Muscle Tissue. PowerPoint Lecture Presentations prepared by Jason LaPres. Lone Star College North Harris Pearson Education, Inc.

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1 10 Muscle Tissue PowerPoint Lecture Presentations prepared by Jason LaPres Lone Star College North Harris

2 An Introduction to Muscle Tissue Muscle Tissue A primary tissue type, divided into: Skeletal muscle tissue Cardiac muscle tissue Smooth muscle tissue

3 10-2 Organization of Muscle Skeletal Muscle Muscle tissue (muscle cells or fibers) Connective tissues Nerves Blood vessels

4 10-2 Organization of Muscle Organization of Connective Tissues Muscles have three layers of connective tissues 1. Epimysium 2. Perimysium 3. Endomysium

5 10-2 Organization of Muscle Epimysium Exterior collagen layer Separates muscle from surrounding tissues

6 10-2 Organization of Muscle Perimysium Surrounds muscle fiber bundles (fascicles) Contains blood vessel and nerve supply to fascicles

7 10-2 Organization of Muscle Endomysium Surrounds individual muscle cells (muscle fibers) Contains capillaries and nerve fibers contacting muscle cells

8 Figure 10-1 The Organization of Skeletal Muscles Skeletal Muscle (organ) Epimysium Perimysium Endomysium Nerve Muscle fascicle Muscle fibers Blood vessels Epimysium Blood vessels and nerves Tendon Endomysium Perimysium

9 Figure 10-1 The Organization of Skeletal Muscles Muscle Fascicle (bundle of fibers) Perimysium Epimysium Blood vessels and nerves Muscle fiber Endomysium Tendon Endomysium Perimysium

10 Figure 10-1 The Organization of Skeletal Muscles Tendon Epimysium Blood vessels and nerves Muscle Fiber (cell) Capillary Myofibril Axon of neuron Endomysium Sarcoplasm Mitochondrion Myosatellite cell Sarcolemma Nucleus Endomysium Perimysium

11 10-2 Organization of Muscle Organization of Connective Tissues Muscle Attachments Endomysium, perimysium, and epimysium come together: At ends of muscles To form connective tissue attachment to bone matrix I.e., tendon (bundle)

12 10-3 Characteristics of Skeletal Muscle Fibers Skeletal Muscle Cells Are very long Become very large Contain hundreds of nuclei

13 10-3 Characteristics of Skeletal Muscle Fibers The Sarcolemma and Transverse Tubules The sarcolemma The cell membrane of a muscle fiber (cell) Surrounds the sarcoplasm (cytoplasm of muscle fiber) A change in transmembrane potential begins contractions

14 10-3 Characteristics of Skeletal Muscle Fibers The Sarcolemma and Transverse Tubules Transverse tubules (T tubules) Transmit action potential through cell Allow entire muscle fiber to contract simultaneously Have same properties as sarcolemma

15 10-3 Characteristics of Skeletal Muscle Fibers Myofibrils Lengthwise subdivisions within muscle fiber Made up of bundles of protein filaments (myofilaments) Myofilaments are responsible for muscle contraction Types of myofilaments: Thin filaments Made of the protein actin Thick filaments Made of the protein myosin

16 10-3 Characteristics of Skeletal Muscle Fibers The Sarcoplasmic Reticulum (SR) A membranous structure surrounding each myofibril Helps transmit action potential to myofibril Similar in structure to smooth endoplasmic reticulum

17 Figure 10-3 The Structure of a Skeletal Muscle Fiber Myofibril Sarcolemma Nuclei Sarcoplasm MUSCLE FIBER Mitochondria Terminal cisterna Sarcolemma Sarcolemma Sarcoplasm Myofibril Myofibrils Thin filament Thick filament Triad Sarcoplasmic reticulum T tubules

18 Figure 10-3 The Structure of a Skeletal Muscle Fiber Myofibril Sarcolemma Nuclei Sarcoplasm MUSCLE FIBER

19 Figure 10-3 The Structure of a Skeletal Muscle Fiber Mitochondria Sarcolemma Terminal cisterna Sarcolemma Sarcoplasm Myofibril Myofibrils Thin filament Thick filament Triad Sarcoplasmic reticulum T tubules

