Chapter 7 The Muscular System

1 Chapter 7 The Muscular SystemBledsoe et al., Anatomy & ...

Author: Ethel Scott

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2 Topics Functions of the Skeletal System The Anatomy of Skeletal MuscleThe Control of Muscle Fiber Contraction Muscle Mechanics The Energetics of Muscular Activity Muscle Performance Cardiac and Smooth Muscle Tissue Anatomy of the Muscular System Aging and the Muscular System Integration with Other Systems Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

4 Functions of the Skeletal SystemSkeletal muscles are organs Composed primarily of skeletal muscle tissue Also contain connective tissues, nerves, and blood vessels Directly or indirectly attached to bones Includes approximately 700 muscles Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

5 Functions of the Skeletal SystemSkeletal muscle functions Produces movement of the skeleton Maintains posture and body position Supports soft tissues Guards entrances and exits Maintains body temperature Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

6 Functions of the Skeletal SystemProduces movement of the skeleton Contractions pull on tendons Moves bones Produces simple and highly coordinated movements Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

7 Functions of the Skeletal SystemMaintains posture and body position Continuous contractions maintain posture Required to sit up or stand Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

8 Functions of the Skeletal SystemSupports soft tissues Layers of muscle tissue in abdominal wall and pelvic cavity Supports the weight of visceral organs Shields internal tissues from injury Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

9 Functions of the Skeletal SystemGuards entrances and exits Encircles openings to the digestive and urinary tracts Provides voluntary control over swallowing, defecation, and urination Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

10 Functions of the Skeletal SystemMaintains body temperature Contractions require energy Some energy is converted to heat Heat released keeps body temperature in normal ranges Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

12 The Anatomy of Skeletal MuscleGross anatomy Contains connective tissue, blood vessels, nerves, and skeletal muscle tissue Each skeletal muscle cell is a single muscle fiber Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

13 The Anatomy of Skeletal MuscleConnective tissue organization 3 layers Epimysium Perimysium Endomysium Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

14 The Anatomy of Skeletal MuscleConnective tissue organization Epimysium Surrounds the entire muscle Layer of collagen fibers Separates the muscle from surrounding tissues and organs Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

15 The Anatomy of Skeletal MuscleConnective tissue organization Perimysium Divides the skeletal muscle into bundles of fibers Bundles referred to as fascicles Consists of collagen and muscle fibers Contains blood vessels and nerves that supply the fascicle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

16 The Anatomy of Skeletal MuscleConnective tissue organization Endomysium Surrounds each muscle fiber within the fascicle Connects adjacent muscle fibers together Stem cells scattered among fibers Repair damaged muscle tissue Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

17 The Anatomy of Skeletal MuscleConnective tissue organization Collagen fibers come together at both ends of the muscle tissue May form either: A bundle referred to as a tendon Broad sheet referred to as an aponeurosis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

18 The Anatomy of Skeletal MuscleConnective tissue organization Tendons Bands of collagen fibers Attach skeletal muscles to bones Fibers interwoven into the periosteum of the bone Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

19 The Anatomy of Skeletal MuscleConnective tissue organization Aponeuroses Bands of collagen fibers Attach different skeletal muscles to each other Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

20 The Anatomy of Skeletal MuscleBlood vessels Pathways provided by epimysium and perimysium Muscle contractions require tremendous energy and create waste Deliver oxygen and nutrients Remove waste Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

21 The Anatomy of Skeletal MuscleNerves Require stimulation from the central nervous system for contraction Axons penetrate epimysium Branch through the perimysium Enter the endomysium to control individual fibers Controlled on both a conscious and subconscious level Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

22 The Anatomy of Skeletal MuscleMicroanatomy Skeletal muscles very large Multinucleate Hundreds of nuclei just beneath the cell membrane 100 μm in diameter and the entire length of the muscle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

23 The Anatomy of Skeletal MuscleThe sarcolemma and transverse tubules Sarcolemma Cell membrane that surrounds the cytoplasm Cytoplasm referred to as sarcoplasm Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

24 The Anatomy of Skeletal MuscleThe sarcolemma and transverse tubules Openings in the sarcolemma lead to narrow tubules Referred to as transverse tubules or T tubules Filled with extracellular fluid Form passageways through the muscle fiber Play a major role in coordinating muscle contractions Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

25 The Anatomy of Skeletal MuscleThe sarcolemma and transverse tubules Muscle fiber contraction Orderly interaction of electrical and chemical events Electrical impulses Conducted by sarcolemma Trigger contraction Alter chemical environment inside the muscle fiber Impulse travels along the transverse tubules Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

26 The Anatomy of Skeletal MuscleMyofibrils Cylindrical structures Encircled by branches of T tubules 1–2 μm in diameter, length of the entire muscle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

27 The Anatomy of Skeletal MuscleMyofibrils Hundreds of thousands in each muscle fiber Bundles of thick and thin myofilaments Protein filaments consisting of: Actin in thin filaments Myosin in thick filaments Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

28 The Anatomy of Skeletal MuscleMyofibrils Responsible for muscle fiber contraction Attached to the sarcolemma at each end of the cell Contraction shortens the entire cell Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

29 The Anatomy of Skeletal MuscleMyofibrils Surrounded by mitochondria and glycogen Breakdown of glucose and mitochondrial activity provide ATP ATP needed to power muscular contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

30 The Anatomy of Skeletal MuscleThe sarcoplasmic reticulum Specialized form of smooth ER Bind with T tubules where they encircle a myofibril Forms a tubular network around each myofibril Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

31 The Anatomy of Skeletal MuscleThe sarcoplasmic reticulum Expanded chambers lie on either side of a T tubule Referred to as terminal cisternae Transverse tubule lies sandwiched between terminal cisternae Forms a triad Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

