Sensory Feedback (week 8) - Part 2 Flashcards
state what it is meant by the key term - reflex
a reflex is a motor response developed in the CNS after sensory input is received
explain the stretch reflex (3 points)
- mechanoreceptors detect large stretch in muscle
- sensory neurone is directly connected to a motor neurone
- motor neurone sends AP to extrafusal muscle fibres to contract (in the same muscle as the stimulated mechanoreceptors)
state 3 facts about the stretch reflex
- has a positive effect on muscle force
- saves muscles from too much stretching
- when stimulated, cases muscles to contract and generate force to resist stretch
state 2 facts about the golgi tendon reflex
- has a negative effect on muscle force
2. when stimulated, causes muscles to relax + produce less force due to tension in the muscle
explain the golgi tendon reflex (2 things)
- signal detected by golgi tendon organ and sends impulse to spinal chord (interneurone)
- interneurone changes excitatory (positive) signal from GTO to a inhibitory (negative) signal which it sends down the motor neurone to the extrafusal muscle fibres in the muscle to stop contraction
state the 4 steps of the stretch reflex in the quadriceps
- stretching stimulates muscle spindles (receptor)
- sensory nerve excited
- interneurone stimulates motor neurone of quadricep to contract and stimulated antagonists to relax
- results in knee extension
state the 6 steps of the tendon reflex
- inc^ tension stimulates GTO (receptor)
- sensory neurone excited
- within integrating centre (spinal chord), sensory centre activates inhibitory interneurone
- motor neurone receives inhibitory stimulation
- effector muscle relaxes and releases tension
- visa versa for antagonist
state the 5 steps of the withdrawal reflex
- nociceptor activated
- sensory neurone excited and sends impulse to spinal chord
- signal goes two paths: interneurone to bring to motor neurone activating fibres in ham-strings; sensory neurone sends info to different levels of spinal chord so different levels of leg can be activated
- knee flexes away from pain
- simultaneously, the cross extensor reflex occurs
state the 5 steps of the cross extensor reflex
- nociceptor activated
- sensory receptor excited and sends Impulse to spinal chord
- within spinal chord, integrating centre activates several interneurones
- motor neurones excited
- effector cells in quadricep in stiff leg contract for weight transfer onto that leg
state 4 common reflexes that we are born with, but lose as we age
- the moro reflex
- grasp reflex
- step reflex
- rooting and sucking reflex
state what it is meant by the key term - stretch shortening cycle
the stretch shortening cycle refers to the pre-stretch, or countermovement action, that is commonly observed during typical human movement (eg - jumping)
if a concentric contraction is proceeded by active stretching, more force is produced during the concentric stage. state the 4 reasons why
- stretch reflex
- energy storage
- more time to develop force
- muscle potentiation
explain how the stretch reflex helps muscles produce more force
when a muscle is stretched, muscle spindles feedback to the CNS and the motor neurone stimulation is increased resulting in an increase in force in the muscle to resist stretch
explain how every storage helps a muscle produce more force (3 points)
- series of elastic elements of muscles stretched during the stretching period
- elastic energy is stored in these units
- this energy is released during the concentric phase
explain how ‘more time to develop force’ helps a muscle produce more force
the muscle is activated during the eccentric phase, therefore does not have to wait for activation to build up at the beginning of the concentric phase
