1. Muscles

2. Types of muscles- skeletal
Attached to bones of skeleton
Voluntary
Multinucleate cells
Striated

3. Types of muscles- smooth
Internal organs/tubes
Involuntary
Lack striations

4. Types of muscles- cardiac
Only found in heart
Involuntary
Uninucleate cells
Striated

5. Skeletal muscle

6. Structure of skeletal muscle

7. Within a muscle cell Sarcolemma- cell membrane
Myofibril- contractile proteins, actin/myosin
Wrapped by sarcoplasmic reticulum

8. Myofibril

9. Myosin Creates the movement Composed of protein chains that intertwine
Long tail, two heads, hinge to allow heads to move
250 myosin
molecules =
thick filament

10. Actin Multiple actin molecules polymerize
Two twist to form thin filaments
One myosin head to one actin molecule

11. Combined

12. Sarcomere- light/dark repeat

13. Muscle contraction

14. Muscle contraction
Tropomyosin- covers actin, prevents myosin from tightly binding
Troponin- gatekeeper

15. Sliding filaments

17. http://www. youtube. com/watch

18. How much tension can be generated?

19. Moving bone Muscles must contract to move bones Attachment to bone
Origin- stationary bone
Insertion- movable bone

20. Can only pull on a bone, not push

21. Types of contractions
Isometric- muscle contracts but does not change length
Isotonic- muscle contracts and changes length
Concentric- shortening
Eccentric- lengthening
Movement
(a) Muscle contracts with
force greater than
resistance and
shortens (concentric
contraction)
(c) Muscle contracts but
does not change length
(isometric contraction)
(b) Muscle contracts
with force less than
lengthens (eccentric No
movement

22. Smooth muscle

23. Smooth muscle Internal organs
Many differences between skeletal and smooth muscle

24. Communicating with neighbors
Uterus

25. Other differences Operate over varying lengths (e.g., bladder)
Layers run in different directions
Contract slower
Sustained contractions without fatiguing
Responds from chemical or electrical signal
Lack specialized receptor regions
Lack sarcomeres

26. Allows for deformation

27. Cardiac muscle

28. Cardiac muscle Features of smooth and skeletal muscle
Striated, sarcomere
Uninucleate
Intercalated discs (gap junctions)