9/15/20141Copyright © 2005 Pearson Education, Inc., publishing as Benjamin CummingsMuscle TissuesStudy tip #4Use the course goalsEach lecture outline starts with a list of goals. After studying the material, how well do you understand each of them? Skeletal Muscle Learning Goals1) Explain how skeletal muscles are classed into several functional types; give specific muscle examples and describe the functions of prime movers (agonists), antagonists, synergists, and fixators.2) Describe the characteristics of muscle tissue that distinguish it from other types of tissues.3) Name the layers of connective tissue that occur in and around a skeletal muscle.4) List general characteristics of skeletal muscle fibers.5) Describe and explain the structural and organizational levels of skeletal muscle. Begin with the muscle as an organ followed by the fascicle, muscle fiber, myofibril, and sarcomere, then end with the myofilament.6) Explain the sliding filament theory in the simplest form.7) Describe the role of titin in the sarcomere.8) Define motor unit.9) Describe the various ways in which muscles attach to their origins and insertions. Explain attachments of muscles to bones through tendons, aponeuroses, and direct and indirect attachments.Muscle tissues contract in response to a stimulus from the nervous system in order to:1. To move material through the body2. To move parts of the body and produce movement3. To generate heatFunctions of muscle tissuesSkeletal 400x Smooth 400xCardiac 400x9/15/20142Figure 11.27a Muscles of the posterior compartment of the right leg.Tendon ofgastrocnemius Calcanealtendon Medial headGastrocnemiusLateral headACTIVITY WORK BY YOURSELF OR IN A GROUP1. Put one foot flat on the ground. Consider this to be the resting length of the muscle.1st:Stand the foot up on “tip toes”, using the gastrocnemius muscle of your calf to raise up the heal.2nd: Return your heal back to the floor.3rd: Point your toes to the ceiling (keeping heal on floor), stretching out the gastrocnemius muscle. 4th: Return toes to the floor. 2. For each step list what is happening to the gastrocnemius..Example: muscle is shortening in lengthCopyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings1. Motor signal to contract reaches gastrocnemius.2. Gastrocnemius contracts and shortens. Heel is lifted off ground.3. Motor signal to & contraction of gastrocnemiusstop—heel returns to floor & gastrocnemius is pulled back to resting length.4. Gastrocnemius is pulled beyond resting length as antagonistic muscles on anterior side of leg contract and dorsiflex foot.5. Motor signal & contractions stop.6. Foot returns to ground.Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings9/15/20143Human Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.Figure 10.10 Motor units.Spinal cordMuscleNerve(b)(a)EXCITABILITYMotor signal to contract reaches muscle and initiates a contractionHuman Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.CONTRACTILITYMuscle contracts and shortens. Human Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.EXTENSIBILITY1. Biceps brachii muscle contracts2. Biceps brachii muscle extends back to resting length NOTE: a contraction of the triceps brachii is responsible for pulling (or extending) the biceps brachiiMotor signal to & contraction of muscle stops and muscle is pulled back to resting length (by gravity and/or an antagonist).Another example:9/15/20144Human Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.ELASTICITY1. Muscle has been stretchedbeyond resting length 2. Muscle is able to regain original shapeNOTE: titin plays a key roleMuscle is pulled beyond resting length by antagonistic muscles and is able to regain resting length after this stretch.Human Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.Excitability: Muscle cell can respond to a stimulus (electrical impulse) Contractility: In response to stimulus, muscle cell contracts (shortens or attempts to shorten)Extensibility: When contraction ends, muscle cell can be pulled back to resting length.Elasticity: Muscle cell can be stretched beyond its resting length and then shorten back to resting length.This image shows a brachialis muscle contracting to flex the forearm at the elbow. Which term best describes the process that will allow that muscle to be pulled back to its resting length?A. ElasticityB. ExtensibilityC. ContractilityD. ExcitabilityE. More than one ofthe aboveCopyright © 2005 Pearson Education, Inc., publishing as Benjamin CummingsBrachialis musclecontracting9/15/20145Human Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.Figure 10.3 Skeletal muscle1 muscle cell = 1 muscle fiber3 Muscle Tissue Types:1. Skeletal muscle•Moves the skeleton•~40% of body weight•Under voluntary control•StriatedCopyright © 2005 Pearson Education, Inc., publishing as Benjamin CummingsFigure 10.10a Cardiac Muscle Tissue1 muscle cell = 1 muscle fiber3 Muscle Tissue Types:2. Cardiac muscle•Only found in heart wall•Under involuntary control•StriatedFigure 22.6a–b Smooth muscle.Smallintestine(a) (b)MucosaLongitudinal layer of smooth muscleCircular layer of smooth muscle3 Muscle Tissue Types:3. Smooth muscle1 muscle cell = 1 muscle fiber•Found within the walls of most internal organs•Under involuntary control9/15/20146What type of muscle would you expect to find within the walls of blood vessels?A. SkeletalB. CardiacC. SmoothD. More than one of the aboveCopyright © 2005 Pearson Education, Inc., publishing as Benjamin CummingsHuman Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.Figure 10.4_a–c Microscopic anatomy of the skeletal muscle fiber (cell). NucleiFiber = a muscle cellNucleusSarcolemma= plasma membraneThin (actin) filamentThick (myosin) filamentStructures found in ALL 3 types of muscle cellsMyofilaments (cytoskeletal units)Human Anatomy, 5eby Marieb, Mallatt, and WilhelmCopyright © 2008 Pearson Education, Inc.,publishing as Benjamin Cummings.Skeletal muscleTypically