Exam 2/Quiz 4- Physiology of the Muscular System Flashcards
Define Muscle Tension.
Force exerted by a contracting skeletal muscle against a load which exerts an opposing force
Define Motor Unit.
Nerve fiber + all muscle fibers it innervates
About how many muscles fibers per motor unit do intrinsic hand muscles have?
fewer than 10 muscle fibers
About how many muscles fibers per motor unit does the gluteus maximus muscle have?
100’s of muscle fibers
Do small specific muscles have many or less muscle fibers per motor unit? What about large muscles with general movements?
- Not many muscles fibers per motor unit
2. Many muscles fibers per motor unit
Define threshold stimulus.
Minimum stimulus strength required to initiate a contraction
When the threshold stimulus is reached, do the muscle fibers in a motor unit contract separately or simultaneously?
simultaneously
Graded contractions is the ability of a muscle to do what?
Ability of a muscle to contract in a smooth, sustained manner at various levels of strength
Define Tetanus.
sustained muscle contraction
What does “requirement of motor units mean”?
strength of the stimulus must increase to activate additional motor units
Does the muscle tension exceed the load (resistance), or is the muscle tension unable to overcome the load (resistance) created by the object in ISOTONIC CONTRACTION?
Muscle tension exceeds the load (resistance) created by the object
Does the muscle tension exceed the load (resistance), or is the muscle tension unable to overcome the load (resistance) created by the object in ISOMETRIC CONTRACTION?
Muscle tension is unable to overcome the load (resistance) created by the object
Do contracting muscles change in length, or do the contracting muscles not change in length in ISOTONIC CONTRACTION?
Contracting muscle changes in length
Do contracting muscles change in length, or do the contracting muscles not change in length in ISOMETRIC CONTRACTION?
Contracting muscles will not change in length
Does the object move in ISOMETRIC CONTRACTION?
NO
Although isometric contractions do not preform work, what are the important for?
- Maintaining posture
2. Stabilizing joints where movements are not desired
What are the two types of isotonic contractions?
- Concentric Isotonic Contraction
2. Eccentric Isotonic Contraction
Which type of isotonic contraction are the muscles shortening in length?
Concentric Isotonic Contraction
Which type of isotonic contraction are the muscles increasing in length?
Eccentric Isotonic Contraction
Which type of isotonic contraction do muscles preform work by moving an object from one position to another?
Concentric Isotonic Contraction
Which type of isotonic contraction do muscles not typically cause an object to be moved?
Eccentric Isotonic Contraction
What type contraction acts in coordination with other muscles that contract concentrically?
Eccentric Isotonic Contraction
Give an example of isotonic contractions regarding the anterior arm muscles:
- Concentric Isotonic Contraction
- Eccentric Isotonic Contraction
- Biceps brachii contracts concentrically
2. Triceps brachii contracts eccentrically
When the biceps “bulge” what type of contraction is occurring?
Isometric contraction