survey of anatomy and physiology chap 7

The Muscular System: Movement for the Journey

7

Muscular System OverviewMuscular System Overview Muscle: general term

for all contractile tissue

Contractile property of muscle tissue allows it to become short and thick in response to nerve impulse and then to relax once impulse removed

Alternative contraction and relaxation causes movement

Muscular System OverviewMuscular System Overview

Muscle cells elongated; resemble fibers such as those in rope

Muscle tissue constructed of bundles of these fibers, each approximately the diameter of a human hair

Types of MusclesTypes of Muscles


Skeletal muscles Voluntary muscles

Under conscious control

Derive name from attachment of muscle to skeletal system

Striated (striped) muscle


Smooth muscles Involuntary muscles

Not under our conscious control

Does not have striped appearance

Found within certain organs, blood vessels, airways; sometimes called visceral muscle


Smooth musclesAllows for internal movement of food

Facilitates movement of blood by changing diameter of blood vessels


Cardiac muscleInvoluntary; specialized muscle with

striated appearance

Found solely in heart

Contraction of muscle causes heart contract; internal movement (circulation) of blood

Figure 7-1Figure 7-1The three types of muscle: The three types of muscle: skeletal, cardiac, and smooth.skeletal, cardiac, and smooth.

Test Your KnowledgeTest Your Knowledge

Review 4 Questions for Section 7-1

Skeletal MusclesSkeletal Muscles Attached to bones, provide movement

for body

Tendons: fibrous tissues that attach skeletal muscles to bones

Ligaments: attach bone to bone

Some muscles attach directly to

bone or soft tissue without tendon

Skeletal MusclesSkeletal Muscles

Called voluntary because movement controlled by conscious thought

Responsible for movement, giving body its shape and form, maintaining body posture, and heat generation

Figure 7-2Figure 7-2Anterior and posterior view of Anterior and posterior view of

major muscles.major muscles.

ShoulderShoulder

RibsRibs

ThoracicThoracic

Arms & LegsArms & Legs

Figure 7-2Figure 7-2 (continued)(continued)Anterior and posterior view of Anterior and posterior view of major muscles.major muscles.

ButtocksButtocks

Figure 7-3Figure 7-3Skeletal facial muscles. Skeletal facial muscles.

Figure 7-4Figure 7-4Skeletal muscles of the posterior Skeletal muscles of the posterior

and anterior trunkand anterior trunk

Figure 7-5Figure 7-5Skeletal muscles of the shoulder, Skeletal muscles of the shoulder,

arm, and handarm, and hand

Figure 7-6Figure 7-6Skeletal muscles of the Skeletal muscles of the

hip and leghip and leg

Contraction and RelaxationContraction and Relaxation

Figure 7-7Coordination of antagonistic muscles to perform movement.

Muscles that cause movement are called Muscles that cause movement are called agonistsagonists or primary movers or primary movers


DiaphragmDiaphragm: primary mover of breathing Dome-shaped muscle

separates abdominal cavity and thoracic cavity

Responsible for performing major work of bringing atmospheric air into lungs

Muscle under both voluntary and involuntary control

Figure 7-8Figure 7-8The diaphragm: The major The diaphragm: The major

muscle of breathingmuscle of breathing

Movement TerminologyMovement Terminology

RotationRotation: circular movement that occurs around an axis

AbductionAbduction: to move away from midline of body

AdductionAdduction: movement toward midline of body

Figure 7-9The types of skeletal movement

Extension of left forearm.

ExtensionExtension: Increasing angle between two bones connected at a joint

Muscle that straightens the joint is called extensorextensor muscle

Figure 7-9The types of skeletal movement

Flexion of left forearm

FlexionFlexion: Opposite of extension, decreasing angle between two bones

Muscle that bends the joint is called flexorflexor muscle

Figure 7-9 (continued)The types of skeletal movement Flexion and extension of the leg

ExtensionExtension is needed when you kick a football is needed when you kick a footballFlexionFlexion occurs when you bend your leg to sit down occurs when you bend your leg to sit down

AtaxiaAtaxia

Some muscular diseases can cause ataxiaataxia, a condition of irregular muscle movement and lack

of muscle coordination

Muscular Movement at theMuscular Movement at theCellular LevelCellular Level

How does this How does this muscle tissue muscle tissue

cause a cause a coordinatedcoordinated and and

smoothsmooth contraction? contraction?

