Muscular System Notes

Muscular system Andy Art Clement M Decretales RMT MD Types of Muscles Skeletal attached to bones striated voluntarily controlled Cardiac located in the heart striated involuntarily controlled Smooth Located in blood vessels, hollow organs Non-striated involuntarily controlled...

Muscular system Andy Art Clement M Decretales RMT MD Types of Muscles Skeletal attached to bones striated voluntarily controlled Cardiac located in the heart striated involuntarily controlled Smooth Located in blood vessels, hollow organs Non-striated involuntarily controlled Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 2 The Muscular System Functions 1. Movement 2. Maintain posture 3. Respiration 4. Production of body heat 5. Communication 6. Constriction of organs and vessels 7. Contraction of the heart Figure 7.1 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 3 Functional Properties of Muscles Contractility - the ability of muscle to shorten forcefully, or contract Excitability - the capacity of muscle to respond to a stimulus Extensibility - the ability to be stretched beyond its normal resting length and still be able to contract Elasticity - the ability of the muscle to recoil to its original resting length after it has been stretched Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 4 Whole Skeletal Muscle Anatomy 1 Skeletal muscle, or striated muscle, with its associated connective tissue, constitutes approximately 40% of body weight. Skeletal muscle is so named because many of the muscles are attached to the skeletal system. Some skeletal muscles attach to the skin or connective tissue sheets. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 5 Whole Skeletal Muscle Anatomy 2 Skeletal muscle is also called striated muscle because transverse bands, or striations, can be seen in the muscle under the microscope. Individual skeletal muscles, such as the biceps brachii, are complete organs, as a result of being comprised of several tissues: muscle, nerve, and connective tissue. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6 Connective Tissue Coverings Each skeletal muscle is surrounded by a connective tissue sheath called the epimysium. A skeletal muscle is subdivided into groups of muscle cells, termed fascicles. Each fascicle is surrounded by a connective tissue covering, termed the perimysium. Each skeletal muscle cell (fiber) is surrounded by a connective tissue covering, termed the endomysium. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7 Skeletal Muscle Fiber Anatomy 1 A muscle fiber is a large cell, with several hundred nuclei located at its periphery. Muscle fibers range in length 1 mm to 30 cm. Alternating light and dark bands give muscle fibers a striated appearance. The number of muscle fibers remains constant after birth so enlargement of muscles results from an increase in the size of muscle fibers, not an increase in fiber number. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 8 Electrical Component Structures 1 The sarcolemma (cell membrane) has many tubelike inward folds, called transverse tubules, or T tubules. T tubules occur at regular intervals along the muscle fiber and extend into the center of the muscle fiber. The T tubules are associated with enlarged portions of the smooth endoplasmic reticulum called the sarcoplasmic reticulum. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 9 Electrical Component Structures 2 The enlarged portions are called terminal cisternae. Two terminal cisternae and their associated T tubule form a muscle triad. The sarcoplasmic reticulum has a relatively high concentration of Ca2+, which plays a major role in muscle contraction. The cytoplasm of a muscle fiber is called the sarcoplasm, which contains many bundles of protein filaments. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 10 Structure of Skeletal Muscle Figure 7.2 Access the text alternative for slide images Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11 Mechanical Component Structures Bundles of protein filaments are called myofibrils. Myofibrils consist of two types of myofilaments, actin (thin filaments) and myosin (thick filaments). Actin and myosin are arranged into repeating units called sarcomeres. The myofilaments in the sarcomere provide for the mechanical aspect of muscle contraction. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 12 The Sarcomere 1 The sarcomere is the basic structural and functional unit of skeletal muscle. Sarcomeres join end to end to create myofibrils. Z disks are network of protein fibers that serve as an anchor for actin myofilaments and separate one sarcomere from the next. A sarcomere extends from one Z disk to the next Z disk. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 13 The Sarcomere 2 The organization of actin and myosin myofilaments gives skeletal muscle its striated appearance and gives it the ability to contract. The myofilaments slide past each other, causing the sarcomeres to shorten. Each sarcomere consists of two light-staining bands separated by a dark-staining band. