lecture8-10pdf

Lecture8-10pdf - Lecture 8 the three types of muscle cells smooth muscle forms contractile portions of tissue such as stomach intestine uterus and

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the three types of muscle cells Lecture 8
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•forms contractile portions of tissue such as stomach, intestine, uterus and arteries. •under involuntary control by autonomic nervous system and hormones •found where slow sustained contraction is needed. Some smooth muscle cells remain contracted entire lives (such as those in arteries leading out of heart) smooth muscle •contraction achieved by sliding thick and thin filaments, but not organized into sarcomeres and myofibrils [they do not have striped appearance (hence the name smooth •they have very slow myosin ATPase activity •contractile units attached to dense bodies serve same function as Z lines. ) •smooth muscle cells usually found in sheets that can form structures like tubes cells are mononucleated and smaller than skeletal fibers, capable of division
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•the principles of contraction are the same as in skeletal muscle: thin and thick Flaments sliding over each other. However, they are not arranged in sarcomeres and the regulation is very different.
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parasympathetic division •active when body is at rest •stimulates digestion •slows down respiration and heart rate •increases blood fow to skin, kidneys sympathetic division •active during stressFul situations •increase heart rate and respiration •increase blood fow to skeletal muscles parasympathetic and sympathetic usually have opposing activities The autonomic nervous system
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•contraction is initiated by entry of Ca 2+ into the cytoplasm -can be either from a sarcoplasmic reticulum or from ECF Myosin Light Chain kinase Calmodulin regulatory molecules in myoplasm signal to contract increases cytoplasmic Ca 2+ Sequence of events for smooth
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This note was uploaded on 02/14/2011 for the course MCDB 111 taught by Professor Smith during the Spring '11 term at UCSB.

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Lecture8-10pdf - Lecture 8 the three types of muscle cells smooth muscle forms contractile portions of tissue such as stomach intestine uterus and

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