Muscle Contraction Muscle Contraction Step-by-StepStep-by-Step

Begins at the Neuromuscular JunctionBegins at the Neuromuscular Junction

MUSCLE TISSUE MUSCLE TISSUE COMPONENTSCOMPONENTS

• EpimysiumEpimysium• FasciculusFasciculus• EndomysiumEndomysium• Perimysium Perimysium • SarcomereSarcomere• MyofibrilMyofibril• ActinActin• MyosinMyosin

Functional Unit of the MuscleFunctional Unit of the Muscle

Typical muscle surrounded by connective tissue, continuous with tendon, called epimysium epimysium

Inside muscle are bundles of muscle fibers surrounded by perimysiumperimysium called fasciclesfascicles

Muscle fibers elongated cells up to 12 inches elongated cells up to 12 inches (30 centimeters) in length


Muscle fiber encased in connective tissue sheath (endomysiumendomysium); filled with cylinders (myofibrilsmyofibrils)

SarcomeresSarcomeres

Myofibril made of protein threads protein threads arranged in contractile units; two types of protein threads

Thick myofilaments made up of protein myosinmyosin

Thin ones made up of protein actinactin


SarcomeresSarcomeres (cont'd)

Actin and myosin filaments arranged in repeating units repeating units (sarcomeres(sarcomeres) separated from each other by dark dark bands called Z linesbands called Z lines

Give striated appearance to skeletal muscle

Each myofibril made up myofibril made up of several sarcomeresof several sarcomeres

ATP and CalciumATP and Calcium

Energy molecule adenosine adenosine triphosphate (ATP) triphosphate (ATP) and calcium (Ca) needed for contraction and relaxation

ATP provides energy to help myosin heads form and break crossbridges form and break crossbridges with actin

When muscle relaxed, calcium stored away from actin and myosin in sarcoplasmic reticulum sarcoplasmic reticulum (SR)

Sarcoplasmic Reticulum (SR) vs. Sarcoplasmic Reticulum (SR) vs. Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

SR are found mainly in smoothSR are found mainly in smooth& skeletal muscles& skeletal muscles

While both have protein molecules in their cells, the endoplasmic reticulumendoplasmic reticulum mainly synthesizes protein

molecules, while the sarcoplasmic reticulum sarcoplasmic reticulum (a type of smooth ER) stores and pumps calcium ions. The

sarcoplasmic reticulum contains large stores of calcium, which it sequesters and then releases when releases when

the muscle cell is stimulatedthe muscle cell is stimulated

Muscular System: Muscular System: Neuromuscular JunctionNeuromuscular Junction

Watch the Video of “Neuromuscular Junction”

http://www.youtube.com/watch?v=vyQWGclkGWQ

Muscular System: Muscular System: Muscle ContractionMuscle Contraction

Watch the Video of “Muscle Contraction”

https://www.youtube.com/watch?v=WVuW560nRII

Muscular FuelMuscular Fuel

Muscles, like all tissue, needs fuel in the form of nutrients nutrients and oxygenoxygen to survive and function

Body stores glycogen in the muscleglycogen in the muscle, where it waits to be converted to useable energy source

When needed, glycogen converted to glucose glycogen converted to glucose which releases energy

Muscular FuelMuscular Fuel

Muscles with very high demands store fat store fat and use it as energy

Energy release causes heat productioncauses heat production; this is why strenuous/prolonged exercises can overheat our bodies

Higher demand muscles have richer blood supply richer blood supply to carry oxygen to muscles giving those muscles a darker colordarker color

Smooth MuscleSmooth Muscle

Also called visceralvisceral muscle, found in organsorgans (except heart), blood vessels (vasodilatationvasodilatation and vasoconstrictionvasoconstriction), and bronchial airways

Ability to expand and contract expand and contract essential to internal processes of body (digestion and regulation of blood pressure)


During asthma attack, smooth muscles in airways of lungs airways of lungs constrict, making it difficult to get air into and out of lungs

Causes wheezingwheezing sound


Special type of smooth muscle (sphinctersphincter) found throughout digestive system

Donut-shaped muscles act as doorways to let doorways to let materials in and out materials in and out by alternately contracting and relaxing

Cardiac MuscleCardiac Muscle

Forms walls of the heartwalls of the heart

Contraction of cardiac muscle squeezes blood squeezes blood out of chambers of the heart, causing blood to circulate through the body

InvoluntaryInvoluntary

Fibers shorter; receive richer receive richer supply of bloodsupply of blood than any other muscle in body

Cardiac MuscleCardiac Muscle

Fibers connected by intercalated intercalated discsdiscs, causing one fiber to contract and then pull next one into contraction creating domino effect; contraction occurs, allowing blood to be squeezed out allowing blood to be squeezed out of the heart of the heart and into the body

Does not regenerateDoes not regenerate; damage often leads to tissue death causing scarring of heart tissue; scar tissue does not help muscles scar tissue does not help muscles of the heart to contract

Figure 7-11Figure 7-11Heart and intercalated discs. Heart and intercalated discs.

Muscle Movements in PairsMuscle Movements in Pairs

Pair off with a partner and perform various muscle movements. Check his/her accuracyMovements will show rotation, abduction, adduction, extension and flexion of these body parts:

Exam Chapters 6 and 7Exam Chapters 6 and 7

Exam will be on Oct 29 at 9:30Oct 29 at 9:30•Multiple Choice•Fill in the Blanks•Short Essays (taken directly from the Short Essays at end of Chap 6 and 7)•Extra Credit: Read page 149 “Muscle Tone”

survey of anatomy and physiology chap 7

Health & Medicine