Muscular System- Year 1 Midterms

are responsible for all types of body movement

Muscles

Three basic muscle types are found in the body

Skeletal, Cardiac, Smooth muscles

___ and ________are elongated (muscle cell = muscle fiber)

Skeletal and smooth muscle cells

Contraction and shortening of muscles are due to the movement of

microfilaments

Prefixes that refer to “muscle”

myo- and mys-

Prefix that refers to “flesh”

sarco-

Study These

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Study these

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Study these

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Most skeletal muscle fibers are attached by _____ to bones

tendons

Skeletal muscle cells are look:

Large, cigar-shaped, and multinucleate

Skeletal muscle is also known as ____ because of its obvious stripes

Striated muscle

Skeletal Muscle is also known as_____ because it is the only muscle tissue subject to conscious control

voluntary muscle

Skeletal muscle cells are surrounded and bundled by

connective tissue

Skeletal muscle connective tissue: encloses a single muscle fiber

Endomysium

Skeletal muscle connective tissue: wraps around a fascicle (bundle) of muscle fibers

Perimysium

Skeletal muscle connective tissue: covers the entire skeletal muscle

Epimysium

Skeletal muscle connective tissue: on the outside of the epimysium

Fascia

study the muscle types

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The ________ of skeletal muscle blends into a connective tissue attachment

epimysium

epimysium: cordlike structures

• Mostly collagen fibers

• Often cross a joint because of their toughness and small size

Tendons

epimysium: sheetlike structures

• Attach muscles indirectly to bones, cartilages, or connective tissue coverings

Aponeuroses

• No striations

• Involuntary—no conscious control

• Found mainly in the walls of hollow visceral organs

• (such as stomach, urinary bladder, respiratory

• passages)

• Spindle-shaped fibers that are uninucleate

• Contractions are slow and sustained

Smooth muscle

• Striations

• Involuntary

• Found only in the walls of the heart

• Uninucleate

• Branching cells joined by gap junctions called intercalated discs

• Contracts at a steady rate set by pacemaker

Cardiac muscle

Maintain posture and body position, Stabilize joints, Generate heat

skeletal muscle

Microscopic Anatomy of Skeletal Muscle: specialized plasma membrane

Sarcolemma

Microscopic Anatomy of Skeletal Muscle: long organelles inside muscle cell

Myofibrils

These bands give the muscle its striated (banded) appearance

Light (I) and dark (A) bands

Banding pattern of myofibrils:

• Contains only thin filaments

• Z disc is a midline interruption

Light (I) band

Banding pattern of myofibrils:

• Contains the entire length of the thick filaments

• H zone is a lighter central area

• M line is in center of H zone

dark (A) bands

Microscopic Anatomy of Skeletal Muscle:

• contractile unit of a muscle fiber

• Structural and functional unit of skeletal muscle

Sarcomere

Myofilaments produce banding (striped) pattern: Thick filaments

myosin filaments

Myofilaments produce banding (striped) pattern: Thin filaments

actin filaments

• Composed of the protein myosin

• Contain ATPase enzymes to split ATP to release energy for muscle contractions

• Possess projections known as myosin heads

• Myosin heads are known as cross bridges when they link thick and thin filaments during contraction

myosin filaments

_______ are known as cross bridges when they link thick and thin filaments during contraction

Myosin heads

Composed of the contractile protein actin

Actin is anchored to the Z disc

At rest, within the A band there is a zone that

lacks actin filaments called the H zone

During contraction, H zones disappear as actin

and myosin filaments overlap