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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22

11

CB

A

FG

D

E

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Muscle Tissue Anatomy Continued

• Muscle cell

• Myofibrils

• Myosin

• Sarcomere

• Z Disc

• Actin

• Fascicle

• Filaments

• Muscle

FF

EE GG

DD

CC

BB

AA

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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11

22

33

44

55

66

77

88

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1111

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1313

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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.