Microscopic Anatomy

—Microscopic Anatomy of the
Skeletal Muscle

—DO NOW:

—Use the terms below to explain what each connective tissue of a muscle covers?

—Perimysium

—Epimysium

—Endomysium

—

—Hmm…Striations

—What are striations and what gives striations their patterns?

—Today’s Objective

—We are diving into the anatomy of a single muscle fiber!

—

—I can define and identify the MICROSCOPIC structure of skeletal muscle

—Structure of a Muscle Fiber

—A muscle fiber is a single, long, cylindrical muscle cell.

—

—Skeletal Muscle Fibers are Multinucleate.

—

—Sarcolemma =

Cell Membrane of Muscle Fiber

—

—What is a cell membrane?

—

—Nuclei are pushed aside by long, ribbon-like organelles called myofibrils.

—

—Multiple myofibrils fill the cytoplasm of the muscle fiber.

—What is the cytoplasm?

—Sarcoplasm = Cytoplasm of Muscle Fiber

—

—

—

—MYOFIBRILS & SARCOMERES

—Myofibrils are divided into chains of tiny contractile units called sarcomeres.

—

—Within the sarcomeres, myofilaments (contractile proteins) give the appearance of striations.

—

—

—Quick Quiz

—What is the name of the cell membrane of a muscle fiber?

—

1.Fascicle

2.Myofibril

3.Sarcoplasm

4.Sarcolemma

—Quick Quiz

—What is the name of the cytoplasm of a muscle fiber?

—

1.Fascicle

2.Myofibril

3.Sarcoplasm

4.Sarcolemma

—Quick Quiz

—What are the ribbon-like organelles that fill the cytoplasm of the muscle fiber?

—

1.Fascicle

2.Myofibril

3.Sarcoplasm

4.Sarcolemma

—

—FILAMENTS

—Thick Filaments = Dark Bands = Made primarily of a protein called Myosin.

—

—Thin Filaments,  = Light Bands =  Made primarily of a protein called Actin.

—

—

—A – BANDS & I - BANDS

—

—A-Bands = Dark

¡Composed of Myosin

¡

¡

—I-Bands = Light

¡Composed of Actin

—Turn To Your Partner

—Partner A = Explain Light Bands

—

—Partner B = Explain Dark Bands

—

1.What type of filaments compose that band?

2.What is the name for that band (A- or I- Band)?

—Quick Quiz

—What are the tiny contractile units that make up the myofibrils?

—

1.Myosin

2.Actin

3.Sarcomere

4.Myofibril

—Quick Quiz

—What gives muscle striations the lighter appearance?

—

1.Myosin

2.Actin

3.Sarcomere

4.Myofibril

—Quick Quiz

—What are thick filaments mostly composed of?

—

1.Myosin

2.Actin

3.Sarcomere

4.Myofibril

—Z-Lines

—

—

—H - Zones

—

—

—Turn To Your Partner

—Partner A – What is important to know about the Z-Line?

—

—Partner B – What is important to know about the H-Zone?

—Quick Quiz

—Which filaments are found within the H-Zone?

—

1.Myosin

2.Actin

3.Z – Line

4.H – Zone

—Quick Quiz

—The length of a sarcomere is from one ______ to the next ____.

—

1.Myosin

2.Actin

3.Z – Line

4.H – Zone

—Quick Quiz

—Which filament is associated with the Z-Line?

—

1.Myosin

2.Actin

3.Z – Line

4.H – Zone

—Diagram Together The Muscle Fiber Structure

—Individual Activity

—You will work in your groups to create your model --- HOWEVER --- you will turn in your own individual work.

—

—Don’t write on the worksheets

—You Will Need

—Toothpicks 3-5

—Straws

—Colored Pencils/Markers

—

—1. First, we will use our straws. In class you learned that every muscle is made up of single muscle fibers. Your straw will represent your muscle fiber in this activity.

—2. We will use our toothpicks to demonstrate the myofibrils. We learned in class that a myofibril is a ribbon-like organelle that contains contractile units called sarcomeres. Take about 3 to 5 toothpicks and insert them into your straw.

—3. We will identify the contractile units, myofilaments and other distinguishing structures on our myofibrils. Remove the myofibrils from your straw piece.

—4.  Using different color markers or colored pencils, you will accurately draw on the myofibrils the following structures: A-Bands, I-Bands, Z-Lines, H-Zones. USE YOUR NOTES AND DIAGRAM FOR REFERENCE!

—5.  Once you have completed your labeling on the myofibrils raise your hand patiently and have it checked off by Miss Gallina.

—6. Finally, once you have been checked off (or while you are waiting) you may complete the following questions and the fill in the blank assignment on the bottom and back of this sheet.

—

—Exit Ticket

—

1.What are thick filaments made of?

2.Are A-Bands the light or dark appearing stripes in the muscle?

3.Z-Lines are most commonly associated with which myofilament:

Actin or Myosin?

4.Myofibrils are composed of small contractile units that extend from Z-Line to Z-Line called _______.

—