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Do Now:
Muscle
Contraction
and
Relaxation
Standard AP 2.7
Name the components of a skeletal muscle
fiber and describe their functions.
Describe how the thin and thick filaments are
organized in the sarcomere.
Video: Muscle Contraction
Last year (according to your Medical
Science notebooks) you learned about
MUSCLE CONTRACTION.
Lets see what you remember!
Today’s essential question:
What microscopic structures are responsible for
contracting and relaxing muscle fibers?
Video: Muscle Contraction
Directions: Watch 3 short videos.
Copy the video questions in your notebook.
You can DRAW or WRITE out your answers!
Video Questions:
1.Name the microscopic parts of cardiac and
skeletal muscle fibers.
2.Describe the function of each part.
3.Describe how the thin and thick filaments are
organized in a sarcomere.
(Remember…you can DRAW or WRITE)
Whiteboard Activity
Directions: Work with your lab group. Write on
your whiteboards. Description and function..
1.Group 1 – Muscle Relaxation
2.Group 2 – Muscle Contraction
3.Group 3 – Thick filaments (myosin)
4.Group 4 – Thin filaments (actin)
5.Group 5 – Sarcomere
6.Group 6 – Myofibril
Notes: Microscopic Anatomy
of Skeletal Muscle and Muscle Contraction
Directions:
Glue this
picture under
the video
questions.
Take out a
highlighter for
today’s notes.
HIGHLIGHT the following structures…
• Muscle fiber
(muscle cell)
• Tendon
• Bone
Notes: Microscopic Anatomy
of Skeletal Muscle and Muscle Contraction
Guiding question: What microscopic structures
are responsible for contracting and relaxing
muscle fibers?
Directions: Cut out ALL diagrams
Be prepared to glue diagrams in your
notebook and HIGHLIGHT structures.
Notes: Microscopic Anatomy
of Skeletal Muscle and Muscle Contraction
 Muscle Fibers are made of myofibrils
 HIGHLIGHT myofibril and glue this
picture in your notebook.
Figure 6.3a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.9a
Checking for Understanding
1. Muscle fibers are made up of…
2. Another word for striations is…
3. True or False?
– Skeletal muscle
has many nuclei.
Notes: Microscopic Anatomy
of Skeletal Muscle and Muscle Contraction
 Myofibrils are made of sarcomeres.
 Sarcomeres are the contractile unit of
muscles contraction.
 HIGHLIGHT sarcomere and glue this
picture in your notebook.
Figure 6.3b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
6.10b
Notes: Microscopic Anatomy
of Skeletal Muscle and Muscle Contraction
 A sarcomere has two kinds of
filaments/protein.
 Thick filaments/protein = myosin filaments
 Thin filaments/protein = actin filaments
 LABEL ACTIN and MYOSIN and HIGHLIGHT
THICK AND THIN glue this picture in your
notebook.
Figure 6.3c
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
6.11a
Notes: Microscopic Anatomy
of Skeletal Muscle and Muscle Contraction
 Myosin (thick) filaments have heads
(cross bridges) shown in red below
 Actin (thin) filaments are twisted chains
shown in blue below
Figure 6.3d
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
6.12a
Checking for Understanding
4. What are the NAMES of the TWO
FILAMENTS located in the sarcomere
responsible for muscle contraction?
5. What are the NAMES of the TWO
proteins that make up these two
filaments?
The Sliding Filament Theory
Figure 6.8
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 6.18
Exit Slip: Muscle Contraction
Put all electronics away and work quietly
on your own.
When you are done…
Stay seated.
Turn your exit slip over.
#5, 6 are ACTIONS
#7, 8 are PROTEINS