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Chapter 8 Muscular System 8-1 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Introduction: A. The three types of muscle in the body are 1. Skeletal 2. Smooth 3. Cardiac 8-2 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Structure of a Skeletal Muscle A. Muscle is made of -skeletal muscle tissue -connective tissues -nervous tissue -blood 8-3 8-4 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. Connective Tissue Coverings 1. Fascia-fibrous connective tissue that separates the individual muscles 2. Tendons-bone to muscle connection -fascia extends beyond muscle to make this. -connect to periosteum 8-5 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Aponeuroses-connective tissue that attaches muscle to muscle -abdominal muscles, lumbar vertebrae, palmar/plantar regions 4. Epimysium-wraps around entire muscle; connective tissue 5. Fascicles-individual muscle compartments 6. Perimysium-separates the fascicles *wraps around each fascicle 7. Endomysium-covers each muscle cell 8. Muscle cells-muscle fiber 8-6 8-7 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8-8 8-9 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. Skeletal Muscle Fibers 1. Each muscle fiber is a single, long, cylindrical muscle cell. 2. 8 - 10 Sarcolemma-cell membrane Sarcoplasm-cytoplasm with many mitochondria and nuclei; -has myofibrils. -myofibrils are separated into compartments called sarcomeres that contain thick filaments and thin filaments. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b. c. Thick filaments of myofibrils are made up of the protein myosin. Thin filaments of myofibrils are made up of the protein actin. The organization of these filaments produces striations. YOU TUBE VIDEOhttp://www.youtube.com/watch?v=XoP1dia XVCI 8 - 11 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 12 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 8 - 13 A sarcomere extends from Z line to Z line. a. I bands -light bands -made up of actin -anchored to Z lines b. A bands -dark bands -made up of overlapping thick and thin filaments. c. In the center of A bands is an H zone, consisting of myosin filaments only. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4. Beneath the sarcolemma of a muscle fiber lies the sarcoplasmic reticulum (endoplasmic reticulum), which is associated with transverse (T) tubules (membrane channels) - activate the muscle contraction mechanism YOU TUBE http://www.youtube.com/watch?v=P1zD_M pTo0M 8 - 14 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 15 8 - 16 Muscle Strain? Muscle fibers and connective tissue are flexible but they tear Only few fibers-mild Fascia tear and muscle function loss-severe Discolored and swollen 8 - 17 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 18 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nervous and muscular system: 1. The site where the motor neuron and muscle fiber meet a. The muscle fiber membrane forms a motor end plate -nuclei and mitochondria are abundant. b. Neurotransmitters (chemicals) are stored at the end of the motor neuron -these are released from the motor neuron and stimulate the muscle 8 - 19 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. 8 - 20 Motor Units -motor neuron and the muscle fiber it contracts 8.3 Skeletal Muscle Contractions 21 Bio 2 HW-TBA; test on Monday next week Agenda: Contraction of the muscle 1. Take out muscle contraction notes. 8 - 22 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Skeletal Muscle Contraction 2 events take place in a muscle contraction -shortening of sarcomeres -pulling of the muscle against its attachments. 8 - 23 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Myosin-thick filament 1. Crossbridges projecting outward Actin-thin filament 1. Globular protein 2. Binding sites for myosin 3. Troponin and tropomyosinproteins that block binding sites of actin -prevent myosin 8 - 24binding from 8 - 25 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. sliding filament theory of muscle contraction 1. Myosin cross-bridges attach to binding site on actin 2. Myosin pulls on actin 3. Myosin releases actin and attaches to next binding site 8 - 26 http://www.youtube.com/watch?v=Ct8AbZn_ A8A 8 - 27 How does ATP help? Myosin has an enzyme ATPase Breaks down ATP into ADP This releases energy for the muscle cell to use. • This energy causes myosin crossbridge to cock its head to attach actin. ADP will be made back into ATP through cell respiration After one pull, another ATP attaches on for the myosin to release actin. 8 - 28 8 - 29 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. How does a muscle know to contract? 1. Neuron neurotransmitter -acetylcholine -triggers a stimulus to the muscle 2. Protein receptors in the motor end plate detect the neurotransmitters. -impulse spreads over sacrolemma -travel through tranverse tubules and into the sarcoplasmic reticulum. 8 - 30 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 4. 8 - 31 sarcoplasmic reticulum releases calcium to the sarcoplasm Calcium -moves troponin and tropomyosin -actin binding sites are exposed so myosin crossbidges can attach -myosin pulls on actin to shorten sarcomere CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 32 Relaxation -After the nervous impulse has been received, acetylcholinesterase (enzyme) rapidly decomposes the acetylcholine. -Then, calcium is returned to the sarcoplasmic reticulum, and the linkages between myosin and actin are broken. 