2. Make a short list of what you do voluntary and involuntary with your muscles… A. Def – organs composed of specialized cells that use chemical energy to contract. B. Three Types 1. *skeletal* 2. smooth 3. cardiac

3. Neuromuscular junctionFascia AponeurosesMyosin NeurotransmittersSarcomere Sarcoplasmic reticulumMyofibrils Motor neuronActin Motor end plateMotor unit

4. A. Connective Tissue Coverings 1. Fascia – surrounding connective tissue that… (pg.170) a. Holds muscle in position b. Separates muscles c. May project into a tendon and connect to the periosteum. 2. Aponeuroses – sheet like connective tissue that… (pg.188) a. Can attach to bone b. Cover adjacent muscles

6. 3. Epimysium – surrounds outside of muscle 4. Perimysium – extend inwards from epimysium and separate into small compartments (fascicles) 5. Endomysium – covers each muscle fiber.

7. Study Analogy You are going to give someone 100 pencils. The pencils will represent muscle fibers. First you wrap each individual pencil in tissue paper. This would be endomysium. Then you take about 10 pencils in a bundle (a fascicle) and wrap them in paper (perimysium). After that you take all the bundles and wrap them in paper (epimysium). But you are going to mail this, so you also have to wrap it in brown paper representing the fascia.

9. B. Skeletal Muscle Fibers 1. Def – single cell that contracts w/ stimulation and relaxes w/o. 2. Sarcolemma – cell membrane 3. Sarcoplasm – cytoplasm -mitochondria -myofibrils (aid in contraction) a. Myosin – thick protein b. Actin – thin protein *produce characteristic of striations

10. 4. Sarcomere – extends from Z line to Z line a. I bands – thin bands of actin filaments -attached to z line b. A bands – thick bands of myosin filaments -myosin overlaps actin filaments -H zone – only thick filaments -M line – protein that holds thick filaments in place. 5. Sarcoplasmic reticulum & T-Tubules – store calcium and activate muscular contraction when stimulated

12. 1. 2. 4. 5. 6. 3. 7. 8.

14. C. Neuromuscular Junction – connection between muscle and motor neuron. 1. Every muscle fiber is connected to an axon from a nerve cell. (motor neuron) 2. Extends from brain to muscle fiber. 3. Motor end plate -nuclei and mitochondria are present 4. Motor neuron branches into muscle fiber. 5. Neurotransmitters – released into the synaptic cleft and cause muscle to fire

16. Questions to think about… 1. Describe the general structure of a skeletal muscle fiber. 2. What is the neuromuscular junction? 3. What is the purpose of the motor end plate and motor neuron axon? 4. What is the function of a neurotransmitter?

17. *myosin binds to actin and exerts a pulling motion. Actin and myosin filaments slide past each other.* A. Roles of Actin and Myosin 1. Myosin – contain cross-bridges that are forked. 2. Actin – are globular structures that have binding sites for cross-bridges. Troponin and tropomyosin are part of the actin filament.

19. 3. Sliding Filament Model a. Sarcomeres shorten b/c cross- bridges pull on actin filament. b. Cross-bridges can then release and move to another biding site and pull again. c. ATPase (enzyme) – breaks down ATP to ADP and phosphate. d. SFM can occur as long as there is ATP.

20. B. Stimulus Contraction 1. Nerve impulse is sent… 2. Acetylcholine (neurotransmitter) is released into synaptic cleft. 3. Acetylcholine diffuses to receptors. 4. Creates a muscle impulse. -sent throughout the muscle fibers -reaches the sarcoplasmic reticulum 5. S.R. releases Ca 2+ ions into the sarcoplasm of the muscle fibers. 6. Ca 2+ ions expose binding site on actin filament. 7. Contraction occurs…ATP and acetylcholine

21. C. Relaxation of Muscles 1. Nerve impulses cease… a. Acetylcholine is decomposed by acetylcholinesterase. b. Prevents continuous contraction 2. Ca 2+ ions are transported back to S.R. a. Troponin and tropomyosin return to normal state. b. Actin and myosin return to normal state.

23. D. Energy Sources for Contraction 1. ATP – energy source for muscles a. Must be a continual supply to continue contraction b. ADP + Phosphate must be regenerated back to ATP - creatine phosphate – reconnects ADP + Phosphate…thus allowing more ATP for your muscles to use.  very abundant *Why would some people take creatine supplements?*

24. E. Oxygen Supply and Cellular Respiration 1. Glycolysis – breakdown of glucose for energy a. Used best with oxygen.. -blood carries O 2 to muscles  hemoglobin -O 2 is released into muscles and stored there  myoglobin

25. F. Oxygen Debt 1. Resting…blood supplies all O 2 needs 2. Active…blood can’t supply O 2 needs a. Lactic acid is produced b. Oxygen debt forms c. No oxygen = no activity 3. Training helps… a. Building mitochondria b. Increase capillaries c. Allows for less O 2 debt and thus less lactic acid in muscles.

26. G. Muscle Fatigue and Heat Production 1. Fatigue – losing the ability to contract -lack of blood, lactic acid -can cause cramps 2. Cellular reactions…lead to heat byproducts -blood transports to other tissues and to skin’s surface.

27. A. Threshold Stimulus – the minimum amount of stimulation required to fire a muscle. 1. Caused by Acetylcholine B. All or None Response – when stimulated, a muscle fiber fires fully. 1. Each muscle fiber is controlled by a motor neuron. 2. The whole muscle (ex: biceps) does not need to fire…only what is needed

28. C. Muscular Contraction 1. Terms… a. Twitch – single muscular contraction b. Tetanus – sustained contractions c. Latent period – delay b/t signal and response. d. Fast Twitch Muscle – high intensity, quick and strong fibers; fatigable e. Slow Twitch Muscle – lower intensity, slower muscle fibers; fatigue resistant

29. A. Smooth Muscle Fibers 1. elongated 2. lack striations 3. sarcoplasmic reticulum not developed B. Types of Smooth Muscle 1. Multiunit a. Muscle fibers are separate b. Found… -irises, blood vessels,

30. 2. Visceral a. Sheet-like b. Found… -walls of hallow organs (stomach, intestines, uterus, bladder… c. Can stimulate each other -“peristalsis” C. Smooth Muscle Contraction 1. Similar to skeletal muscle 2. norepinephrine and acetylcholine 3. Slow to contract 4. longer contractions 5. have the ability to stretch

31. A. Location – heart B. Functions… 1. similar to skeletal and smooth 2. contains more actin, myosin and striations 3. intercalated discs -join cells together better -pass muscle impulses better 4. rhythmic