32 The Anatomy of Skeletal MuscleThe sarcoplasmic reticulum Terminal cisternae Contains high concentrations of calcium ions Cytoplasm concentrations are very low Initiates muscle contraction when calcium released into sarcoplasm Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

33 The Anatomy of Skeletal MuscleSarcomeres Repeating functional units of myofilaments Smallest functional unit of the muscle fiber Approximately 10,000 end to end in each myofibril Interactions thin and thick filaments result in muscle contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

34 The Anatomy of Skeletal MuscleSarcomeres Arrangement of thick and thin filaments create a banded appearance Myofibrils arranged parallel to the long axis of the muscle Sarcomeres arranged side by side Entire muscle has striated appearance Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

35 The Anatomy of Skeletal MuscleSarcomeres Resting length of 2 μm Thick filaments lie in the center of the sarcomere Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

36 The Anatomy of Skeletal MuscleSarcomeres Thin filaments found at either end Attached to interconnecting proteins Make up Z line Boundaries of each sarcomere Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

37 The Anatomy of Skeletal MuscleSarcomeres Thin filaments Extend from each Z line Pass among the thick filaments Form the zone of overlap Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

38 The Anatomy of Skeletal MuscleSarcomeres M line Made of proteins Connect the central portion of the thick filament to its neighbors Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

39 The Anatomy of Skeletal MuscleSarcomeres Banded appearance Created by size and density variations Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

40 The Anatomy of Skeletal MuscleSarcomeres A band Dark Contains the thick filaments Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

41 The Anatomy of Skeletal MuscleSarcomeres I band Light region between 2 A bands Includes the Z line Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

42 The Anatomy of Skeletal MuscleThin filaments Consist of a twisted strand of actin molecules Active site Capable of interacting with myosin Covered by strands of tropomyosin Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

43 The Anatomy of Skeletal MuscleThin filaments Tropomyosin Protein Held in position by molecules of troponin Bound to actin strand Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

44 The Anatomy of Skeletal MuscleThick filaments Composed of myosin molecules Have a tail and a globular head Oriented away from the center of a sarcomere Heads project outward Connect to actin molecules during contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

45 The Anatomy of Skeletal MuscleThin and thick filaments Interaction Can only occur when troponin changes position Moves the tropomyosin Exposes the active sites Calcium helps unlock the active site Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

46 The Anatomy of Skeletal MuscleThin and thick filaments Interaction Calcium binds to troponin Protein changes shape Tropomyosin moves away from the active site Myosin and actin bind, initiating contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

47 The Anatomy of Skeletal MuscleSliding filaments and cross-bridges Sarcomere contraction I bands get smaller Z lines move closer together Zones of overlap get larger Width of A bands remains the same Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

48 The Anatomy of Skeletal MuscleSliding filaments and cross-bridges Thin filaments slide toward sarcomere Thick filaments remain stationary Called sliding filament theory Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

49 The Anatomy of Skeletal MuscleSliding filaments and cross-bridges Contraction Myosin heads of thick filaments bind with active sites on thin filaments When connected, myosin heads referred to as cross-bridges Cross-bridges pivot toward the center of the sarcomere Thin filaments pulled in that direction Cross-bridges detach and return to original position Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

53 The Control of Muscle Fiber ContractionContract only under control of the nervous system Communication link between the nervous system and skeletal muscle fiber Specialized intercellular connection Referred to as a neuromuscular junction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

54 The Control of Muscle Fiber ContractionThe neuromuscular junction Skeletal muscle finer controlled by a nerve cell Referred to as a motor neuron Axon of neuron branches within the perimysium Axon ends at an expanded synaptic terminal Communication occurs midway along the fiber’s length Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

55 The Control of Muscle Fiber ContractionThe neuromuscular junction Synaptic terminal cytoplasm contains: Mitochondria Vesicles Filled with acetylcholine Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

56 The Control of Muscle Fiber ContractionThe neuromuscular junction Acetylcholine or ach Neurotransmitter Chemical released by neuron to communicate with other cells Changes the properties of another cell’s membrane Affects permeability at this location Results in changes to the sarcolemma that trigger contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

57 The Control of Muscle Fiber ContractionThe neuromuscular junction Narrow cleft separates synaptic terminal and sarcolemma Referred to as the synaptic cleft Membrane contains receptors that bind Ach Referred to as the motor end plate Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

58 The Control of Muscle Fiber ContractionThe neuromuscular junction Acetylcholinesterase or AChE Also known as cholinesterase Enzyme Found in both the synaptic cleft and motor end plate Breaks down molecules of Ach Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

59 The Control of Muscle Fiber ContractionThe neuromuscular junction Neurons stimulate the production of an action potential Electrical impulse in the sarcolemma Allows control of skeletal muscle fibers Four-step process Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

60 The Control of Muscle Fiber ContractionThe neuromuscular junction Step 1: Arrival of an action potential at the synaptic terminal Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

61 The Control of Muscle Fiber ContractionThe neuromuscular junction Step 2: The release of acetylcholine Action potential reaches synaptic terminal Vesicles in synaptic cleft release acetylcholine into synaptic cleft Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

62 The Control of Muscle Fiber ContractionThe neuromuscular junction Step 3: The binding of Ach at the motor end plate ACh molecules diffuse across the synaptic cleft Bind to ACh receptors on the sarcolemma Changes the permeability of the membrane to sodium ions Rush of sodium into the sarcoplasm produces action potential in sarcolemma Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

63 The Control of Muscle Fiber ContractionThe neuromuscular junction Step 4: Appearance of an action potential at the sarcolemma Action potential spreads over the entire surface of the sarcolemma Travels down all the transverse tubules toward terminal cisternae Encircle the sarcomeres of the muscle fiber Action potential triggers sudden, massive release of calcium ions by terminal cisternae Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

