LECTURE 28 - closed loop control - - proprioception Flashcards
what are the four proprioceptor types ?
- vestibular
- muscle receptors
- joint receptors
- cutaneous receptors
what is a proprioceptor ?
a sensory receptor which receives stimuli from within the body, especially one that responds to position and movement
sensory information comes from propeioceptor types and provides _____
information
what is the vestibular system ?
is a sensory system that is responsible for detecting and processing information about balance and spatial orientation
where is the vestibular system located ?
in the inner ear
how many structures does the vestibular system consist of ?
consists of two structures called the utricle and the saccule, as well as three semicircular canals
what does bending of the cilia do ?
sends the output to know the movements
what are semicircular canals ?
- three fluid-filled “half-circles”
- provide information regarding position of the head compared to the rest of the body
- sensitive t each directional plane
describe the horizontal (lateral) canal :
detects head rotation around vertical axis (i.e., spinning)
describe the anterior canal :
detects head rotation in the sagittal plane (i.e., nodding up and down)
describe the posterior canal :
detects head rotation in frontal planes (i.e., completing a somersault)
angular acceleration are detected by _____
semicircular canals
what does sensory mismatch lead to ?
motion sickness (simply can close eyes to try to help)
what type of organs detect changes in gravity and accelerations ?
otolith organs
what are the two otolith organs ?
utricle and saccule
what changes does the utricle detect ?
change in horizontal movement and linear acceleration (e.g., walking) - important for eye movements
what changes does the saccule detect ?
changes in vertical movement and linear acceleration (i.e., elevator sensation) - important for posture
what is the utricle important for ?
eye movements
what is the saccule important for ?
posture
what does VOR stand for ?
vestibular ocular reflex
what is the vestibular ocular reflex ?
- a reflexive movement of the eyes that helps to stabilize vision during head movement
- it is a critical component of the vestibular system and works by generating eye movements in response to movements of the head
what are the 3 steps of VOR :
- detection of rotation
- inhibition/excitation of extra ocular muscles on one side/on the other side
- compensating eye movement
what is the term used to “lock the ocular muscles on the target object” ?
fixation
what happens if someone looses VOR ?
they cannot focus / maintain their target image
If your head is moving back and forth but your eyes are looking straight, it means that your vestibulo-ocular reflex (VOR) is ________
working properly
what is the primary goal of the VOR ?
to stabilize vision during head movement by generating equal and opposite movements of the eyes in response to movements of the head
what is nystagmus ?
an involuntary eye movement characterized by repetitive oscillations of the eyes. It can be either horizontal, vertical or rotary in nature, and can be present in one or both eyes. Nystagmus can occur in a rhythmic or non-rhythmic pattern and can be slow or fast.
describe eyes when nystagmus is present :
- non intact
- more watery
- rapid one way and smooth the other
- involuntary
describe muscles spindles (intrafusal) :
- cigar-shaped structures connected in parallel with extradural muscle fibers
- innervated by gamma-motorneurons
- provide information about stretch of the muscle
- many types; type 1a and type II
- provide system with information about limb position
describe type 1a muscle spindles :
sensitive to rapid stretch of the muscle (i.e., when the agonist first begins contraction) (velocity dependent)
describe type II muscle spindles :
sensitive to sustained against contract
what is info from muscle spindles very important for ?
environment awareness
what type of stretch is 1a muscle spindles sensitive to?
dynamic
what type of stretch is II muscle spindles sensitive to ?
static
what is the monosynaptic stretch reflex ?
- is a reflexive response of the muscle to stretch
- it is a simple reflex arc that involves only one synapse between sensory neurons and motor neurons.
what are the four steps of the monosynaptic stretch reflex ?
- hammer strike on patella tendon results in stretch of the quad muscles
- muscle spindles of quads send stretch info to the spinal cord (CNS)
- single synapse onto alpha motoneuron of quads and contraction of that muscle
- the simplest of all stretch reflexes - only one synapse
what type pop muscle spindles have been stretch during a monosynaptic stretch reflex ?
type 1a
what is hyperreflexia ?
a lot of reflexes
what are two postural control strategies ?
hip and ankle strategy
describe the ankle strategy :
- standing on a moving platform
- small adjustments of the ankle joint to maintain a stable base of support
- effective in maintaining balance in the sagittal plane
- is activated when the body experiences small perturbations, such as a gentle push or a shift in weight
- distal to proximal
describe the proximal to distal :
- standing on a moving platform
- much slower and less efficient
- more likely to lead to a fall
- requires recruitment of many muscles
- proximal to distal
which postural control strategy is more likely to lead to fall, injury, etc.
hip strategy
what does GTO stand for ?
golgi tendon organ
describe the golgi tendon organ :
- located in metro-tendinous junction between muscle and tendon
- provide information about tension (force) in the muscle
- prevents ov erstratch and rupture by inhibiting alpha-motorneuron
- oligosynaptic
what does oligosynaptic mean ?
multiple neurones associated with this pathway
