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October 29-30, 2014

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What are the functions of muscles?

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Producing movement Producing movement Muscle contraction allows movement Of the body For facial expression To move fluids, digesting food, and other substances through the body Maintain blood pressure

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Maintaining posture Maintaining posture Muscles are constantly varying their contraction to maintain posture while we are seated or standing. Stabilizing joints Muscle contraction helps Muscle contraction helps keep joints in keep joints in position position

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Generating heat Muscle contraction requires an enormous amount of energy. When food is converted to ATP to power the muscles, nearly 75% of the energy is lost to heat. Remember: shivering functions to raise body temperatures by contracting muscles

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Notice the prefixes! -mys, -myo, and -sarco

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muscle fiber A single muscle cell is called a muscle fiber. Muscle fibers are LONG (up to 1 ft). Each muscle fiber is wrapped in a delicate connective tissue called endomysiumRemember: Endo = inside

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fascicle. Multiple fibers (cells!) are grouped together to form a fascicle. Each fascicle is wrapped up with a connective tissue called perimyscium. perimyscium. Remember: Remember: peri = around peri = around

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Blood vessels branch out between the fascicles. The whole muscle is covered by a thick, tough layer of connective tissue called epimysium. Epi = outer Epi = outer

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to The epimysia fuse to The periosteum (outer connective tissue) of bone The periosteum (outer connective tissue) of bone - or - - or - The perichondrium (outer connective tissue)of cartilage The perichondrium (outer connective tissue)of cartilage - or - - or - Tendons (rope like connective tissue that connects muscle to bone) Tendons (rope like connective tissue that connects muscle to bone) - or - - or - Aponeuroses (sheetlike connective tissue that attaches muscle to bones, cartilage, or other muscles) Aponeuroses (sheetlike connective tissue that attaches muscle to bones, cartilage, or other muscles)

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This is a micrograph of muscle tissue, magnified ~70 X Identify: Nuclei, Muscle fibers, Endomysium Perimysium Blood vessels

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This is a micrograph of muscle tissue, magnified ~70 X Identify: Nuclei, Muscle fibers, Endomysium Perimysium Blood vessels

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What do you already know about the three types of muscles?

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Attached to bones (or, in the face, to skin) Walls of hollow organs, airways, and arteries Walls of heart

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SkeletalSmoothCardiac Regulation of contraction Nervous system excites contraction. No effect of hormones Nervous system excites or inhibits contraction. Hormones and other chemicals (e.g. CO 2, pH, low O 2, ) may stimulate or inhibit contraction. Intrinsic regulation from a pacemaker within the heart. Natural rhythm can be excited or inhibited by the nervous system OR by body hormones Speed of contraction Slow to fastVery slow slow Rhythmic contraction NoYes, can be triggered by stretch receptors Yes, has internal pacemaker Muscle contraction is stimulated by nervous system. Hormones have no effect Contraction can be stimulated (excited) OR reduced (inhibited) by EITHER the nervous system OR hormones OR body chemicals (e.g. pH)

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Relate at least 3 differences between skeletal, cardiac, and smooth muscle to differences in their function.

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Make a Venn Diagram comparing and contrasting skeletal, smooth, and cardiac muscle

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1) The connective tissue covering that encloses the sarcolemma of an individual muscle fiber is called the a) Epimysium b) Perimysium c) Endomysium d) periosteum

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2) A fascicle is a) A muscle b) A bundle of muscle fibers c) A bundle of myofibrils d) A group of myofilaments

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3) Muscle tissue that is involuntary a) cardiac muscle only b) Smooth muscle only c) Skeletal muscle only d) Cardiac and smooth muscle e) Cardiac and skeletal muscle

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4) The muscle tissue that consists of single, very long, cylindrical, multinucleate cells with very obvious striations is: a) cardiac muscle only b) Smooth muscle only c) Skeletal muscle only d) Cardiac and smooth muscle e) Cardiac and skeletal muscle

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5) Which of the following is NOT a function of the muscular system a) Producing movement b) Maintaining posture c) Stabilizing joints d) Generating heat e) hematopoiesis