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MUSCULAR SYSTEM. Types of muscles SkeletalCardiacSmooth.

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Presentation on theme: "MUSCULAR SYSTEM. Types of muscles SkeletalCardiacSmooth."— Presentation transcript:

1 MUSCULAR SYSTEM

2 Types of muscles SkeletalCardiacSmooth

3 Skeletal Muscle Fibers are striated tubular multinucleated Attached to skeletal bones Is Voluntary (you have conscious control)

4 Cardiac Muscle Fibers are Striated Branched Uninucleated Occurs in walls of heart Is Involuntary

5 Smooth Muscle Fibers are Spindle shaped Nonstriated Uninucleated Occurs in walls of internal organs (digestive tract, blood vessels) Is involuntary

6 Classification of Muscle Voluntary Involuntary Skeletal Cardiac Smooth Limbs Heart Viscera Striated Non-striated SkeletalCardiac Smooth Note: Control, Location and Structure Control Location Type Structure

7 What is a muscle? Bundle of muscle cells called muscle fibers

8 Each muscle fiber is made up of strands called myofilaments Muscle Fibers

9 myofibril sarcolemma SarcoplasmSarcoplasmic reticulum Striated muscle fibers pack their myofilaments into tight strands called Myofibrils myofilament

10 To contract: to get shorter Muscle cells Contract when stimulated by motor impulses or hormones Only contract (tighten up) or relax can only pull - never push Muscle Contraction

11 Inside a Myofibril Functional Units called Sarcomeres Two types of protein filaments: Actin (thin) and Myosin

12 Actin myofilaments slide over myosin - sarcomeres shorten Actin and myosin do not change length During relaxation - sarcomeres lengthen H-zone Sliding Filament Model

13 Myosin

14 Actin In a relaxed muscle, tropomyosin covers the binding sites for myosin heads

15 Myosin filaments alternate with actin filaments

16 Ca ++ An Impulse opens calcium channels and Ca++ enters cell Ca++ binds to the troponin complex Tropomyosin shifts and cross-bridge-binding sites are exposed Contraction

17 Cross-bridge formation Myosin heads can now attach at the cross bridge binding sites

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20 Muscle Contraction Cycle In the presence of calcium, myosin binds to the actin filaments. The myosin head flexes inward and backward, causing the actin filament to shorten. In the presence of ATP, the myosin head detaches and then reattaches at a new position on the actin filament. This cycle repeats to continue the shortening of the muscle (contraction).

21 Relaxation Calcium is pumped into sarcoplasmic reticulum. Crossbridges are detached from the thin filaments. Troponin-tropomyosin regulated inhibition of actin and myosin interaction is restored. Active tension disappears and the rest length is restored.

22 Muscle can only contract (pull on bone) can’t push bone in opposite direction Another muscle is required to pull bone in opposite direction Skeletal muscles act in antagonistic pairs You have two sets of muscles attached to many of your bones which allow them to move. Skeletal Muscle and Bones:

23 Attached to bones by tendons Moves bones Origin: Bone that does not move when muscle contracts Insertion: Bone that moves when muscle contracts The skeleton and muscles function together as the musculoskeletal system Skeletal Muscle and Bones:

24 Skeletal Muscle Biceps – Origin is scapula (2 places), Insertion is radius Triceps are antagonistic to the biceps

25 Joint Movement Terms ABDUCT vs. ADDUCT Away from the sagittal planeTowards the sagittal plane

26 Joint Movement Terms FLEXION vs. EXTENSION flexion extension hyperextend flexion neutral extend Flexion: decrease in joint angle


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