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Musculature in vertebrates

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Bhupen Koch

This document summarizes the three main types of muscle in vertebrates: skeletal, cardiac, and smooth muscle. Skeletal muscle is striated and voluntary, found in limbs, and produces movement. Cardiac muscle is also striated but involuntary, found only in the heart. Smooth muscle is not striated, involuntary, and found in internal organs. The document describes the structure, function, and characteristics of each muscle type in more detail. It also discusses muscle control and how muscles generate force through the sliding filament model of contraction.

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Musculature in vertebrates Presented by:- Bhupen chandra koch Roll no- 23 M.Sc 3rd samester Dept. of zoology Gauhati university
The Muscular System Muscles are responsible for all movement of the body There are three basic types of muscle Skeletal Cardiac Smooth
3 Types of Muscles
Three types of muscle Skeletal Cardiac Smooth
Classification of Muscle Skeletal- found in limbs Cardiac- found in heart Smooth- Found in viscera Striated, multi- nucleated Striated, 1 nucleus Not striated, 1 nucleus voluntary involuntary involuntary
Characteristics of Muscle Skeletal and smooth muscle are elongated Muscle cell = muscle fiber Contraction of a muscle is due to movement of microfilaments (protein fibers) All muscles share some terminology Prefixes myo and mys refer to muscle Prefix sarco refers to flesh
Shapes of Muscles Triangular- shoulder, neck Spindle- arms, legs Flat- diaphragm, forehead Circular- mouth, anus
Skeletal Muscle Most are attached by tendons to bones Cells have more than one nucleus (multinucleated) Striated- have stripes, banding Voluntary- subject to conscious control Tendons are mostly made of collagen fibers Found in the limbs Produce movement, maintain posture, generate heat, stabilize joints
Structure of skeletal muscle Each cell (fibre) is long and cylindrical Muscle fibres are multi-nucleated Typically 50-60mm in diameter, and up to 10cm long The contractile elements of skeletal muscle cells are myofibrils
Skeletal muscle - Summary Voluntary movement of skeletal parts Spans joints and attached to skeleton Multi-nucleated, striated, cylindrical fibres
Smooth Muscle No striations Spindle shaped Single nucleus Involuntary- no conscious control Found mainly in the walls of hollow organs
Smooth muscle Lines walls of viscera Found in longitudinal or circular arrangement Alternate contraction of circular & longitudinal muscle in the intestine leads to peristalsis
Structure of smooth muscle Spindle shaped uni-nucleated cells Striations not observed Actin and myosin filaments are present( protein fibers)
Smooth muscle - Summary Found in walls of hollow internal organs Involuntary movement of internal organs Elongated, spindle shaped fibre with single nucleus
Cardiac Muscle Striations Branching cells Involuntary Found only in the heart Usually has a single nucleus, but can have more than one
Cardiac muscle Main muscle of heart Pumping mass of heart Critical in humans Heart muscle cells behave as one unit Heart always contracts to its full extent
Structure of cardiac muscle Cardiac muscle cells (fibres) are short, branched and interconnected Cells are striated & usually have 1 nucleus Adjacent cardiac cells are joined via electrical synapses (gap junctions) These gap junctions appear as dark lines and are called
Cardiac muscle - Summary Found in the heart Involuntary rhythmic contraction Branched, striated fibre with single nucleus and intercalated discs
Muscle Control Type of muscle Nervous control Type of control Example SkeletalSkeletal Controlled by CNS Voluntary Lifting a glass Cardiac Regulated by ANS Involuntary Heart beating Smooth Controlled by ANS Involuntary Peristalsis
Types of Responses Twitch- A single brief contraction Not a normal muscle function Tetanus One contraction immediately followed by another Muscle never completely returns to a relaxed state Effects are compounded
Where Does the Energy Come From? Energy is stored in the muscles in the form of ATP ATP comes from the breakdown of glucose during Cellular Respiration This all happens in the Mitochondria of the cell When a muscle is fatigued (tired) it is unable to contract because of lack of Oxygen
How are Muscles Attached to Bone? Origin-attachment to a movable bone Insertion- attachment to an immovable bone Muscles are always attached to at least 2 points Movement is attained due to a muscle moving an attached bone
Structure of Skeletal Muscle: Microstructure Sarcolemma Muscle cell membrane Myofibrils Threadlike strands within muscle fibers Actin (thin filament) Troponin Tropomyosin Myosin (thick filament)
Musculature in vertebrates
Structure of Skeletal Muscle: The Sarcomere Further divisions of myofibrils Z-line A-band I-band Within the sarcoplasm Sarcoplasmic reticulum Storage sites for calcium Transverse tubules Terminal cisternae
Sliding Filament Theory Rest uncharged ATP cross-bridge complex Excitation-coupling charged ATP cross- bridge complex, turned on Contraction actomyosin ATP > ADP & Pi + energy Recharging reload cross-bridge with ATP Relaxation cross-bridges turned off
The Sliding Filament Model of Muscle Contraction
Musculature in vertebrates
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Musculature in vertebrates

