3Smooth MuscleMakes up walls of hollow body organs, respiratory passagewaysInvoluntary movementCell structureTapered endsSingle, central nucleusNo visible bands (striations)Stimulated by nerve impulses, hormones, stretching
4Cardiac Muscle Makes up wall of heart Involuntary movement Cell structureBranching interconnectionsSingle, central nucleusStriatedMembranes are intercalated disksStimulated by electrical impulses, nervous stimuli, hormones
5Skeletal Muscle Attached to bones, muscles, or skin Voluntary movement Cell structureLong and cylindricalMultiple nuclei per cellHeavily striatedStimulated by nervous system
6Checkpoint 8-1: What are the three types of muscle?
7Question: Which type of muscle has intercalated disks. a Question: Which type of muscle has intercalated disks? a. smooth muscle b. cardiac muscle c. skeletal muscle
9The Muscular System Skeletal muscle has three primary functions Skeletal movementPosture maintenanceHeat generation
10Checkpoint 8-2: What are the three main functions of skeletal muscle?
11Structure of a Muscle Fascicles (muscle fibers) Endomysium Perimysium Epimysium (deep fascia)Tendons
12Structure of a skeletal muscle. Structure of a muscle showing the tendon that attaches it to a bone. (B) Muscle tissue seen under a microscope. Portions of several fascicles are shown with connective tissue coverings.ZOOMING IN • What is the innermost layer of connective tissue in a muscle? • What layer of connective tissue surrounds a fascicle of muscle fibers?
13Question: What is the name of the connective tissue structure that connects muscle to bone? a. fascicle b. ligament c. tendon
15Muscle Cells in ActionMotor unit is a single neuron and all the muscle fibers itstimulatesNeuromuscular junction (NMJ)NeurotransmitterSynaptic cleftReceptorsMotor end plate
16Checkpoint 8-3: Muscles are activated by the nervous system Checkpoint 8-3: Muscles are activated by the nervous system. What is the name of the special synapse where a nerve cell makes contact with a muscle cell?Checkpoint 8-4: What neurotransmitter is involved in the stimulation of skeletal muscle cells?
17Neuromuscular junction (NMJ). (A) The branched end of a motor neuron makes contact with the membrane of a muscle fiber (cell). (B) Enlarged view of the NMJ showing release of neurotransmitter (acetylcholine) into the synaptic cleft.(C) Acetylcholine attaches to receptors in the motor end plate, whose folds increase surface area. (D) Electron microscope photograph of the neuromuscular junction.
18Properties of Muscle Tissue ExcitabilityAction potentialContractilityActinMyosinSarcomereATP
19Sliding filament mechanism of skeletal muscle contraction. Muscle is relaxed and there is no contact between the actin and myosin filaments.Cross-bridges form and the actin filaments are moved closer together as the muscle fiber contracts. (C) The cross-bridges return to their original position and attach to new sites to prepare for another pull on the actin filaments and further contraction. ZOOMING IN • Do the actin or myosin filaments change in length as contraction proceeds?
20Checkpoint 8-5: What are two properties of muscle cells that are needed for response to a stimulus? Checkpoint 8-6: What are the filaments that interact to produce muscle contraction?
21The Role of Calcium Calcium Is released when nerve fiber stimulates muscle cellAttaches to proteins blocking receptor sitesAllows cross-bridges to form between actin and myosinReturns to endoplasmic reticulum (ER), which is called “sarcoplasmic reticulum” in muscle cells.
22Energy SourcesMuscle contraction requires energy (ATP), oxidized in muscle cells fromOxygenGlucose or other usable nutrientCompounds in muscle cells that store oxygen, energy, or nutrientsMyoglobinGlycogenCreatine phosphate
23Checkpoint 8-7: What mineral is needed to allow actin and myosin to interact? Checkpoint 8-8: Muscle cells obtain energy for contraction from the oxidation of nutrients. What compound is formed in oxidation that supplies the energy for contraction?
30The Mechanics of Muscle Movement Tendons attach muscles to bonesOrigin—attached to more fixed part of skeletonInsertion—attached to more moveable part of skeleton
31Checkpoint 8-10: Muscles are attached to bones by means of tendons: one attached to a less movable part of the skeleton and one attached to a movable part. What are the names of these two attachment points?
32Muscles Work Together Many muscles function in pairs Prime movers AntagonistsSynergistsIn development, nervous system must learn to coordinate movement. Children learning new skills may use some muscles unnecessarily or not use the correct muscles.
33Checkpoint 8-11: Muscles work together to produce movement Checkpoint 8-11: Muscles work together to produce movement. What is the name of the muscle that produces a movement as compared with the muscle that produces an opposite movement?
34Question: What is the name for a muscle that helps the prime mover and the antagonist muscles? a. a supplemental b. an effector c. a synergist
36Levers and Body Mechanics Musculoskeletal system as a lever systemLever—boneFulcrum—jointForce—applied by muscleThree classes of leversFirst classSecond classThird class—most body systems
37Three classes of levers are shown along with tools and anatomic examples that illustrate each type. R = resistance (weight);E = effort (force);F = fulcrum (pivot point).
38Checkpoint 8-12: Muscles and bones work together as lever systems Checkpoint 8-12: Muscles and bones work together as lever systems. Of the three classes of levers, which one represents the action of most muscles?
39Skeletal Muscle Groups Characteristics for naming muscles (often combined)LocationSizeShapeDirection of fibersNumber of heads (attachment points)Action
40Superficial muscles, anterior view. Associated structure is labeled in parentheses.
41Superficial muscles, posterior view. Associated structures are labeled in parentheses.
42Muscles of the Head Facial expression (orbicularis) muscles Orbicularis oculiOrbicularis orisLevator palpebrae superiorisBuccinatorMastication (chewing) musclesTemporalisMasseterIntrinsicExtrinsic
43Muscles of the head.Associated structure is labeled in parentheses. ZOOMING IN• Which of the muscles in this illustration is named for a bone it is near?
44Question: What is the name for the muscle that surrounds the eye. a Question: What is the name for the muscle that surrounds the eye? a. orbicularis oculi b. orbicularis oris c. frontalis