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 14 The Sarcomere 3 Light bands, consist only of actin, and are called I bands. They extend from the Z disc, toward the center of the sarcomere, to the ends of the myosin myofilaments. Dark staining bands are called A bands. They extend the length of the myosin myofilaments. Actin and myosin myofilaments overlap for some distance on both ends of the A band; this overlap causes the contraction. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 15 Myofilament Structure Actin myofilaments are made up of three components: actin, troponin, and tropomyosin. Troponin molecules have binding sites for Ca2+ and tropomyosin filaments block the myosin myofilament binding sites on the actin myofilaments. Myosin myofilaments, or thick myofilaments, resemble bundles of tiny golf clubs. Myosin heads have ATP binding sites, ATPase and attachment spots for actin. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 16 Skeletal Muscle Fiber (a) SPL/Getty Images Figure 7.3 Access the text alternative for slide images Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 17 Neuromuscular Junction Structure 1 A motor neuron is a nerve cell that stimulates muscle cells. A neuromuscular junction is a synapse where a neuron connects with a muscle fiber. A synapse refers to the cell-to-cell junction between a nerve cell and either another nerve cell or an effector cell, such as in a muscle or a gland. A motor unit is a group of muscle fibers that a single motor neuron stimulates. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18 Neuromuscular Junction Structure 2 A presynaptic terminal is the end of a neuron cell axon fiber. A synaptic cleft is the space between the presynaptic terminal and postsynaptic membrane. The postsynaptic membrane is the muscle fiber membrane (sarcolemma). A synaptic vesicle is a vesicle in the presynaptic terminal that stores and releases neurotransmitter chemicals. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19 Neuromuscular Junction Structure 3 Neurotransmitters are chemicals that stimulate or inhibit postsynaptic cells. Acetylcholine is the neurotransmitter that stimulates skeletal muscles. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20 Neuromuscular Junction (b) Ed Reschke/Photolibrary/Getty Images Figure 7.4 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 21 Sliding Filament Model When a muscle contracts, the actin and myosin myofilaments in the sarcomere slide past one another and shorten the sarcomere. When sarcomeres shorten, myofibrils, muscle fibers, muscle fascicles, and muscles all shorten to produce muscle contraction. During muscle relaxation, sarcomeres lengthen. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 22 Excitability of Muscle Fibers Muscle fibers are electrically excitable. Electrically excitable cells are polarized. The inside of the cell membrane is negatively charged compared with the outside. A voltage difference, or electrical charge difference, exists across each cell membrane. The charge difference is due to differences in concentrations of ions on either side of the membrane. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 23 Ion Channels The phospholipid bilayer is impermeable to ions. Two types of membrane proteins, called ion channels, permit ions to pass through the membrane. Leak channels allow the slow leak of ions down their concentration gradient. Gated channels may open or close in response to various types of stimuli. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 24 Resting Membrane Potential 1 The electrical charge difference across the cell membrane of an unstimulated cell is called the resting membrane potential. Muscle cells (fibers) have a resting membrane potential but can also perform action potentials. The resting membrane potential is due to the inside of the membrane being negatively charged in comparison to the outside of the membrane which is positively charged. Action potentials are due to the membrane having gated channels. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 25 Resting Membrane Potential 2 The resting membrane potential exists because of: The concentration of K+ being higher on the inside of the cell membrane and the concentration of Na+ being higher on the outside The presence of many negatively charged molecules, such as proteins, inside the cell that are too large to exit the cell The presence of leak channels in the membrane that are more permeable to K+ than they are to Na+ Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 26 Resting Membrane Potential 3 Na+ tends to diffuse into the cell and K+ tends to diffuse out. In order to maintain the resting membrane potential, the sodium-potassium pump recreates the Na+ and K+ ion gradient by pumping Na+ out of the cell and K+ into the cell. