Challenge Problem1. Where can smooth muscle be found?

2. Can we control smooth muscle with our brain?

3. Where can we find cardiac muscle?

4. If you had to lose function of one of the types of muscle, which would it be? Why?

5. Which type of muscle cells can have more than one nucleus?***

6. Why might they need more than one nucleus?***

Challenge Problem1. Identify 2 characteristics of skeletal muscle

2. To which bones of a human did the chicken wing compare?

3. What was that outer covering that wrapped around the muscles and turned into a tendon?

4. Using the words muscle, brain, nerves, tendons, and bones, describe how we move our arms

5. Get out your lab

Microanatomy of Muscles

Ch. 6b

Microscopic Anatomy of SkeletalMicroscopic Anatomy of SkeletalMuscleMuscle

Slide 6.9aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscle Fibers are composed of bundles of myofibrils

Figure 6.3a

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.10a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Myofibril

Made of bundles of myofilaments

Myofibrils are aligned to give distinct bands

I band = light band

A band = dark band

Figure 6.3b

Quick Quiz

• A muscle fiber is made up of what?

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.10b

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Sarcomere Contractile unit of a muscle fiber

Makes muscles contract

Extends from the center of one I band to the center of the next I band

Figure 6.3b

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.11a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Organization of the sarcomere Thick filaments = myosin filaments

Thin filaments = actin filaments

Figure 6.3c

Microscopic Anatomy of Skeletal Microscopic Anatomy of Skeletal MuscleMuscle

Slide 6.12a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Myosin filaments have heads (extensions, or cross bridges)

Myosin and actin overlap somewhat

Figure 6.3d

Quick Quiz 1 of 3

• What are the names of the microfilaments responsible for muscle contraction?

Assignment

• Draw, color, label a muscle & Myofibril

Welcome back!1. The s_______ is the functional unit of the

muscle fiber. ***

2. Muscle Fibers are composed of bundles of _______

3. Epimysium wraps around the inner most cell or the outermost bundle? Circle one

4. Endomysium wraps around something inside or outside? Circle one

5. How do you know the answer for 3 & 4?

Properties of Skeletal Muscle Properties of Skeletal Muscle ActivityActivity

Slide 6.13Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Irritability – ability to receive and respond to a stimulus

Contractility – ability to shorten when an adequate stimulus is received

Nerve Stimulus to MusclesNerve Stimulus to Muscles

Slide 6.14Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Skeletal muscles must be stimulated by a nerve to contract

Figure 6.4a

The Sliding Filament TheoryThe Sliding Filament Theory

Slide 6.18Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 6.8

Sliding Filament Animation

Muscle Response to Strong StimuliMuscle Response to Strong Stimuli

Slide 6.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Muscle force depends upon the number of fibers stimulated

More fibers contracting results in greater muscle tension

Muscles can continue to contract unless they run out of energy

Tallest person

• Remind the group about the video last semester when the dude pushed the huge rock off of his chest

Energy for Muscle ContractionEnergy for Muscle Contraction

Slide 6.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Initially, muscles used stored ATP for energy

Bonds of ATP are broken to release energy

Only 4-6 seconds worth of ATP is stored by muscles

After this initial time, other pathways must be utilized to produce ATP

Challenge Problem1. Where do humans get the initial burst of

energy, about 4-6 seconds?

2. When talking about muscle cells, contract = ________

3. Epimysium = inner or outer?

4. Endomysium = inner or outer?

Energy for Muscle ContractionEnergy for Muscle Contraction

Slide 6.25Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Aerobic Respiration Series of metabolic

pathways that occur in the mitochondria

Glucose is broken down to carbon dioxide and water, releasing energy

This is a slower reaction that requires continuous oxygen

Figure 6.10c

Shortest person

• Give an example of someone doing aerobic respiration

• According to the previous chart, describe how humans can lose weight

Energy for Muscle ContractionEnergy for Muscle Contraction

Slide 6.26a

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Anaerobic glycolysis

Reaction that breaks down glucose without oxygen

Glucose is broken down to pyruvic acid to produce some ATP

Pyruvic acid is converted to lactic acid

Figure 6.10b

Lightest Colored Hair

• Give your group an example of anaerobic respiration

Energy for Muscle ContractionEnergy for Muscle Contraction

Slide 6.26b

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Anaerobic glycolysis (continued)

This reaction is not as efficient, but is fast

Huge amounts of glucose are needed

Lactic acid produces muscle fatigue

Figure 6.10b

Quick Quiz 2 of 3

• Stored _____ is used for initial energy in muscles, but only lasts a few seconds.

• Aerobic respiration provides ATP, but only in the presence of __________

• ________ acid is a result of anaerobic glycolysis.

Challenge Problem

• 1. Aerobic respiration uses oxygen or no?

• 2. Anaerobic respiration uses oxygen or no?

• 3. Give an example of each pathway to make energy.

Muscle FatigueMuscle Fatigue

Slide 6.27Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

When a muscle is fatigued, it is unable to contract

Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less

Types of Muscle ContractionsTypes of Muscle Contractions

Slide 6.28Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Isotonic contractions Myofilaments are able to slide past each

other during contractions

The muscle shortens

Ex: Lifting a book

Isometric contractions Tension in the muscles increases

The muscle is unable to shorten

Ex: Trying to lift a car

Muscle ToneMuscle Tone

Slide 6.29Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Some fibers are contracted even in a relaxed muscle

Different fibers contract at different times to provide muscle tone

The process of stimulating various fibers is under involuntary control

Effects of Exercise on MuscleEffects of Exercise on Muscle

Slide 6.31Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Results of increased muscle use

Increase in muscle size

Increase in muscle strength

Increase in muscle efficiency

Muscle becomes more fatigue resistant

Quick Quiz 3 of 3

• Why type of muscle contraction is at work when doing a wall sit?

• Give an example of an isotonic muscle contraction.

Steroid Prevention Poster for Teens

• Create a poster identifying the dangers of steroid abuse

• Use the handout as reference

• Use color and creativity

• You may even say what steroids are and how they should be used