Download Muscle & Muscle Tissue

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 reticulum
 Function 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