Sistem Otot Muskular 2 (Muscular System)

8/2/2019 Sistem Otot Muskular 2 (Muscular System)

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Muscular System

Introduction Muscles convert chemical energy into

mechanical energy.

Muscles make up the bulk of the body andaccount for about one-third of its weight.

Their ability to contract not only enables thebody to move, but also provides the forcethat pushes substances, such as blood andfood, through the body.



Without the muscular system, none of the other organ systems would be able

to function.



Three types of muscle

Skeletal Cardiac Smooth



Types of Muscle Tissue Skeletal Muscle Cells are striated

(striped) with multiple nuclei; are

arranged as many, long, cylindrical cellsbundled together; with several bundlesenclosed in tough connective tissuesheath to form a muscle; they are

responsible for voluntary movement,and are generally connected to bonesvia tendons



Skeletal Muscle Cells



Skeletal muscle

Large muscles

Maintain posture

Facilitate locomotion

Move jointed bones

Found in antagonistic pairs Joined to bones by tendons



Smooth Muscle Cells are not striated, have a single nucleus; the cells are

tapered at both ends, are held together by tight junctions; and are located in the walls of "hollow

organs" i.e., blood vessels, stomach, bladder, andother internal organs; they are responsible forinvoluntary movements i.e., peristalsis, and althoughthey are wrapped by connective tissue, they are notconnected by tendons. Although considered

involuntary muscles, they do respond topsychological states such as stress and excitement



Smooth muscle

Lines walls of viscera

Found in longitudinal orcircular arrangement

Alternate contraction ofcircular & longitudinalmuscle in the intestineleads to peristalsis



Smooth Muscle Cells



Cardiac Muscle Cells

are striated with multiple nuclei per cell likeskeletal muscles; however, the cells arebranched and connected end-to-end by

junctions (fused cell membranes) that

allow electrical current flow; they are locatedonly in the heart wall. Although also consideredinvoluntary muscles, they do respond topsychological states such as stress and

excitement, and significant evidence suggeststhat some degree of voluntary control can begained over cardiac muscles, through practicessuch as meditation and biofeedback



Cardiac muscle

Main muscle of heart

Pumping mass of heart

Critical in humans

Heart muscle cellsbehave as one unit

Heart always contractsto it’s full extent



Cardiac Muscle Cells



Classification of muscle

Voluntary Involuntary

Limbs Heart Viscera

Striated Non-striated

Skeletal Cardiac Smooth

Note: Control, Location and Structure



Functional Organization of Skeletal Muscle



Single Muscle Fibers

A muscle fiber is a single, multinucleatedmuscle cell.

A muscle is made up of hundreds or eventhousands of muscle fibers, depending on themuscles size.

Although muscle fiber makes up most of themuscle tissue, a large amount of connectivetissue, blood vessels, and nerves are alsopresent.



Connective tissue covers and supportseach muscle fiber and reinforces themuscle as a whole.

The health of muscle depends on asufficient nerve and blood supply. Eachskeletal muscle has a nerve ending thatcontrols its activity (innervation ), and an

individual system to supply and drainblood (vascularization ).



Bundles of Muscles Muscle Fibers consist of bundles of

threadlike structures called myofibrils

Each myofibril is made up of two types of protein filaments- Thick ones and Thin ones.

The thick filaments are made up of aprotein called myosin .

The thin filaments are made of a protein

called actin .



Myosin and Actin filaments are

arranged to form overlapping patterns,which are responsible for the light anddark bands (striations) that can beseen in skeletal muscle.

Thin actin filaments are anchored attheir midpoints to a structure calledthe z-line .

The region from one z-line to the nextis called a sarcomere , which is thefunctional unit of muscle contractions.





http://www.ebsa.org/npbsn41/pictures/sarcomere.gif











How Muscles and Bones Interact

Skeleton muscles generate force andproduce movement only by contracting

or pulling on body parts. Individual muscles can only pull; they

cannot push.

Skeleton muscles are joined to bone bytough connective tissue called tendons.



Tendons attach muscle to bone; the origin isthe more stationary bone, the insertion is themore movable bone.

Tendons are attached in such a way thatthey pull on the bones and make them work like levers. The movements of the musclesand joints enable the bones to act as levers.

Most skeletal muscles work in pairs.

When one muscle or set of musclescontracts, the other relaxes.



The muscles of the upper arm are a goodexample of this dual action: a flexor , is a

muscle that bends a joint, while an extensor is a muscle that straightens a joint.

a.when the biceps muscle (on the front of the

upper arm, flexor) contracts, it bends or flexes the elbow joint.

b.when the triceps muscle (on the back of the upper arm, extensor) contracts, it opens, or extends, the elbow joint.

c.a controlled movement requires contraction by both muscles.





Names of Skeletal Muscles

Individual muscles are named on thebasis of several criteria, each of which

focuses on a particular structural orfunctional characteristic. Paying closeattention to these cues can greatly

simplify your task of learning musclenames and actions:



Direction of the muscle fibers

Some muscles are named in reference tosome imaginary line (usually the midline) onthe body. When a muscle name includes the

term rectus (straight), its fibers run parallelto that imaginary line. The term oblique (slanted) in a name tells you that the musclefibers run at an angle to the imaginary line.

The rectus femoris is a straight muscle of the thigh. The external oblique is a muscleslanted across the abdomen.



Relative size of the muscle

Such terms as maximus (largest),minimus (smallest), and longus

(longest) are often used in musclenames.

The gluteus maximus is the largest

muscle of the gluteus muscle group.



Location of the muscle

Some muscles are named for the bone with which they are associated.

The temporalis and frontalis musclesoverlie the temporal and frontal bonesof the skull.



Number of origins

Some muscle names begin with aprefix indicating the number of origins.

- The biceps , triceps , and quadriceps have two, three, and four originsrespectively.



Location of the muscle'sorigin and insertion

Some muscles are named for theirattachment sites.

- The sternocleidomastoid muscle hasits origin on the sternum (sterno ) andclavicle (cleido ) and inserts on the

mastoid process of the temporal bone.



Shape of the muscle

Some muscles have a distinctive shape that helps to identify them.

- The deltoid muscle is roughlytriangular. (Deltoid means "triangular".)



Action of the muscle

Action terms like flexor, extensor,and adductor appear in the names.



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Sistem Otot Muskular 2 (Muscular System)