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How do Muscles Work? Muscles serve FOUR functions for us: Muscles serve FOUR functions for us: -- motion; they move us -- motion; they move us -- stability.

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Presentation on theme: "How do Muscles Work? Muscles serve FOUR functions for us: Muscles serve FOUR functions for us: -- motion; they move us -- motion; they move us -- stability."— Presentation transcript:

1 How do Muscles Work? Muscles serve FOUR functions for us: Muscles serve FOUR functions for us: -- motion; they move us -- motion; they move us -- stability and posture -- stability and posture -- controlling organ function -- controlling organ function -- generate body heat -- generate body heat

2 Characteristics of Muscle Tissue Excitability – ability of the muscles to be stimulated by nerves Excitability – ability of the muscles to be stimulated by nerves Contractility – muscles can contract Contractility – muscles can contract Extensibility – muscles lengthen Extensibility – muscles lengthen Elasticity – after shortening or lengthening, muscle can return to its original shape Elasticity – after shortening or lengthening, muscle can return to its original shape Muscles PULL, they never push!

3 Roman Ship Analogy… Muscles work much like an old roman ship that used a galley of slaves roaring the oars in unison. Muscles work much like an old roman ship that used a galley of slaves roaring the oars in unison. Each slave had only so much strength, but together gave the ships oars incredible power. Each slave had only so much strength, but together gave the ships oars incredible power.

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5 Muscles need help… Muscles need to be connected to the rest of the body Muscles need to be connected to the rest of the body -- they need motor nerves -- they need motor nerves -- they need energy and O 2 -- they need energy and O 2 -- H 2 0, CO 2 waste & glucose transport -- H 2 0, CO 2 waste & glucose transport Requires nerves, blood vessels, and Requires nerves, blood vessels, and the lymphatic system to carry them the lymphatic system to carry them These are held in connective tissues called These are held in connective tissues called FASCIA FASCIA

6 Fascia Galore! Fascia is connective tissue that surrounds muscles Fascia is connective tissue that surrounds muscles Provides protection and stability Provides protection and stability

7 Superficial Fascia Closest to the skin and holds muscle to the skin Closest to the skin and holds muscle to the skin Also contains adipose tissue Also contains adipose tissue Stores fat and water, provides insulation from heat loss, protects, and is a place for vessels and nerves to carry things in and out of muscles Stores fat and water, provides insulation from heat loss, protects, and is a place for vessels and nerves to carry things in and out of muscles

8 Deep Fascia Separates muscle groups Separates muscle groups Allows muscles to contract without interference from other muscles Allows muscles to contract without interference from other muscles Each muscle has its own outer fascia called epimysium which is then surrounded by deep fascia Each muscle has its own outer fascia called epimysium which is then surrounded by deep fascia

9 Individual muscle fibers are called myofibers (muscle cells) Individual muscle fibers are called myofibers (muscle cells) Arranged in groups of myofibers and these groups are called fascicles Arranged in groups of myofibers and these groups are called fascicles Perimysium surrounds fascicles Perimysium surrounds fascicles Endomysium surrounds individual myofibers Endomysium surrounds individual myofibers Myofibers

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12 Myofibrils (actin & myosin) Proteins are arranged in a thread-like appearance in the sarcoplasm Proteins are arranged in a thread-like appearance in the sarcoplasm Give skeletal and cardiac muscle tissue their striations Give skeletal and cardiac muscle tissue their striations muscle cell

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14 Skeletal Muscle Fiber Contraction Sliding Filament Theory Sliding Filament Theory When muscle fibers are stimulated to contract, myofilaments (actin an myosin) slide past one another. When muscle fibers are stimulated to contract, myofilaments (actin an myosin) slide past one another. This causes sarcomeres (muscle units) to shorten and the whole muscle fiber shortens. This causes sarcomeres (muscle units) to shorten and the whole muscle fiber shortens.

15 Sarcomere

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18 Whole Muscle Contraction The whole length of one muscle fiber must contract; however, the whole muscle does not have to contact. The whole length of one muscle fiber must contract; however, the whole muscle does not have to contact. The number of muscle fibers contracting determines the strength of the contraction. The number of muscle fibers contracting determines the strength of the contraction.

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20 The Effect of Exercise A regular exercise program will bring about A regular exercise program will bring about 1. Increased endurance 1. Increased endurance 2. Increased strength of muscles. 2. Increased strength of muscles. Muscle enlarge, not due to increase in number of muscle fibers, but increased amounts of actin and myosin myofibrils inside each muscle fiber making them bigger and stronger. Muscle enlarge, not due to increase in number of muscle fibers, but increased amounts of actin and myosin myofibrils inside each muscle fiber making them bigger and stronger. Use it or lose it ! Use it or lose it !

21 Arnold….then and now!

22 Exercise increases muscle size, strength, and endurance Exercise increases muscle size, strength, and endurance –Aerobic (endurance) exercise (biking, jogging) results in stronger, more flexible muscles with greater resistance to fatigue Makes body metabolism more efficient Makes body metabolism more efficient Improves digestion, coordination Improves digestion, coordination Resistance exercise like weight lifting increases muscle size and strength

23 Effect of Exercise on Muscles


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