle fibers• low myoglobin• anaerobic glycolysis• few mitochondria• fast twitch fibers• high glycogen stores• short bursts• fatigues easily
Slow oxidative:
• red muscle• aerobic• high myoglobin• low glycogen stores• lots mitochondria• slow• tonic• long distance
Fast oxidative-glycolitic:
• red pink• Aerobic & anaerobic• fast• high myoglobin• intermediate amt. of mitochondria• intermediate glycogen• intermediate fatigue resistance
Tuna- long distance swimmer
Snapper- short bursts
Sprinter- anaerobic respiration
Long distance Runner- aerobic respiration
Smooth Muscle FibersSmooth Muscle Fibers
• Mainly aerobic• Arranged in
opposing sheets
Smooth Muscle FibersSmooth Muscle Fibers
peristalsis
Cardiac TissueCardiac Tissue
• More mitochondria• Longer refractory period• Mainly aerobic respiration• Can use multiple fuel molecules
Effects of ExerciseEffects of ExerciseHypertrophy- excessive enlargement of muscle tissue
Atrophy- disuse
Muscles must be physically active if they are to remain healthy
CastCast- muscle strength can decrease at a rate of 5%/ day; can use e- stimulus
Avoid muscle injuries:Avoid muscle injuries:
-warm up muscles- walk fast 5 minutes
-then stretch- avoids pulls and tares
SteroidsSteroidsAnabolic steroids • similar to testosterone • large doses required for good
effect • Side effects:
• overall - kidney and heart damage, aggressiveness
• females - sterility, facial hair, breast & uterine atrophy
• males - baldness, atrophy of testis
• cramp- sustained spasm or tetanic contraction; may be due to low blood sugar levels, electrolyte depletion, dehydration
how to care for cramp: RICE• strain- muscle pull• spasm- tics• hernia- protrusion of organ through body cavity
wall may be due to heavy wts.
Muscle DisordersMuscle Disorders
Inquiry
1. What is stored in SER?2. Which protein blocks the heads of myosin?3. When a neuron synapses with a muscle it is called---.4. The neuron going to a muscle is called ____.5. A muscle that shortens or lengthens is called ____.6. Which ion floods into the sarcolemma after stimulation by a
neuron?7. Which neurotransmitter binds to the sarcolemma?8. Which type of muscles undergo aerobic respiration?9. Which type of fuel is stored in muscle tissues?10.Which pigment is stored in muscles that has a high affinity
for oxygen?11.Which muscle tissue has intercalated discs?12.What is depolarization?