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UNE PHSL 1010 Exam 2 Questions And 100% Correct Answers Latest Update
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UNE PHSL 1010 Exam 2 Questions And 100% CorrectAnswers Latest Update
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?
The muscles produce maximum force at resting length and minimal force when
shortened or lengthened from the rest length.
,What is summation?
When the time interval between action potentials is shortened, muscle fiber doesn't get
adequate time for relaxation between the two stimuli. This will result in a stronger
contraction.
What is incomplete or unfused tetanus?
The stimulation rate of the muscle fiber is not a maximum value, and consequently the
fibre relaxes slightly between stimuli
What is complete or fused tetanus?
The stimulation rate is sufficiently fast that the muscle fibre does not have time to relax.
Instead it reaches maximum tension, and stays 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?
Low threshold, low force muscle fibers fire first, then fast twitch high force fibers.
Asynchronous recruitment avoids fatigue in sustained contractions.
What is an isometric contraction?
A contraction that develops force without movement
What is an isotonic contraction?
a contraction that develops force and moves a load
Describe and give examples of how bones and muscles form fulcrums and levers
- Bones serve as levers, while the flexible joints serve as fulcrums. The muscles
attached to bones apply force by contracting
,Describe anatomy of smooth muscle
single unit smooth muscle cell = electronically coupled by gap junctions so they contract
as a single unit. multi -unit smooth muscle = not electronically coupled 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
Describe 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: when chemical signals alter muscle tension via signal
transduction pathways with minimal/absolutely 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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Compare and contrast cardiac, skeletal, and smooth muscle: Fiber arrangement
-Skeletal & Cardiac: Sarcomeres
-Smooth: No sarcomeres
Compare and contrast cardiac, skeletal and smooth muscle: Location
-Skeletal: Attached to bones; a few sphincters close off hollow organs
-Smooth: Forms the walls of hollow organs and tubes; some sphincters
-Cardiac: Heart muscle
Compare and contrast cardiac, skeletal and smooth muscle: Tissue Morphology
-Skeletal: Multinucleate; large, cylindrical fibers
-Smooth: Uninucleate; small spindle-shaped fibers
-Cardiac: Uninucleate; shorter branching fibers
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