1. Anatomy of skeletal muscle ppt #1 Unit 4 Muscles

2. Muscular System Chapter 11

3. Muscle Intro Functions of muscles
Movement: respiration, circulation, defecation
Stability: resists gravity and provides tension to tendons
Communication
Heat Production: muscle provides 85% of body heat

4. Types of Muscle Skeletal – striated & voluntary Smooth – involuntary
Cardiac - heart
The word “striated” means striped. Skeletal muscle appears striped under a microscope.

5. Connective Tissue
Perimysium: A thick connective layer that surrounds each fascicle.
Epimysium/Deep Fasciae: a layer that surrounds each muscle
Superficial fascia: the layer of connective tissue between the muscle and skin, can be fatty

6. EPIMYSIUM = outermost layer, surrounds entire muscle.
PERIMYSIUM = separates and surrounds fascicles (bundles of muscle fibers)
ENDOMYSIUM = surrounds each individual muscle fiber
This model of the muscles uses straws to represent fibers.
Green = endomysium Yellow = perimysium Blue = epimysium

7. Muscles and Muscle Fiber Structure
Muscles are composed of many FIBERS that are arranged in bundles called FASCICLES

8. Individual muscles are separated by FASCIA, which also forms tendons

9. Muscle Layers
Muscle Fiber
Endomysium
Perimysium
Epimysium

10. Epimysium
Perimysium
Endomysium

11. How are muscle cells created?
In embryonic development, STEM CELLS called Myoblasts fuse to produce each muscle fiber.
Each muscle fiber= 1 muscle cell with many myofibrils
Each muscle fiber= many flattened or sausage shaped nuclei pushed against
the plasma membrane
Fiber (cell) plasma membrane= Sarcolemma
Fiber (cell) cytoploasm = Sarcoplasm

12. Nucleus
Sarcolemma
Mitochondrion
Sarcoplasm
Myofibril

13. myofibrils Muscle Fiber (cell) plasma membrane= Sarcolemma
Muscle Fiber (cell) cytoploasm = Sarcoplasm
The Sarcoplasm contains many long protein bundles=
myofibrils
The Sarcoplasm also contains lots of Glycogen (stored carb) which provides energy and red pigment Myoglobin
Which stores Oxygen.
Other organelles are packed into the spaces between the myofibrils like:
Sarcoplastic Reticulum: has channels to release FLOOD of Ca+ Forms a network around each myofibril
T Tubules= Transverse tubules which signal the SR to release Ca+ Mitochondria: Produces ATP from O2 and glucose (cellular respiration)

14. Structure of Myofibrils
Myofibrils are the long protein cords that fill most of the muscle cell
Each Myofibril is a bundle of parallel protein microfilaments called: Myofilaments
3 kinds of Myofilaments:
Thick Filaments: hundreds of protein called : MYOSIN
looks like golf clubs
Thin Filaments: 2 intertwined strands of protein ACTIN Fibrous Actin with “globs” of Globular Actin
F-Actin G-Actin
each G-Actin has a site that binds to the head of myosin
Myosin and Actin are Contractile Proteins

15. Thin Filaments continued
Thin Filaments also have protein bundles of
Tropomyosin
When muscle is relaxed, the tropomyosin blocks the actins and prevents myosin from binding.
Thin filaments also have Troponin: a Ca+ binding protein
Tropomyosin and Troponin are Regulatory proteins
Elastic Filaments: made of huge springy proteins called Titan, this helps stabilize the thick filaments and helps prevent overstretching.
Accessory Proteins include Dystrophin

16. Myofibrils are made of
ACTIN = thin filaments
MYOSIN = thick filaments

17. Myofilaments ACTIN (thin) and MYOSIN (thick)
  form dark and light bands
A band = dArk • thick (myosin)
I band = lIght • thIn (actin)

18. Filament organization
Actin and Myosin are in all cells and control motility they are
Contractile proteins (act to shorten muscle fibers)
Actin and Myosin are organized in a precise array which then is seen as striations in the muscle.
Striated muscle has DARK A bands
alternating with light I bands

19. A bands= thick filaments lying side by side
- very dark where thick and thin overlap
H bands= lighter region with no overlap of thick and thin…just thick
I Bands = is region with only thin filaments and is anchored to Z disc by elastic filaments
Z disc = Protein disc to which thin and elastic filaments are anchored
Sarcomere= segment of myofibril from one Z disc to the next Z disc

20. A muscle shortens because individual sarcomeres shorten and pull the z discs closer to each other. As discs are pulled closer they pull on the sarcolemma to achieve shortening of the cell.

24. It is important to remember the hierarchy
fasicles
myofibrils
myofilaments
actin
myosin