MUSCLE CELLS

Skeletal Muscle

MOST ARE ATTACHED BY TENDONS TO BONES

• These muscles are LARGE, CIGAR SHAPED & MULTINUCLEATE

• KNOWN AS STRIATED MUSCLE

• THE ONLY VOLUNTARY MUSCLE because it is subject to conscious control.

Endomysium

SURROUNDED & BUNDLED BY CONNECTIVE TISSUES:

• It ENCLOSES A SINGLE MUSCLE FIBER

Perimysium

SURROUNDED & BUNDLED BY CONNECTIVE TISSUES:

• WRAPS AROUND FASCICLE (BUNDLE) OF MUSCLE FIBERS.

Epimysium

SURROUNDED & BUNDLED BY CONNECTIVE TISSUES:

COVERS THE ENTIRE SKELETAL MUSCLE.

Fascia

SURROUNDED & BUNDLED BY CONNECTIVE TISSUES:

• On the OUTSIDE OF EPIMYSIUM.

Tendons

These are CORDLIKE STRUCTURE

• MOSTLY COLLAGEN FIBERS

• OFTEN CROSSES A JOINT DUE TO TOUGHNESS & SMALL SIZE

Aponeuroses

It is a SHEETLIKE STRUCTURE.

• ATTACHES MUSCLES INDIRECTLY TO BONES, CARTILAGE, CONNECTIVE TISSUE COVERINGS.

Functions of Skeletal Muscle

MAIN: PRODUCE MOVEMENT

1. TO MAINTAIN POSTURE and body position

2. STABILIZE JOINTS

3. GENERATE HEAT

Sarcolemma

ORGANELLES

IT IS THE PLASMA MEMBRANE OF MUSCLE CELL.

Myofibrils

ORGANELLES

THE LONG ORGANELLES INSIDE MUSCLE CELLS

• The (I) bands and (A) bands GIVES THE MUSCLE A STRIATED LOOK.

Sacromere

It is the CONTRACTILE UNIT OF MUSCLE FIBER

• STRUCTURAL & FUNCTIONAL UNIT OF HUMAN SKELETON

ORGANIZATION:

1. Myofilaments

2. Thick Filaments

3. Thin Filments

Myofilaments

1. BLUE LINE = PROTEIN ACTIN

2. RED LINE = PROTEIN MYOSIN

3. (I) Band = (+) ACTIN

4. (A) Band = (+) ACTIN (+) PROGESTERONE

Thick Filaments

It is COMPOSED OF MOSTLY PROTEIN MYOSIN

• Contains ATP ENZY,ES TP S[PLIT INTO ADP TO RELEASE ENERGY FOR MUSC;E CPMTRACTKON.

Thin Filaments

MOSTLY OF THE CONTRACTILE PROTEIN ACTIN

• ACTIN IS ANCHORED TO Z DISC

• It is a ZONE THAT LACKS ACTIN FILAMENTS

• IT IS FOUND WHERE IT LACKS ACTIN = H ZONE

Sarcoplasmic Reticulum

SPECIALIZED SMOOTH ENDO RETICULUM

• SURROUNDS THE MYOFIBRIL

• STORES & RELEASE CALCIUM

• THE CALCIUM IS THE “GO” SIGNAL FOR CONTRACTOION.