9 15 2014 Muscle Tissues Study tip 4 Use the course goals Each lecture outline starts with a list of goals After studying the material how well do you understand each of them Copyright 2005 Pearson Education Inc publishing as Benjamin Cummings Skeletal Muscle Learning Goals 1 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 Functions of muscle tissues Muscle tissues contract in response to a stimulus from the nervous system in order to 1 2 3 To move material through the body To move parts of the body and produce movement To generate heat Skeletal 400x Cardiac 400x Smooth 400x 1 9 15 2014 Figure 11 27a Muscles of the posterior compartment of the right leg Gastrocnemius Medial head Lateral head Tendon of gastrocnemius Calcaneal tendon ACTIVITY WORK BY YOURSELF OR IN A GROUP 1 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 length Copyright 2005 Pearson Education Inc publishing as Benjamin Cummings 1 2 3 4 5 6 Motor signal to contract reaches gastrocnemius Gastrocnemius contracts and shortens Heel is lifted off ground Motor signal to contraction of gastrocnemius stop heel returns to floor gastrocnemius is pulled back to resting length Gastrocnemius is pulled beyond resting length as antagonistic muscles on anterior side of leg contract and dorsiflex foot Motor signal contractions stop Foot returns to ground Copyright 2005 Pearson Education Inc publishing as Benjamin Cummings 2 9 15 2014 EXCITABILITY Motor signal to contract reaches muscle and initiates a contraction Spinal cord Nerve Muscle a Human Anatomy 5e by Marieb Mallatt and Wilhelm Figure 10 10 Motor units CONTRACTILITY Muscle contracts and shortens Human Anatomy 5e by Marieb Mallatt and Wilhelm EXTENSIBILITY Copyright 2008 Pearson Education Inc b publishing as Benjamin Cummings Copyright 2008 Pearson Education Inc publishing as Benjamin Cummings Motor signal to contraction of muscle stops and muscle is pulled back to resting length by gravity and or an antagonist Another example 1 Biceps brachii muscle contracts 2 Biceps brachii muscle extends back to resting length NOTE a contraction of the triceps brachii is responsible for pulling or extending the biceps brachii Human Anatomy 5e by Marieb Mallatt and Wilhelm Copyright 2008 Pearson Education Inc publishing as Benjamin Cummings 3 9 15 2014 ELASTICITY Muscle is pulled beyond resting length by antagonistic muscles and is able to regain resting length after this stretch 1 Muscle has been stretched beyond resting length 2 Muscle is able to regain original shape NOTE titin plays a key role Human Anatomy 5e by Marieb Mallatt and Wilhelm Copyright 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 Human Anatomy 5e by Marieb Mallatt and Wilhelm Copyright 2008 Pearson Education Inc publishing as Benjamin Cummings 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 Elasticity Brachialis muscle contracting B Extensibility C Contractility D Excitability E More than one of the above Copyright 2005 Pearson Education Inc publishing as Benjamin Cummings 4 9 15 2014 Figure 10 3 Skeletal muscle 3 Muscle Tissue Types 1 Skeletal muscle Moves the skeleton 40 of body weight Under voluntary control Striated 1 muscle cell 1 muscle fiber Human Anatomy 5e by Marieb Mallatt and Wilhelm Copyright 2008 Pearson Education Inc publishing as Benjamin Cummings Figure 10 10a Cardiac Muscle Tissue 3 Muscle Tissue Types 2 Cardiac muscle Only found in heart wall Under involuntary control Striated 1 muscle cell 1 muscle fiber Copyright 2005 Pearson Education Inc publishing as Benjamin Cummings Figure 22 6a b Smooth muscle 3 Muscle Tissue Types 3 Smooth muscle Found within the walls of most internal organs Under involuntary control 1 muscle cell 1 muscle fiber Longitudinal layer of smooth muscle Small intestine Mucosa a b Circular layer of smooth muscle 5 9 15 2014 What type of muscle would you expect to find within the walls of blood vessels A Skeletal B Cardiac C Smooth D More than one of the above Copyright 2005 Pearson Education Inc publishing as Benjamin Cummings Figure 10 4 a c Microscopic anatomy of the skeletal muscle fiber cell Structures found in ALL 3 types of muscle cells Nuclei Fiber a muscle cell Sarcolemma plasma membrane Nucleus Myofilaments cytoskeletal units Human Anatomy 5e Thin actin filament Thick myosin filament Copyright 2008 Pearson Education Inc publishing as Benjamin Cummings by Marieb Mallatt and Wilhelm Skeletal muscle Typically attaches bone bone May also attach bone to skin or connective tissue 1 muscle fiber cell can be the length of entire muscle Can range in length from 1 inch to over a foot Long cylindrical multinucleated cells fibers Human Anatomy 5e by Marieb Mallatt and Wilhelm Copyright 2008 Pearson Education Inc