  • 1. Musculature in vertebrates Presented by:- Bhupen chandra koch Roll no- 23 M.Sc 3rd samester Dept. of zoology Gauhati university
  • 2. The Muscular System Muscles are responsible for all movement of the body There are three basic types of muscle Skeletal Cardiac Smooth
  • 3. 3 Types of Muscles
  • 4. Three types of muscle Skeletal Cardiac Smooth
  • 5. Classification of Muscle Skeletal- found in limbs Cardiac- found in heart Smooth- Found in viscera Striated, multi- nucleated Striated, 1 nucleus Not striated, 1 nucleus voluntary involuntary involuntary
  • 6. Characteristics of Muscle Skeletal and smooth muscle are elongated Muscle cell = muscle fiber Contraction of a muscle is due to movement of microfilaments (protein fibers) All muscles share some terminology Prefixes myo and mys refer to muscle Prefix sarco refers to flesh
  • 7. Shapes of Muscles Triangular- shoulder, neck Spindle- arms, legs Flat- diaphragm, forehead Circular- mouth, anus
  • 8. Skeletal Muscle Most are attached by tendons to bones Cells have more than one nucleus (multinucleated) Striated- have stripes, banding Voluntary- subject to conscious control Tendons are mostly made of collagen fibers Found in the limbs Produce movement, maintain posture, generate heat, stabilize joints
  • 9. Structure of skeletal muscle Each cell (fibre) is long and cylindrical Muscle fibres are multi-nucleated Typically 50-60mm in diameter, and up to 10cm long The contractile elements of skeletal muscle cells are myofibrils
  • 10. Skeletal muscle - Summary Voluntary movement of skeletal parts Spans joints and attached to skeleton Multi-nucleated, striated, cylindrical fibres
  • 11. Smooth Muscle No striations Spindle shaped Single nucleus Involuntary- no conscious control Found mainly in the walls of hollow organs
  • 12. Smooth muscle Lines walls of viscera Found in longitudinal or circular arrangement Alternate contraction of circular & longitudinal muscle in the intestine leads to peristalsis
  • 13. Structure of smooth muscle Spindle shaped uni-nucleated cells Striations not observed Actin and myosin filaments are present( protein fibers)
  • 14. Smooth muscle - Summary Found in walls of hollow internal organs Involuntary movement of internal organs Elongated, spindle shaped fibre with single nucleus
  • 15. Cardiac Muscle Striations Branching cells Involuntary Found only in the heart Usually has a single nucleus, but can have more than one
  • 16. Cardiac muscle Main muscle of heart Pumping mass of heart Critical in humans Heart muscle cells behave as one unit Heart always contracts to its full extent
  • 17. Structure of cardiac muscle Cardiac muscle cells (fibres) are short, branched and interconnected Cells are striated & usually have 1 nucleus Adjacent cardiac cells are joined via electrical synapses (gap junctions) These gap junctions appear as dark lines and are called
  • 18. Cardiac muscle - Summary Found in the heart Involuntary rhythmic contraction Branched, striated fibre with single nucleus and intercalated discs
  • 19. Muscle Control Type of muscle Nervous control Type of control Example SkeletalSkeletal Controlled by CNS Voluntary Lifting a glass Cardiac Regulated by ANS Involuntary Heart beating Smooth Controlled by ANS Involuntary Peristalsis
  • 20. Types of Responses Twitch- A single brief contraction Not a normal muscle function Tetanus One contraction immediately followed by another Muscle never completely returns to a relaxed state Effects are compounded
  • 21. Where Does the Energy Come From? Energy is stored in the muscles in the form of ATP ATP comes from the breakdown of glucose during Cellular Respiration This all happens in the Mitochondria of the cell When a muscle is fatigued (tired) it is unable to contract because of lack of Oxygen
  • 22. How are Muscles Attached to Bone? Origin-attachment to a movable bone Insertion- attachment to an immovable bone Muscles are always attached to at least 2 points Movement is attained due to a muscle moving an attached bone
  • 23. Structure of Skeletal Muscle: Microstructure Sarcolemma Muscle cell membrane Myofibrils Threadlike strands within muscle fibers Actin (thin filament) Troponin Tropomyosin Myosin (thick filament)
  • 25. Structure of Skeletal Muscle: The Sarcomere Further divisions of myofibrils Z-line A-band I-band Within the sarcoplasm Sarcoplasmic reticulum Storage sites for calcium Transverse tubules Terminal cisternae
  • 26. Sliding Filament Theory Rest uncharged ATP cross-bridge complex Excitation-coupling charged ATP cross- bridge complex, turned on Contraction actomyosin ATP > ADP & Pi + energy Recharging reload cross-bridge with ATP Relaxation cross-bridges turned off
  • 27. The Sliding Filament Model of Muscle Contraction