20 Figure 10-3 The Structure of a Skeletal Muscle Fiber Mitochondria Sarcolemma Myofibril Thin filament Thick filament

21 Figure 10-3 The Structure of a Skeletal Muscle Fiber Terminal cisterna Sarcolemma Sarcoplasm Myofibrils Triad Sarcoplasmic reticulum T tubules

22 10-3 Structural Components of a Sarcomere Sarcomeres The contractile units of muscle Structural units of myofibrils Form visible patterns within myofibrils A striped or striated pattern within myofibrils Alternating dark, thick filaments (A bands) and light, thin filaments (I bands)

23 Figure 10-4a Sarcomere Structure, Part I I band A band H band Z line Titin A longitudinal section of a sarcomere, showing bands Zone of overlap M line Sarcomere Thin Thick filament filament

24 Figure 10-4b Sarcomere Structure, Part I I band A band H band Z line A corresponding view of a sarcomere in a myofibril from a muscle fiber in the gastrocnemius muscle of the calf Myofibril TEM 64,000 Z line Zone of overlap M line Sarcomere

Figure 10-6 Levels of Functional Organization in a Skeletal Muscle Skeletal Muscle Myofibril Epimysium Surrounded by: Epimysium Contains: Muscle fascicles Surrounded by: Sarcoplasmic reticulum

25 Figure 10-6 Levels of Functional Organization in a Skeletal Muscle Skeletal Muscle Myofibril Epimysium Surrounded by: Epimysium Contains: Muscle fascicles Surrounded by: Sarcoplasmic reticulum Consists of: Sarcomeres (Z line to Z line) Sarcomere I band A band Muscle Fascicle Perimysium Surrounded by: Perimysium Contains: Muscle fibers Z line M line H band Titin Z line Contains: Thick filaments Thin filaments Muscle Fiber Endomysium Surrounded by: Endomysium Contains: Myofibrils

26 Figure 10-6 Levels of Functional Organization in a Skeletal Muscle Skeletal Muscle Epimysium Surrounded by: Epimysium Contains: Muscle fascicles

27 Figure 10-6 Levels of Functional Organization in a Skeletal Muscle Muscle Fascicle Perimysium Surrounded by: Perimysium Contains: Muscle fibers

28 Figure 10-6 Levels of Functional Organization in a Skeletal Muscle Muscle Fiber Endomysium Surrounded by: Endomysium Contains: Myofibrils

29 Figure 10-6 Levels of Functional Organization in a Skeletal Muscle Myofibril Surrounded by: Sarcoplasmic reticulum Consists of: Sarcomeres (Z line to Z line)

30 Figure 10-6 Levels of Functional Organization in a Skeletal Muscle Sarcomere I band A band Contains: Thick filaments Thin filaments Z line M line Titin Z line H band

31 10-3 Structural Components of a Sarcomere Thin Filaments F-actin (filamentous actin) Is two twisted rows of globular G-actin The active sites on G-actin strands bind to myosin

32 10-3 Structural Components of a Sarcomere Thin Filaments Tropomyosin Is a double strand Prevents actin myosin interaction Troponin A globular protein Binds tropomyosin to G-actin Controlled by Ca 2+

Figure 10-7ab Thick and Thin Filaments Sarcomere H band Actinin Z line Titin Myofibril Z line M line The gross structure of a thin filament, showing the attachment at the Z line

33 Figure 10-7ab Thick and Thin Filaments Sarcomere H band Actinin Z line Titin Myofibril Z line M line The gross structure of a thin filament, showing the attachment at the Z line Troponin Active site Nebulin Tropomyosin G-actin molecules The organization of G-actin subunits in an F-actin strand, and the position of the troponin tropomyosin complex F-actin strand

34 Figure 10-7b Thick and Thin Filaments Troponin Active site Nebulin Tropomyosin G-actin molecules The organization of G-actin subunits in an F-actin strand, and the position of the troponin tropomyosin complex F-actin strand

