Muscular System Mader Study Questions 6-10

6. What is the all-or-none law? What is the difference between a single muscle twitch, summation and tetanus (p.114) An individual muscle fiber will contract completely or not at all, HOWEVER, An individual muscle fiber will contract completely or not at all, HOWEVER, The strength of a contraction of an entire muscle can increase according to how many fibers are contracted (not necessarily all of the fibers) The strength of a contraction of an entire muscle can increase according to how many fibers are contracted (not necessarily all of the fibers) THEREFORE, the entire muscle does not follow the all-or-none law. THEREFORE, the entire muscle does not follow the all-or-none law.

6. Continued: What is the difference between a single muscle twitch, summation and tetanus (p.114) Smt: 3 periods Smt: 3 periods 1. Latent – time between stim. & contraction 2. Contraction 3. Relaxation Summation: many impulses in rapid successtion Summation: many impulses in rapid successtion Tetanus: when a muscle is not allowed to relax completely between stimuli Tetanus: when a muscle is not allowed to relax completely between stimuli

Tetanus is an infectious disease caused by contamination of wounds from bacteria that live in the soil.

7. Describe how muscles are attached to bone. Define the terms prime mover, synergist and antagonist. (p. 115) Origin – on the stationary bone Origin – on the stationary bone Insertion – on the bone that moves Insertion – on the bone that moves Prime mover – the one muscle that does most of the work when several muscles work together to move a bone Prime mover – the one muscle that does most of the work when several muscles work together to move a bone Synergists – muscles assisting the prime mover [muscles can only pull not push] Synergists – muscles assisting the prime mover [muscles can only pull not push] Antagonists – muscle pairs that work in opposition to bring about movement in opposite directions Antagonists – muscle pairs that work in opposition to bring about movement in opposite directions

8. What is the difference between isotonic and isometric contraction? What is muscle tone? How does muscle contraction affect muscle size? (p. 115) Isotonic – muscles contract, shorten and movement occurs Isotonic – muscles contract, shorten and movement occurs Isometric – muscles contract but don’t shorten and no movement occurs Isometric – muscles contract but don’t shorten and no movement occurs Muscle tone – applies to whole muscle refers to condition where some fibers are always contracted (posture – neck, trunk, legs) Muscle tone – applies to whole muscle refers to condition where some fibers are always contracted (posture – neck, trunk, legs)

8. Continued: How does muscle contraction affect muscle size? Hypertrophy – strenuous exercise over a prolonged period causes muscles to get bigger Hypertrophy – strenuous exercise over a prolonged period causes muscles to get bigger Muscles are stronger and fatigue slowly Muscles are stronger and fatigue slowly Increases the number of myofibrils Increases the number of myofibrils Atrophy – decrease in muscle mass due to inactivity (astronauts) Atrophy – decrease in muscle mass due to inactivity (astronauts) Causes muscle fibers to shorten and leave body parts contracted in contorted positions Causes muscle fibers to shorten and leave body parts contracted in contorted positions

According to researchers, after just 5 to 11 days in space, astronauts can lose up to 20 percent of their muscle fibers - that is a lot of loss!

9. How do muscles get their names? Give an example for each method of naming a muscle? (p. 117) 1. Size – gluteus maximus 2. Shape – deltoid 3. Direction of fibers – rectus (straight) abdominalis 4. Location – frontalis overlies frontal bone 5. Number of attachments – biceps, triceps 6. Action – extensor digitorum extends fingers

10. Which of the head muscles are used for facial expression? Which are used for chewing? (p. 120) Orbicularis oculi - ~ eye = crows feet Orbicularis oculi - ~ eye = crows feet Orbicularis orbis - ~ mouth = pucker Orbicularis orbis - ~ mouth = pucker Buccinator – compresses cheek (trumpeter’s muscle) Buccinator – compresses cheek (trumpeter’s muscle) Zygomaticus – cheek bone attachment = smiles Zygomaticus – cheek bone attachment = smiles

10. Continued: Which are used for chewing = mastication Masseter – zygomatic arch to mandible & raises mandible (prime mover) Masseter – zygomatic arch to mandible & raises mandible (prime mover) Temporalis – fan-shaped muscle over the temporal bone & acts as synergist to the masseter Temporalis – fan-shaped muscle over the temporal bone & acts as synergist to the masseter