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The minimal stimulus needed to start a muscle contraction.
The contractile response of a single muscle fiber to the ACh released by a single action potential.
A recording of the events of a muscle twitch.
List the four main parts of a myogram.
1) Stimulation 2) Latent Period 3) Contraction Period 4) Relaxation Period
A brief delay between the time of stimulation and the beginning of contraction; may be less than 2 milliseconds.
The period when a muscle fiber is generating force or contracting.
The period when a muscle fiber is decreasing tension.
Combining the force of individual twitches is known as what?
Contractions that lack relaxation due to sustained contraction resulting from summation.
A motor neuron and the muscle fibers it controls constitute a ______.
The fewer muscle fibers in a motor unit, the more ______ the movements will be.
An increase in the number of activated motor units as stimulation increases and more motor units are needed.
During ______, smaller motor units are more easily stimulated and recruited earlier.
A certain amount of sustained contractions in a muscle, even when a muscle appears to be at rest; is important for maintaining posture.
Type of contraction that produces movement of a body part.
Type of isotonic contraction in which shortening of a muscle occurs.
Type of isotonic contraction in which lengthening of the muscle occurs.
Type of contraction in which muscle tension increases but no movements of body parts are produced.
Whenever body parts move, muscles and bones interact together as mechanical devices called ______.
What are the four basic components of a lever system?
1) a bar 2) a fulcrum or pivot on which the bar turns 3) an object moved against resistance 4) a force that supplies the energy to move the bar
The immovable end of a muscle.
The moveable end of a muscle.
The muscle primarily responsible for producing an action.
Agonist or Prime Mover
A muscle that assists the agonist.
A muscle that resists the action of an agonist.
Chapter 9 Topics 6-7 Muscular Responses and Actions