Muscular SystemMuscular System

MaderMader

Study Questions 6-10Study Questions 6-10

6. What is the all-or-none law? What is 6. What is the all-or-none law? What is the difference between a single muscle the difference between a single muscle twitch, summation and tetanus (p.114)twitch, summation and tetanus (p.114) An individual muscle fiber will An individual muscle fiber will

contract completely or not at all, contract completely or not at all, HOWEVER,HOWEVER,

The strength of a contraction of an The strength of a contraction of an entire muscle can increase according entire muscle can increase according to how many fibers are contracted to how many fibers are contracted (not necessarily all of the fibers)(not necessarily all of the fibers)

THEREFORE, the entire muscle does THEREFORE, the entire muscle does not follow the all-or-none law.not follow the all-or-none law.

6. Continued: 6. Continued: What is the What is the difference between a single muscle difference between a single muscle twitch, summation and tetanus (p.114)twitch, summation and tetanus (p.114) Smt: 3 periodsSmt: 3 periods

1.1. Latent – time between stim. & contractionLatent – time between stim. & contraction2.2. Contraction Contraction 3.3. RelaxationRelaxation

Summation: many impulses in rapid Summation: many impulses in rapid successtionsuccesstion

Tetanus: when a muscle is not allowed Tetanus: when a muscle is not allowed to relax completely between stimulito 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 7. Describe how muscles are attached to bone. Define the terms prime mover, bone. Define the terms prime mover, synergist and antagonist. (p. 115)synergist and antagonist. (p. 115) Origin – on the stationary boneOrigin – on the stationary bone Insertion – on the bone that movesInsertion – on the bone that moves Prime mover – the one muscle that does Prime mover – the one muscle that does

most of the work when several muscles most of the work when several muscles work together to move a bonework together to move a bone

Synergists – muscles assisting the prime Synergists – muscles assisting the prime mover [muscles can only pull not push]mover [muscles can only pull not push]

Antagonists – muscle pairs that work in Antagonists – muscle pairs that work in opposition to bring about movement in opposition to bring about movement in opposite directionsopposite directions

8. What is the difference between 8. What is the difference between isotonic and isometric contraction? isotonic and isometric contraction? What is muscle tone? How does What is muscle tone? How does muscle contraction affect muscle size? muscle contraction affect muscle size? (p. 115)(p. 115) Isotonic – muscles contract, shorten Isotonic – muscles contract, shorten

and movement occursand movement occurs Isometric – muscles contract but Isometric – muscles contract but

don’t shorten and no movement don’t shorten and no movement occursoccurs

Muscle tone – applies to whole Muscle tone – applies to whole muscle refers to condition where muscle refers to condition where some fibers are always contracted some fibers are always contracted (posture – neck, trunk, legs)(posture – neck, trunk, legs)

8. Continued: How does muscle 8. Continued: How does muscle contraction affect muscle size?contraction affect muscle size?

Hypertrophy – strenuous exercise over a Hypertrophy – strenuous exercise over a prolonged period causes muscles to get prolonged period causes muscles to get biggerbigger Muscles are stronger and fatigue slowlyMuscles are stronger and fatigue slowly Increases the number of myofibrilsIncreases the number of myofibrils

Atrophy – decrease in muscle mass due to Atrophy – decrease in muscle mass due to inactivity (astronauts)inactivity (astronauts) Causes muscle fibers to shorten and leave Causes muscle fibers to shorten and leave

body parts contracted in contorted positionsbody parts contracted in contorted positions

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

9. How do muscles get their names? Give an 9. How do muscles get their names? Give an example for each method of naming a example for each method of naming a muscle? (p. 117)muscle? (p. 117)

1.1. Size – gluteus maximusSize – gluteus maximus2.2. Shape – deltoid Shape – deltoid 3.3. Direction of fibers – rectus (straight) Direction of fibers – rectus (straight)

abdominalisabdominalis4.4. Location – frontalis overlies frontal boneLocation – frontalis overlies frontal bone5.5. Number of attachments – biceps, Number of attachments – biceps,

tricepstriceps6.6. Action – extensor digitorum extends Action – extensor digitorum extends

fingersfingers

10. Which of the head muscles are 10. Which of the head muscles are used for facial expression? Which are used for facial expression? Which are used for chewing? (p. 120)used for chewing? (p. 120)

Orbicularis oculi - ~ eye = crows feetOrbicularis oculi - ~ eye = crows feet Orbicularis orbis - ~ mouth = puckerOrbicularis orbis - ~ mouth = pucker Buccinator – compresses cheek Buccinator – compresses cheek

(trumpeter’s muscle)(trumpeter’s muscle) Zygomaticus – cheek bone Zygomaticus – cheek bone

attachment = smilesattachment = smiles

10. Continued: Which are used for 10. Continued: Which are used for chewing = masticationchewing = mastication

Masseter – zygomatic arch to Masseter – zygomatic arch to mandible & raises mandible (prime mandible & raises mandible (prime mover)mover)

Temporalis – fan-shaped muscle over Temporalis – fan-shaped muscle over the temporal bone & acts as the temporal bone & acts as synergist to the massetersynergist to the masseter