Lec19 - MUSCLES: LAST DAY. SOME REVIEW, S OME NEW Review...

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MUSCLES: LAST DAY…. SOME REVIEW, SOME NEW Review Aspects of Skeletal Muscle, Smooth Muscle, Energy Sources And Clinical Aspects
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What is a MOTOR UNIT? Motor unit One neuron All of the Muscle cells stimulated by that neuron
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How Does Smooth Muscle Differ From Skeletal? 1. Smooth is involuntary muscle; it does not have a CNS to stimulate it but rather the autonomic nervous system stimulates this muscle. There are DIFFUSE JUNCTIONS ( no motor end plate) NT is Ach or epinephrine from nerve fibers (viscosities). SM NOT organized in sacromeres. But rather in single cells with ONE nucleus . There are NO Z-Dis ks Actin filaments are attached to dens e bodies in cell. There are NO T-tubules. No Troponin on Tropomyos in.
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Of Course If You Are Speaking About Skeletal Muscle You Will Innervate Them With … The CENTRAL NERVOUS SYSTEM AND we will refer to MOTOR NEURONS and Yes, I guess THE MOTOR UNIT BUT WHAT ABOUT the other MUSCLES like, for instance…… SMOOTH MUSCLE
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What is Smooth Muscle? Found mainly in walls of hollow visceral organs such as the stomach, urinary bladder and respiratory passages. Smooth muscle propels substances along a definite tract within the body. Nonstriated, involuntary .
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Regulation of SM Contraction When stimulated neurally, it is identical to skeletal muscle stimulation. 2 NTs used: ACh and Norepinephrine. However, CHEMICAL stimulation occurs in response to: Hormones, (gastrin-contracts stomach) Seratonin, (contracts SM Histamine, ( relaxes SM) Lack of Oxygen (relaxes SM) Low pH ( relaxes SM) Excess Co2 (relaxes SM) These factors affect Ca++ levels in cell. i.e. High Histamine will cause less Ca++ to be released in sarcoplasm, hence, relaxation rather than contraction.
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Special Features of Smooth Muscle Responds Well to stretching; Smooth muscle has a great deal of PLASTICITY. Plasticity is ability to adjust tension to degree of stretch. They also stretch More and generate more tension. Hyperplasia . The cells can and do multiply. Ex. Uterus, during gestation, grows to accommodate fetus. Smooth muscles is used to secrete.
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Contraction of Smooth Muscle
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Types of Smooth Muscle Single-unit smooth muscle most blood vessels and viscera as circular and longitudinal muscle layers electrically coupled by gap junctions large number of cells contract as a unit
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Stimulation of Smooth Muscle
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Contraction of Smooth Muscle
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Contraction in Smooth Muscles: It’s mechanism is slightly different From Skeletal BUT….The Result is the same. 1.
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Lec19 - MUSCLES: LAST DAY. SOME REVIEW, S OME NEW Review...

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