8 - 33 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Energy Sources for Contraction 1. ATP is needed -adenosine triphosphate -limited supply so constantly must be made through cellular respiration 2. Creatine phosphate -quick back up energy supply -can change ADP into ATP 3. Creatine Phosphokinase -creates creatine phosphate 8 - 34 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Oxygen Supply and Cellular Respiration Cell Respiration Glucose + oxygen= ATP and carbon dioxide + water -muscles need a lot of oxygen to create the most ATP -hemoglobin carries oxygen to muscles -pigment called myoglobin stores oxygen in muscle tissue 8 - 35 http://www.youtube.com/watch?v=CepeYF vqmk4&feature=fvsr 8 - 36 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Oxygen Debt -rest or moderate activity-oxygen supply is good -oxygen deficiency occurs -lactic acid is made -travels to liver -liver has oxygen debt -amount of oxygen needs for the liver to change lactic acid into glucose and regain the original amount of ATP and creatine phosphate 8 - 37 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Muscle Fatigue 1. When a muscle loses its ability to contract during strenuous exercise, it is referred to as fatigue. 2. Muscle fatigue usually arises from the accumulation of lactic acid in the muscle. -A lowered pH as a result of accumulated lactic acid prevents the muscle from contracting. 3. A muscle cramp occurs due to a lack of ATP required to return calcium ions back to the sarcoplasmic reticulum so muscle fibers can relax. 8 - 38 Section 8.4 Notes 8 - 39 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Muscular Responses A. One method of studying muscle function is to remove a single fiber and connect it to a device that records its responses to electrical stimulation. B. Threshold Stimulus 1. A muscle fiber remains unresponsive to stimulation unless the stimulus is of a certain strength, called the threshold stimulus. 8 - 40 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. All-or-None Response 1. When a muscle fiber contracts, it contracts to its full extent (all-ornone response); it cannot contract partially. 8 - 41 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Recording a Muscular Contraction 1. A myogram is the recording of an electrically stimulated muscle contraction. 2. A single, short contraction involving only a few motor units is referred to as a twitch. 8 - 42 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. The time delay between when the stimulus is applied and when the muscle contracts is called the latent period, which is less than 0.01 second. 4. The latent period is followed by a period of contraction and a period of relaxation. 8 - 43 Types of muscle contraction Concentric (shorten) Lifting weights Any action that causes the muscle to overcome the resistance of an object Eccentric (lengthen) Returning the muscle to standard position Bicep lengthens as you lower it from the curled position Normal everyday activities Isometric (stays the same) Carry an object in front of you 8 - 44 Summation -muscle receives several stimuli arrives at the muscle before the end of the relaxation phase If the sustained contraction lacks any relaxation, it is called a tetanic contraction. *action potentials are so rapid *Ca can’t be reclaimed by SR *occurs in most muscle movements CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 45 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Recruitment of Motor Units 1. An increase in the number of activated motor units within a muscle at higher intensities of stimulation is called recruitment. 8 - 46 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. Sustained Contractions 1. Summation and recruitment together can produce a sustained contraction of increasing strength. 2. Muscle tone is achieved by a continuous state of sustained contraction of motor units within a muscle. 8 - 47 8 - 48 8.5-8.6 Notes 8 - 49 Muscle fibers continued Red fibers Low glycogen High myoglobin and capillaries High mitochondria Take 3 times longer to contract after stimulation Have oxygen reserves so uses more Can’t use a lot of force, but can do small amounts for a long time Intermediate fibers-both red and white fibers Look more like red fibers but can sustain activity 8 - 50 longer Would you like white meat or dark meat? White meat-fast muscle fibers Little myoglobin and capillaries Mitochondria is low; have a lot of glycogen Use a lot of ATP in a short time; after 10 seconds, use lactic acid fermentation up to 3 minutes Used for short activities 8 - 51 Dark meat-red muscle fibers 8 - 52 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. *Smooth Muscle Fibers *elongated *tapered ends *no striations *underdeveloped *Visceral smooth muscle-sheets of muscle *walls of hollow organs *fibers stimulate one another *show rhythmicity (peristalsis) * multiunit smooth muscle *blood vessels and eye iris 8 - 53 *fibers are separate and not sheets CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Smooth Muscle Contraction *similar mechanism to skeletal muscle *acetylcholine and norepinephrine stimulate and inhibit muscle contraction *hormones can also stimulate and inhibit contraction *slower to contract and relax than skeletal *can contract longer using the same amount of ATP 8 - 54 8 - 55 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cardiac Muscle *contraction mechanism similar *has extra calcium *contract for longer periods * self-exciting and rhythmic *whole structure contracts as a unit. *intercalated disks -membrane junctions that joins cells and transmit the contraction from one cell to the next *makes the signal travel fast *do not need neural stimulation like 8 - 56 skeletal; have pacemaker 8 - 57 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Skeletal Muscle Actions *origin-immovable end *insertion-movable end *contraction-pulls the insertion toward the origin *Muscle names based on: size, shape, location, action, number of attachments, or direction of its fibers *prime mover-the main worker *synergist-helpers *antagonist-opposing muscles 8 - 58 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. B. 8 - 59 Muscles of Facial Expression 1. Muscles of facial expression attach to underlying bones and overlying connective tissue of skin, and are responsible for the variety of facial expressions possible in the human face. 2. Major muscles include the epicranius, orbicularis oculi, orbicularis oris, buccinator, and zygomatigus. