The Muscular System
Muscle Tissue Characteristics• Is made up of contractile fibers• Provides movement• Controlled by the nervous
system– Voluntary- consciously
controlled– Involuntary- not under
conscious control• Examples
– Skeletal– Smooth– Cardiac
CardiacCardiac
SkeletalSkeletal
SmoothSmooth
Types of Muscle Tissue
• There are three main types of muscle tissue– Skeletal
(striated)– Cardiac
(heart)– Smooth
(visceral)
Comparison of Muscle Types
Muscle TypeMuscle Type CardiacCardiac
FunctionFunctionMovement of Movement of
bonebone
Walls of internal Walls of internal organs + in skinorgans + in skinLocationLocation
Attached to Attached to bonebone
HeartHeart
SmoothSmoothSkeletalSkeletal
Striated- light Striated- light and dark bandsand dark bands
Many nucleiMany nuclei
StriatedStriatedOne or two One or two
nucleinuclei
CharacteristicsCharacteristicsNon-striatedNon-striatedOne nucleusOne nucleus
(visceral)(visceral)
Long + slenderLong + slender BranchingBranchingShapeShape Spindle shapeSpindle shape
Control ModeControl Mode
Beating of heartBeating of heart
InvoluntaryInvoluntary InvoluntaryInvoluntary
Movement of Movement of internal organsinternal organs
VoluntaryVoluntary
Skeletal Muscles• Provides voluntary
movement of body– Enables speaking,
blinking, and smiling
– Allows you to hop, skip, jump, or do push-ups
• Maintains posture• Produces heat
Examples…
• Biceps• Triceps• ABS!
Cardiac Muscle
• Causes heart beat• Directs circulation of
blood – Regulates
blood pressure
– Sends blood to different areas of the body
Smooth Muscles• Provides movement of
internal organs– Moves food through digestive
tract– Enables bladder control
• Causes involuntary actions– Reflex actions – Adjusts opening of pupils– Causes hair to stand– breathing
Location of Muscles
• InvoluntaryMuscles– Diaphragm– Digestive
organs– Arrector pili – Heart– Urinary
bladder– Muscles
aroundblood vessels
Muscle Tissue Anatomy
bundle of muscle bundle of muscle fibers – fasciclefibers – fascicle
Muscle
• Muscles are made up of bundlesof muscle fibers, called fascicles– Fascicle is a bundle of
muscle fibers• A muscle fiber is a
muscle cell….made up of many small myofibrils
– Myofibrils contain filaments
» Two types ofprotein filaments
TTIIssssuuee
AAnnaattoommyy
MuscleMuscle
FilamentsFilaments
MyofibrilsMyofibrils
Muscle FibersMuscle Fibers
FascicleFascicle
SarcomereSarcomere
Myofibril
• Contain two types of protein filaments– Actin- thin
proteinfilaments
– Myosin- thickprotein filaments
– Z disc- point of anchor of actin
– Sarcomere- functional unit of a myofibril, region between Z discs,
Thin FilamentsThin Filaments
ActinActinMoleculeMolecule
Thick FilamentsThick Filaments
Myosin MoleculeMyosin Molecule
Z DiscZ Disc
SarcomereSarcomere
DD
CC
BBAA
Muscle TissueAnatomy
• What parts do you remember?
1. Muscle2. Fascicle
(bundle of fibers)3. Muscle fiber
(muscle cell)4. Myofibrils
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A
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Muscle Tissue Anatomy Continued
• Muscle cell
• Myofibrils
• Myosin
• Sarcomere
• Z Disc
• Actin
• Fascicle
• Filaments
• Muscle
FF
EE GG
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What parts do you remember?....continuedWhat parts do you remember?....continued
HH
HH
MyofibrilMyofibril
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Mechanics of a Muscle Contraction
• What stimulates a muscle to contract?– Your nervous system
• What cells are involved?– Muscle cells and a motor neuron– Motor neuron sends
impulse to muscle cells– One neuron will form
synapses with many muscle cells
• What is this called?– A motor unit– Let’s take a look under
the microscope.…
A motor unitA motor unit
Mechanics of a Muscle Contraction
• What do calcium ions do?– Cause interaction between actin and myosin
• How do actin and myosin interact?– Actin filaments slide over the myosin filaments.
• What model explains this?– Sliding Filament Model
Mechanics of a Muscle Contraction
• What causes actin to slide over myosin?– The head of myosin connects to actin
and pivots.• What is this connection called?
– cross-bridge • The binding of the myosin heads
throughout the sarcomere occur asynchronously…
– some myosin heads are binding while other heads are releasing the actin filaments.
– This process must be performed repeatedly during a single muscle contraction so that the muscle is able to generate a smooth force
Mechanics of a Muscle Contraction
• What provides the energy to swivel the head of myosin? _____• How exactly does the sliding filament model work?
