muscles & muscular tissues 12 feb. 2013musc-tissue-lab.ppt1
TRANSCRIPT
12 Feb. 2013 Musc-tissue-lab.ppt 2
MUSCLE TISSUE
• Abundant, dense tissue– 40-50% of body weight
• High metabolic activity– high energy use/output;
– O2 consumption;
– CO2 production
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Characteristics of Muscle Tissue
• Contractility– Muscle tissue shortens producing force.– “Muscles can only contract!”
• Excitability– Responds to nerve impulses by contracting.
• Extensibility– Can be stretched by outside force (such as by
another muscle).
• Elasticity– Recoils after being stretched
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Functions of Muscle Tissue
• Produce movement by contracting– Locomotion & manipulation– Movement of blood, food, urine, etc. through
hollow organs
• Maintenance of posture• Stabilize joints
– so that other muscles can produce movement or maintain posture
• Heat production– Maintenance of body temperature.
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Gross structure of a skeletal muscle: • Tendons connect muscle
to bone, transmit force.
• Origin = attachment to more stationary (proximal) bone
• Insertion = attachment to more mobile (distal) bone
• Belly = muscular tissue
• Head = one of multiple origins (-ceps)
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Naming of muscles • Shape, arrangement of
fibers – Deltoid, orbicularis oris
• Location, origins/insertions– Pectoralis major
• Size– Latissimus dorsi
• Action – Flexor carpi ulnaris
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Muscle Groups
• Agonist (prime mover) vs. AntagonistMuscles can only CONTRACT !!Muscle must be stretched by antagonist(s) before it can
contract again.
• Synergist(s) = muscle(s) that works with prime mover.
• Fixator(s) = muscle(s) that stabilizes body part.– Prevents one kind of motion so another can happen.
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Three Kinds of Muscle Tissue
• Skeletal muscle: – Striated, usu. voluntary, attached to skeleton
• Cardiac muscle: – Striated, involuntary, walls of heart
• Smooth muscle: – Non-striated, involuntary, wrapping of hollow organs
– Stomach, intestines, arteries, bladder, vas deferens, uterus, etc.
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Skeletal Muscle:
• Long, cylindrical cells,• Multinucleate (nuclei peripheral),• Covered by plasma membrane (sarcolemma),• Striated.