35 10-3 Structural Components of a Sarcomere Initiating Contraction Ca 2+ binds to receptor on troponin molecule Troponin tropomyosin complex changes Exposes active site of F-actin

36 10-3 Structural Components of a Sarcomere Thick Filaments Contain about 300 twisted myosin subunits The mysosin molecule Tail Binds to other myosin molecules Head Made of two globular protein subunits Reaches the nearest thin filament

37 Figure 10-7cd Thick and Thin Filaments Titin The structure of thick filaments, showing the orientation of the myosin molecules M line Myosin tail Hinge The structure of a myosin molecule Myosin head

38 10-3 Structural Components of a Sarcomere Myosin Action During contraction, myosin heads: Interact with actin filaments, forming crossbridges Pivot, producing motion

39 10-3 Structural Components of a Sarcomere Sliding Filaments and Muscle Contraction Sliding filament theory Thin filaments of sarcomere slide toward M line, alongside thick filaments The width of A zone stays the same Z lines move closer together

40 Figure 10-8a Changes in the Appearance of a Sarcomere during the Contraction of a Skeletal Muscle Fiber I band A band Z line H band Z line A relaxed sarcomere showing location of the A band, Z lines, and I band.

Figure 10-8b Changes in the Appearance of a Sarcomere during the Contraction of a Skeletal Muscle Fiber I band A band Z line H band Z line During a contraction, the A band stays the same width, but

41 Figure 10-8b Changes in the Appearance of a Sarcomere during the Contraction of a Skeletal Muscle Fiber I band A band Z line H band Z line During a contraction, the A band stays the same width, but the Z lines move closer together and the I band gets smaller. When the ends of a myofibril are free to move, the sarcomeres shorten simultaneously and the ends of the myofibril are pulled toward its center.

42 10-3 Structural Components of a Sarcomere Skeletal Muscle Contraction The process of contraction Neural stimulation of sarcolemma Causes excitation contraction coupling Muscle fiber contraction Interaction of thick and thin filaments Tension production

43 Figure 10-9 An Overview of Skeletal Muscle Contraction Neural control Excitation contraction coupling Excitation Calcium release triggers ATP Thick-thin filament interaction Muscle fiber contraction leads to Tension production

44 Figure 10-9 An Overview of Skeletal Muscle Contraction Neural control

45 Figure 10-9 An Overview of Skeletal Muscle Contraction Excitation Calcium release triggers ATP Thick-thin filament interaction

46 Figure 10-9 An Overview of Skeletal Muscle Contraction Muscle fiber contraction leads to Tension production

47 10-4 Components of the Neuromuscular Junction The Control of Skeletal Muscle Activity The neuromuscular junction (NMJ) Special intercellular connection between the nervous system and skeletal muscle fiber Controls calcium ion release into the sarcoplasm

Figure 10-11 Skeletal Muscle Innervation Motor neuron Path of electrical impulse (action potential) Axon

48 Figure Skeletal Muscle Innervation Motor neuron Path of electrical impulse (action potential) Axon Neuromuscular junction SEE BELOW Synaptic terminal Sarcoplasmic reticulum Motor end plate Myofibril Motor end plate

Figure 10-11 Skeletal Muscle Innervation The cytoplasm of the synaptic terminal contains vesicles filled with molecules of acetylcholine, or ACh.

49 Figure Skeletal Muscle Innervation The cytoplasm of the synaptic terminal contains vesicles filled with molecules of acetylcholine, or ACh. Acetylcholine is a neurotransmitter, a chemical released by a neuron to change the permeability or other properties of another cell s plasma membrane. The synaptic cleft and the motor end plate contain molecules of the enzyme acetylcholinesterase (AChE), which breaks down ACh. Vesicles ACh The synaptic cleft, a narrow space, separates the synaptic terminal of the neuron from the opposing motor end plate. Junctional AChE fold of motor end plate