64 The Control of Muscle Fiber ContractionThe neuromuscular junction Calcium ion concentration increases Active sites exposed Cross-bridge interactions occur Contraction begins Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

65 The Control of Muscle Fiber ContractionThe neuromuscular junction All terminal cisternae of muscle fiber are affected Contraction is combined effort of every sarcomere on every myofibril AChE begins to break down ACh Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

66 The Control of Muscle Fiber ContractionThe contraction cycle Resting sarcomere Each cross-bridge binds to ADP and phosphate group Products released by breakdown of ATP molecule The energy released is stored in cross-bridge Cross-bridge is “primed” for contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

67 The Control of Muscle Fiber ContractionThe contraction cycle 5 interlocking steps Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

68 The Control of Muscle Fiber ContractionThe contraction cycle: step 1 Active site exposed as calcium ions bind to troponin Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

69 The Control of Muscle Fiber ContractionThe contraction cycle: step 2 Myosin cross-bridge forms Attaches to exposed active sites Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

70 The Control of Muscle Fiber ContractionThe contraction cycle: step 3 Attached myosin head pivots toward the center of the sarcomere ADP and phosphate group are released Step uses the energy stored in the resting myosin molecule Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

71 The Control of Muscle Fiber ContractionThe contraction cycle: step 4 Cross-bridges detach Myosin head binds another ATP molecule Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

72 The Control of Muscle Fiber ContractionThe contraction cycle: step 5 ATP split by detached myosin head Myosin head captures the released energy Cycle is now ready to be repeated from step 2 Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

73 The Control of Muscle Fiber ContractionThe contraction cycle Cycle is broken when calcium ion concentration returns to resting level Occurs primarily through active transport into the SR Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

74 The Control of Muscle Fiber ContractionThe contraction cycle Calcium ion removal occurs rapidly with a single action potential Contraction is very brief Sustained contraction occurs when action potential occurs one after another Calcium loss from cisternae continues Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

76 Muscle Mechanics Coordinated contractions of entire population of muscle fibers Individual muscle cells surrounded and tied together by connective tissues Muscle cells contract Pull on collagen fibers Produce an active force called tension Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

77 Muscle Mechanics TensionWhen applied, pulls an object toward the source Must overcome the object’s resistance to move it Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

78 Muscle Mechanics Resistance Passive force that opposes movementDepends on object’s weight, shape, friction, and other factors Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

79 Muscle Mechanics Tension produced by an individual muscle fiberDepends solely on the number of pivoting cross-bridges it contains No mechanism to regulate the amount of tension produced Muscle fiber is either contracting or relaxing Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

80 Muscle Mechanics Tension can vary depending on:Fiber’s resting length at the time of stimulation Determines the degree of overlap between thick and thin filaments Frequency of stimulation Determines the internal concentration of calcium ions Amount of calcium bound to troponin Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

81 Muscle Mechanics Entire skeletal muscle contractionAmount of tension produced as a whole determined by: Frequency of neural stimulation Number of muscle fibers activated Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

82 Muscle Mechanics The frequency of muscle fiber stimulation TwitchSingle stimulus-contraction-relaxation sequence Duration as brief as 7.5 msec in eye muscle fibers Duration of 100 msec in soleus Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

83 Muscle Mechanics The frequency of muscle fiber stimulation MyogramGraph of tension development during a twitch Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

84 Muscle Mechanics The frequency of muscle fiber stimulationLatent period Begins at stimulation Lasts about 2 msec Action potential sweeps across sarcolemma Calcium ions released by SR No tension produced Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

85 Muscle Mechanics The frequency of muscle fiber stimulationContraction phase Tension rises to a peak Cross-bridges interacting with active sites Maximum tension reached after approximately 15 msec Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

86 Muscle Mechanics The frequency of muscle fiber stimulationRelaxation phase Muscle tension falls to resting levels Calcium levels drop Active sites are covered Number of cross-bridges declines Lasts about 25 msec Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

87 Muscle Mechanics The frequency of muscle fiber stimulationSingle stimulation produces single twitch Twitches do not accomplish anything Normal activities involve sustained contractions Result from repeated stimulations Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

88 Muscle Mechanics Summation and incomplete tetanus SummationOccurs when a stimulus arrives before relaxation phase ends Creates a second, more powerful contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

89 Muscle Mechanics Summation and incomplete tetanusTension rises and peaks Muscle stimulated repeatedly Never allowed to relax completely Muscle in this state is said to be in incomplete tetanus Produces almost peak tension Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

90 Muscle Mechanics Complete tetanusOccurs when stimulation rate increased Relaxation phase completely eliminated Produces maximum tension Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

91 Muscle Mechanics Complete tetanusSR does not have time to reclaim calcium ions High calcium concentration in cytoplasm Prolongs contraction until continuous Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

92 Muscle Mechanics The number of muscle fibers involvedTension exerted by skeletal muscles controlled during normal movement Allows smooth contraction Accomplished by controlling the number of stimulated muscle fibers Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

93 Muscle Mechanics The number of muscle fibers involvedSkeletal muscle contains thousands of muscle fibers Some motor neurons control a single fiber Most control hundreds or thousands Accomplished through multiple synaptic terminals All fibers controlled by a single motor neuron constitute a motor unit Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

94 Muscle Mechanics The number of muscle fibers involvedMotor unit size indicates how fine the control of the movement Muscle fibers of each motor unit intermingled with other motor unit fibers Intermingling ensures that the direction of pull does not change Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

96 Muscle Mechanics The number of muscle fibers involvedContraction begins with activation of the smallest motor unit Gradual increase in the number of motor units activated Referred to as recruitment Results in a smooth, steady increase in muscle tension Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

97 Muscle Mechanics The number of muscle fibers involved Peak tensionResults when all motor units in the muscle are in complete tetanus Contractions do not last long Energy supplies utilized quickly Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

