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Human Anatomy and Physiology
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Review Sheet for Test on Muscles
As you well know, you must learn the origins, insertions and actions of the first set of 25
muscles you presented to the class. You must be able to identify the second set of 25
muscles on diagrams for the test. The following is an outline of everything you should be
able to do for the test, which is Thursday, February 3, 2011.
o
draw and label all the parts of a muscle, a muscle cell, a neuromuscular junction, a
sarcomere, etc. Be able to draw, label, and explain the sliding filament theory and
give the series of events for a muscle to contract or relax
o
answer all of the 12 questions about muscle structure and function
o
give the significance of muscle lab (Mr. Stuart’s lab) in terms of muscle structure
and function
o
recognize and label a myogram
o
explain the five overall functions of the muscular system:
o produce skeletal movement
o maintain posture and body position
o support soft tissues (skeletal muscle on abdominal cavity and floor of
pelvic cavity to support weight of visceral organs and to protect from
injury)
o guard entrances and exits (voluntary control over swallowing, urination,
and defecation)
o maintain body temperature (75% of ATP is lost as heat, while only 25% is
actually used as work in the contraction and relaxation of muscles)
o
explain what types of tissues are associated with the muscles, and why
o
give (and explain) the two factors that determine the amount of muscle tension as
a whole:
o the frequency of stimulation
o the number of muscle fibers stimulated
o
recognize that there are different kinds of contractions, but that all normal
activities require sustained muscle contractions
o
explain why our muscles create lactic acid – know the details
o aerobic respiration only produces ATP and CO2
o anaerobic respiration produces lactic acid and just a little bit of ATP
o
explain what power and endurance are:
o power is the maximum amount of tension produced by a particular muscle
or muscle group
o endurance is the amount of time for which the individual can perform a
particular activity
o
explain how tension is related to power:
o the tension produced by a muscle fiber is directly proportional to the
number of sarcomeres present in a muscle
o
give the two major factors that determine the performance capabilities of any
skeletal muscle:
o the types of muscle fibers in the muscle
o physical conditioning or training
o
explain the differences among the three types of skeletal muscle fibers in the
body:
o fast fibers (also known as white muscle fibers, fast-twitch)
 most of skeletal muscle in body
 contract in 0.01 sec or less after stimulation
 large in diameter
 contain densely packed myofibrils
 contain large glycogen reserves
 have relatively few mitochondria
 muscles dominated by fast fibers produce powerful contractions
 fatigue rapidly because their contractions use massive amounts of
ATP, so prolonged activity is supported primarily by anaerobic
metabolism
o slow fibers (also known as red muscle fibers, slow twitch)
 half the diameter of fast fibers
 take three times as long to contract after stimulation
 specialized to enable them to continue contracting for extended
periods (long after a fast muscle would have become fatigued)
 contains more extensive network of capillaries, with dramatically
higher oxygen supply
 contain red pigment myoglobin (skeletal muscles dominated by
slow fibers are dark red)
 more mitochondria than fast fibers
 less dependent on anaerobic respiration
 some of the mitochondrial energy production involves the
breakdown of stored lipids rather than glycogen
 therefore, lower glycogen reserves
o intermediate fibers (also known as fast-twitch oxidative fibers)
 closely resemble fast fibers in appearance
 more extensive capillary network than fast fibers
 much less myoglobin than slow fibers
 more resistant to fatigue than fast fibers
o
explain that in muscles that contain a mixture of fast and intermediate fibers, the
proportion of fibers can change with conditioning
o if a muscle is used repeatedly for an endurance event, some of the fast
fibers will develop the appearance and functional capabilities of
intermediate fibers (and as a whole, the muscle will become much more
resistant to fatigue)
o
give examples of muscles of each type:
o no slow fibers in the muscles of the eye or the hand (contractions must be
swift and brief)
o many back and calf muscles are dominated by slow fibers (muscles
contract almost continuously to maintain posture)
o
explain how the percentage of fast versus slow fibers in each muscle is genetically
determined (but the proportion of intermediate fibers to fast fibers can increase as
a result of athletic training)
o
explain how muscles get larger as a result of repeated, exhaustive stimulation
o develop more mitochondria, a higher concentration of glycolytic enzymes,
and larger glycogen reserves
o more myofibrils with more thick and thin filaments
o hypertrophy is the net effect: an enlargement of stimulated muscle
 number of muscle fibers does not change significantly, but the
muscle as a whole enlarges because each muscle fiber increases in
diameter
 occurs in muscle that have been repeatedly stimulated to produce
near-maximal tension
explain how physical conditioning and training enable athletes to improve both
power and endurance
o anaerobic endurance is the length of time muscular contraction can
continue to be supported by glycolysis and by the existing energy reserves