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 27 Resting Membrane Potential 4 Figure 7.6b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 28 Action Potentials 1 An action potential reverses the resting membrane potential so that the inside of the cell becomes positive and the outside negative. Occurs because gated ion channels open when the cell is stimulated. The diffusion of ions through these channels changes the charge across the cell membrane and produces an action potential. Action potential lasts for 1 to 3 milliseconds. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 29 Action Potential 2 The entry of Na+ causes the inside of the cell membrane to become more positive than when the cell is at resting membrane potential. This increase in positive charge inside the cell membrane is called depolarization. If the depolarization changes the membrane potential to a value called threshold, an action potential is triggered. An action potential is a rapid change in charge across the cell membrane. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 30 Action Potential 3 The action potential travels across the sarcolemma. Near the end of depolarization, the positive charge causes gated Na+ channels to close and gated K+ channels to open. Opening of gated K+ channels starts repolarization of the cell membrane. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 31 Action Potential 4 Repolarization is due to the exit of K+ from the cell. The outward diffusion of K+ returns the cell to its resting membrane conditions and the action potential ends. In a muscle fiber, an action potential results in muscle contraction. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 32 Resting Membrane Potential Figure 7.7(1) Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 33 Depolarization change in charges inside becomes more + and outside more – Na+ channels open Figure 7.7 (2) Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 34 Repolarization Na+ channels close change back to resting potential Figure 7.7 (3) Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 35 Ion Channels and Action Potentials Figure 7.7 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 36 Function of the Neuromuscular Junction 1 Each muscle fiber is innervated by a branch of a motor neuron at a neuromuscular junction. Contact between the axon terminal and the sarcolemma results in an action potential in the muscle fiber which, in turn, stimulates the fiber to contract. The action potential is stimulated by the release of acetylcholine from the motor neuron. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 37 Function of the Neuromuscular Junction 2 Figure 7.8 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 38 Muscle Contraction 1 1. An action potential travels down the motor neuron to the presynaptic terminal. 2. The action potential causes Ca2+ channels to open and Ca2+ to enter the terminal. 3. Ca2+ causes synaptic vesicles to release acetylcholine into synaptic cleft. 4. Acetylcholine opens Na+ channels in the sarcolemma and causes an action potential. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 39 Muscle Contraction 2 5. The action potential travels along the entire sarcolemma 6. The action potential moves down T tubules. 7. Action potentials open gated Ca2+ channels in the sarcoplasmic reticulum which releases stored calcium. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 40 Muscle Contraction 3 8. Ca2+ binds to troponin which is attached to actin causing tropomyosin to move exposing attachment sites for myosin. Myosin heads bind to actin. Muscles contract when cross bridges move. 9. The heads of the myosin myofilaments bend, causing the actin to slide past the myosin. As long as Ca2+ is present, the cycle repeats. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 41 Skeletal Muscle Excitation 1 Figure 7.9 (1,2,3,4) Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 42 Skeletal Muscle Excitation 4 Figure 7.9 (5,6,7) Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 43 Skeletal Muscle Excitation 6 Figure 7.9 (8,9) Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 44 Cross Bridge Movement The mechanical component of muscle contraction is called cross-bridge cycling. The energy from one ATP molecule is required for one cross bridge cycle. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 45 ATP and Muscle Contractions Energy for muscle contractions is supplied by ATP. Energy is released as ATP → ADP + Pi and energy from ATP is stored in myosin heads. A new ATP must bind to myosin before cross-bridge is released. Rigor mortis will occur when a person dies and no ATP is available to release cross-bridges. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 46 ATP Breakdown and Cross-Bridge Movement Figure 7.10 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 47 Muscle Relaxation 1 Muscle relaxation occurs when acetylcholine is no longer released at the neuromuscular junction. Action potentials to the sarcoplasmic reticulum stop. Ca2+ is actively transported back into the sarcoplasmic reticulum using energy supplied by ATP. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 48 Muscle Relaxation 2 Ca2+ diffuses away from the troponin molecules and tropomyosin again blocks the attachment sites on the actin molecules. The cross-bridge cycle stops and the muscle relaxes. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 49 Muscle Twitch 1 A muscle twitch is a single contraction of a muscle fiber in response to a stimulus. A muscle twitch has three phases: latent phase, contraction phase, and relaxation phase. The latent phase is the time between the application of a stimulus and the beginning of contraction. The contraction phase is the time during which the muscle contracts and the relaxation phase is the time during which the muscle relaxes. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 50 Muscle Twitch 2 Figure 7.11 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 51 Types of Contractions There are two types of muscle contractions: isometric and isotonic. The isometric contraction has an increase in muscle tension, but no change in length. The isotonic contraction increases the tension in a muscle and decreases the length. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 52 Summation and Recruitment 1 The strength of muscle contraction strength depends on two factors: The amount of force in an individual muscle fiber, called summation The amount of force in a whole muscle, called recruitment. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 53 Motor Unit A motor unit consists of a single motor neuron and all the muscle fibers it innervates. An action potential in the neuron of a motor unit causes contraction of all the muscle fibers in that unit. Small, delicate muscles have very few fibers per motor unit. Large, powerful, less precise muscles have fewer, larger motor units. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 54 Force of Contraction in Individual Muscle Fibers 1 Individual muscle fibers can generate different amounts of force. The amount of force generated depends upon the number of cross-bridges formed. More cross-bridges creates more force. One factor that influences the number of cross-bridges formed is the frequency of stimulation. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 55 Force of Contraction in Individual Muscle Fibers 2 A low frequency of stimuli allows a muscle fiber to undergo twitches that contract then fully relax. If the frequency of stimuli increases, the muscle fiber is unable to relax completely between twitches, more cross bridges form and summation occurs. The tension generated by the muscle increases. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 56 Summation and Recruitment 2 Incomplete Tetanus occurs when the frequency of stimulation only allows for partial relaxation of the muscle fiber. Tetanus is a sustained contraction that occurs when the frequency of stimulation is so rapid that no relaxation occurs. Recruitment is the stimulation of several motor units. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 57 Multiple-Wave Summation Figure 7.12 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 58 Muscle Tone Muscle tone is the constant tension produced by body muscles over long periods of time. Muscle tone is responsible for keeping the back and legs straight, the head in an upright position, and the abdomen from bulging. Muscle tone depends on a small percentage of all the motor units in a muscle being stimulated at any point in time, causing their muscle fibers to contract tetanically and out of phase with one another. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 59 Types of Isotonic Contractions 2 Concentric contractions are isotonic contractions in which muscle tension increases as the muscle shortens. Eccentric contractions are isotonic contractions in which tension is maintained in a muscle, but the opposing resistance causes the muscle to lengthen. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 60 Skeletal Muscle Fiber Types 1 Slow twitch fibers contract slowly fatigue slowly have a considerable amount of myoglobin use aerobic respiration are dark in color used by long distance runners Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 61 Skeletal Muscle Fiber Types 2 Fast twitch fibers contract quickly fatigue quickly use anaerobic respiration energy from glycogen light color used by sprinters Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 62 Skeletal Muscle Fiber Types 3 Most human muscles have a blend of fast twitch and slow twitch fibers. The amount of each type varies for each muscle. The large postural muscles of the back and lower limbs contain more slow-twitch fibers. The muscles of the upper limbs contain more fast-twitch muscle fibers. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 63 Energy for Muscle Contractions 1 Muscle fibers have three ATP dependent proteins The myosin head The Na+/K+ ATPase to maintain resting membrane potential The Ca2+ pump in the sarcoplasmic reticulum Muscle fibers store enough ATP to contract for about 5–6 seconds. If contraction is to continue beyond this time, more ATP must be produced. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 64 Energy for Muscle Contractions 2 ATP is derived from four processes in skeletal muscle. 1. Conversion of two ADP to one ATP and one adenosine monophosphate (AMP) by the enzyme adenylate kinase 2. Transfer of a phosphate from a molecule called creatine (krē′a-tēn) phosphate by the enzyme creatine kinase from ADP to form ATP Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 65 Energy for Muscle Contractions 3 3. Anaerobic production of ATP during intensive short-term exercise 4. Aerobic production of ATP during most exercise and normal conditions Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 66 ATP Production as Exercise Progresses 1 Muscle fibers store enough ATP for about 5 to 6 seconds of contraction. Next, ATP production by adenylate kinase and creatine kinase occurs. This is depleted after about 15 seconds. When a muscle fiber is working too strenuously for ATP stores and creatine phosphate to be able to provide enough ATP, anaerobic respiration predominates. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 67 ATP Production as Exercise Progresses 2 Fast-twitch muscle fibers are the primary anaerobic muscle fibers. Slow-twitch fibers utilize aerobic pathways. The lactate produced by anaerobic fast-twitch fibers is used as a starting point for aerobic ATP production in slow-twitch fibers. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 68 Muscle Fatigue 1 Fatigue is a temporary state of reduced work capacity. Without fatigue, muscle fibers would be worked to the point of structural damage to them and their supportive tissues. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 69 Muscle Fatigue 2 Mechanisms of fatigue include: Acidosis and ATP depletion due to either an increased ATP consumption or a decreased ATP production Oxidative stress, which is characterized by the buildup of excess reactive oxygen species (ROS; free radicals) Local inflammatory reactions Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 70 Muscle Soreness Following vigorous exercise, people sometimes experience muscle pain, which can last for several days. The pain is related to the effects of inflammatory chemicals on the muscle fibers. Exercise schedules that alternate exercise with periods of rest, such as lifting weights every other day, provide time for the repair of muscle tissue. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 71 Oxygen Deficit There are two distinct phases of O2 use: Oxygen deficit is the lag time between when a person begins to exercise and when they begin to breathe more heavily because of the exercise. Excess postexercise oxygen consumption is the lag time before breathing returns to its preexercise rate once exercise stops. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 72 Smooth Muscle Smooth muscle cells are non-striated small, spindle-shaped muscle cells, usually with one nucleus per cell. The myofilaments are not organized into sarcomeres. The cells comprise organs controlled involuntarily, except the heart. Neurotransmitter substances, hormones, and other factors can stimulate smooth muscle. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 73 Cardiac Muscle 1 Cardiac muscle cells are long, striated, and branching, with usually only one nucleus per cell. Cardiac muscle is striated as a result of the sarcomere arrangement. Cardiac muscle contraction is autorhythmic. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 74 Cardiac Muscle 2 Cardiac muscle cells are connected to one another by specialized structures that include desmosomes and gap junctions called intercalated disks. Cardiac muscle cells function as a single unit in that action potential in one cardiac muscle cell can stimulate action potentials in adjacent cells. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 75 Skeletal Muscle Anatomy 1 A tendon connects skeletal muscle to bone. Aponeuroses are broad, sheetlike tendons. A retinaculum is a band of connective tissue that holds down the tendons at each wrist and ankle. Skeletal muscle attachments have an origin and an insertion, with the origin being the attachment at the least mobile location. The insertion is the end of the muscle attached to the bone undergoing the greatest movement. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 76 Skeletal Muscle Anatomy 2 The part of the muscle between the origin and the insertion is the belly. A group of muscles working together are called agonists. A muscle or group of muscles that oppose muscle actions are termed antagonists. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 77 Muscle Attachment Figure 7.14 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 78 Muscle Names 1 Muscles are named according to: 1. Location – a pectoralis muscle is located in the chest. 2. Size – the size could be large or small, short or long. 3. Shape - the shape could be triangular, quadrate, rectangular, or round. 4. Orientation of fascicles – fascicles could run straight (rectus) or at an angle (oblique). Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 79 Muscle Names 2 5. Origin and insertion. The sternocleidomastoid has its origin on the sternum and clavicle and its insertion on the mastoid process of the temporal bone. 6. Number of heads. A biceps muscle has two heads (origins), and a triceps muscle has three heads (origins). 7. Function. Abductors and adductors are the muscles that cause abduction and adduction movements. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 80 Skeletal Muscles 1 Figure 7.15a Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 81 Skeletal Muscles 2 Figure 7.15b Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 82 Muscles of Mastication Temporalis Masseter Pterygoids (two pairs) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 83 Muscles of Facial Expression and Mastication Figure 7.16 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior (b) McGraw Hillwritten consent of and Education/Photo McGraw Hill LLC. Dissection by Christine Eckel 84 Tongue and Swallowing Muscles Figure 7.17 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 85 Deep Neck and Back Muscles Figure 7.18 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 86 Thoracic Muscles External intercostals: elevate ribs for inspiration Internal intercostals: depress ribs during forced expiration Diaphragm: moves during quiet breathing Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 87 Muscles of the Thorax Figure 7.19 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 88 Abdominal Wall Muscles 1 Rectus abdominis: center of abdomen compresses abdomen External abdominal oblique: sides of abdomen compresses abdomen Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 89 Abdominal Wall Muscles 2 Internal abdominal oblique: compresses abdomen Transverse abdominis: compresses abdomen Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 90 Muscles of the Anterior Abdominal Wall Figure 7.20 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 91 Pelvic Diaphragm Muscles 1 Levator ani Ischiocavernosus Bulbospongiosus Deep transverse perineal Superficial transverse perineal Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 92 Pelvic Diaphragm Muscles 2 Figure 7.21 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 93 Upper Scapular and Limb Muscles 1 Trapezius: shoulders and upper back extends neck and head Pectoralis major: chest elevates ribs Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 94 Upper Scapular and Limb Muscles 2 Serratus anterior: between ribs elevates ribs Deltoid: shoulder abductor or upper limbs Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 95 Muscles of the Shoulder Figure 7.22 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 96 Upper Limb Muscles 1 Triceps brachii: 3 heads extends elbow Biceps brachii: “flexing muscle” flexes elbow and shoulder Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 97 Upper Limb Muscles 2 Brachialis: flexes elbow Latissimus dorsi: lower back extends shoulder Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 98 Arm Muscles (a) McGraw Hill Education/Photo and Dissection by Christine Eckel Figure 7.23 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 99 Forearm Muscles Flexor longus Flexor carpi radialis Flexor carpi ulnaris Flexor digitorum profundus Flexor digitorum superficialis Pronator Brachioradialis Extensor carpi radialis brevis Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 100 Muscles of the Forearm Figure 7.24 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 101 Muscles of Hips and Thighs Iliopsoas: flexes hip Gluteus maximus: buttocks extends hip and abducts thigh Gluteus medius: Hip abducts and rotates thigh Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 102 Muscles of the Upper Leg 1 The quadriceps femoris is comprised of 4 thigh muscles: The rectus femoris: front of thigh extends knee and flexes hip The vastus lateralis: extends knee The vastus medialis: extends knee The vastus intermedius: extends knee Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 103 Muscles of the Upper Leg 2 Gracilis: adducts thigh and flexes knee Biceps femoris, semimembranosus, semitendinosus: Hamstring back of thigh flexes knee, rotates leg, extends hip Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 104 Muscles of the Upper Leg 3 The rectus femoris: front of thigh extends knee and flexes hip The vastus lateralis: extends knee The vastus medialis: extends knee The vastus intermedius: extends knee Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 105 Muscles of the Hip and Thigh Figure 7.25 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 106 Muscles of Lower Leg Tibialis anterior: front of lower leg inverts foot Gastrocnemius: calf flexes foot and leg Soleus: attaches to ankle flexes foot Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 107 Lower Leg Muscles Figure 7.26 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 108  THANK YOU SO MUCH Figure 7.26 Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 109