98 Muscle Mechanics The number of muscle fibers activatedSustained contraction Motor units activated on a rotating basis Produce slightly less than maximal tension Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

99 Muscle Mechanics Muscle tone Some motor units are always activeContractions do not produce enough tension to cause movement Tense and firm the muscle Resting tension referred to as muscle tone Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

100 Muscle Mechanics Muscle toneResting muscle tone stabilizes the positions of bones and joints Limp muscles have little muscle tone Firm, solid muscles have moderate muscle tone Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

101 Muscle Mechanics Muscle tone AtrophyOccurs in skeletal muscles that are not stimulated on a regular basis Muscle fibers become smaller and weaker Reversible initially Functional loss is permanent in extreme atrophy Dying muscle fibers are not replaced Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

102 Muscle Mechanics Isotonic and isometric contractionsIsotonic contractions Tension rises and muscle’s length changes Tension remains at a constant level until relaxation Examples: Lifting an object, walking, and running Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

103 Muscle Mechanics Isotonic and isometric contractionsMuscle as a whole does not change length Tension produced never exceeds resistance Examples: Pushing against a closed door Trying to pick up a car Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

104 Muscle Mechanics Isotonic and isometric contractionsCombination required for normal daily activities Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

105 Muscle Mechanics Muscle elongationNo active mechanism for muscle fiber elongation Elongation is passive Occurs through: Elastic forces Movements of opposing muscles Gravity Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

106 Muscle Mechanics Muscle elongation Elastic forcesGenerated when a muscle fiber contracts Tugs on flexible extracellular fibers of endomysium, perimysium, epimysium, and tendons These fibers also somewhat elastic Gradual recoil helps return the muscle fiber to resting length Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

107 Muscle Mechanics Muscle elongation Contraction of opposing musclesResults in more rapid return to resting length Example: Biceps brachii contracts, stretching the triceps brachii Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

108 Muscle Mechanics Muscle elongation Gravity Example:Biceps brachii contracting with elbow pointing toward the floor Muscle relaxes Gravity pulls the forearm down Biceps brachii stretched Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

110 The Energetics of Muscular ActivityMuscle contraction requires large amounts of energy Up to 600 trillion molecules of ATP/sec Does not include energy to return calcium to SR Resting muscles contain only enough energy to sustain contraction until ATP generated ATP generated at roughly the same rate it is consumed Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

111 The Energetics of Muscular ActivityATP and CP reserves ATP transfers energy from one location to another Not utilized for long-term storage of energy Muscles at rest produce more ATP than needed ATP transfers energy to creatine Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

112 The Energetics of Muscular ActivityATP and CP reserves Creatine Small molecule Assembled from amino acid fragments in muscle cells Energy transfer creates creatine phosphate (CP) High energy compound Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

113 The Energetics of Muscular ActivityATP and CP reserves ATP + creatine → ADP + creatine phosphate Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

114 The Energetics of Muscular ActivityATP and CP reserves During a contraction: Cross-bridge breaks down ATP Produces ADP and phosphate group Energy in CP used to “recharge” ADP Creates ATP Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

115 The Energetics of Muscular ActivityATP and CP reserves ADP + creatine phosphate → ATP + creatine Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

116 The Energetics of Muscular ActivityATP and CP reserves Creatine phosphokinase (CPK or CK) Enzyme that regulates the reaction Leaks into bloodstream when muscle cells are damaged Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

117 The Energetics of Muscular ActivityATP and CP reserves Resting skeletal muscle Contains 6 times more creatine phosphate than ATP Reserves exhausted after 15 seconds of sustained contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

118 The Energetics of Muscular ActivityATP generation Aerobic metabolism in mitochondria Anaerobic metabolism through glycolysis in cytoplasm Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

119 The Energetics of Muscular ActivityAerobic metabolism Normally provides 95% of ATP requirement in resting cells Mitochondria absorb oxygen, ADP, phosphate ions, small organic substrates Organic substrates are carbon chains Produced through breakdown of carbohydrates, lipids, or proteins Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

120 The Energetics of Muscular ActivityAerobic metabolism Substrates enter the tricarboxylic acid cycle (TCA) Also referred to as the citric acid cycle or Krebs cycle Substrates are disassembled through a series of chemical reactions Carbon and oxygen atoms are released as CO2 Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

121 The Energetics of Muscular ActivityAerobic metabolism Hydrogen atoms Transported to respiratory enzymes in the inner mitochondrial membrane Electrons are removed Eventually recombine with oxygen to form water Large amount of energy released Used to make ATP Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

122 The Energetics of Muscular ActivityAerobic metabolism Pyruvic acid Common carbohydrate substrate Very efficient One molecule breaks down and produces 17 ATP molecules Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

123 The Energetics of Muscular ActivityAerobic metabolism Resting skeletal muscle fibers Rely on aerobic metabolism of fatty acids to make ATP Fatty acids absorbed from circulation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

124 The Energetics of Muscular ActivityAerobic metabolism Contracting skeletal muscle fibers Mitochondria break down pyruvic acid instead Pyruvic acid provided through glycolysis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

125 The Energetics of Muscular ActivityAerobic metabolism ATP generation Regulated by the availability of oxygen within the mitochondria Difficult to maintain sufficient oxygen levels as demand increases Mitochondria only produce about one-third of ATP required at peak exertion Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

126 The Energetics of Muscular ActivityGlycolysis Breakdown of glucose into pyruvic acid Occurs in the cytoplasm ATP yield lower than with aerobic metabolism Can proceed in the absence of oxygen Continues to produce ATP when oxygen concentration limits the mitochondria Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

