Chapter 9 Muscles and Muscle Tissue

 

Objectives:

• Review the differences between skeletal, cardiac and smooth muscle
• Examine the gross anatomical features of skeletal muscle
• Explore the microscopic anatomy of skeletal muscle, and the specific arrangement of each element in relation to the others
• Explain the sliding filament theory of muscle contraction
• Describe the structural arrangement of the neuromuscular junction, and explain the generation of an action potential across the sacrolemma
• Define a motor unit, and explain the events of a muscle twitch
• Identify the graded muscle response, and explain how factors affect graded responses.
• Define muscle tone, and discuss in the context of isometric and isotonic contraction
• Describe the mechanism through which muscles are supplied with ATP.
• Underscore the effects of exercise.
• Explain the muscle disorder, muscular dystrophy.

 

 

Review:

I.  Comparison of Skeletal, Cardiac and Smooth Muscle

 

Skeletal Muscle	Cardiac Muscle	Smooth Muscle

 

II.  Internal Structure of a Skeletal Muscle

 

Skeletal Muscle is composed of connective tissue and contractile cells

 

            The entire muscle is surrounded by -

 

            Skeletal tissue is made up of-

 

            Each fascicle is surrounded by a connective tissue later -

 

 

III.  Internal Structure of a Fascicle

 

Within the fascicle, the third connective tissue layer, the -

 

 

All 3 connective tissue layers bind the muscle cells together, providing strength and support to the entire muscle. They merge at the ends of the muscle and are continuous with the ___________.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Muscle Cell

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IV.  Internal structure of a skeletal muscle cell (fiber)

 

            Skeletal muscle cells are often referred to as __________.

 

            Nucleus-

 

 

            Sarcolemma-

 

 

 

            Sarcoplasmic reticulum-

 

           

 

Terminal cisternae-

 

 

 

            T tubule-

 

 

 

            Triad-

 

 

            Cytosol-

 

 

            Mitochondrion-

 

 

 

            Myofibril-

 

 

 

 

V.  Structure of a Myofibril

 

 

            The myofibril is made of contractile proteins called __________________.

 

                        Two types of myofilaments

 

                                    Thin filaments (made of protein ____________)

 

                                    Thick filaments (made of protein _____________)

 

 

Arrangement of Myofilaments

 

 

            Thick myofilaments form _____________bands

 

            Thin myofilament form _______________ bands.

 

            The bands are alternating form ______________________.

 

 

            A band

 

 

            I band

 

 

 

                        During contraction the I band gets ____________________.

 

 

            Z line

 

 

            H zone

 

                        During contraction the H zone gets __________________

 

 

            M line

 

 

            Sarcomere-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

V.  Review Organizational Levels of a Skeletal Muscle

 

            Bundle within a bundle organization

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pyramid

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VII.  Sliding Filament Theory of Muscle Contraction

 

Components includes the following:

 

Thick filaments

 

 

 

 

 

 

 

 

 

 

           

 

 

 

Thin filaments

 

 

 

 

 

 

 

Thick and thin filaments

 

 

 

 

 

 

 

ATP

 

 

 

Calcium Ions

 

 

 

6 Step of Cross Bridge Cycling

 

1.  Exposure of Binding site on Actin

 

 

2.  Binding of Mysoin to Actin

 

 

3.  Power Stroke of the Cross bridges

 

 

4.  Disonnecting the Cross Bridge from Actin

 

 

5.  Re-energizing and repositioning  the cross bridge

 

 

6.  Removal of Calcium Ions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Calcium Pumps

 

 

 

 

 

 

 

 

Multiple Cross Bridge Cycles

 

 Mutiple Filaments

 

 

Review of the Role of ATP

 

 

The Neuromuscular Junction

 

            Definitions

 

Resting Membrane potential

 

 

                        Action Potential

 

 

                        Depolarization

 

 

 

Role of the Motor Neuron

 

 

 

Overview of Neuromuscular Junction Action

 

 

            Arrival of Action Potential At Axon Terminal

 

 

            Fusion of Synaptic vesicle

 

            Acetylcholine Binds to Receptor Sites

 

            Breakdown of Acetylcholine

 

            Action  Potential Propagation

 

            Calcium Release from Terminal Cisternal

 

            Contraction of Muscle Cell

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Contraction of a Muscle Cell

 

           

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Motor Unit-

 

 

 

Muscle Twitch

 

            Latent period

 

            Period of contraction

 

            Period of relaxation

 

 

Graded muscle responses

 

                        Wave Summation

 

                        Incomplete tetnus

 

                        Complete tetnus

 

                        Multiple unit summation or Recruitment

 

                        Treppe

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Muscle tone

 

 

 

Isotonic contractions

 

 

 

Isometric contractions

 

 

 

 

 

Muscle Metabolism

 

 

            ATP is regenerated from 3 pathways

 

 

                        Direct phosphorylation

 

 

 

                        Anaerobic mechanism (glycolysis and lactic acid formation)

 

 

 

 

                        Aerobic mechanism (aerobic cellular respiration)

                       

 

 

 

 

Muscle Fatigue

 

 

 

 

 

Oxygen Debt

 

 

 

Effect of Exercise on Muscles

 

            Aerobic exercise

 

 

 

 

            Resistance exercise

 

 

 

 

 

            Disuse atrophy

 

 

 

            Overuse injuries

 

 

 

 

            Anabolic Steroids

 

 

 

 

 

Muscle Disorder

 

            Muscular Dystrophy