Comparison of Muscle Types

Skeletal shape of cell

Large diameter, long in length, run parallel to each other

Cardiac shape of cell

Branched

Smooth shape of cell

Spindle-shaped, thickest in middle, taper at ends

Skeletal nuclei

Multi-nucleated, located by sarcolemma

Cardiac nuclei

Generally single, centrally located

Smooth nuclei

Single, centrally located

Skeletal striation

Striated. Tells you that actin and myosin are organized into myofibrils and sarcomeres AND cell shortens when it contracts

Cardiac striation

Striated. Also, contains intercalated discs (gap junctions and desmosomes) - important for cells to act as a single functional unit. Striations - tells you that actin and myosin are organized into myofibrils and sarcomeres AND cell shortens when it contracts

Smooth striation

No. Actin and myosin are NOT organized into myofibrils and sarcomere. Cells DO NOT shorten when they contract, inside cell does twisting motion when it contracts

Skeletal neural signal

Neural signal is required for contraction. Control is voluntary. Neural control at single NMJ/cell

Cardiac neural signal

No, neural signal is not required for contraction. Control is involuntary. Automaticity - has pacemaker cells which can generate an electrical signal without the need of the NS. However, NS and/or hormones can influence pacemaker cells but is not required.

Smooth neural signal

No, neural signal is not required for contraction. Control is involuntary. Automaticity - has pacemaker cells which can generate an electrical signal without the need of the NS. However, NS and/or hormones can influence pacemaker cells but is not required.

Skeletal muscle tone

Has tone or resting tension. Occurs because there are always a few motor units contracting in a resting muscle. Contractions do not cause enough tension for movement, but aids in posture, resting body temperature

Cardiac muscle tone

Do not have cells that are contracting in background or resting tension. Cardiac muscle cells must do a very distinct pattern of contracting then they must relax before contracting again

Smooth muscle tone

Has tone or resting tension. Occurs because there are always some contractions of smooth muscle cells at rest. For blood vessels, causes resting amount of vasoconstriction -helps blood move. Give resting tone to tracts:digestive tract, respiratory tract, etc

Skeletal energy source

Aerobic (uses oxygen) at resting and moderate levels. Anaerobic (glycolysis) (uses stored energy) during maximum activity (peak tension)

Cardiac energy source

Aerobic (uses oxygen) usually lipid or carbs as substrates

Smooth energy source

Aerobic (uses oxygen), primarily

Skeletal Contractions and Muscle Fatigue

Rapid onset, rapid fatigue at peak tensions

Cardiac Contractions and Muscle Fatigue

Slower onset, resistant to fatigue

Smooth Contractions and Muscle Fatigue

Slower onset, resistant to fatigue

Skeletal Summate producing Sustained Tetanic Contractions

Yes, have a short refractory period. Muscle can be stimulated quickly causes tension to build or summate to a peak tension

Cardiac Summate producing Sustained Tetanic Contractions

No, have a long refractory period. Muscle can not be stimulated quickly causes tension to summate. Cardiac muscle cells must do a distinct cycle of contracting, then relaxing, contracting, then relaxing in order for blood to flow properly

Smooth Summate producing Sustained Tetanic Contractions

Yes, can reach sustainedtetanic contractions