1. Muscle Anatomy Anatomy and Physiology L2/L3

2. Long, thin & multinucleated Striated Involuntary Contracts rhythmically Found in cardiac tissue Voluntary Contractions are slow and steady Walls of visceral organs & blood vessels Contract rapidly & vigorously Lets Review!!What type of muscle tissue does each describe?

3. Functions of skeletal muscle • Movement: of skeleton by use of muscles acting in pairs or groups • Posture Maintenance: keeping upright • Heat generation: product of movement. Serves to maintain norm. body temp (homeostasis)

4. Gross Anatomy of skeletal muscle • muscle cell aka (fiber): made up of many myofibrils • Epimysium (deep fascia: outer, toughest covering of Dense connective tissue • Fascicles/fasciculus :name given to bundles of muscle fibers/cells

5. Anatomy of skeletal muscle

6. Myofibril: many make up a cell/fiber Sarcolemma (plasma membrane): it is the cell membrane surrounding cell/fiber SR: similar to ER Sarcomere: contractile units making up myofibrils containing actin &myosin. -Multi-nucleated Anatomy of skeletal muscle (cont)

7. Thread-like protein structures 2 types: Thick– Myosin Thin – Actin Alternating light/dark create striations Allow muscle to contract (shorten) and relax (lengthen) Myofibril: many sarcomeres make up the myofibrils

9. Contaction and Relaxation of Skeletal Muscle fiber

10. NM Jxn Terminal end stores ACh ACh released into fiber ACh acts as stimulus Chemical Part of Muscle Contraction: Motor Unit: Composed of motor neuron & all the muscle fibers

11. Steps in Muscle Contraction • Nerve impulse travels down motor neuron to NM junction • Acetylcholine (ACh) released into muscle • ACh diffuses across muscle fiber • Signals the SR to release stored Calcium • Ca initiates formation of cross bridges between Actin and Myosin • *Ca stimulates a change in actin shape 6. sacrcomeres shorten and muscle fibers contract

13. Steps in Muscle Relaxation • Motor neuron impulse to stop contraction so Ach is inactivated. • Ca moves (Active transport) back into SR (to be stored) (*ATP) • Absence of Ca causes crossbridges to break because actin changes back its shape (*ATP) • Actin filaments slide back • RESULT: Muscle relaxes

16. Homework: #1and #2 • #1 Based on knowledge of muscle physiology; what steps must or do not occur in the condition Rigor Mortis at the chemical level and what happens to the body? • #2. What causes Botulism?and how might we (humans) come in contact with the toxin? • What physiological/chemical effects can Botulism have? What treatments?

17. Homework: #3 and #4 • #3. Look up compartment syndrome • Cause: what happens at the chemical level? • symptoms • Treatment • #4. Look up multiple sclerosis • Be able to discuss: • Cause; and what happens at the chemical level? • symptoms • treatment

18. Homework: #5 Muscular Dystrophy • Protein structure of muscle is mainly Actin & Myosin. • What is the function of dystrophin? • Muscular Dystrophy? • Cause: at the chemical level? • Types? • Physiological effects on body

19. Take a Break and Review! • Go to following animation • www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/muscles/muscles.html • Great animations and review activities!

20. Quick Quiz: 18 pts (3 each) • 1. Describe each: epimysium, fascicles, fiber/cell, sarcoplasm • 2. Explain where the sarcomere is and what is has to do with muscle contraction • 3. What has to happen in order for a body part to move?

21. Quiz cont. • 4. What happens at the neuromuscular junction? • 5. Explain steps in muscle contraction • 6. Explain steps in muscle relaxation