50 Figure Skeletal Muscle Innervation The stimulus for ACh release is the arrival of an electrical impulse, or action potential, at the synaptic terminal. An action potential is a sudden change in the transmembrane potential that travels along the length of the axon. Arriving action potential

Figure 10-11 Skeletal Muscle Innervation When the action potential reaches the neuron s synaptic terminal, permeability changes in the

51 Figure Skeletal Muscle Innervation When the action potential reaches the neuron s synaptic terminal, permeability changes in the membrane trigger the exocytosis of ACh into the synaptic cleft. Exocytosis occurs as vesicles fuse with the neuron s plasma membrane. Motor end plate

52 Figure Skeletal Muscle Innervation ACh molecules diffuse across the synatpic cleft and bind to ACh receptors on the surface of the motor end plate. ACh binding alters the membrane s permeability to sodium ions. Because the extracellular fluid contains a high concentration of sodium ions, and sodium ion concentration inside the cell is very low, sodium ions rush into the sarcoplasm. ACh receptor site

53 Figure Skeletal Muscle Innervation The sudden inrush of sodium ions results in the generation of an action potential in the sarcolemma. AChE quickly breaks down the ACh on the motor end plate and in the synaptic cleft, thus inactivating the ACh receptor sites. Action potential AChE

Figure 10-10 The Exposure of Active Sites SARCOPLASMIC RETICULUM Calcium channels open Myosin tail (thick filament) Tropomyosin strand G-actin (thin filament) Active site Troponin Nebulin In a

54 Figure The Exposure of Active Sites SARCOPLASMIC RETICULUM Calcium channels open Myosin tail (thick filament) Tropomyosin strand G-actin (thin filament) Active site Troponin Nebulin In a resting sarcomere, the tropomyosin strands cover the active sites on the thin filaments, preventing cross-bridge formation. When calcium ions enter the sarcomere, they bind to troponin, which rotates and swings the tropomyosin away from the active sites. Cross-bridge formation then occurs, and the contraction cycle begins.

55 Figure The Contraction Cycle Contraction Cycle Begins The contraction cycle, which involves a series of interrelated steps, begins with the arrival of calcium ions within the zone of overlap. Myosin head Troponin Tropomyosin Actin

56 Figure The Contraction Cycle Active-Site Exposure Calcium ions bind to troponin, weakening the bond between actin and the troponin tropomyosin complex. The troponin molecule then changes position, rolling the tropomyosin molecule away from the active sites on actin and allowing interaction with the energized myosin heads. Sarcoplasm Active site

57 Figure The Contraction Cycle Cross-Bridge Formation Once the active sites are exposed, the energized myosin heads bind to them, forming cross-bridges.

Figure 10-12 The Contraction Cycle Myosin Head Pivoting After cross-bridge formation, the energy that was stored in the resting state is released

58 Figure The Contraction Cycle Myosin Head Pivoting After cross-bridge formation, the energy that was stored in the resting state is released as the myosin head pivots toward the M line. This action is called the power stroke; when it occurs, the bound ADP and phosphate group are released.

59 Figure The Contraction Cycle Cross-Bridge Detachment When another ATP binds to the myosin head, the link between the myosin head and the active site on the actin molecule is broken. The active site is now exposed and able to form another cross-bridge.

60 Figure The Contraction Cycle Myosin Reactivation Myosin reactivation occurs when the free myosin head splits ATP into ADP and P. The energy released is used to recock the myosin head.

Figure 10-12 The Contraction Cycle Resting

61 Figure The Contraction Cycle Resting Sarcomere Zone of overlap (shown in sequence above)

62 Figure The Contraction Cycle Contracted Sarcomere

63 10-4 Skeletal Muscle Contraction Fiber Shortening As sarcomeres shorten, muscle pulls together, producing tension

64 10-4 Skeletal Muscle Relaxation Relaxation Contraction Duration Depends on: Duration of neural stimulus Number of free calcium ions in sarcoplasm Availability of ATP

65 10-4 Skeletal Muscle Relaxation Relaxation Ca 2+ concentrations fall Ca 2+ detaches from troponin Active sites are re-covered by tropomyosin