127 The Energetics of Muscular ActivityGlycolysis Glucose obtained from glycogen reserves in sarcoplasm Glycogen is a polysaccharide chain of glucose molecules Large glycogen reserves in skeletal muscles Insoluble granules Broken down by enzymes when ATP levels drop Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

128 The Energetics of Muscular ActivityEnergy use and the level of muscle activity ATP demand in resting muscles is low Oxygen supply sufficient for mitochondria Produce surplus ATP Surplus used to create reserves of CP and glycogen Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

129 The Energetics of Muscular ActivityEnergy use and the level of muscle activity Moderate activity levels Demand for ATP increases Rate of oxygen consumption increases ATP demand met by mitochondria if enough oxygen is available ATP provided though glycolysis is minimal Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

130 The Energetics of Muscular ActivityEnergy use and the level of muscle activity Periods of peak activity Oxygen cannot diffuse through muscle fiber fast enough Mitochondria cannot produce required ATP Only about 1/3 of ATP needed Glycolysis becomes the primary source of ATP Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

131 The Energetics of Muscular ActivityEnergy use and the level of muscle activity Periods of peak activity Drawbacks of anaerobic metabolism Glycolysis produces pyruvic acid faster than it is used Pyruvic acid levels rise in the sarcoplasm Pyruvic acid converted to lactic acid Related three-carbon molecule Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

132 The Energetics of Muscular ActivityEnergy use and the level of muscle activity Lactic acid conversion Organic acid Dissociates into hydrogen ion and lactate ion Hydrogen ions accumulate Lowers the pH and alters the functioning of key enzymes Muscle fibers cannot continue to contract Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

133 The Energetics of Muscular ActivityEnergy use and the level of muscle activity Glycolysis Inefficient method of ATP production During anaerobic metabolism One glucose generates 2 pyruvic acids Converted to lactic acid Cell gains 2 ATP molecules Aerobic metabolism would produce 34 ATP molecules Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

134 The Energetics of Muscular ActivityMuscle fatigue Muscle fiber cannot contract despite continued neural stimulation Caused by: Exhaustion of energy reserves Buildup of lactic acid Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

135 The Energetics of Muscular ActivityMuscle fatigue Aerobic metabolism ATP utilized below the maximum rate of mitochondrial ATP generation Fatigue occurs when glycogen, lipids, or amino acid reserves depleted Affects muscles in endurance athletes after hours of exertion Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

136 The Energetics of Muscular ActivityMuscle fatigue Anaerobic metabolism Muscle produces sudden, intense bursts of activity ATP provided by glycolysis Lactic acid levels lower pH Muscle can no longer function normally Affects muscles in athletes running sprints Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

137 The Energetics of Muscular ActivityThe recovery period Conditions created through contraction are returned to normal Metabolic activity of muscle Removes lactic acid Replaces intracellular energy reserves Body loses the heat that was generated Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

138 The Energetics of Muscular ActivityThe recovery period Lactic acid recycling Pyruvic acid conversion to lactic acid is freely reversible Pyruvic acid then used to help synthesize glucose or generate ATP ATP used to convert creatine to CP and store glucose as glycogen Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

139 The Energetics of Muscular ActivityThe recovery period Oxygen demand remains elevated Additional oxygen required is called oxygen debt Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

140 The Energetics of Muscular ActivityThe recovery period Oxygen debt Liver cells Oxygen used to produce ATP Converts lactic acid to glucose Muscle cells Produce ATP to restore reserves ATP, CP, and glycogen Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

141 The Energetics of Muscular ActivityThe recovery period Heat loss Muscle activity generates heat Warms the entire body Blood flow to skin increases Promotes heat loss to environment Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

143 Muscle Performance Force EnduranceThe maximum amount of tension produced by a muscle Endurance The length of time an individual can perform an activity Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

144 Muscle Performance 2 factors to determine performance capabilitiesTypes of muscle fibers within the muscle Physical conditioning or training Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

145 Muscle Performance Types of skeletal muscle fibers Fast or fast-twitchSlow or slow-twitch Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

146 Muscle Performance Fast fibers Majority of skeletal muscle fibersContract in 0.01 sec or less following stimulation Large in diameter Densely packed myofibrils Large glycogen reserves Relatively few mitochondria Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

147 Muscle Performance Fast fibersTension production directly proportional to the number of myofibrils Produce powerful contractions Use ATP quickly Activity primarily supported by glycolysis Fatigue quickly Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

148 Muscle Performance Slow fibersApproximately half the diameter of fast fibers Take 3 times as long to contract after stimulation Can continue to contract for extended periods Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

149 Muscle Performance Slow fibers Oxygen supplyMore extensive network of capillaries than fast fibers Oxygen supply increased dramatically Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

150 Muscle Performance Slow fibers Oxygen storage Contain myoglobinRed pigment Globular protein structurally related to hemoglobin Oxygen-carrying pigment found in blood Binds oxygen, creating a reserve Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

151 Muscle Performance Slow fibers Oxygen useContain greater quantity of mitochondria than fast fibers Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

152 Muscle Performance The distribution of muscle fibers and muscle performance Muscles dominated by fast fibers Often called white muscles Muscles dominated by slow fibers Often called red muscles Due to extensive blood vessels and myoglobin Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

153 Muscle Performance The distribution of muscle fibers and muscle performance Most human muscle contain a mixture Appear pink No slow fibers in the hands or eye Back and calf muscles dominated by slow fibers Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

154 Muscle Performance The distribution of muscle fibers and muscle performance Distribution is determined genetically Athletic training increases the fatigue resistance of fast fibers Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

155 Muscle Performance Physical conditioningEnables improvements in both power and endurance Depends on how the activity is supported Anaerobic vs. aerobic endurance Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

156 Muscle Performance Physical conditioning Anaerobic enduranceThe length of time muscle contractions can be supported by glycolysis and energy reserves Involves contractions of fast fibers Requires frequent, brief workouts Results in hypertrophy of stimulated muscles Muscle fibers increase in diameter, not quantity Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

