1. Muscle Anatomy and Physiology

2. Muscle Tissue

3. Muscle Tissue ½ of body mass
same brief description as tissue chapter
½ of body mass
able to convert ATP (chemical energy) to mechanical energy

4. 1. Cardiac Muscle
in heart only
striated and branching
involuntary

5. 2. Smooth Muscle visceral – GI tract walls, urinary bladder, bronchi,
arrector pili,
iris

6. 2. Smooth Muscle smooth spindle shape involuntary
contractions are slow and sustained without fatigue

7. 2. Smooth Muscle
cells are surrounded by connective tissue - endomysium
usually arranged in sheets running in different directions

8. 3. Skeletal Muscle make up the skeletal muscles striated (banded)
voluntary
muscles respond rapidly but fatigue easily

9. Functions of Skeletal Muscle

10. Functional Characteristics of Skeletal Muscle
contractibility - shortens with force
excitability - responds
extensibility - stretches
elasticity - recoils

11. Function of Muscle Movement
Posture maintenance - continuous tiny adjustments
Heat generation - by product of metabolism
nearly ¾ of energy released from ATP escapes as heat
skeletal muscle is at least 40% of body mass

12. Structure of Skeletal Muscle

14. Structure of Skeletal Muscle
entire gross structure covered by connective tissue - epimysium
muscle is made of small bundles called fascicle which are bound by perimysium
each fascicle is made of a bundle of muscle cells or fibers which are surrounded by endomysium
(all coverings are continuous extensions)

16. Muscle Fiber Structure

18. Muscle Fiber Structure
sarcolemma – muscle fiber plasma membrane
sarcoplasm – muscle fiber cytoplasm, contains myoglobin – a red pigment that stores oxygen
Each muscle fiber is made of bundles of rod-shaped structures of myofibrils (organelles).
(100’s to 1000’s per cell)

19. They have repeating pattern of striations called sarcomeres.

20. The banding is caused by an orderly overlapping arrangement of protein filaments - myofilaments.

21. Myofilaments:
myosin - thick, extend entire length of A band
actin - thin, extend across the I band and part way into A band

22. Z line - attachment site for actin, ends of sarcomere
I band - light bands, actin only
A band - dark bands, myosin and actin overlap

23. H zone - only visible in relaxed, myosin only
M line - sarcomere center

24. (contracting organelle) Myosin – thick filament
Structure
Connective Tissue
surrounds
organ
Gross muscle
Epimysium
Fascicle
(bundles of cells)
surrounds
tissues
Perimysium
Muscle fiber
(muscle cell)
Endomysium
cells
surrounds
Myofibril
(contracting organelle)
organelles
Myofilaments
Actin – thin filament
Myosin – thick filament
molecules

25. (contracting organelle) Myosin – thick filament
Connective Tissue
Structure
surrounds
Gross muscle
organ
Epimysium
Fascicle
(bundles of cells)
tissues
surrounds
Perimysium
Muscle fiber
(muscle cell)
Endomysium
surrounds
cells
Myofibril
(contracting organelle)
organelles
Myofilaments
Actin – thin filament
Myosin – thick filament
molecules

26. Molecular Structure of Myofilaments

28. Myosin
rod like tail or axis ending in 2 globular heads - “crossbridges”
- heads contain ATPase (enzyme)
tail
heads

29. Actin
globular subunits - G actin are found in long strands, like a double strand of twisted beads

30. Actin
tropomyosin spirals around beads, to add strength and stiffen, thin ribbon
troponin molecules bond actin to tropomyosin, has binding sites that will join with myosin crossbridge
Binding sites

32. Sarcoplasmic Reticulum

33. Sarcoplasmic Reticulum
smooth endoplasmic reticulum of muscle cells
storage area for Ca ions
At H zones and A - I junctions tubes fuse and form lateral channels - terminal cisternae which feed into transverse tubules (T tubules) at each Z line.
T tubules receive nerve stimuli and provide a pathway for oxygen, glucose, and Ca ions.
(because continuous with membrane, nerve impulse allowed deep into muscle)

35. The End

36. Muscles are attached to bones directly or indirectly by extensions of epimysium.
indirect - are more common
1. rope like tendons
2. flat aponeurosis
direct - a direct connection

37. Patterns of Arrangement
arrangement of fascicle produce muscles with different shapes and function
most common arrangements are:
1. parallel - strap-like muscles, ex: biceps
2. pennate - short, obliquely attached to central tendon, feather shape, ex: rectus femoris
3. convergent - broad origin converging to a single tendon, ex: pectoralis major
4. circular - circular fibers, control openings and closings, ex: sphincters, orbicularis oris, orbicularis oculi

40. They have repeating pattern of striations called sarcomeres.
Z line - attachment site for actin, ends of sarcomere
I band - light bands, actin only
A band - dark bands, myosin and actin overlap
H zone - only visible in relaxed, myosin only
M line - sarcomere center

41. The banding is caused by an orderly overlapping arrangement of protein filaments - myofilaments.
myosin - thick, extend entire length of A band
actin - thin, extend across the I band and part way into A band
Z line - disklike protein sheet, anchors actin and connects each myofibril to the next
H line - less dense (myosin only)
M line - darker, fine strands connect adjacent myosins in this area

42. Sarcoplasmic Reticulum
smooth endoplasmic reticulum of muscle cells
its connecting tubules lie in spaces between myofibrils and run parallel to them
storage area for Ca ions
At H zones and A - I junctions tubes fuse and form lateral channels - terminal cisternae
which feed into transverse tubules (T tubules) at each Z line. (from penetration of sarcolemma)
T tubules receive nerve stimuli and provide a pathway for oxygen, glucose, and Ca ions.
(because continuous with membrane, nerve impulse allowed deep into muscle)