Study guide…

1. Study guide… • What are the three types of muscle tissue, their structure and location? • What are the functions of the muscular system? • How are skeletal muscles and muscle fibers structured from largest to smallest? • What are the steps of skeletal muscle contraction? • How do skeletal muscle cells acquire ATP for contraction? • Distinguish between slow and fast twitch fibers. • What are some common muscular disorders?

2. Review: 3 types of muscle tissue

3. What are the functions of skeletal muscles? • Support • Movement • Homeostasis-How do skeletal muscles help us maintain body temperature? • Protection internal organs and stabilize joints

4. How are skeletal muscles arranged? • Attachments: • Tendon • Origin • Insertion • Action: • Antagonistic • Synergistic

5. An example of muscle arrangement

6. Examples of how skeletal muscles are named • Size –gluteus maximus, vastus lateralis • Shape – deltoid, trapezius • Location –frontalis, tibialis anterior • Direction of muscle fiber – rectus abdominus, external oblique • Attachment – brachioradialis • Number of attachments –biceps brachii • Action –extensor digitorum

7. Skeletal Muscle Structure • Terminology for cell structure • plasma membrane =______________________ • Cytoplasm=___________________ • ER=_______________ ___________________ • Muscle fascicle (bundle of fibers) • Muscle fiber • Myofibrils • Sarcomeres consisting of myofilaments

8. Visualizing muscle structure

9. The sarcomere • Made of protein myofilaments • Thick: myosin • Thin: actin, troponin, tropomyosin • These filaments slide over one another during muscle contraction

10. The beginning of muscle contraction: The sliding filament model • 1. What type of neuron carries information toward the muscle? • 2. What is released from the pre-synaptic cell? 3. What does it bind to? (This binding will cause calcium to be released from the SR.)

11. The beginning of muscle contraction

12. Muscle contraction continued… • 4. Released calcium combines with troponin • 5. Myosin binding sites exposed • 6. Cross-bridges form • 7. ATP binds and power stroke occurs

13. Visualizing the role of calcium and myosin in muscle contraction

14. What are the sources of ATP for muscle contraction? • Limited amounts of ATP are stored in muscle fibers • Creatine phosphate pathway (CP) – fastest way to acquire ATP but only sustains a cell for seconds; builds up when a muscle is resting • Fermentation – fast-acting but results in lactate build up • Cellular respiration (aerobic) – not an immediate source of ATP but the best long term source

15. Muscle fibers come in two forms • Fast-twitch fibers: • rely on CP and fermentation (anaerobic) • Designed for strength • Light in color • Few mitochondria • Fewer blood vessels • Slow-twitch fibers: • Rely on aerobic respiration • Designed for endurance • Dark in color • Many mitochondria • Many blood vessels Where in the body would you have examples of each of these?

16. Types of muscle fibers

17. Muscular diseases • Fibromyalgia – chronic achy muscles that is not well understood • Muscular dystrophy – group of genetic disorders in which muscles progressively degenerate and weaken • Myasthenia gravis – immune system attacks ACh receptor and weakens muscles of the face, neck and extremities-What kind of disorder is this?

18. Amyotrophic lateral sclerosis (ALS) commonly known as Lou Gehrig’s disease motor neurons degenerate and die leading to loss of voluntary muscle movement