1. The Muscular System

2. The Muscular System
Muscles are responsible for all types of body movement
Three basic muscle types are found in the body
_______________

3. Characteristics of Muscles
Skeletal and smooth muscle cells are elongated (______________ = muscle fiber)
Contraction of muscles is due to the movement of ______________
All muscles share some terminology
Prefixes _____ and ____ refer to “muscle”
Prefix _____ refers to “flesh”

4. Comparison of Skeletal, Cardiac, and Smooth Muscles
Table 6.1 (1 of 2)

5. Comparison of Skeletal, Cardiac, and Smooth Muscles
Table 6.1 (2 of 2)

6. Skeletal Muscle Characteristics
Most are attached by ___________ to bones
Cells are _____________
__________ —have visible banding
___________ —subject to conscious control

7. Connective Tissue Wrappings of Skeletal Muscle
Cells are surrounded and bundled by connective tissue
Endomysium—encloses a single muscle fiber
Perimysium—wraps around a fascicle (bundle) of muscle fibers
Epimysium—covers the entire skeletal muscle
Fascia—on the outside of the epimysium

8. Connective Tissue Wrappings of Skeletal Muscle
Figure 6.1

9. Skeletal Muscle Attachments
_____________ blends into a connective tissue attachment
Tendons—cord-like structures
Mostly collagen fibers
Often cross a joint due to toughness and small size
_________________—sheet-like structures
Attach muscles indirectly to bones, cartilages, or connective tissue coverings

10. Skeletal Muscle Attachments
Sites of muscle attachment
_________
____________
Connective tissue coverings

11. Smooth Muscle Characteristics
______________
Spindle-shaped cells
Single nucleus
_____________—no conscious control
Found mainly in the walls of _________ __________

12. Smooth Muscle Characteristics
Figure 6.2a

13. Cardiac Muscle Characteristics
__________
Usually has a single nucleus
____________ _______
Joined to another muscle cell at an _____________ ________
_______________
Found only in the heart

14. Cardiac Muscle Characteristics
Figure 6.2b

15. Skeletal Muscle Functions
Produce ___________
Maintain __________
Stabilize _______
________________

16. Microscopic Anatomy of Skeletal Muscle
_____________—specialized plasma membrane
____________—long organelles inside muscle cell
_____________ _________—specialized smooth endoplasmic reticulum

17. Microscopic Anatomy of Skeletal Muscle
Figure 6.3a

18. Microscopic Anatomy of Skeletal Muscle
Myofibrils are aligned to give distinct bands
________ = light band
Contains only ________ filaments
________ = dark band
Contains the entire length of the ________ filaments

19. Microscopic Anatomy of Skeletal Muscle
Figure 6.3b

20. Microscopic Anatomy of Skeletal Muscle
_____________—contractile unit of a muscle fiber
Organization of the sarcomere
Myofilaments
Thick filaments = ________ filaments
Thin filaments = ______ filaments

21. Microscopic Anatomy of Skeletal Muscle
Thick filaments = myosin filaments
Composed of the protein myosin
Has ATPase enzymes
Myosin filaments have heads (extensions, or cross bridges)
Myosin and actin overlap somewhat
Thin filaments = actin filaments
Composed of the protein actin
Anchored to the Z disc

22. Microscopic Anatomy of Skeletal Muscle
Figure 6.3c

23. Microscopic Anatomy of Skeletal Muscle
At rest, there is a bare zone that lacks actin filaments called the ____ zone
Sarcoplasmic reticulum (SR)
Stores and releases _________
Surrounds the ___________

24. Microscopic Anatomy of Skeletal Muscle
Figure 6.3d

25. The Nerve Stimulus and Action Potential
Neuromuscular junction
Association site of axon terminal of the motor neuron and muscle

26. The Nerve Stimulus and Action Potential
Figure 6.5a

27. The Nerve Stimulus and Action Potential
____________
Gap between nerve and muscle
Nerve and muscle _______________________
Area between nerve and muscle is filled with interstitial fluid

28. The Nerve Stimulus and Action Potential
Figure 6.5b

29. Transmission of Nerve Impulse to Muscle
Neurotransmitter—chemical released by nerve upon arrival of nerve impulse
The neurotransmitter for skeletal muscle is __________________
Acetylcholine attaches to receptors on the sarcolemma
_______________ becomes permeable to sodium (Na+)

30. Transmission of Nerve Impulse to Muscle
Figure 6.5c

31. Transmission of Nerve Impulse to Muscle
Sodium rushes into the cell generating an action potential
Once started, muscle contraction cannot be stopped

32. Transmission of Nerve Impulse to Muscle
Figure 6.6

33. The Sliding Filament Theory of Muscle Contraction
Activation by nerve causes myosin heads (cross bridges) to attach to binding sites on the thin filament
Myosin heads then bind to the next site of the thin filament and pull them toward the center of the sarcomere
This continued action causes a sliding of the myosin along the actin
The result is that the muscle is shortened (contracted)

34. The Sliding Filament Theory of Muscle Contraction
Figure 6.7a–b

35. The Sliding Filament Theory
Figure 6.8a

36. The Sliding Filament Theory
Figure 6.8b

37. The Sliding Filament Theory
Figure 6.8c