– In the sliding filament model of muscle contraction, the (thin) actin filaments[red] (that are attachedto the Z-line) slide (areactually pulled) inward along the (thick)myosin filaments [blue], and the sarcomere (measuredfrom one Z line to thenext) is shortened.
ATPATP
Mechanics of a Muscle Contraction
• When each sarcomere becomes shorter it causes each myofibril to become shorter.
• When each myofibril becomesshorter it causes the muscle fibers to become shorter
• When each muscle fiber shortens the overall muscle contracts.
SarcomereSarcomere
Macroscopic Structure of Muscle • _________- attaches
muscle to bone
• _______- attachment of muscle to immovable (fixed) bone (anchors muscle)
• ________- attachment to bone that moves when muscle contracts
• _____- bulging middle part of the muscle
Belly ofBelly of BicepsBiceps
TendonTendon
OriginOrigin
InsertionInsertion
BellyBelly
Muscle Movement• Muscles originate on a _______bone in our body, cross over a ______,
and insert onto a _________ bone.
• It is important to understand that all muscles move from the _____________ point going toward the ______________ point.
• It is because of the placement of the muscles that we can move.
jointjointfixedfixedmovingmoving
insertioninsertionoriginationorigination
Muscle Movement• Tendons
– attach _________ to bone– are inelastic – don’t stretch when the force of the muscle
acts on them
• When muscle contracts, it pulls on the _______
• Individual muscles can only ____ in ____ direction
• Muscles work in opposing ______
musclemuscle
bonebone
pullpull oneone
pairspairs
Muscle Movement
• ______- Muscle that bends the joint when contracted.
• ________- Muscle that straightens the joint when contracted.
• __________ muscleis short, firm, tight and thicker around.
• _______ muscle is stretched, long, loose and thinner around.
FlexorFlexor
ExtensorExtensor
RelaxedRelaxed
ContractedContracted
Muscle Movement
• When the biceps in the arm contracts the triceps ________ causing ________ of the arm.
• When the triceps in the arm _________ the biceps relaxes causing ____________ of the arm.
• ______ of muscles are needed because the only active _________ of a muscle is to _______, to lengthen it must be _________ by the action of an opposing _______.
relaxesrelaxes bendingbending
contractscontracts
straighteningstraightening
PairsPairs
movementmovement
contractcontract
stretchedstretched
musclemuscle
Location of Muscles
• SkeletalMuscles– Anterior
viewQuadricepQuadricep
s groups group
Rectus abdominisRectus abdominis
Quadriceps GroupQuadriceps Group
External ObliquesExternal Obliques
FrontalisFrontalis
MasseterMasseter
Tibialis AnteriorTibialis Anterior
DeltoidDeltoidPectoralis MajorPectoralis Majorbiceps brachiibiceps brachii
BrachioradialisBrachioradialis
Locationof Muscles• Skeletal
Muscles– Posterior
view
Hamstring group
TrapeziusTrapezius
Hamstring Hamstring groupgroup
GastrocnemiusGastrocnemius
Latissimus dorsiLatissimus dorsi
Gluteus Gluteus maximusmaximus
Triceps brachiiTriceps brachii
FF
AA
DD
CC
BB
EE
LL
KK
JJ
HH
GG
PP
OO
NN
MM
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Muscles You Need to Know
• 1. brachioradialis• 2. biceps brachii• 3. deltoid• 4. external oblique• 5. frontalis• 6. gastrocnemius• 7. gluteus maximus• 8. hamstring group• 9. latissimus dorsi• 10. masseter• 11. pectoralis major• 12. quadriceps group• 13. rectus abdominis• 14. tibialis anterior• 15. trapezius• 16. triceps brachii
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•APPLICATION
1. Drugs are often used to relax muscles during surgery. Which of the following two chemicals do you think would make the best relaxant and why? Chemical A: blocks acetylcholine receptors on muscle cells. Chemical B: floods the cytoplasm of muscle cells with calcium.
2.When a person dies, muscles often become rigid and fixed in position – a condition known as rigor mortis, which often figures importantly in mystery novels. Rigor mortis occurs because muscle cells use up their supply of ATP as they die. The rigor disappears several hours after death because the biological molecules break down. Explain in terms of the mechanism of contraction why the lack of ATP would cause muscles to become rigid, rather than limp after death.
ASSIGNMENT
1. Describe the following diseases/disorders of the muscular system:A. muscle cramps/spasmB. Myasthenia GravisC. StrainD. Duchenne Muscular Dystrophy
2. Fill in the information on the table
TYPE OF NUTRIENT
USES SOURCES
1. Proteins
2. Carbohydrates3. Fats and Oils4. Minerals
5. Vitamins
6. Water
3. On an oslo paper, make a collage of the food pyramid showing the different food groups.
NOTE: Items 1-3 will be checked on Monday.
4. Bring food on Monday.