157 Muscle Performance Physical conditioning Aerobic enduranceThe length of time muscle contractions can be supported through mitochondrial activities Determined by availability of substrates Training involves low levels of muscular activity Do not require peak tension production Glucose is the preferred energy source Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

159 Cardiac and Smooth Muscle TissueCardiac muscle tissue Cells are relatively small Typically have a single, centrally placed nucleus Found only in the heart Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

161 Cardiac and Smooth Muscle TissueDifferences between cardiac muscle and skeletal muscle Structural differences Cardiac muscle cells are branched Each cell contacts several other cells Contacts called intercalated discs Contain gap junctions for rapid passage of action potentials Result in simultaneous contraction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

162 Cardiac and Smooth Muscle TissueDifferences between cardiac muscle and skeletal muscle Functional differences Cardiac muscle contracts without neural stimulation Referred to as automaticity Contractions determined by specialized cells Referred to as pacemaker cells Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

163 Cardiac and Smooth Muscle TissueDifferences between cardiac muscle and skeletal muscle Functional differences Cardiac muscle contractions last 10 times longer than skeletal muscles Membrane properties of cardiac muscle are different Cannot undergo tetanus Heart could not pump blood while in tetany Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

164 Cardiac and Smooth Muscle TissueDifferences between cardiac muscle and skeletal muscle Functional differences Action potential triggers release of calcium from SR Increases membrane permeability to extracellular calcium Cardiac muscle relies on aerobic metabolism Sarcoplasm contains large quantity of mitochondria Abundant reserves of myoglobin Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

165 Cardiac and Smooth Muscle TissueSimilar in size to cardiac muscle cells Contain a single, centrally located nucleus Spindle-shaped cell Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

166 Cardiac and Smooth Muscle TissueLocations Found within almost every organ Forms sheets, bundles, or sheaths around other tissue Around the blood vessels Regulate blood flow throughout the body Create rings called sphincters Regulate movement in the digestive and urinary tract Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

167 Cardiac and Smooth Muscle TissueDifferences between smooth muscle and other muscle tissues Structural differences Internal organization of the smooth muscle cell Lacks myofibrils, sarcomeres, and striations Thick filaments scattered throughout the sarcoplasm Thin filaments anchored within cytoplasm and to sarcolemma Anchors adjacent cells and transmit forces Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

168 Cardiac and Smooth Muscle TissueDifferences between smooth muscle and other muscle tissues Functional differences Calcium ions trigger contractions through a different mechanism Most enter from the extracellular fluid Contract over a greater range of length Actin and myosin filaments not rigidly organized Allows large changes in volume Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

169 Cardiac and Smooth Muscle TissueDifferences between smooth muscle and other muscle tissues Functional differences Many cells are not innervated by motor neurons Not under voluntary control Cells contract automatically In response to pacesetter cells Cells contract in response to environmental or hormonal stimulation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

171 Anatomy of the Muscular SystemIncludes all skeletal muscles Nearly 700 General appearance provides clues to function Supports soft tissue by forming sheets or slings Guards an entrance or exit by encircling the opening Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

172 Anatomy of the Muscular SystemOrigins, insertion, and actions Begins at the origin Ends at the insertion Contracts to produce a specific action Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

173 Anatomy of the Muscular SystemOrigins, insertion, and actions Origin remains stationary Insertion moves Example: Gastrocnemius in the calf Origin on the distal femur, insertion on the calcaneus Contraction results in plantar flexion Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

174 Anatomy of the Muscular SystemOrigins, insertion, and actions Actions of muscles described in 2 ways In terms of the bone affected Example: Biceps brachii flexes the forearm In terms of the joint involved Used by specialist in human motion (kinesiologists) Example: Biceps brachii performs flexion at the elbow Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

175 Anatomy of the Muscular SystemOrigins, insertion, and actions Can be described by their primary actions Prime mover or agonist Muscle whose contraction is chiefly responsible for a particular movement Example: Biceps brachii is a prime mover that flexes the elbow Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

176 Anatomy of the Muscular SystemOrigins, insertion, and actions Primary actions Antagonist Muscles whose action opposes the movement produced by another muscle May also be a prime mover Example: Triceps brachii is a prime mover that extends the elbow Therefore it is an antagonist of the biceps brachii Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

177 Anatomy of the Muscular SystemOrigins, insertion, and actions Primary actions Synergist Muscle that helps a prime mover work efficiently May provide additional pull near the insertion May stabilize the origin Fixators stabilize the origin by preventing movement in another joint Example: Deltoid muscle lifts the arm away from the body. Supraspinatus muscle assists the deltoid in starting the movement. Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

178 Anatomy of the Muscular SystemNames of skeletal muscles Methods in which muscles may be named Orientation of muscle fibers Structural features Shape Length Size Relationship to the skin surface Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

179 Anatomy of the Muscular SystemNames of skeletal muscles First part of the name refers to origin Second part refers to insertion Example: sternohyoid Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

180 Anatomy of the Muscular SystemNames of skeletal muscles May refer to the primary function of the muscle Example: extensor carpi radialis muscle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

181 Anatomy of the Muscular SystemNames of skeletal muscles Axial musculature Arises on the axial skeleton Positions the head and spinal column Moves the rib cage Does not move pelvic or pectoral girdles or appendages Encompasses roughly 60% of the skeletal muscles Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

182 Anatomy of the Muscular SystemNames of skeletal muscles Appendicular musculature Stabilizes or moves components of the appendicular skeleton Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

183 Anatomy of the Muscular SystemThe axial muscles 4 groups based on location and/or function The muscles of the head and neck The muscles of the spine The muscles of the trunk The muscles of the pelvic floor Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

