Chapter 3 Structure and Functions of the Muscular System CON. Flashcards
what are the stages of nervous control of muscle action
brain initiates message.
nervous impulse travels down spinal cord to motor nerve.
message passes into motor neuron.
message branches off to arrive at all muscle fibers controlled by that nerve: travels across gap at a neuromuscular junction, aided by acetylcholine, and all connected muscle fibers contract.
motor unit
consists of a single motor neuron and all the muscle fibers it innervates
small motor units
slow contracting
fatigue resistant
utilised for prolonged activities
large motor units
fast contracting
rapidly fatigable
utilised for high force activities
the henneman principle
states that the recruitment of motor units in skeletal muscles starts with small motor units to large motor units.
the all or nothing principle
states that muscle fibers contract fully when a certain threshold is met or not at all in response to neural signals.
agonist
is the prime mover and cause the major movement in an action
antagonist
must relax and lengthen to allow movement to occur
causes opposite action of agonist
synergist
assists the agonist to produce the required movement
stabiliser
ensures the joint remains stable while the agonist and antagonist are working.
slow twitch (type 1)
slow twitch oxidative
red in colour
very resistant to fatigue
suited for low-intensity, longer duration, aerobic work
fast twitch (type 2A)
fast twitch oxidative
pinkish in colour
relatively resistant to fatigue
partially aerobic suited to events that require both aerobic and anaerobic elements
fast twitch (type 2B)
fast twitch glycolytic
white colour
fatigue easily
suited to high intensity, short duration, anaerobic work
concentric movement
the muscle length shortens and casues joint movement to create teh contraction
eccentric movement
occurs when the muscle lengthens while the force is developed to decelrate the motion of a joint
