Ch2 Flashcards
(28 cards)
What is a motor unit?
A motor neuron and all the muscle fibers it innervates.
What is ‘recruitment’ in muscle contraction?
The activation of additional motor units to increase strength of contraction.
What is a tetanic contraction?
A sustained muscle contraction at full force.
What is the first energy storehouse used during muscle activity?
Creatine phosphate.
True or False: Each muscle has a mix of all three muscle fiber types.
True.
Which muscle fiber type has the lowest mitochondrial density?
Fast glycolytic.
Which muscle fiber type has the highest glycogen storage?
Fast glycolytic.
Which muscle fiber type contains large amounts of myoglobin?
Slow oxidative.
What is myoglobin?
An oxygen-binding protein that stores oxygen in muscle cells.
True or False: Fast oxidative fibers are the most resistant to fatigue.
False.
What muscle fiber type dominates in a world-class sprinter?
A higher proportion of fast glycolytic fibers.
Which sarcomere regions shorten during contraction?
I band and H zone.
What does calcium bind to during contraction?
Troponin.
What does troponin do when bound to calcium?
It causes tropomyosin to shift, exposing binding sites on actin.
Name one role of ATP in contraction.
Detaches myosin head from actin.
Name another role of ATP in contraction.
Hydrolysis re-cocks the myosin head.
Final role of ATP in contraction?
Powers calcium pumps to return Ca²⁺ to sarcoplasmic reticulum.
What are the three means of controlling muscle contraction strength?
Motor unit recruitment, stimulation frequency, and optimal sarcomere length.
Thick filaments are made of what protein?
Myosin.
Thin filaments are made of what protein?
Actin.
What neurotransmitter do all muscle types receive?
Acetylcholine.
Which receptor type does skeletal muscle use?
Nicotinic receptors.
Which receptor type do smooth and cardiac muscle use?
Muscarinic receptors.
What enzyme breaks down acetylcholine at the neuromuscular junction?
Acetylcholinesterase.
