Muscle & Muscle Tissue. Types of Muscle Tissue Skeletal Are striated Controlled voluntarily Tires easily.

Muscle & Muscle Tissue

Types of Muscle Tissue

Skeletal Are striated Controlled

voluntarily Tires easily

Types of Muscle cont.

Smooth Walls of visceral

organs Force fluids through

internal channels Not voluntary Not striated

Cardiac Found only in the

heart Striated Not voluntary

Muscle structure

Made up of 4 connective tissue Epimysium Fascicle Perimysium Endomysium

Gross Anatomy of a Skeletal Muscle

Epimysium Outermost layer Connective tissue surrounding the entire

muscle tapers at end to form tendon

Fascicle Inside the muscle are discrete areas of

muscle tissue

Perimysium Connective tissue

surrounding each fascicle

Endomysium Thin connective tissue surrounding each

muscle fiber (cell) Smallest unit of muscle visible without a

microscope

Skeletal Muscle

Muscles always contract actively Can extend only passively Ability to move a bone part in opposite

directions requires that muscles be attached to the skeleton

Tire easily Bundle of long fibers running the length of the

muscle Each fiber is a single cell with many nuclei &

consists of bundles of smaller myofibrils arranged longitudinally

Muscle Fiber

Single muscle cell Cylindrical in structure Surrounded by membrane capable of excitation &

impulse propagation Contains muscle fiber bundles called myofibrils

Sarcolemma

Delicate sheath (cell membrane)

Made up of lipid molecules

Transport nutrients & synthesizes proteins

Sodium/potassium pump

Maintain shape of muscle cell

Sarcoplasm

Aqueous substance – cytoplasm

Surrounds myofibrils House the

mitochondria Houses blood

vessels, glycogen & nerve endings

Myofibrils

Fibers functional unit Threadlike structure within muscle fiber Contains sarcomeres at intervals Made up of 2 protein fibers – microfilaments

Sarcoplasmic Reticulum

Specialized endoplasmic reticulumFunction is to store calcium and release

it on demand when a muscle fiber is stimulated to contract

Initiates muscle contraction at the sarcomere

Sarcomere

Segment of myofibril Composed of 2

contractile proteins Actin Myosin

Sarcomeres are separated by Z lines

Sarcomere

Has a dark band – A band

The A band has light zone called the H band (this disappears when contracted)

Center of the H band is the M line

Sarcomere

I band contains Actin Length varies with

the start of muscle contraction

Myofilaments

Protein fibers Composed of 2

filaments Actin – thin Myosin - thick

Divided into bands which alternate light and dark

Thick filaments

A bands are dark areas Dark areas represent

thick filaments 2 thick filament dark

areas are connected by the M line

Consist of myosin & ATPase

Enzyme splits ATP to generate the power of muscle contractions

Thin filaments

I band Light areas contain

thin filaments Made up of actin,

troponin and tropomyosin