Muscular System:
Characteristics Skeletal Cardiac Smooth
Body Location Attached to bones or, for facial muscles, to skin Walls of the heart Mostly in walls of hollow visceral organs (other than the heart)
Cell Shape and Appearance Single, very long, cylindrical, multinucleate cells with very obvious striations Branching chains of cells; uninucleate, striations; intercalated discs Single, fusiform, uninucleate; no striations
Connective Tissue Components Epimysium, perimysium, and endomysium Endomysium attached to the fibrous skeleton of the heart Endomysium
Regulation of Contraction Voluntary; via nervous system controls Involuntary; the heart has a pacemaker; also nervous system controls; hormones Involuntary; …show more content…
Other functions include the following: skeletal muscles protect fragile internal organs by enclosure. Smooth muscles form valves to regulate the passage of substances through internal body openings, dilate and constrict the pupils of our eyes, and activate the arrector pili muscles that cause our hairs to stand on end (Marieb).
4. Recent findings have shown that impairment of the degradation systems leads to accumulation of unfolded/misfolded proteins and altered organelles, which turns into toxicity for the muscle cells (Sandri).
5. Conversely, excessive activation of proteolytic machinery, including lysosomal-dependent degradation, contributes to muscle loss, weakness, and finally to death (Sandri).
6. These findings will help to define the role of the lysosomal system in muscle homeostasis during physiological or pathological conditions (Sandri).
7. Lysosomes control the half-life of long-lived proteins and the turnover of organelles and therefore, are critical for cellular homeostasis (Sandri).
8. Skeletal muscle contraction is a potential source of metabolic, mechanical, and thermal stressors. Therefore, the quality control of proteins and of organelles is particularly active in this tissue (Sandri).
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