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UNE PHSL 1010 Exam 2.
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UNE PHSL 1010 Exam 2.
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UNE PHSL 1010 Exam2 2024 with 100%
correct answers
What are the different levels of organization of the
skeletal muscles?
Skeletal muscle, muscle fascicles, muscle fibers,
sarcoplasm, myofibrils
What is the sliding filament theory of contraction?
The current model for muscle contraction in which
muscle proteins slide past each other to generate
force
What are the causes of muscle fatigue?
Excitation-contraction failure and changes in
contraction force in the muscle fibers
What are slow twitch fibers?
Muscle fiber that contracts slowly especially during
sustained physical activity requiring endurance
What are fast twitch oxidative-glycolytic fibers?
Fast muscle fibers that use a combination of
aerobic and anaerobic metabolism and therefore
do not fatigue as fast as glycolytic fibers
What are fast twitch glycolytic fibers?
,Fast muscle fibers that rely on anaerobic
metabolism and therefore fatigue rapidly
How does muscle length influence force of
contraction?
Muscles generate the greatest force when at their
resting length, and the least amount of force when
shortened or stretched relative to the resting
length.
What is summation?
When the interval of time between action
potentials is shortened, the muscle fiber does not
have time to relax, completely between two
stimuli, resulting in a more forceful contraction
What is incomplete or unfused tetanus?
The stimulation rate of the muscle fiber is not a
maximum value, and consequently the fiber
relaxes slightly between stimuli
What is complete or fused tetanus?
The stimulation rate is fast enough that the muscle
fiber does not have time to relax. Instead it
reaches maximum tension and remains there
What is a motor unit?
Group of skeletal muscle fibers and the somatic
motor neuron that controls them
How do skeletal muscles use motor units to create
graded contractions?
,Muscle fibers with low thresholds and low force fire
first, then fast twitch high force fibers.
Asynchronous recruitment prevents fatigue in
sustained contractions.
What is an isometric contraction?
A contraction that creates force without movement
What is an isotonic contraction?
a contraction that creates force and moves a load
Describe and give examples of how bones and
muscles form fulcrums and levers
The body uses bones as levers and the flexible
joints as fulcrums and the muscles attached to the
bones create force by contracting
Describe smooth muscle anatomy
single unit smooth muscle cell = electronically
connected by gap junctions so they contract as a
single unit. multi -unit smooth muscle = not linked
electronically so they are stimulated independently
What is the first step of muscle contraction?
1. Ca comes in from cytosol and binds to
calmodulin
What is the second step of muscle contraction?
2. Calcium+ calmodulin activates myosin light
chain kinase (MLCK)
What is the third step of muscle contraction?
, 3. MLCK phosphorylates light chains in myosin
heads and increases myosin ATPase activity
What is the fourth step of muscle contraction?
4. Activates myosin cross bridges slide along actin
and create muscle tension
Explain slow wave potentials
Slow wave potentials: Fire action potentials when
they reach threshold
Explain pacemaker potentials
pacemaker potentials: always depolarize to
threshold
Explain pharmacomechanical coupling
Pharmacomechanical coupling: occurs when
chemical signals change muscle tension through
signal transduction pathways with little or no
change in membrane potential
Compare and contrast cardiac, skeletal, and
smooth muscle: Appearance under Light
Microscope
-Skeletal & Cardiac:Striated
-Smooth: Smooth
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