66 10-4 Skeletal Muscle Contraction and Relaxation Summary Skeletal muscle fibers shorten as thin filaments slide between thick filaments Free Ca 2+ in the sarcoplasm triggers contraction SR releases Ca 2+ when a motor neuron stimulates the muscle fiber Contraction is an active process Relaxation and return to resting length are passive

Table 10-1 Steps Involved in Skeletal Muscle Contraction and Relaxation Steps in Initiating Muscle Contraction Steps in Muscle Relaxation Synaptic terminal Motor end plate T tubule Sarcolemma ACh

67 Table 10-1 Steps Involved in Skeletal Muscle Contraction and Relaxation Steps in Initiating Muscle Contraction Steps in Muscle Relaxation Synaptic terminal Motor end plate T tubule Sarcolemma ACh released, binding to receptors Sarcoplasmic reticulum releases Ca 2 Active site exposure, cross-bridge formation Ca 2 Actin Myosin Action potential reaches T tubule ACh broken down by AChE Sarcoplasmic reticulum recaptures Ca 2 Active sites covered, no cross-bridge interaction Contraction begins Contraction ends Relaxation occurs, passive return to resting length

68 10-6 Energy to Power Contractions ATP Provides Energy For Muscle Contraction Sustained muscle contraction uses a lot of ATP energy Muscles store enough energy to start contraction Muscle fibers must manufacture more ATP as needed

69 10-6 Energy to Power Contractions ATP and CP Reserves Adenosine triphosphate (ATP) The active energy molecule Creatine phosphate (CP) The storage molecule for excess ATP energy in resting muscle Energy recharges ADP to ATP Using the enzyme creatine kinase (CK) When CP is used up, other mechanisms generate ATP

70 10-6 Energy to Power Contractions ATP Generation Cells produce ATP in two ways 1. Aerobic metabolism of fatty acids in the mitochondria 2. Anaerobic glycolysis in the cytoplasm

71 10-6 Energy to Power Contractions Aerobic Metabolism Is the primary energy source of resting muscles Breaks down fatty acids Produces 34 ATP molecules per glucose molecule Glycolysis Is the primary energy source for peak muscular activity Produces two ATP molecules per molecule of glucose Breaks down glucose from glycogen stored in skeletal muscles

72 10-6 Energy to Power Contractions Energy Use and the Level of Muscular Activity Skeletal muscles at rest metabolize fatty acids and store glycogen During light activity, muscles generate ATP through anaerobic breakdown of carbohydrates, lipids, or amino acids At peak activity, energy is provided by anaerobic reactions that generate lactic acid as a byproduct

Figure 10-20 Muscle Metabolism Fatty acids Fatty acids Blood vessels Glucose Glycogen Glucose Glycogen Pyruvate Mitochondria Creatine Resting muscle: Fatty acids are catabolized; the ATP produced is

73 Figure Muscle Metabolism Fatty acids Fatty acids Blood vessels Glucose Glycogen Glucose Glycogen Pyruvate Mitochondria Creatine Resting muscle: Fatty acids are catabolized; the ATP produced is used to build energy reserves of ATP, CP, and glycogen. To myofibrils to support muscle contraction Moderate activity: Glucose and fatty acids are catabolized; the ATP produced is used to power contraction. Lactate Glucose Glycogen Pyruvate Creatine Lactate To myofibrils to support muscle contraction Peak activity: Most ATP is produced through glycolysis, with lactate as a by-product. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed.

74 Figure 10-20a Muscle Metabolism Fatty acids Blood vessels Glucose Glycogen Mitochondria Creatine Resting muscle: Fatty acids are catabolized; the ATP produced is used to build energy reserves of ATP, CP, and glycogen.