184 Anatomy of the Muscular SystemMuscles of the face Originate on the surface of the skull Insert into the dermis of the skin Move skin when they contract Example: Frontalis muscle raises the eyebrows and pulls on the scalp Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

185 Anatomy of the Muscular SystemMuscles of the face Largest group associated with the mouth Orbicularis oris constricts the corners of the mouth Buccinator compresses the cheeks Masseter produces chewing motions Assisted by temporalis and pterygoid muscles Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

186 Anatomy of the Muscular SystemMuscles of the face Epicranium or scalp Frontalis and occipitalis Separated by the epicranial aponeurosis Platysma Covers the ventral surface of the neck Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

188 Anatomy of the Muscular SystemMuscles of the neck Control the position of the larynx Depress the mandible Tense the floor of the mouth Provide foundation for muscles of the tongue and pharynx Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

189 Anatomy of the Muscular SystemMuscles of the neck Digastric opens the mouth Mylohyoid supports the tongue Stylohyoid connects the hyoid bone and styloid process Sternocleidomastoid rotates the head and flexes the neck Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

191 Anatomy of the Muscular SystemMuscles of the spine Covered by superficial back muscles Most superior spinal muscles are posterior neck muscles Assist in extending and tilting the head Superficial splenius capitis Deeper semispinalis capitis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

192 Anatomy of the Muscular SystemMuscles of the spine Spinal extensors Also referred to as the erector spinae Act to maintain an erect spinal column and head Subdivided as they move laterally Spinalis Longissimus Iliocostalis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

193 Anatomy of the Muscular SystemMuscles of the spine Lumbar and sacral region Longissimus and iliocostalis muscles Border is indistinct Referred to as the sacrospinalis Extend the spinal column Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

195 Anatomy of the Muscular SystemThe axial muscles of the trunk Oblique and rectus muscles Form the muscular walls of the thoracic and abdominopelvic cavities Located between the first thoracic vertebrae and pelvis Partitioned by the ribs Form broad sheets in the abdomen Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

196 Anatomy of the Muscular SystemThe axial muscles of the trunk Oblique and rectus muscles Oblique muscles compress underlying structures Rotate the spinal column Rectus muscles are flexors of the spinal column Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

197 Anatomy of the Muscular SystemThe axial muscles of the trunk External and internal intercostals Diaphragm External and internal obliques Transverse abdominis Rectus abdominis Muscles that form the floor of the pelvic cavity Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

199 Anatomy of the Muscular SystemMuscles of the pelvic floor Referred to as the perineum Broad sheet of muscles Connect the sacrum and coccyx to the ischium and pubis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

200 Anatomy of the Muscular SystemMuscles of the pelvic floor Support organs of the pelvic cavity Flex the coccyx Control movement of material through the urethra and anus Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

202 Anatomy of the Muscular SystemThe appendicular muscles Muscles of the shoulders and upper limbs Increased mobility and shock absorption Muscles of the pelvic girdle and lower limbs Transfer weight from the axial to appendicular skeleton Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

203 Anatomy of the Muscular SystemMuscles of the shoulders and upper limbs Trapezius muscles Superficial Cover the back and portions of the neck Regions can contract independently Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

204 Anatomy of the Muscular SystemMuscles of the shoulders and upper limbs Rhomboid and levator scapulae muscles Covered by the trapezius Originate on vertebrae Insert on the scapula Rhomboid adducts the scapula Levator scapulae elevates the scapula Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

205 Anatomy of the Muscular SystemMuscles of the shoulders and upper limbs Serratus anterior Originates on the anterior surface of several ribs Inserts on the vertebral border of the scapula Pulls shoulder anteriorly Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

207 Anatomy of the Muscular SystemMuscles of the shoulders and upper limbs Pectoralis minor Attaches to the coracoid process of the scapula Depresses and protracts the scapula Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

208 Anatomy of the Muscular SystemMuscles that move the arm Grouped by primary actions Deltoid is the major abductor Supraspinatus assists at the start of the movement Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

209 Anatomy of the Muscular SystemMuscles that move the arm Rotation of the arm Subscapularis Teres major Infraspinatus Teres minor Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

210 Anatomy of the Muscular SystemMuscles that move the arm Pectoralis major Produces flexion at the shoulder Extends between the chest and greater tubercle of the humerus Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

211 Anatomy of the Muscular SystemMuscles that move the arm Latissimus dorsi Produces extension at the shoulder Extends between thoracic vertebrae and the intertubercular groove of the humerus Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

212 Anatomy of the Muscular SystemMuscles that move the arm Provide substantial support for the shoulder Tendons blend with and support the capsular fibers of the joint Form the rotator cuff Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

213 Anatomy of the Muscular SystemMuscles that move the forearm and wrist Most of the muscles originate on the humerus Exceptions Biceps brachii Long head tendon of triceps brachii Originate on the scapula Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

214 Anatomy of the Muscular SystemMuscles that move the forearm and wrist Biceps brachii Primary action flexes the elbow Secondary effect on the shoulder Supinates the forearm Only works effectively when forearm is supinated Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

215 Anatomy of the Muscular SystemMuscles that move the forearm and wrist Triceps brachii Primary action extends the elbow Secondary effect on the shoulder Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

216 Anatomy of the Muscular SystemMuscles that move the forearm and wrist Brachialis and brachioradialis Flex the elbow Opposed by the triceps brachii Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

217 Anatomy of the Muscular SystemMuscles that move the forearm and wrist Flexor carpi ulnaris, flexor carpi radialis, palmaris longus Superficial muscles Produce flexion of the wrist Flexor carpi radialis also abducts the wrist Flexor carpi ulnaris also adducts the wrist Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

218 Anatomy of the Muscular SystemMuscles that move the forearm and wrist Extensor carpi radialis Produces extension and abduction of the wrist Extensor carpi ulnaris Produces extension and adduction of the wrist Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

