1. Chapter 9: Muscles and Muscle Tissue

2. Governor Arnold Schwarzenegger

3. Muscle Functions Producing Movement Maintaining Posture
Stabilizing Joints
Generating Heat

4. 3 Types of Muscle
Skeletal Muscle
Cardiac Muscle
Smooth Muscle

5. Skeletal Muscle attaches to bones which form levers
used for bodily movement

6. Cardiac Muscle forms the heart
used to pump blood through circulatory system

7. Smooth Muscle lines gut and blood vessels
controls diameter of these tubes and in gut helps to propel the digested food

8. Cells Connected by Intercalated Discs or Gap Junctions?
 Property
 Skeletal Muscle
 Cardiac Muscle
 Smooth Muscle
 Striations?
 Yes
Yes
 No
 Nuclei per Cell
 Many
 Single
 Cells Connected by Intercalated Discs or Gap Junctions?

9. Relative Speed of Contraction
 Property
 Skeletal Muscle
 Cardiac Muscle
 Smooth Muscle
 Relative Speed of Contraction
Fast
  Intermediate
 Slow
 Voluntary Control?
Yes
 No No
 Control of Contraction
 Nerves
 Beats spontaneously but modulated by nerves
 Nerves Hormones Stretch

10. Muscle cells Large, long cells called FIBERS
Contain two types of proteins--actin and myosin
Excitable (irritable), contractile, extensible, and elastic
Myo-, mys, or Sarco code for muscle

11. Skeletal Muscle Anatomy
Rich blood supply to center of muscle, branch to capillaries sheathing cells
Rich nerve supply, branching into each muscle, ending one branch to each muscle fiber

12. Structure of Skeletal Muscle
Cigar shaped, multinucleate cells
Packed with myofilaments made of actin and myosin creating visible bands (striations)
Varied length, may be over a foot long

13. Structure cont.
Surrounded by dense, fibrous Connective tissue (CT) sheaths
Endomysium around each fiber
Perimysium around bundles of fibers (fascicles)
Epimysium around all fascicles

14. Figure 6. 1 Connective tissue wrappings of skeletal muscle
Figure 6.1 Connective tissue wrappings of skeletal muscle. © 2000  The Benjamin/Cummings Publishing Company

15. Microscopic structure
Muscle fibers filled with Sarcoplasm
Glycogen and myoglobin
Nuclei pushed to the edge of sarcolemma by long protein strands that run length of the cell, myofibrils
Composed of contractile units, sarcomeres, made of myofilaments

16. Figure 6. 3 Anatomy of a skeletal muscle cell (fiber)
Figure 6.3 Anatomy of a skeletal muscle cell (fiber). (a) A portion of a muscle fiber. One myofibril has been extended. (b) Enlarged view of a myofibril showing its banding pattern. (c) Enlarged view of one sarcomere (contractile unit) of a myofibril. (d) Structure of the thick and thin myofilaments found in the sarcomeres. © 2000  The Benjamin/Cummings Publishing Company

17. Myofilaments
Two types--actin and myosin -Filaments are clusters of actin and myosin
Actin forms thin filaments
Myosin forms thick filaments

18. Sarcomere structure Alternating dark and light bands
Lateral dark bands--A-band
End in light I-bands, with Z-line in center marking joint with next sarcomere on each side

21. Muscle Contraction Sarcomere - basic unit of muscle contraction
Skeletal and cardiac muscle are striated
The striations are caused by alignment of bands: the most prominent are the A and I bands and the Z line
The unit between 2 Z lines is called the sarcomere

22. Muscle Contraction-Sarcomere
In the A band the 2 proteins overlap
The I band contains only the actin protein
When muscle contracts the sarcomere shortens and the Z lines move closer together

24. Muscle Contraction-relaxed state
When Muscle Contracts Protein Filaments Slide Together
Thin filaments: actin, attached to Z line, found in both A and I bands
Thick filaments: myosin, found in A band
Relaxed state:

25. Muscle Contraction-Contracted state
When muscle contracts the actin filaments slide into the A band, overlapping with myosin

26. Muscle Contraction-Contracted state
Notice what happens when muscle contracts:
a) the Z lines move closer together
b) the I band becomes shorter
c) the A band stays at the same length
This is called the "sliding filament" model of muscle contraction

27. Muscle Contraction-Crossbridge
The filaments slide together because myosin attaches to actin and pulls on it
myosin head(H) attaches to actin filament (A), forming a crossbridge
After the crossbridge is formed the myosin head bends, pulling on the actin filaments and causing them to slide:

28. Actin Molecule