Ultrastructure of skeletal muscle...pptx

ULTRASTRUCUTRE OF MUSCHLE CELL IS a vast way to study the anatomy of muscle cell. Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined to bones through tendons.
Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi.
Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers.
Muscle fibers are composed of myofibrils.
Myofibrils are made up of thin and thick filaments.
Skeletal muscles are joined

1. BHAVNA 23MSCZOO024 ULTRASTRUCTURE OF SKELETAL MUSCLES

2. CONTENT 01 02 03 04 05 06 07 Types of Muscle Overview O f Ultrastructure Ultrastructure of Skeletal Muscle Muscle Fiber Muscle Proteins Sliding Filament Theory Conclusion

3. TYPES OF MUSCLES CARDIAC MUSCLE SKELETAL MUSCLE SMOOTH MUSCLE Striated muscle that is under voluntary control from the somatic nervous system. Identifying features are cylindrical cells and multiple peripheral nuclei. Striated muscle that is found only in the heart. Identifying features are single nuclei and the presence of intercalated discs between the cells. Non-striated muscle that is controlled involuntarily by the autonomic nervous system. The identifying feature is the presence of one spindle-shaped central nucleus per cell.

4. Skeletal muscle Most are attached by tendons to bones Cells are multinucleate Striated – have visible banding Voluntary – subject to conscious control Cells are surrounded and bundled by connective tissue = great force, but tires easily Sarcolemma = Cell membrane Sarcoplasm = Cytoplasm Sarcoplasmic Reticulum = Endoplasmic Reticulum.

5. OVERVIEW Skeletal muscles are joined to bones through tendons. Muscle tissue is made up of many muscle bundles called as Muscle Bundles or Fasciculi. Each fasciculi is made up of many long and cylindrical muscle cells or muscle fibers. Muscle fibers are composed of myofibrils. Myofibrils are made up of thin and thick filaments.

6. Skeletal Muscle tissue is made up of thousands of muscle fibers that are bundled together and wrapped in connective tissue sheaths: Muscle fibers: Each muscle fiber is made up of myofibrils, which contain myofilaments. When a muscle contracts, the filaments in the myofibrils fold together, shortening the muscle fiber. Fasciculi : Bundles of muscle fibers are called fasciculi. Sheaths : The connective tissue sheaths that surround muscle tissue are: Epimysium : The outermost sheath that surrounds the entire muscle Perimysium : The middle sheath that surrounds the fasciculi Endomysium : The innermost sheath that surrounds individual muscle fibers ULTRASTRUCTURE OF SKELETAL MUSCLES

7. MUSCLE FASCICULI Muscle fasciculi, also known as fascicles are bundles of skeletal muscle fibers surrounded by a layer of connective tissue called as perimysium. Are arranged parallel to each other Variable in size Contain sarcoplasmic reticulum , mitochondria and myofibrils.

8. MUSCLE FIBER Muscle fibers are composed of myofibrils. Each skeletal muscle fiber is a single cylindrical muscle cell. Plasma membrane of muscle fiber is known as sarcolemma. Sarcoplasmic Reticulum SR is an elaborate, smooth endoplasmic reticulum runs longitudinally and surrounds each myofibril Form chambers called terminal cisternae on either side of the T-tubules A single T-tubule and the 2 terminal cisternae form a triad SR stores Ca ++ when muscle not contracting When stimulated, calcium released into sarcoplasm SR membrane has Ca ++ pumps that function to pump Ca ++ out of the sarcoplasm back into the SR after contraction

9. MYOFIBRILS Myofibrils -cylindrical structures within muscle fiber Are bundles of protein filaments (= myofilaments ) Two types of myofilaments Actin filaments (thin filaments) Myosin filaments (thick filaments) At each end of the fiber, myofibrils are anchored to the inner surface of the sarcolemma When myofibril shortens, muscle shortens (contracts)

10. Contractile proteins Actin - thin myofiliment Myosin- thick filament Regulatory proteins Tropomyosin Troponin Attachment proteins Titin , nebulin , alpha actinin , dystrophin MUSCLE PROTEINS

11. ACTIN (THIN) MYOFILAMENTS Thin Filament: composed of 3 major proteins F (fibrous) actin Tropomyosin Troponin Two strands of fibrous (F) actin form a double helix extending the length of the myofilament ; attached at either end at sarcomere . Composed of G actin monomers each of which has a myosin-binding site Actin site can bind myosin during muscle contraction. Tropomyosin : an elongated protein winds along the groove of the F actin double helix. Troponin is composed of three subunits: Tn -A : binds to actin Tn -T :binds to tropomyosin , Tn -C :binds to calcium ions. 15

12. Many elongated myosin molecules shaped like golf clubs. Single filament contains roughly 300 myosin molecules Molecule consists of two heavy myosin molecules wound together to form a rod portion lying parallel to the myosin myofilament and two heads that extend laterally. Myosin heads Can bind to active sites on the actin molecules to form cross-bridges. ( Actin binding site) Attached to the rod portion by a hinge region that can bend and straighten during contraction. Have ATPase activity: activity that breaks down adenosine triphosphate (ATP), releasing energy. Part of the energy is used to bend the hinge region of the myosin molecule during contraction 16 MYOSIN (THICK) MYOFILAMENTS

13. Sarcomere - repeating functional units of a myofibril About 10,000 sarcomeres per myofibril, end to end Each is about 2 µm long Differences in size, density, and distribution of thick and thin filaments gives the muscle fiber a banded or striated appearance. A bands: a dark band; full length of thick (myosin) filament M line - protein to which myosins attach H zone - thick but NO thin filaments I bands: a light band; from Z disks to ends of thick filaments Thin but NO thick filaments Extends from A band of one sarcomere to A band of the next sarcomere Z disk: filamentous network of protein. Serves as attachment for actin myofilaments Titin filaments: elastic chains of amino acids; keep thick and thin filaments in proper alignment SARCOMERE

14. Sliding Filament Model of Contraction Thin filaments slide past the thick ones so that the actin and myosin filaments overlap to a greater degree In the relaxed state, thin and thick filaments overlap only slightly Upon stimulation, myosin heads bind to actin and sliding begins 19

15. CONCLUSION Skeletal muscle tissue is a complex, dynamic and essential tissue that enables movement , maintains posture and regulates body functions. The ultrastructure of skeletal muscle reveals a complex and highly organized architecture designed for efficient contraction and movement. The precise arrangement of myofibrils, sarcomeres and myofilaments enables rapid transmission of neural signals, leading to coordinated muscle contraction. Sales