75 Figure 10-20b Muscle Metabolism Fatty acids Glucose Glycogen Pyruvate Moderate activity: Glucose and fatty acids are catabolized; the ATP produced is used to power contraction. To myofibrils to support muscle contraction

Figure 10-20c Muscle Metabolism Lactate Glucose Glycogen Pyruvate Creatine Lactate To myofibrils to support muscle contraction Peak activity: Most ATP

76 Figure 10-20c Muscle Metabolism Lactate Glucose Glycogen Pyruvate Creatine Lactate To myofibrils to support muscle contraction Peak activity: Most ATP is produced through glycolysis, with lactate as a by-product. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed.

77 10-6 Energy to Power Contractions Muscle Fatigue When muscles can no longer perform a required activity, they are fatigued Results of Muscle Fatigue Depletion of metabolic reserves Damage to sarcolemma and sarcoplasmic reticulum Low ph (lactic acid) Muscle exhaustion and pain

78 10-6 Energy to Power Contractions The Recovery Period The time required after exertion for muscles to return to normal Oxygen becomes available Mitochondrial activity resumes

79 10-6 Energy to Power Contractions Lactic Acid Removal and Recycling The removal and recycling of lactic acid by the liver Liver converts lactate to pyruvate Glucose is released to recharge muscle glycogen reserves

80 10-6 Energy to Power Contractions Heat Production and Loss Active muscles produce heat Up to 70% of muscle energy can be lost as heat, raising body temperature

81 10-7 Types of Muscles Fibers and Endurance Three Major Types of Skeletal Muscle Fibers 1. Fast fibers 2. Slow fibers 3. Intermediate fibers

82 10-7 Types of Muscles Fibers and Endurance Fast Fibers Contract very quickly Have large diameter, large glycogen reserves, few mitochondria Have strong contractions, fatigue quickly

83 10-7 Types of Muscles Fibers and Endurance Slow Fibers Are slow to contract, slow to fatigue Have small diameter, more mitochondria Have high oxygen supply Contain myoglobin (red pigment, binds oxygen)

84 10-7 Types of Muscles Fibers and Endurance Intermediate Fibers Are mid-sized Have low myoglobin Have more capillaries than fast fibers, slower to fatigue

Figure 10-21 Fast versus Slow Fibers Slow fibers Smaller diameter, darker color due to

85 Figure Fast versus Slow Fibers Slow fibers Smaller diameter, darker color due to myoglobin; fatigue resistant LM 170 Fast fibers Larger diameter, paler color; easily fatigued LM 170 LM 783

86 10-7 Types of Muscles Fibers and Endurance Muscle Performance and the Distribution of Muscle Fibers White muscles Mostly fast fibers Pale (e.g., chicken breast) Red muscles Mostly slow fibers Dark (e.g., chicken legs) Most human muscles Mixed fibers Pink

87 10-7 Types of Muscles Fibers and Endurance Muscle Hypertrophy Muscle growth from heavy training Increases diameter of muscle fibers Increases number of myofibrils Increases mitochondria, glycogen reserves Muscle Atrophy Lack of muscle activity Reduces muscle size, tone, and power

88 10-7 Types of Muscles Fibers and Endurance Physical Conditioning Improves both power and endurance Anaerobic activities (e.g., 50-meter dash, weightlifting) Use fast fibers Fatigue quickly with strenuous activity Improved by: Frequent, brief, intensive workouts Causes hypertrophy

89 10-7 Types of Muscles Fibers and Endurance Physical Conditioning Improves both power and endurance Aerobic activities (prolonged activity) Supported by mitochondria Require oxygen and nutrients Improves: Endurance by training fast fibers to be more like intermediate fibers Cardiovascular performance

90 10-7 Types of Muscles Fibers and Endurance Importance of Exercise What you don t use, you lose Muscles become flaccid when inactive for days or weeks Muscle fibers break down proteins, become smaller and weaker With prolonged inactivity, fibrous tissue may replace muscle fibers

Muscle Tissue- 3 Types

AN INTRODUCTION TO MUSCLE TISSUE Muscle Tissue- 3 Types Skeletal muscle (focus on these) Cardiac muscle Smooth muscle FUNCTIONS OF SKELETAL MUSCLES Produce movement of the skeleton Maintain posture and