> body movement> maintenance of body posture
> respiration
> production of body heat
> communication
> constriction of organs and vessels
> heart beat
Table. Comparison of Muscle Types
Muscle Type
Characteristic Skeletal Cardiac Smooth
Nuclei Multinucleated; Single nucleus; centrally Single nucleus; centrally
peripherally located located located
Banding Actin and myosin form Actin and myosin form Actin and myosin; no
distinctive bands distinctive bands distinctive bands
Z disks Present Present Z disks not present;
cytoplasmic dense bodies
are present
T tubules T tubules at A-I T tubules at Z disk; No T tubules; no triads
junction; triads diads present or diads; caveolae are
present present
Cellular No junctional Intercalated disks Gap junctions
junctions complexes
Neuromuscular Present Not present; contraction Not present; contraction
junctions is intrinsic is intrinsic, neural, or
hormonal
Ca 2+-binding Troponin Troponin Calmodulin
Regeneration Limited; satellite cells None High
Characteristics of Muscle
> contractility
> excitability
> extensibility
> elasticity
Muscle fibers
Sliding Filament model
Ion channels
> ligand gates
> voltage-gated ion channels
Action potentials
Neuromuscular junction
Muscle relaxation
> excitation-contraction coupling results in the release of Calcium from the sarcoplasmic reticulum and the binding of Calcium to troponin.
Characteristics of Muscle Types
| Fibre Type | Type I fibres | Type II A fibres | Type II B fibres |
| Contraction time | Slow | Fast | Very Fast |
| Size of motor neuron | Small | Large | Very Large |
| Resistance to fatigue | High | Intermediate | Low |
| Activity Used for | Aerobic | Long term anaerobic | Short term anaerobic |
| Force production | Low | High | Very High |
| Mitochondrial density | High | High | Low |
| Capillary density | High | Intermediate | Low |
| Oxidative capacity | High | High | Low |
| Glycolytic capacity | Low | High | High |
| Major storage fuel | Triglycerides | CP, Glycogen | CP, Glycogen |
Types of smooth muscle
> involuntary muscle
> muscle of the viscera (e.g., in walls of blood vessels, intestine, & other 'hollow' structures and organs in the body)
Functional properties of smooth muscles
> smooth muscle is capable of authorhytmic contraction.
> a typical smooth muscles contracts and relaxes.
> smooth muscle tone.
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