219 Anatomy of the Muscular SystemMuscles that move the forearm and wrist Pronators and supinator Rotate the radius at the proximal and distal articulations Do not flex or extend the elbow Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

220 Anatomy of the Muscular SystemMuscles that move the hand and fingers Muscles of the forearm flex and extend the finger joints Muscles end before they reach the hand Relatively large muscles Only the tendons cross the wrist Held in place by tendon sheaths Wide, tubular bursae that reduce friction Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

221 Anatomy of the Muscular SystemMuscles that move the hand and fingers Carpal tunnel syndrome Inflammation of the tendon sheaths Restricts movement Irritates the median nerve Innervates the palm of the hand Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

222 Anatomy of the Muscular SystemMuscles that move the hand and fingers Intrinsic muscles Allow for fine control of the hand Originate on the carpal and metacarpal bones Only tendons extend across the distal joints of the fingers No muscles originate on the phalanges Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

223 Anatomy of the Muscular SystemMuscles of the pelvis and lower limbs Divided into 3 functional groups Muscles that work across the hip to move the thigh Muscles that work across the knee to move the leg Muscles that work across the foot to move the ankles, feet, and toes Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

224 Anatomy of the Muscular SystemMuscles that move the thigh Gluteal muscles Cover the lateral surfaces of the ilia Produce extension, rotation, and abduction of the hip Gluteus maximus Largest and most posterior Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

225 Anatomy of the Muscular SystemMuscles that move the thigh Adductor magnus, adductor brevis, adductor longus, pectineus, and gracilis Adduct the thigh Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

226 Anatomy of the Muscular SystemMuscles that move the thigh Iliopsoas 2 muscles Psoas major Iliacus Hip flexors Share a common insertion at the lesser trochanter of the femur Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

227 Anatomy of the Muscular SystemMuscles that move the leg Distribution similar to the upper limb Extensors found along anterior and lateral surfaces Flexors lie along the posterior and medial surfaces Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

228 Anatomy of the Muscular SystemMuscles that move the leg 4 flexors of the knee Sartorius Include 3 muscles known as the hamstrings Biceps femoris Semimembranosus Semitendinosus Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

229 Anatomy of the Muscular SystemMuscles that move the leg Knee extensors Collectively referred to as the quadriceps femoris 3 vastus muscles and rectus femoris Insert on the patella Attached to the tibial tuberosity by the patellar ligament Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

230 Anatomy of the Muscular SystemMuscles that move the leg Popliteus Medially rotates the tibia into its normal position Unlocks the knee after standing for long periods of time Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

231 Anatomy of the Muscular SystemMuscles that move the foot and toes Most of the muscles produce plantar flexion Involved with walking and running Gastrocnemius in the calf Assisted by the underlying soleus Share the calcaneal or Achilles tendon Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

232 Anatomy of the Muscular SystemMuscles that move the foot and toes Fibularis muscles Deep pair of muscles Also referred to as the peroneus muscles Produce eversion of the foot Produce plantar flexion at the ankle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

233 Anatomy of the Muscular SystemMuscles that move the foot and toes Tibialis muscles Produce inversion of the foot Tibialis anterior Dorsiflexes the ankle Opposes the gastrocnemius Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

234 Anatomy of the Muscular SystemMuscles that move the foot and toes Digital muscles Originate on the surface of the tibia and/or fibula Tendons pass through tendon sheaths at the ankle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

235 Anatomy of the Muscular SystemMuscles that move the foot and toes Intrinsic muscles Originate on the tarsal and metatarsal bones Contractions move the toes Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

238 Aging and the Muscular SystemGeneral reduction in the size and power of all muscle tissue Skeletal muscle fibers become smaller in diameter Skeletal muscles become less elastic Tolerance for exercise decreases Ability to recover from muscular injuries decreases Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

239 Aging and the Muscular SystemSkeletal muscle fibers become smaller in diameter Reflects a decrease in the number of myofibrils Reduces muscle strength and endurance Causes rapid fatigue Blood flow to active muscles decreases Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

240 Aging and the Muscular SystemSkeletal muscles become less elastic Develop increasing amounts of fibrous connective tissue Process called fibrosis Makes the muscles less flexible Collagen fibers restrict movement and circulation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

241 Aging and the Muscular SystemThe tolerance for exercise decreases Tendency for rapid fatigue Reduction in thermoregulatory ability Leads to overheating Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

242 Aging and the Muscular SystemThe ability to recover from muscular injuries decreases Repair capabilities are limited Results in scar tissue formation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

243 Aging and the Muscular SystemRate of decline in muscular performance is the same in all people Regardless of exercise patterns and lifestyle Regular exercise more important than demanding exercise Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

245 Integration with Other SystemsMust be supported by other systems to operate efficiently Active muscles consume oxygen and generate heat and carbon dioxide Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

246 Integration with Other SystemsCardiovascular system Blood vessels in active muscles and skin dilate Heart rate increases Speeds up the delivery of oxygen and removal of carbon dioxide Brings heat to the skin surface for radiation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

247 Integration with Other SystemsRespiratory system Rate and depth of respiration increase Keeps pace with the increased blood flow through the lungs Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

248 Integration with Other SystemsIntegumentary system Blood vessels dilate Sweat glands increase secretions Promotes evaporation to remove excess heat Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

249 Integration with Other SystemsNervous and endocrine systems Direct the responses of other organ systems Control heart rate, respiratory rate, and sweat gland activity Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

250 Summary Review the functions of the skeletal systemReview the anatomy of skeletal muscles Understand how the muscles contract Understand how the muscle obtains the energy necessary for contraction Review the anatomy of cardiac and smooth muscles Understand how muscles are named and how they interact to produce movement Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ

Chapter 7 The Muscular System

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