Microscopic Muscle Anatomy
This structure anchors thin filaments and defines the boundary of a sarcomere
Z-Disc
What is ATP
The energy used to detach a myosin head from actin
What is an isometric contraction
A contraction where tension increases but muscle length remains constant
What are slow-twitch fibers?
Fibers have the greatest resistance to fatigue due to aerobic metabolism.
What are the names of the different arrangements of fasciles
This band shortens during contraction but never disappears
I-Band
What is sarcoplasmic reticulum
Structure releases calcium in response to an action potential traveling down T-tubules
What is an eccentric contraction
This contraction occurs when a muscle lengthens while still producing tension
What is anaerobic glycolysis?
Fast-twitch fibers fatigue quickly because they rely heavily on this metabolic process.
What is tetanus?
This disorder prevents muscles from relaxing because acetylcholine is not broken down at the synapse.
What is titin
The protein that connects thick filaments to the Z disc and prevents overstretching
What event directly exposes myosin-binding sites on actin
calcium binding to troponin
What is wave summation
The increase in muscle tension caused by rapid, repeated stimulation
What molecule temporarily stores high-energy phosphate groups for ATP regeneration
Creatine
What change contributes to decreased strength due to fewer motor neurons
Loss of motor units
What are T-tubules
Tubular structures allow action potentials to rapidly penetrate deep into the muscle fiber
What is continuous contraction called, and what causes it
tetany, acetylcholinesterase is inhibited
What phenomenon explains why a second contraction is stronger than the first
treppe
Why do sprinters develop more fast-twitch muscle fibers than marathon runners
muscle fiber recruitment and hypertrophy
What are the different ways a muscle is named?
Arrange the following structures from smallest to largest
myofilament → sarcomere → myofibril → muscle fiber → fascicle → muscle
If calcium is released normally but ATP is unavailable, cross-bridges will form but muscles will be unable to do this
Relax
What is motor unit recruitment?
The principle that explains how a whole muscle can produce varying amounts of force even though individual muscle fibers obey the all-or-none law
What condition occurs when oxygen demand remains elevated after exercise
Oxygen debt
When you squat, what is the agonist, antagonist, and joint action? Define agonist and antagonist
Agonist: Muscle that bears the major responsibility for effecting a particular movement
Antagonist: Muscle that reverses, or opposes, the action of another muscle
Squat: Agonist: gluteus maximus, quadriceps group (synergist)
Antagonist: Hamstring group
Joint movement: knee/hip extension