BIO_2113_Lecture_notes_Muscles_Chap_9 - BIO 2113 Anatomy...

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BIO 2113 Anatomy and Physiology Spring Quarter 2010 Chap 9 Lecture Notes Hugh D. Dookwah DVM, PhD Muscle Overview and Similarities The three types of muscle tissue are skeletal, cardiac, and smooth These types differ in structure, location, function, and means of activation Skeletal and smooth muscle cells are elongated and are called muscle fibers Muscle contraction depends on two kinds of myofilaments – actin and myosin Muscle terminology is similar Sarcolemma – muscle plasma membrane Sarcoplasm – cytoplasm of a muscle cell Prefixes – myo, mys, and sarco all refer to muscle Skeletal Muscle Tissue Packaged in skeletal muscles that attach to and cover the bony skeleton Has obvious stripes called striations Is controlled voluntarily (i.e., by conscious control) Contracts rapidly but tires easily Is responsible for overall body motility Is extremely adaptable and can exert forces ranging from a fraction of an ounce to over 70 pounds Cardiac Muscle Tissue Occurs only in the heart Is striated like skeletal muscle but is not voluntary Cells are not elongated, so the term “fiber” is not used Contracts at a fairly steady rate set by the heart’s pacemaker Neural controls allow the heart to respond to changes in bodily needs Smooth muscle Found in the walls G.I. tract, respiratory tract, urinary tract, reproductive tract, walls of blood and lymph vessels, iris of the eye Consists of small elongated cells that are not striated Cells are elongated, so the term “muscle fiber” is used Involuntary control. 1
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Functional Characteristics of Muscle Tissue 1. Excitability, or irritability, is the ability to receive and respond to a stimulus. The stimulus is usually a neurotransmitter released by neurons that innervate the muscle. 2. Contractility is the ability to shorten forcibly when stimulated. No other tissue type can do this. 3. Extensibility is the ability to be stretched. 4. Elasticity is the ability to recoil and resume the cells’ original length once stretched. 5. Muscles produce movement by acting on the bones of the skeleton, pumping blood (cardiac), or propelling substances throughout hollow organ systems and maintaining blood pressure (smooth). 6. Muscles aid in maintaining posture by adjusting the position of the body with respect to gravity (skeletal). 7. Muscles stabilize joints by exerting tension around the joint (skeleteal). 8. Muscles generate heat as a function of their cellular metabolic processes. Skeletal muscle is the muscle type most responsible for generating heat. Gross Anatomy of Skeletal Muscle 1. Each muscle has a nerve and blood supply that allows neural control and ensures adequate nutrient delivery and waste removal. 2.
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This note was uploaded on 06/11/2010 for the course BIOL 2113 taught by Professor Dookwah during the Spring '10 term at Athens Tech.

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BIO_2113_Lecture_notes_Muscles_Chap_9 - BIO 2113 Anatomy...

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