Muscle Tissue
smooth muscle can contract over a wider range of resting lengths than skeletal muscle can. Why?
actin and myosin filament arrangement is less organized in smooth muscle
fast fibers
anaerobic glycolysis
a band
anywhere there is thick filaments
speed and load
are inversely related
fascicle
bundle of fibers which are never activated all at one time
the a band comprises which of the following subunits
m line, h band, and zone of overlap
why are cardiac and smooth muscle contractions more affected by changes in extracellular Ca +2 than skeletal
most of the calcium for contractions comes from the extrecellular fluid
a motor unit is/are_____. You would need a small motor unit to control movement of the fingers______.
muscle fibers controlled by a single motor neuron; because you need precise control
isometric contraction
muscle remains the same length
concentric contraction
muscle shortening
perimysium
surrounds muscle fiber bundles(fascicles)
big motor unit
used for walking
how would a drug that blocks ACH from the axon terminal affect muscle contraction
contraction would be prevented
what would happen to muscles if a pesticide that inhibits ACHase were present at the motor end plate
contraction would be unable to happen
z lines have nothing to do with myosin
do not line up
myoblasts
fuse to form individual multinucleate skeletal muscle fibers...each nucleus in a skeletal muscle fiber reflects the contribution of a single myoblast. The unfused ones in adults become myosatellite cells to repair tissues
what feature of cardiac muscle tissue allow the heart to act as functional syncytium(cells working together)
gap junctions
mechanism primarily responsible for ATP production at peak levels
glycolysis in the cytoplasm
why is skeletal muscle striated
z lines and myosin filaments align within a muscle fiber
in what ways does the appearance of a sarcomere change during contraction of a skeletal muscle fiber
z lines move closer together; I bands and A bands both get smaller
what statements are false in regard to the contraction of skeletal muscle
a given muscle always uses the same number of motor units no matter what the muscle is trying to accomplish
with excitation-contraction coupling
both the nervous and muscular system! motor neuron releases ACh which allows an electrical event to be transferred to the muscular system
actinin
protein in z line
basic functional unit of the muscle
sarcomeres
myofibrils are organized into repeating sub units called
sarcomeres(the basic functional unit)
______ predominate in the large leg muscles of someone who excels at endurance activities, such as cycling. This is because _______
slow fibers; they have extensive capillary networks and much myoglobin
describe the characteristics of slow muscle fibers
small diameter, rich in myoglobin(makes them red and stores oxygen), and very vascular(brings in extra glucose as you use it up)
two cardiologists talk about functional characteristics of cardiac muscle tissue
special gap junctions, intrinsic conduction system allows contraction without neural stimulation
describe a neuromuscular junction (structure)
special intercellular connection between axon branches and a skeletal muscle fiber
why would a sprinter has muscle fatigue sooner than a marathon runner
sprinting involves anaerobic endurance
what anchors thin filaments of smooth muscle
dense bodies(desmin)
only layer with myosatellite cells
endomysium
does not have capillaries and nerves
epimysium because you need the connection with muscle fibers
epimysium
exterior collagen layer, connected to deep fascia, separates muscle from surrounding tissue ENTIRE MUSCLE
why does a muscle that has been overstretched produce less tension
few cross bridges form, causing weak contraction
what would you expect to happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to CA+2
increased strength of contraction and decreased ability to relax
which activity is more likely to create an oxygen debt: swimming laps or lifting weights
lifting weights
which of the following is not a major function of skeletal muscle
lining hollow organs
responsible for skeletal muscle contraction
myofibrils
z line anchors thin filaments in cardiac and skeletal muscle
yes
where would you expect the greatest concentrations of Ca+2 in resting
cisternae
severing the tendon attached to a muscle affect the muscle's ability to move a body part
no movement is possible without the muscle to bone connection
nonvascular fibers
no such thing
epimysium, perimysium, and endomysium are interrelated because
they are connective tissues and blend with tendons to provide firm attachments to bone