BIOL 1117 Midterm: Anatomy and Physiology exam 3
1 Dec 2016
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Document Summary
Composed only of myocytes that have a fusiform shape with only one nucleus, located near the middle of the cell. No visible striations: thick and thin filaments but not aligned with each other. Z discs are absent and replaced by dense bodies: ordered array of protein masses in cytoplasm. Sarcoplasmic reticulum is limited and there are no t tubules. Injured smooth muscle regenerates itself (can repair itself, divides and makes copies) In contrast, skeletal muscle (in which membrane activation is dependent on just somatic neurons): many different inputs can go to plasma membrane of smooth muscle: can affect control. Inputs into smooth muscle can be nerves, hormones, or local factors, call all increase or decrease contraction. Some smooth muscle con contract or relax in response to temperature and chemical stimuli. Some smooth muscle contracts in response to stretch. All inputs that alter contractile activity by alternating cytosolic calcium levels.