of ATP and CP
o anaerobic endurance is limited by:
 amount of ATP and CP on hand
 the amount of glycogen available for breakdown
 the ability of the muscle to tolerate the lactic acid generated during
the anaerobic period (usually, muscle fatigue begins within 2
minutes of the start of maximal activity)
o
o
give examples of activities that require above average levels of anaerobic
endurance and use fast fibers
o 50-meter dash or swim
o pole vault
o weight-lifting competition
 the energy for the first 10 – 20 seconds comes from ATP and CP
reserves of the sarcoplasm
 then, glycogen breaks down through glycolysis to provide more
energy
 athletes training to improve anaerobic endurance perform frequent,
brief, intensive workouts that stimulate hypertrophy
o
give examples of activities that are aerobic and use slow fibers
o aerobic endurance is the length of time a muscle can continue to contract
while supported by mitochondrial activities
o aerobic endurance is determined by the availability of substrates for
aerobic respiration (carbohydrates, lipids, or amino acids)
o initially, many of the nutrients catabolized by the muscle fiber are
obtained from reserves in the sarcoplasm
o prolonged activity is supported by nutrients from blood
o warm-up periods are important because they stimulate circulation in the
muscles before serious workout begins
 training to improve aerobic endurance involves sustained low
levels of muscular activity
 jogging
 distance swimming
 any other exercises that do not require peak tension production
o
explain the two ways that aerobic endurance can result from altering the
characteristics of muscle fibers and improving the performance of the
cardiovascular system: 1) altering the characteristics of muscle fibers and 2)
improving cardiovascular performance
o the composition of fast and slow fibers in each muscle is genetically
determined, and the individual differences are significant
o variations affect aerobic endurance because a person with more slow
fibers in a particular muscle will be better able to perform under aerobic
conditions than will a person with fewer
o skeletal muscle cells respond to changes in the pattern of neural
stimulation
o fast fibers trained for aerobic competition develop the characteristics of
intermediate fibers, which improves aerobic endurance
o cardiovascular activity affects muscular performance by delivering oxygen
and nutrients to active muscles
o physical training alters cardiovascular function by accelerating blood flow,
improving oxygen and nutrient availability
o
o
o
o
explain why interval training benefits all those who participate in aerobic
activities that are punctuated by brief periods of anaerobic effort
o a combination of aerobic and anaerobic exercises will enlarge muscles and
both anaerobic and aerobic endurance will improve
explain the three classes of levers in the human body
o first-class: fulcrum lies between the applied force and the resistance
(extension of the neck)
o second-class: the resistance is located between the applied force and the
fulcrum
 example is a wheelbarrow (a small force can balance a larger
weight because the force is farther from the fulcrum than the
resistance is)
 plantar flexion: the calf muscles use a second-class lever
o third-class: a force is applied between the resistance and the fulcrum
 example is a ladder that you raise against a building (the fulcrum is
the base of the ladder, in contact with the ground; force is applied
where you grasp the ladder, and the resistance is the weight of the
ladder between your hands and the free end)
 the effect of a third-class lever is that speed and distance traveled
are increased at the expense of effective force (biceps brachii – the
resistance is six times farther from the fulcrum than is the applied
force)
 in the biceps brachii, the muscle must generate 180 kg of tension at
its attachment to the forearm to support 30 kg held in the hand
 the load will ravel 45 cm when the point of attachment moves 7.5
cm (the distance traveled and the speed of movement are increased
by the same 6:1 ratio)
give the three kinds of muscles, based on their size and range of motion:
o agonist (prime mover): muscle whose contraction is chiefly responsible
for a particular movement
o antagonist: muscle whose action opposes that of the muscle under
consideration (triceps and biceps brachii are antagonistic; if one produces
flexion, the other will produce flexion)
 agonist/antagonist pairs: flexors/extensors and abductors/adductors
o synergist: a muscle that helps a larger agonist work more efficiently
 example: latissimus dorsi extends, adducts, and medially rotates
arm at shoulder joint; teres major assists in starting such
movements when the should joint is at full flexion
 synergists may also assist and agonist by preventing movement at
another joint and thereby stabilizing the origin of the agonist
(fixators)
explain how the origin and insertion of a muscle help to produce a specific muscle
action (movement)
o origin

the site at which the muscle begins, where the muscle remains
stationary -attached to a bone or structure that doesn’t move
(usually always proximal to the insertion)
o insertion
 the site at which the muscle ends (usually always distal to the
origin)
o example: gastrocnemius has its origin at the femur and its insertion at the
calcaneus
o if a muscle extends between a broad aponeurosis and a narrow tendon, the
aponeurosis is the origin and the tendon is the insertion (sometimes a
muscle can have multiple origins and a single insertion if there are several
tendons at one end)