Neuromuscular system Flashcards
APPLIED ANATOMY AND PHYSIOLOGY
what is the repeating unit of a myofibril called?
sarcomere
characteristics of type 1 muscle fibre
slow oxidative
slow twitch fibre
- high oxidative capacity
- high resistance to fatigue
- low force production
- low glycolytic capacity
- high capillary density
- slow contraction time
e.g.
marathon runners
characteristics of type 2a/IIa muscle fibre
fast oxidative glycotic
fast twitch fibre
- high oxidative capacity
- fast contraction time
- suited fro lengthy anaerobic exercise
- medium resistance to fatigue
- high force production
- high glycolytic capacity
- medium capillary density
e.g.
- 400m runners
- team sports
characteristics of type 2b/IIx muscle fibre
fast glycotic
fast twitch
- low oxidative capacity
- fast contraction time
- suited for short anaerobic exercise
- low resistance to fatigue
- high force production
- high glycolytic capacity
- low capillary density
e.g.
- 100m runners
- sprinters
what is the muscle fibre recruitment dependent on?
- size of principle
- amount and size of motor units
- intensity of exercise
- units are recruited from smallest to largest (type 1 - type 2a - type 2b)
how does the nervous system control our skeletal muscles?
sympathetic - excites the body and prepares for exercise (fight or flight)
parasympathetic - relaxes the body
what is PNF?
proprioceptive neuromuscular facilitation
form of flexibility training that involves stretching the muscle beyond its normal range of motion via a sequence of contracting and relaxing
what is the role of the 2 proprioceptors in PNF
muscle spindles
- found in muscle fibres
- sensitive
- inform how quickly and how far muscle is stretched
- message sent to tell muscle to contract
- stretch reflex is triggered
- contraction of muscle to prevent injury
golgi tendon organ
- found between muscle fibres and tendons
- detects tension
- form isometric contractions, allowing agonist muscle to relax and then lengthen
what do motor neurons do
specialised cells that transmit nerve impulses from the CNS in the spinal cord and brain to muscle fibres
what is the structure of the motor neuron in the CNS
cell body - located in spinal cord
axons - branch off the cell body and send impulses to the motor end plates
motor end plates - where action potential from an action travels to stimulate a muscle
what is a motor unit
where the motor neuron meets the muscle fibres
what does the number of fibres within a motor unit depend on?
the control a movement requires
what does the number of motor units recruited depend on?
size of contraction required (different for gross and fine movements)
gross:
- hundreds of muscle fibres per motor neuron require more motor units to be recruited
fine:
- have one muscle fibre per motor neuron and require fewer units to be recruited
what is the ‘all or none’ law
a muscle fibre doesn’t partially contract - it either fully or doesn’t contract at all
what is summation?
a muscle can contract at a varying degrees, depending on the circumstance
what is wave summation (graph)
repeated stimulation of nerve impulses with no time for relaxation, giving a greater force of contraction
force N
time m/s
what is a tetanic contraction (graph)
a sustained muscle contraction that results from fast repeated stimuli caused by a build up of calcium in muscle.
calcium is released each time a muscle cell receives a nerve impulse
force N
time m/s
what is spacial summation (graph)
impulses received at the same time from different motor units, having a steady contraction where workload is shared and therefore reduces fatigue
force N
time m/s
what is a concentric contraction
where the muscle shortens under tension
what is a eccentric contraction
where the muscle lengthens under tension
what is a isometric contraction
where the muscle doesn’t lengthen or shorten under tension
e.g.
holding a crucifix position in gymnastics
