1. THE MUSCULAR SYSTEM

2. What types of muscles can be found in the body?

3. Smooth Muscle

4. Cardiac Muscle

5. Skeletal Muscle Fibers

6. Pectoralis major Trapezius Deltoid Biceps brachii Triceps brachi
Figure 6.1
Pectoralis major
Draws arm forward
and toward the body
Trapezius
Lifts shoulder blade
Braces shoulder
Draws head back
Deltoid
Raises arm
Biceps brachii
Bends forearm at elbow
Triceps brachi
Straightens forearm
at elbow
Rectus abdominus
Compresses abdomen
Bends backbone
Compresses chest cavity
Latissimus dorsi
Rotates and draws
arm backward and
toward body
External oblique
Lateral rotation of trunk
Compresses abdomen
Gluteus maximus
Extends thigh
Rotates thigh laterally
Figure 6.1 Major skeletal muscle groups and their functions.
Gastrocnemius
Bends lower leg at
knee
Bends foot away from 6

7. What is the contractile unit of a muscle?

10. Skeletal muscle microstructure.
Myofibril
Z-line
Z-line
Sarcomere
A closer view of a section of a myofibril
showing that it is composed of
sarcomeres joined end to end at the
Z-line.
Myosin
Actin
An electron micrograph
cross section of a sarcomere
in a region that contains both
actin and myosin.
Thin filament
(actin)
Thick filament
(myosin)
Sarcomeres contain thin filaments of
actin that attach to the Z-lines and
thicker filaments of myosin that span
the gap between actin molecules.
Figure 6.5 Structure of a myofibril.
A transmission electron micrograph ( 11,300)
of a longitudinal section of a sarcomere. The
rounded red objects are mitochondria. 10

11. Microscopic View of Actin and Myosin

12. Exercise 9

13. Activity 1: Skeletal Muscle
Has striated cells with multiple nuclei
Occurs in the muscles attached to skeleton
Functions in voluntary movement of body
Examine figure 1.
Identify the long, multinucleated fibers arranged in a parallel fashion. How do you know the muscle fibers are striated?

14. Figure 1.

15. Activity 1 Draw a sarcomere.
Identify and label the following structures:
Z-lines
Thick and Thin filaments

16. Identify the Following Structures: A, B, C, and D.

17. Activity 2. Examine the model of the neuromuscular junction.
Examine the branching of the motor neuron to several muscle cells.
Identify the motor neuron, synaptic cleft, sarcoplasmic reticulum and T- tubules.
Draw the neuromuscular junction.

18. The release of acetylcholine at the neuromuscular junction causes an
Figure 6.6 1
The release of acetylcholine at the
neuromuscular junction causes an
electrical impulse to be generated
in the muscle cell plasma membrane
Motor neuron
Acetylcholine 2
Electrical
impulse
The electrical impulse
( ) is carried
to the cell’s interior
by the T tubules
Ca2
T tubule
Sarcoplasmic
reticulum 3
The electrical impulse
triggers the release
of Ca2 from the
sarcoplasmic
reticulum
Figure 6.6 How nerve activation leads to calcium release within a muscle cell.
Muscle cell
plasma
membrane
Myofibrils
Z-line 18

19. Questions
How do a motor neuron and a skeletal muscle fiber join at a neuromuscular junction?
What events occur at this neuromuscular junction?

20. Activity 3 Examine the figure of a muscle cross section.
Identify the following structures: tendon, fascicles, perimysium, epimysium.
Draw and label whole muscle.

21. Activity 4: observing the gross anatomy of skeletal muscles.

22. Pectoralis major Trapezius Serratus anterior Deltoid Biceps brachii
Figure 6.1
Pectoralis major
Draws arm forward
and toward the body
Trapezius
Lifts shoulder blade
Braces shoulder
Draws head back
Serratus anterior
Helps raise arm
Contributes to pushes
Draws shoulder blade forward
Deltoid
Raises arm
Biceps brachii
Bends forearm at elbow
Triceps brachi
Straightens forearm
at elbow
Rectus abdominus
Compresses abdomen
Bends backbone
Compresses chest cavity
Latissimus dorsi
Rotates and draws
arm backward and
toward body
External oblique
Lateral rotation of trunk
Compresses abdomen
Gluteus maximus
Extends thigh
Rotates thigh laterally
Adductor longus
Flexes thigh
Rotates thigh laterally
Draws thigh toward body
Hamstring group
Draws thigh backward
Bends knee
Figure 6.1 Major skeletal muscle groups and their functions.
Sartorius
Bends thigh at hip
Bends lower leg at knee
Rotates thigh outward
Gastrocnemius
Bends lower leg at
knee
Bends foot away from
Quadriceps group
Flexes thigh at hips
Extends leg at knee
Achilles tendon
Connects
gastrocnemius
muscle to heel
Tibialis anterior
Flexes foot toward knee 22

23. Activity 4
Complete table 9.4

24. Activity 5: Contraction of Skeletal Muscles
Work in pairs
Obtain a gripper
Read the directions
Complete questions 1-3.

25. Due Date
March 11-14

26. Introduction
Function of the muscular system Types of muscles and functions Basic structure of skeletal muscles Skeletal muscles work in pairs Name and actions of skeletal muscles Leave procedures out

27. Results Include your results from each activity.
Drawing, label your drawings see the following example.
Complete table or box. Label the table and include a description of the table or box.

28. Figure 1. Motor neuron anatomy
Figure 1. Motor neuron anatomy. Neurons are cells specialized to conduct nerve impulses.

29. Conclusion Include motor neuron and motor unit.
Include all the components of a neuromuscular junction. How do a motor neuron and skeletal muscle fiber join at a neuromuscular junction? What events occur at the neuromuscular junction? What is the function of ACh?
Include the microscopic anatomy of a muscle fiber
Describe the sarcomere(include all the components in a sarcomere)
Describe the contraction cycle.
What are the roles played by calcium and ATP during muscular contraction?
Explain cross-bridge, power stroke and the sliding filament model.
What is the function of ATPase?
Isometric and Isotonic contractions
Complete the questions page 113 and 114.