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 60 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. C. 8 - 61 Muscles of Mastication 1. Chewing movements include up and down as well as sideto-side grinding motions of muscles attached to the skull and lower jaw. 2. Chewing muscles include masseter and temporalis. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. D. Muscles that Move the Head 1. Paired muscles in the neck and back flex, extend, and turn the head. 2. Major muscles include sternocleidomastoid, splenius capitis, and semispinalis capitis. 8 - 62 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. E. Muscles that Move the Pectoral Girdle 1. The chest and shoulder muscles move the scapula. 2. Major muscles include the trapezius, rhomboideus major, levator scapulae, serratus anterior, and pectoralis minor. 8 - 63 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 64 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. F. Muscles that Move the Arm 1. Muscles connect the arm to the pectoral girdle, ribs, and vertebral column, making the arm freely movable. 2. Flexors include the coracobrachialis and pectoralis major. 8 - 65 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 4. 5. 8 - 66 Extensors include the teres major and latissimus dorsi. Abductors include the supraspinatus and the deltoid. Rotators are the subscapularis, infraspinatus, and teres minor. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. G. 8 - 67 Muscles that Move the Forearm 1. These muscles arise from the humerus or pectoral girdle and connect to the ulna and radius. 2. Flexors are the biceps brachii, the brachialis, and the brachioradialis. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 68 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 4. 8 - 69 An extensor is the triceps brachii muscle. Rotators include the supinator, pronator teres, and pronator quadratus. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. H. Muscles that Move the Wrist, Hand, and Fingers 1. Movements of the hand are caused by muscles originating from the distal zumerus, and the radius and ulna. 2. Flexors include the flexor carpi radialis, flexor carpi ulnaris, palmaris longus, and flexor digitorum profundus. 8 - 70 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 8 - 71 Extensors include the extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, and extensor digitorum. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. I. Muscles of the Abdominal Wall 1. This group of muscles connects the rib cage and vertebral column to the pelvic girdle. a. A band of tough connective tissue, the linea alba, extending from the xiphoid process to the symphysis pubis, serves as an attachment for certain abdominal wall muscles. 8 - 72 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2. 8 - 73 These four muscles include: external oblique, internal oblique, transverse abdominis, and rectus abdominis. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. J. Muscles of the Pelvic Outlet 1. The superficial urogenital diaphragm fills the space within the pubic arch, and the deeper pelvic diaphragm forms the floor of the pelvic cavity. 2. Pelvic diaphragm includes the levator ani. 8 - 74 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. Urogenital diaphragm: includes the superficial transversus, perinei, bulbospongiosus, and ischiocavernosus. 8 - 75 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. K. Muscles that Move the Thigh 1. The muscles that move the thigh are attached to the femur and to the pelvic girdle. 2. Anterior group includes the psoas major and iliacus. 8 - 76 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 77 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 4. 8 - 78 Posterior group is made up of the gluteus maximus, gluteus medius, gluteus minimus, and tensor fasciae latae. Thigh adductors include the adductor longus, adductor magnus, and gracilis. CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. L. Muscles that Move the Leg 1. This group connects the tibia or fibula to the femur or pelvic girdle. 2. Flexors are the biceps femoris, semitendinosus semimembranosus, and sartorius. 3. An extensor is the quadruceps femoris group made up of four parts: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. 8 - 79 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 80 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. M. Muscles that Move the Ankle, Foot, and Toes 1. Muscles that move the foot are attached to the femur, fibula, or tibia, and move the foot upward, downward, or in a turning motion. 2. Dorsal flexors include the tibialis anterior, peroneus tertius, and extensor digitorum longus. 8 - 81 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 - 82 CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3. 4. 5. 8 - 83 Plantar flexors are the gastrocnemius soleus, and flexor digitorum longus. An invertor is the tibialis posterior. An evertor is the peroneus longus.